Source/kwsys/SystemTools.cxx

/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   file Copyright.txt or https://cmake.org/licensing#kwsys for details.  */
#ifdef __osf__
#  define _OSF_SOURCE
#  define _POSIX_C_SOURCE 199506L
#  define _XOPEN_SOURCE_EXTENDED
#endif

#if defined(_WIN32) && (defined(_MSC_VER) || defined(__MINGW32__))
#  define KWSYS_WINDOWS_DIRS
#else
#  if defined(__SUNPRO_CC)
#    include <fcntl.h>
#  endif
#endif

#if defined(_WIN32) && !defined(_WIN32_WINNT)
#  define _WIN32_WINNT _WIN32_WINNT_VISTA
#endif

#include "kwsysPrivate.h"
#include KWSYS_HEADER(RegularExpression.hxx)
#include KWSYS_HEADER(SystemTools.hxx)
#include KWSYS_HEADER(Directory.hxx)
#include KWSYS_HEADER(FStream.hxx)
#include KWSYS_HEADER(Encoding.h)
#include KWSYS_HEADER(Encoding.hxx)
#include KWSYS_HEADER(String.h)

#include <algorithm>
#include <fstream>
#include <iostream>
#include <set>
#include <sstream>
#include <utility>
#include <vector>

#ifdef _WIN32
#  include <cwchar>
#  include <unordered_map>
#endif

// Work-around CMake dependency scanning limitation.  This must
// duplicate the above list of headers.
#if 0
#  include "Directory.hxx.in"
#  include "Encoding.h.in"
#  include "Encoding.hxx.in"
#  include "FStream.hxx.in"
#  include "RegularExpression.hxx.in"
#  include "String.h.in"
#  include "SystemTools.hxx.in"
#endif

#ifdef _MSC_VER
#  pragma warning(disable : 4786)
#endif

#if defined(__sgi) && !defined(__GNUC__)
#  pragma set woff 1375 /* base class destructor not virtual */
#endif

#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

#if defined(_WIN32) && !defined(_MSC_VER) && defined(__GNUC__)
#  include <strings.h> /* for strcasecmp */
#endif

#ifdef _MSC_VER
#  define umask _umask
#endif

// support for realpath call
#ifndef _WIN32
#  include <climits>
#  include <pwd.h>
#  include <sys/ioctl.h>
#  include <sys/time.h>
#  include <sys/wait.h>
#  include <unistd.h>
#  include <utime.h>
#  ifndef __VMS
#    include <sys/param.h>
#    include <termios.h>
#  endif
#  include <csignal> /* sigprocmask */
#endif

#ifdef __linux
#  include <linux/fs.h>
#endif

#if defined(__APPLE__) &&                                                     \
  (__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ - 0 >= 101200)
#  define KWSYS_SYSTEMTOOLS_HAVE_MACOS_COPYFILE_CLONE
#  include <copyfile.h>
#  include <sys/stat.h>
#endif

// Windows API.
#if defined(_WIN32)
#  include <windows.h>
#  include <winioctl.h>
#  ifndef INVALID_FILE_ATTRIBUTES
#    define INVALID_FILE_ATTRIBUTES ((DWORD) - 1)
#  endif
#  ifndef SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
#    define SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE (0x2)
#  endif
#  if defined(_MSC_VER) && _MSC_VER >= 1800
#    define KWSYS_WINDOWS_DEPRECATED_GetVersionEx
#  endif
#  ifndef IO_REPARSE_TAG_APPEXECLINK
#    define IO_REPARSE_TAG_APPEXECLINK (0x8000001BL)
#  endif
// from ntifs.h, which can only be used by drivers
typedef struct _REPARSE_DATA_BUFFER
{
  ULONG ReparseTag;
  USHORT ReparseDataLength;
  USHORT Reserved;
  union
  {
    struct
    {
      USHORT SubstituteNameOffset;
      USHORT SubstituteNameLength;
      USHORT PrintNameOffset;
      USHORT PrintNameLength;
      ULONG Flags;
      WCHAR PathBuffer[1];
    } SymbolicLinkReparseBuffer;
    struct
    {
      USHORT SubstituteNameOffset;
      USHORT SubstituteNameLength;
      USHORT PrintNameOffset;
      USHORT PrintNameLength;
      WCHAR PathBuffer[1];
    } MountPointReparseBuffer;
    struct
    {
      UCHAR DataBuffer[1];
    } GenericReparseBuffer;
    struct
    {
      ULONG Version;
      WCHAR StringList[1];
      // In version 3, there are 4 NUL-terminated strings:
      // * Package ID
      // * Entry Point
      // * Executable Path
      // * Application Type
    } AppExecLinkReparseBuffer;
  } DUMMYUNIONNAME;
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;

namespace {
WCHAR* GetAppExecLink(PREPARSE_DATA_BUFFER data, size_t& len)
{
  // We only know the layout of version 3.
  if (data->AppExecLinkReparseBuffer.Version != 3) {
    return nullptr;
  }

  WCHAR* pstr = data->AppExecLinkReparseBuffer.StringList;

  // Skip the package id and entry point strings.
  for (int i = 0; i < 2; ++i) {
    len = std::wcslen(pstr);
    if (len == 0) {
      return nullptr;
    }
    pstr += len + 1;
  }

  // The third string is the executable path.
  len = std::wcslen(pstr);
  if (len == 0) {
    return nullptr;
  }
  return pstr;
}
}
#endif

#if !KWSYS_CXX_HAS_ENVIRON_IN_STDLIB_H
extern char** environ;
#endif

// getpwnam doesn't exist on Windows and Cray Xt3/Catamount
// same for TIOCGWINSZ
#if defined(_WIN32) || defined(__LIBCATAMOUNT__) ||                           \
  (defined(HAVE_GETPWNAM) && HAVE_GETPWNAM == 0)
#  undef HAVE_GETPWNAM
#  undef HAVE_TTY_INFO
#else
#  define HAVE_GETPWNAM 1
#  define HAVE_TTY_INFO 1
#endif

#define VTK_URL_PROTOCOL_REGEX "([a-zA-Z0-9]*)://(.*)"
#define VTK_URL_REGEX                                                         \
  "([a-zA-Z0-9]*)://(([A-Za-z0-9]+)(:([^:@]+))?@)?([^:@/]*)(:([0-9]+))?/"     \
  "(.+)?"
#define VTK_URL_BYTE_REGEX "%[0-9a-fA-F][0-9a-fA-F]"
#ifdef _MSC_VER
#  include <sys/utime.h>
#else
#  include <utime.h>
#endif

// This is a hack to prevent warnings about these functions being
// declared but not referenced.
#if defined(__sgi) && !defined(__GNUC__)
#  include <sys/termios.h>
namespace KWSYS_NAMESPACE {
class SystemToolsHack
{
public:
  enum
  {
    Ref1 = sizeof(cfgetospeed(0)),
    Ref2 = sizeof(cfgetispeed(0)),
    Ref3 = sizeof(tcgetattr(0, 0)),
    Ref4 = sizeof(tcsetattr(0, 0, 0)),
    Ref5 = sizeof(cfsetospeed(0, 0)),
    Ref6 = sizeof(cfsetispeed(0, 0))
  };
};
}
#endif

#if defined(_WIN32) && (defined(_MSC_VER) || defined(__MINGW32__))
#  include <direct.h>
#  include <io.h>
#  define _unlink unlink
#endif

/* The maximum length of a file name.  */
#if defined(PATH_MAX)
#  define KWSYS_SYSTEMTOOLS_MAXPATH PATH_MAX
#elif defined(MAXPATHLEN)
#  define KWSYS_SYSTEMTOOLS_MAXPATH MAXPATHLEN
#else
#  define KWSYS_SYSTEMTOOLS_MAXPATH 16384
#endif

#if defined(__BEOS__) && !defined(__ZETA__)
#  include <be/kernel/OS.h>
#  include <be/storage/Path.h>

// BeOS 5 doesn't have usleep(), but it has snooze(), which is identical.
static inline void usleep(unsigned int msec)
{
  ::snooze(msec);
}

// BeOS 5 also doesn't have realpath(), but its C++ API offers something close.
static inline char* realpath(char const* path, char* resolved_path)
{
  size_t const maxlen = KWSYS_SYSTEMTOOLS_MAXPATH;
  snprintf(resolved_path, maxlen, "%s", path);
  BPath normalized(resolved_path, nullptr, true);
  char const* resolved = normalized.Path();
  if (resolved) // nullptr == No such file.
  {
    if (snprintf(resolved_path, maxlen, "%s", resolved) < maxlen) {
      return resolved_path;
    }
  }
  return nullptr; // something went wrong.
}
#endif

#ifdef _WIN32
static time_t windows_filetime_to_posix_time(const FILETIME& ft)
{
  LARGE_INTEGER date;
  date.HighPart = ft.dwHighDateTime;
  date.LowPart = ft.dwLowDateTime;

  // removes the diff between 1970 and 1601
  date.QuadPart -= ((LONGLONG)(369 * 365 + 89) * 24 * 3600 * 10000000);

  // converts back from 100-nanoseconds to seconds
  return date.QuadPart / 10000000;
}
#endif

#ifdef KWSYS_WINDOWS_DIRS
#  include <wctype.h>
#  ifdef _MSC_VER
typedef KWSYS_NAMESPACE::SystemTools::mode_t mode_t;
#  endif

static inline int Mkdir(std::string const& dir, mode_t const* mode)
{
  int ret =
    _wmkdir(KWSYS_NAMESPACE::Encoding::ToWindowsExtendedPath(dir).c_str());
  if (ret == 0 && mode)
    KWSYS_NAMESPACE::SystemTools::SetPermissions(dir, *mode);
  return ret;
}
static inline int Rmdir(std::string const& dir)
{
  return _wrmdir(
    KWSYS_NAMESPACE::Encoding::ToWindowsExtendedPath(dir).c_str());
}
static inline char const* Getcwd(char* buf, unsigned int len)
{
  std::vector<wchar_t> w_buf(len);
  if (_wgetcwd(&w_buf[0], len)) {
    size_t nlen = kwsysEncoding_wcstombs(buf, &w_buf[0], len);
    if (nlen == static_cast<size_t>(-1)) {
      return 0;
    }
    if (nlen < len) {
      // make sure the drive letter is capital
      if (nlen > 1 && buf[1] == ':') {
        buf[0] = kwsysString_toupper(buf[0]);
      }
      return buf;
    }
  }
  return 0;
}
static inline int Chdir(std::string const& dir)
{
  // We cannot use ToWindowsExtendedPath here because that causes a
  // UNC path to be recorded as the process working directory, and
  // can break child processes.
  return _wchdir(KWSYS_NAMESPACE::Encoding::ToWide(dir).c_str());
}
static inline void Realpath(std::string const& path,
                            std::string& resolved_path,
                            std::string* errorMessage = nullptr)
{
  std::wstring tmp = KWSYS_NAMESPACE::Encoding::ToWide(path);
  wchar_t fullpath[MAX_PATH];
  DWORD bufferLen = GetFullPathNameW(
    tmp.c_str(), sizeof(fullpath) / sizeof(fullpath[0]), fullpath, nullptr);
  if (bufferLen < sizeof(fullpath) / sizeof(fullpath[0])) {
    resolved_path = KWSYS_NAMESPACE::Encoding::ToNarrow(fullpath);
    KWSYS_NAMESPACE::SystemTools::ConvertToUnixSlashes(resolved_path);
  } else if (errorMessage) {
    if (bufferLen) {
      *errorMessage = "Destination path buffer size too small.";
    } else if (unsigned int errorId = GetLastError()) {
      LPSTR message = nullptr;
      DWORD size = FormatMessageA(
        FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
          FORMAT_MESSAGE_IGNORE_INSERTS,
        nullptr, errorId, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPSTR)&message, 0, nullptr);
      *errorMessage = std::string(message, size);
      LocalFree(message);
    } else {
      *errorMessage = "Unknown error.";
    }

    resolved_path = "";
  } else {
    resolved_path = path;
  }
}
#else
#  include <sys/types.h>

#  include <fcntl.h>
#  include <unistd.h>
static inline int Mkdir(std::string const& dir, mode_t const* mode)
{
  return mkdir(dir.c_str(), mode ? *mode : 00777);
}
static inline int Rmdir(std::string const& dir)
{
  return rmdir(dir.c_str());
}
static inline char const* Getcwd(char* buf, unsigned int len)
{
  return getcwd(buf, len);
}

static inline int Chdir(std::string const& dir)
{
  return chdir(dir.c_str());
}
static inline void Realpath(std::string const& path,
                            std::string& resolved_path,
                            std::string* errorMessage = nullptr)
{
  char resolved_name[KWSYS_SYSTEMTOOLS_MAXPATH];

  errno = 0;
  char* ret = realpath(path.c_str(), resolved_name);
  if (ret) {
    resolved_path = ret;
  } else if (errorMessage) {
    if (errno) {
      *errorMessage = strerror(errno);
    } else {
      *errorMessage = "Unknown error.";
    }

    resolved_path = "";
  } else {
    // if path resolution fails, return what was passed in
    resolved_path = path;
  }
}
#endif

namespace KWSYS_NAMESPACE {

double SystemTools::GetTime()
{
#if defined(_WIN32) && !defined(__CYGWIN__)
  FILETIME ft;
  GetSystemTimeAsFileTime(&ft);
  return (429.4967296 * ft.dwHighDateTime + 0.0000001 * ft.dwLowDateTime -
          11644473600.0);
#else
  struct timeval t;
  gettimeofday(&t, nullptr);
  return 1.0 * double(t.tv_sec) + 0.000001 * double(t.tv_usec);
#endif
}

/* Type of character storing the environment.  */
#if defined(_WIN32)
typedef wchar_t envchar;
#else
using envchar = char;
#endif

/* Order by environment key only (VAR from VAR=VALUE).  */
struct kwsysEnvCompare
{
  bool operator()(envchar const* l, envchar const* r) const
  {
#if defined(_WIN32)
    wchar_t const* leq = wcschr(l, L'=');
    wchar_t const* req = wcschr(r, L'=');
    size_t llen = leq ? (leq - l) : wcslen(l);
    size_t rlen = req ? (req - r) : wcslen(r);
    if (llen == rlen) {
      return wcsncmp(l, r, llen) < 0;
    } else {
      return wcscmp(l, r) < 0;
    }
#else
    char const* leq = strchr(l, '=');
    char const* req = strchr(r, '=');
    size_t llen = leq ? static_cast<size_t>(leq - l) : strlen(l);
    size_t rlen = req ? static_cast<size_t>(req - r) : strlen(r);
    if (llen == rlen) {
      return strncmp(l, r, llen) < 0;
    } else {
      return strcmp(l, r) < 0;
    }
#endif
  }
};

class kwsysEnvSet : public std::set<envchar const*, kwsysEnvCompare>
{
public:
  class Free
  {
    envchar const* Env;

  public:
    Free(envchar const* env)
      : Env(env)
    {
    }
    ~Free() { free(const_cast<envchar*>(this->Env)); }

    Free(Free const&) = delete;
    Free& operator=(Free const&) = delete;
  };

  envchar const* Release(envchar const* env)
  {
    envchar const* old = nullptr;
    auto i = this->find(env);
    if (i != this->end()) {
      old = *i;
      this->erase(i);
    }
    return old;
  }
};

#ifdef _WIN32
/**
 * SystemTools static variables singleton class.
 */
class SystemToolsStatic
{
public:
  static char const* GetEnvBuffered(char const* key);
  // This map exists so that the encoding conversion performed on Windows has a
  // storage location which behaves like the global environment. Note that if
  // an environment variable is set, previously returned values of that
  // variable's value may be invalidated (and it is just as hazardous as
  // keeping `getenv` results across `setenv` calls on POSIX platforms).
  std::map<std::string, std::string> EnvMap;
};

// Do NOT initialize.  Default initialization to zero is necessary.
static SystemToolsStatic* SystemToolsStatics;

char const* SystemToolsStatic::GetEnvBuffered(char const* key)
{
  std::string env;
  if (SystemTools::GetEnv(key, env)) {
    std::string& menv = SystemToolsStatics->EnvMap[key];
    if (menv != env) {
      menv = std::move(env);
    }
    return menv.c_str();
  }
  return nullptr;
}
#endif

// adds the elements of the env variable path to the arg passed in
void SystemTools::GetPath(std::vector<std::string>& path, char const* env)
{
  size_t const old_size = path.size();
#if defined(_WIN32) && !defined(__CYGWIN__)
  char const pathSep = ';';
#else
  char const pathSep = ':';
#endif
  if (!env) {
    env = "PATH";
  }
  std::string pathEnv;
  if (!SystemTools::GetEnv(env, pathEnv)) {
    return;
  }

  // A hack to make the below algorithm work.
  if (!pathEnv.empty() && pathEnv.back() != pathSep) {
    pathEnv += pathSep;
  }
  std::string::size_type start = 0;
  bool done = false;
  while (!done) {
    std::string::size_type endpos = pathEnv.find(pathSep, start);
    if (endpos != std::string::npos) {
      path.push_back(pathEnv.substr(start, endpos - start));
      start = endpos + 1;
    } else {
      done = true;
    }
  }
  for (auto i = path.begin() + old_size; i != path.end(); ++i) {
    SystemTools::ConvertToUnixSlashes(*i);
  }
}

char const* SystemTools::GetEnv(char const* key)
{
#if defined(_WIN32)
  return SystemToolsStatic::GetEnvBuffered(key);
#else
  return getenv(key);
#endif
}

char const* SystemTools::GetEnv(std::string const& key)
{
#if defined(_WIN32)
  return SystemToolsStatic::GetEnvBuffered(key.c_str());
#else
  return getenv(key.c_str());
#endif
}

bool SystemTools::GetEnv(char const* key, std::string& result)
{
#if defined(_WIN32)
  std::wstring const wKey = Encoding::ToWide(key);
  std::vector<wchar_t> heapBuf;
  wchar_t stackBuf[256];
  DWORD bufSz = static_cast<DWORD>(sizeof(stackBuf) / sizeof(stackBuf[0]));
  wchar_t* buf = stackBuf;
  DWORD r;
  while ((r = GetEnvironmentVariableW(wKey.c_str(), buf, bufSz)) >= bufSz) {
    heapBuf.resize(r);
    bufSz = r;
    buf = &heapBuf[0];
  }
  if (r == 0 && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
    return false;
  }
  result = Encoding::ToNarrow(buf);
  return true;
#else
  char const* v = getenv(key);
  if (v) {
    result = v;
    return true;
  }
#endif
  return false;
}

bool SystemTools::GetEnv(std::string const& key, std::string& result)
{
  return SystemTools::GetEnv(key.c_str(), result);
}

bool SystemTools::HasEnv(char const* key)
{
#if defined(_WIN32)
  std::wstring const wKey = Encoding::ToWide(key);
  DWORD r = GetEnvironmentVariableW(wKey.c_str(), nullptr, 0);
  return !(r == 0 && GetLastError() == ERROR_ENVVAR_NOT_FOUND);
#else
  return getenv(key) != nullptr;
#endif
}

bool SystemTools::HasEnv(std::string const& key)
{
  return SystemTools::HasEnv(key.c_str());
}

#if KWSYS_CXX_HAS_UNSETENV
/* unsetenv("A") removes A from the environment.
   On older platforms it returns void instead of int.  */
static int kwsysUnPutEnv(std::string const& env)
{
  size_t pos = env.find('=');
  if (pos != std::string::npos) {
    std::string name = env.substr(0, pos);
    unsetenv(name.c_str());
  } else {
    unsetenv(env.c_str());
  }
  return 0;
}

#elif defined(__CYGWIN__) || defined(__GLIBC__)
// putenv("A") removes A from the environment with the GNU runtime.
// It cannot put the memory in the environment since there is no  "=" syntax.

static int kwsysUnPutEnv(std::string const& env)
{
  int err = 0;
  std::string buf = env.substr(0, env.find('='));
  if (putenv(&buf[0]) < 0 && errno != EINVAL) {
    err = errno;
  }
  if (err) {
    errno = err;
    return -1;
  }
  return 0;
}

#elif defined(_WIN32)
// putenv("A=") removes A from the environment with the MSVC runtime.

static int kwsysUnPutEnv(std::string const& env)
{
  std::wstring wEnv = Encoding::ToWide(env);
  size_t const pos = wEnv.find('=');
  size_t const len = pos == std::string::npos ? wEnv.size() : pos;
  wEnv.resize(len + 1, L'=');
  return _wputenv(wEnv.c_str());
}

#else
/* Manipulate the "environ" global directly.  */
static int kwsysUnPutEnv(std::string const& env)
{
  size_t pos = env.find('=');
  size_t const len = pos == std::string::npos ? env.size() : pos;
  int in = 0;
  int out = 0;
  while (environ[in]) {
    if (strlen(environ[in]) > len && environ[in][len] == '=' &&
        strncmp(env.c_str(), environ[in], len) == 0) {
      ++in;
    } else {
      environ[out++] = environ[in++];
    }
  }
  while (out < in) {
    environ[out++] = 0;
  }
  return 0;
}
#endif

#if KWSYS_CXX_HAS_SETENV

/* setenv("A", "B", 1) will set A=B in the environment and makes its
   own copies of the strings.  */
bool SystemTools::PutEnv(std::string const& env)
{
  size_t pos = env.find('=');
  if (pos != std::string::npos) {
    std::string name = env.substr(0, pos);
    return setenv(name.c_str(), env.c_str() + pos + 1, 1) == 0;
  } else {
    return kwsysUnPutEnv(env) == 0;
  }
}

bool SystemTools::UnPutEnv(std::string const& env)
{
  return kwsysUnPutEnv(env) == 0;
}

#else

/* putenv("A=B") will set A=B in the environment.  Most putenv implementations
   put their argument directly in the environment.  They never free the memory
   on program exit.  Keep an active set of pointers to memory we allocate and
   pass to putenv, one per environment key.  At program exit remove any
   environment values that may still reference memory we allocated.  Then free
   the memory.  This will not affect any environment values we never set.  */

#  ifdef __INTEL_COMPILER
#    pragma warning disable 444 /* base has non-virtual destructor */
#  endif

class kwsysEnv : public kwsysEnvSet
{
public:
  ~kwsysEnv()
  {
    for (iterator i = this->begin(); i != this->end(); ++i) {
#  if defined(_WIN32)
      std::string const s = Encoding::ToNarrow(*i);
      kwsysUnPutEnv(s);
#  else
      kwsysUnPutEnv(*i);
#  endif
      free(const_cast<envchar*>(*i));
    }
  }
  bool Put(char const* env)
  {
#  if defined(_WIN32)
    std::wstring wEnv = Encoding::ToWide(env);
    wchar_t* newEnv = _wcsdup(wEnv.c_str());
#  else
    char* newEnv = strdup(env);
#  endif
    Free oldEnv(this->Release(newEnv));
    this->insert(newEnv);
#  if defined(_WIN32)
    // `_wputenv` updates both the C runtime library's `_wenviron` array
    // and the process's environment block.
    if (_wputenv(newEnv) != 0) {
      return false;
    }
    // There seems to be no way to add an empty variable to `_wenviron`
    // through the C runtime library: `_wputenv("A=")` removes "A".
    // Add it directly to the process's environment block.
    // This is used by child processes, and by our `GetEnv`.
    std::string::size_type const eqPos = wEnv.find(L'=');
    if (eqPos != std::string::npos && (eqPos + 1) == wEnv.size()) {
      wEnv.resize(eqPos);
      return SetEnvironmentVariableW(wEnv.c_str(), L"");
    }
    return true;
#  else
    return putenv(newEnv) == 0;
#  endif
  }
  bool UnPut(char const* env)
  {
#  if defined(_WIN32)
    std::wstring const wEnv = Encoding::ToWide(env);
    Free oldEnv(this->Release(wEnv.c_str()));
#  else
    Free oldEnv(this->Release(env));
#  endif
    return kwsysUnPutEnv(env) == 0;
  }
};

static kwsysEnv kwsysEnvInstance;

bool SystemTools::PutEnv(std::string const& env)
{
  return kwsysEnvInstance.Put(env.c_str());
}

bool SystemTools::UnPutEnv(std::string const& env)
{
  return kwsysEnvInstance.UnPut(env.c_str());
}

#endif

char const* SystemTools::GetExecutableExtension()
{
#if defined(_WIN32) || defined(__CYGWIN__) || defined(__VMS)
  return ".exe";
#else
  return "";
#endif
}

FILE* SystemTools::Fopen(std::string const& file, char const* mode)
{
#ifdef _WIN32
  // Remove any 'e', which is supported on UNIX, but not Windows.
  std::wstring trimmedMode = Encoding::ToWide(mode);
  trimmedMode.erase(std::remove(trimmedMode.begin(), trimmedMode.end(), L'e'),
                    trimmedMode.end());
  return _wfopen(Encoding::ToWindowsExtendedPath(file).c_str(),
                 trimmedMode.c_str());
#else
  return fopen(file.c_str(), mode);
#endif
}

Status SystemTools::MakeDirectory(char const* path, mode_t const* mode)
{
  if (!path) {
    return Status::POSIX(EINVAL);
  }
  return SystemTools::MakeDirectory(std::string(path), mode);
}

Status SystemTools::MakeDirectory(std::string const& path, mode_t const* mode)
{
  if (path.empty()) {
    return Status::POSIX(EINVAL);
  }
  if (SystemTools::PathExists(path)) {
    if (SystemTools::FileIsDirectory(path)) {
      return Status::Success();
    }
    return Status::POSIX(EEXIST);
  }
  std::string dir = path;
  SystemTools::ConvertToUnixSlashes(dir);

  std::string::size_type pos = 0;
  std::string topdir;
  while ((pos = dir.find('/', pos)) != std::string::npos) {
    // all underlying functions use C strings, so temporarily
    // end the string here
    dir[pos] = '\0';

    Mkdir(dir, mode);
    dir[pos] = '/';

    ++pos;
  }
  topdir = dir;
  if (Mkdir(topdir, mode) != 0 && errno != EEXIST) {
    return Status::POSIX_errno();
  }

  return Status::Success();
}

// replace replace with with as many times as it shows up in source.
// write the result into source.
void SystemTools::ReplaceString(std::string& source,
                                std::string const& replace,
                                std::string const& with)
{
  // do while hangs if replaceSize is 0
  if (replace.empty()) {
    return;
  }

  SystemTools::ReplaceStringImpl(source, replace.c_str(), replace.size(),
                                 with);
}

void SystemTools::ReplaceString(std::string& source, char const* replace,
                                char const* with)
{
  // do while hangs if replaceSize is 0
  if (!*replace) {
    return;
  }

  SystemTools::ReplaceStringImpl(source, replace, strlen(replace),
                                 with ? with : "");
}

void SystemTools::ReplaceStringImpl(std::string& source, char const* replace,
                                    size_t replaceSize,
                                    std::string const& with)
{
  char const* src = source.c_str();
  char* searchPos = const_cast<char*>(strstr(src, replace));

  // get out quick if string is not found
  if (!searchPos) {
    return;
  }

  // perform replacements until done
  char* orig = strdup(src);
  char* currentPos = orig;
  searchPos = searchPos - src + orig;

  // initialize the result
  source.erase(source.begin(), source.end());
  do {
    *searchPos = '\0';
    source += currentPos;
    currentPos = searchPos + replaceSize;
    // replace
    source += with;
    searchPos = strstr(currentPos, replace);
  } while (searchPos);

  // copy any trailing text
  source += currentPos;
  free(orig);
}

#if defined(_WIN32) && !defined(__CYGWIN__)

#  if defined(KEY_WOW64_32KEY) && defined(KEY_WOW64_64KEY)
#    define KWSYS_ST_KEY_WOW64_32KEY KEY_WOW64_32KEY
#    define KWSYS_ST_KEY_WOW64_64KEY KEY_WOW64_64KEY
#  else
#    define KWSYS_ST_KEY_WOW64_32KEY 0x0200
#    define KWSYS_ST_KEY_WOW64_64KEY 0x0100
#  endif

static bool hasPrefix(std::string const& s, char const* pattern,
                      std::string::size_type spos)
{
  size_t plen = strlen(pattern);
  if (spos != plen)
    return false;
  return s.compare(0, plen, pattern) == 0;
}

static bool SystemToolsParseRegistryKey(std::string const& key,
                                        HKEY& primaryKey, std::wstring& second,
                                        std::string* valuename)
{
  size_t start = key.find('\\');
  if (start == std::string::npos) {
    return false;
  }

  size_t valuenamepos = key.find(';');
  if (valuenamepos != std::string::npos && valuename) {
    *valuename = key.substr(valuenamepos + 1);
  }

  second = Encoding::ToWide(key.substr(start + 1, valuenamepos - start - 1));

  if (hasPrefix(key, "HKEY_CURRENT_USER", start)) {
    primaryKey = HKEY_CURRENT_USER;
  } else if (hasPrefix(key, "HKEY_CURRENT_CONFIG", start)) {
    primaryKey = HKEY_CURRENT_CONFIG;
  } else if (hasPrefix(key, "HKEY_CLASSES_ROOT", start)) {
    primaryKey = HKEY_CLASSES_ROOT;
  } else if (hasPrefix(key, "HKEY_LOCAL_MACHINE", start)) {
    primaryKey = HKEY_LOCAL_MACHINE;
  } else if (hasPrefix(key, "HKEY_USERS", start)) {
    primaryKey = HKEY_USERS;
  }

  return true;
}

static DWORD SystemToolsMakeRegistryMode(DWORD mode,
                                         SystemTools::KeyWOW64 view)
{
  // only add the modes when on a system that supports Wow64.
  static FARPROC wow64p =
    GetProcAddress(GetModuleHandleW(L"kernel32"), "IsWow64Process");
  if (!wow64p) {
    return mode;
  }

  if (view == SystemTools::KeyWOW64_32) {
    return mode | KWSYS_ST_KEY_WOW64_32KEY;
  } else if (view == SystemTools::KeyWOW64_64) {
    return mode | KWSYS_ST_KEY_WOW64_64KEY;
  }
  return mode;
}
#endif

#if defined(_WIN32) && !defined(__CYGWIN__)
bool SystemTools::GetRegistrySubKeys(std::string const& key,
                                     std::vector<std::string>& subkeys,
                                     KeyWOW64 view)
{
  HKEY primaryKey = HKEY_CURRENT_USER;
  std::wstring second;
  if (!SystemToolsParseRegistryKey(key, primaryKey, second, nullptr)) {
    return false;
  }

  HKEY hKey;
  if (RegOpenKeyExW(primaryKey, second.c_str(), 0,
                    SystemToolsMakeRegistryMode(KEY_READ, view),
                    &hKey) != ERROR_SUCCESS) {
    return false;
  } else {
    wchar_t name[1024];
    DWORD dwNameSize = sizeof(name) / sizeof(name[0]);

    DWORD i = 0;
    while (RegEnumKeyW(hKey, i, name, dwNameSize) == ERROR_SUCCESS) {
      subkeys.push_back(Encoding::ToNarrow(name));
      ++i;
    }

    RegCloseKey(hKey);
  }

  return true;
}
#else
bool SystemTools::GetRegistrySubKeys(std::string const&,
                                     std::vector<std::string>&, KeyWOW64)
{
  return false;
}
#endif

// Read a registry value.
// Example :
//      HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.1\InstallPath
//      =>  will return the data of the "default" value of the key
//      HKEY_LOCAL_MACHINE\SOFTWARE\Scriptics\Tcl\8.4;Root
//      =>  will return the data of the "Root" value of the key

#if defined(_WIN32) && !defined(__CYGWIN__)
bool SystemTools::ReadRegistryValue(std::string const& key, std::string& value,
                                    KeyWOW64 view)
{
  bool valueset = false;
  HKEY primaryKey = HKEY_CURRENT_USER;
  std::wstring second;
  std::string valuename;
  if (!SystemToolsParseRegistryKey(key, primaryKey, second, &valuename)) {
    return false;
  }

  HKEY hKey;
  if (RegOpenKeyExW(primaryKey, second.c_str(), 0,
                    SystemToolsMakeRegistryMode(KEY_READ, view),
                    &hKey) != ERROR_SUCCESS) {
    return false;
  } else {
    DWORD dwType, dwSize;
    dwSize = 1023;
    wchar_t data[1024];
    if (RegQueryValueExW(hKey, Encoding::ToWide(valuename).c_str(), nullptr,
                         &dwType, (BYTE*)data, &dwSize) == ERROR_SUCCESS) {
      if (dwType == REG_SZ) {
        value = Encoding::ToNarrow(data);
        valueset = true;
      } else if (dwType == REG_EXPAND_SZ) {
        wchar_t expanded[1024];
        DWORD dwExpandedSize = sizeof(expanded) / sizeof(expanded[0]);
        if (ExpandEnvironmentStringsW(data, expanded, dwExpandedSize)) {
          value = Encoding::ToNarrow(expanded);
          valueset = true;
        }
      }
    }

    RegCloseKey(hKey);
  }

  return valueset;
}
#else
bool SystemTools::ReadRegistryValue(std::string const&, std::string&, KeyWOW64)
{
  return false;
}
#endif

// Write a registry value.
// Example :
//      HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.1\InstallPath
//      =>  will set the data of the "default" value of the key
//      HKEY_LOCAL_MACHINE\SOFTWARE\Scriptics\Tcl\8.4;Root
//      =>  will set the data of the "Root" value of the key

#if defined(_WIN32) && !defined(__CYGWIN__)
bool SystemTools::WriteRegistryValue(std::string const& key,
                                     std::string const& value, KeyWOW64 view)
{
  HKEY primaryKey = HKEY_CURRENT_USER;
  std::wstring second;
  std::string valuename;
  if (!SystemToolsParseRegistryKey(key, primaryKey, second, &valuename)) {
    return false;
  }

  HKEY hKey;
  DWORD dwDummy;
  wchar_t lpClass[] = L"";
  if (RegCreateKeyExW(primaryKey, second.c_str(), 0, lpClass,
                      REG_OPTION_NON_VOLATILE,
                      SystemToolsMakeRegistryMode(KEY_WRITE, view), nullptr,
                      &hKey, &dwDummy) != ERROR_SUCCESS) {
    return false;
  }

  std::wstring wvalue = Encoding::ToWide(value);
  if (RegSetValueExW(hKey, Encoding::ToWide(valuename).c_str(), 0, REG_SZ,
                     (CONST BYTE*)wvalue.c_str(),
                     (DWORD)(sizeof(wchar_t) * (wvalue.size() + 1))) ==
      ERROR_SUCCESS) {
    return true;
  }
  return false;
}
#else
bool SystemTools::WriteRegistryValue(std::string const&, std::string const&,
                                     KeyWOW64)
{
  return false;
}
#endif

// Delete a registry value.
// Example :
//      HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.1\InstallPath
//      =>  will delete the data of the "default" value of the key
//      HKEY_LOCAL_MACHINE\SOFTWARE\Scriptics\Tcl\8.4;Root
//      =>  will delete the data of the "Root" value of the key

#if defined(_WIN32) && !defined(__CYGWIN__)
bool SystemTools::DeleteRegistryValue(std::string const& key, KeyWOW64 view)
{
  HKEY primaryKey = HKEY_CURRENT_USER;
  std::wstring second;
  std::string valuename;
  if (!SystemToolsParseRegistryKey(key, primaryKey, second, &valuename)) {
    return false;
  }

  HKEY hKey;
  if (RegOpenKeyExW(primaryKey, second.c_str(), 0,
                    SystemToolsMakeRegistryMode(KEY_WRITE, view),
                    &hKey) != ERROR_SUCCESS) {
    return false;
  } else {
    if (RegDeleteValueW(hKey, Encoding::ToWide(valuename).c_str()) ==
        ERROR_SUCCESS) {
      RegCloseKey(hKey);
      return true;
    }
  }
  return false;
}
#else
bool SystemTools::DeleteRegistryValue(std::string const&, KeyWOW64)
{
  return false;
}
#endif

#ifdef _WIN32
SystemTools::WindowsFileId::WindowsFileId(unsigned long volumeSerialNumber,
                                          unsigned long fileIndexHigh,
                                          unsigned long fileIndexLow)
  : m_volumeSerialNumber(volumeSerialNumber)
  , m_fileIndexHigh(fileIndexHigh)
  , m_fileIndexLow(fileIndexLow)
{
}

bool SystemTools::WindowsFileId::operator==(WindowsFileId const& o) const
{
  return (m_volumeSerialNumber == o.m_volumeSerialNumber &&
          m_fileIndexHigh == o.m_fileIndexHigh &&
          m_fileIndexLow == o.m_fileIndexLow);
}

bool SystemTools::WindowsFileId::operator!=(WindowsFileId const& o) const
{
  return !(*this == o);
}
#else
SystemTools::UnixFileId::UnixFileId(dev_t volumeSerialNumber,
                                    ino_t fileSerialNumber, off_t fileSize)
  : m_volumeSerialNumber(volumeSerialNumber)
  , m_fileSerialNumber(fileSerialNumber)
  , m_fileSize(fileSize)
{
}

bool SystemTools::UnixFileId::operator==(UnixFileId const& o) const
{
  return (m_volumeSerialNumber == o.m_volumeSerialNumber &&
          m_fileSerialNumber == o.m_fileSerialNumber &&
          m_fileSize == o.m_fileSize);
}

bool SystemTools::UnixFileId::operator!=(UnixFileId const& o) const
{
  return !(*this == o);
}
#endif

bool SystemTools::GetFileId(std::string const& file, FileId& id)
{
#ifdef _WIN32
  HANDLE hFile =
    CreateFileW(Encoding::ToWide(file).c_str(), GENERIC_READ, FILE_SHARE_READ,
                nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
  if (hFile != INVALID_HANDLE_VALUE) {
    BY_HANDLE_FILE_INFORMATION fiBuf;
    GetFileInformationByHandle(hFile, &fiBuf);
    CloseHandle(hFile);
    id = FileId(fiBuf.dwVolumeSerialNumber, fiBuf.nFileIndexHigh,
                fiBuf.nFileIndexLow);
    return true;
  } else {
    return false;
  }
#else
  struct stat fileStat;
  if (stat(file.c_str(), &fileStat) == 0) {
    id = FileId(fileStat.st_dev, fileStat.st_ino, fileStat.st_size);
    return true;
  }
  return false;
#endif
}

bool SystemTools::SameFile(std::string const& file1, std::string const& file2)
{
#ifdef _WIN32
  HANDLE hFile1, hFile2;

  hFile1 =
    CreateFileW(Encoding::ToWide(file1).c_str(), GENERIC_READ, FILE_SHARE_READ,
                nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
  hFile2 =
    CreateFileW(Encoding::ToWide(file2).c_str(), GENERIC_READ, FILE_SHARE_READ,
                nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
  if (hFile1 == INVALID_HANDLE_VALUE || hFile2 == INVALID_HANDLE_VALUE) {
    if (hFile1 != INVALID_HANDLE_VALUE) {
      CloseHandle(hFile1);
    }
    if (hFile2 != INVALID_HANDLE_VALUE) {
      CloseHandle(hFile2);
    }
    return false;
  }

  BY_HANDLE_FILE_INFORMATION fiBuf1;
  BY_HANDLE_FILE_INFORMATION fiBuf2;
  GetFileInformationByHandle(hFile1, &fiBuf1);
  GetFileInformationByHandle(hFile2, &fiBuf2);
  CloseHandle(hFile1);
  CloseHandle(hFile2);
  return (fiBuf1.dwVolumeSerialNumber == fiBuf2.dwVolumeSerialNumber &&
          fiBuf1.nFileIndexHigh == fiBuf2.nFileIndexHigh &&
          fiBuf1.nFileIndexLow == fiBuf2.nFileIndexLow);
#else
  struct stat fileStat1, fileStat2;
  if (stat(file1.c_str(), &fileStat1) == 0 &&
      stat(file2.c_str(), &fileStat2) == 0) {
    // see if the files are the same file
    // check the device inode and size
    if (memcmp(&fileStat2.st_dev, &fileStat1.st_dev,
               sizeof(fileStat1.st_dev)) == 0 &&
        memcmp(&fileStat2.st_ino, &fileStat1.st_ino,
               sizeof(fileStat1.st_ino)) == 0 &&
        fileStat2.st_size == fileStat1.st_size) {
      return true;
    }
  }
  return false;
#endif
}

bool SystemTools::PathExists(std::string const& path)
{
  if (path.empty()) {
    return false;
  }
#if defined(_WIN32)
  return (GetFileAttributesW(Encoding::ToWindowsExtendedPath(path).c_str()) !=
          INVALID_FILE_ATTRIBUTES);
#else
  struct stat st;
  return lstat(path.c_str(), &st) == 0;
#endif
}

bool SystemTools::FileExists(char const* filename)
{
  if (!filename) {
    return false;
  }
  return SystemTools::FileExists(std::string(filename));
}

bool SystemTools::FileExists(std::string const& filename)
{
  if (filename.empty()) {
    return false;
  }
#if defined(_WIN32)
  std::wstring const path = Encoding::ToWindowsExtendedPath(filename);
  DWORD attr = GetFileAttributesW(path.c_str());
  if (attr == INVALID_FILE_ATTRIBUTES) {
    return false;
  }

  if (attr & FILE_ATTRIBUTE_REPARSE_POINT) {
    // Using 0 instead of GENERIC_READ as it allows reading of file attributes
    // even if we do not have permission to read the file itself
    HANDLE handle = CreateFileW(path.c_str(), 0, 0, nullptr, OPEN_EXISTING,
                                FILE_FLAG_BACKUP_SEMANTICS, nullptr);

    if (handle == INVALID_HANDLE_VALUE) {
      // A reparse point may be an execution alias (Windows Store app), which
      // is similar to a symlink but it cannot be opened as a regular file.
      // We must look at the reparse point data explicitly.
      handle = CreateFileW(
        path.c_str(), 0, 0, nullptr, OPEN_EXISTING,
        FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, nullptr);

      if (handle == INVALID_HANDLE_VALUE) {
        return false;
      }

      BYTE buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
      DWORD bytesReturned = 0;

      if (!DeviceIoControl(handle, FSCTL_GET_REPARSE_POINT, nullptr, 0, buffer,
                           MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &bytesReturned,
                           nullptr)) {
        CloseHandle(handle);
        return false;
      }

      CloseHandle(handle);

      PREPARSE_DATA_BUFFER data =
        reinterpret_cast<PREPARSE_DATA_BUFFER>(&buffer[0]);

      // Assume that file exists if it is an execution alias.
      return data->ReparseTag == IO_REPARSE_TAG_APPEXECLINK;
    }

    CloseHandle(handle);
  }

  return true;
#else
// SCO OpenServer 5.0.7/3.2's command has 711 permission.
#  if defined(_SCO_DS)
  return access(filename.c_str(), F_OK) == 0;
#  else
  return access(filename.c_str(), R_OK) == 0;
#  endif
#endif
}

bool SystemTools::FileExists(char const* filename, bool isFile)
{
  if (!filename) {
    return false;
  }
  return SystemTools::FileExists(std::string(filename), isFile);
}

bool SystemTools::FileExists(std::string const& filename, bool isFile)
{
  if (SystemTools::FileExists(filename)) {
    // If isFile is set return not FileIsDirectory,
    // so this will only be true if it is a file
    return !isFile || !SystemTools::FileIsDirectory(filename);
  }
  return false;
}

bool SystemTools::TestFileAccess(char const* filename,
                                 TestFilePermissions permissions)
{
  if (!filename) {
    return false;
  }
  return SystemTools::TestFileAccess(std::string(filename), permissions);
}

bool SystemTools::TestFileAccess(std::string const& filename,
                                 TestFilePermissions permissions)
{
  if (filename.empty()) {
    return false;
  }
#if defined(_WIN32) && !defined(__CYGWIN__)
  // If execute set, change to read permission (all files on Windows
  // are executable if they are readable).  The CRT will always fail
  // if you pass an execute bit.
  if (permissions & TEST_FILE_EXECUTE) {
    permissions &= ~TEST_FILE_EXECUTE;
    permissions |= TEST_FILE_READ;
  }
  return _waccess(Encoding::ToWindowsExtendedPath(filename).c_str(),
                  permissions) == 0;
#else
  return access(filename.c_str(), permissions) == 0;
#endif
}

int SystemTools::Stat(char const* path, SystemTools::Stat_t* buf)
{
  if (!path) {
    errno = EFAULT;
    return -1;
  }
  return SystemTools::Stat(std::string(path), buf);
}

int SystemTools::Stat(std::string const& path, SystemTools::Stat_t* buf)
{
  if (path.empty()) {
    errno = ENOENT;
    return -1;
  }
#if defined(_WIN32) && !defined(__CYGWIN__)
  // Ideally we should use Encoding::ToWindowsExtendedPath to support
  // long paths, but _wstat64 rejects paths with '?' in them, thinking
  // they are wildcards.
  std::wstring const& wpath = Encoding::ToWide(path);
  return _wstat64(wpath.c_str(), buf);
#else
  return stat(path.c_str(), buf);
#endif
}

Status SystemTools::Touch(std::string const& filename, bool create)
{
  if (!SystemTools::FileExists(filename)) {
    if (create) {
      FILE* file = Fopen(filename, "a+b");
      if (file) {
        fclose(file);
        return Status::Success();
      }
      return Status::POSIX_errno();
    } else {
      return Status::Success();
    }
  }
#if defined(_WIN32) && !defined(__CYGWIN__)
  HANDLE h = CreateFileW(Encoding::ToWindowsExtendedPath(filename).c_str(),
                         FILE_WRITE_ATTRIBUTES, FILE_SHARE_WRITE, 0,
                         OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0);
  if (!h) {
    return Status::Windows_GetLastError();
  }
  FILETIME mtime;
  GetSystemTimeAsFileTime(&mtime);
  if (!SetFileTime(h, 0, 0, &mtime)) {
    Status status = Status::Windows_GetLastError();
    CloseHandle(h);
    return status;
  }
  CloseHandle(h);
#elif KWSYS_CXX_HAS_UTIMENSAT
  // utimensat is only available on newer Unixes and macOS 10.13+
  if (utimensat(AT_FDCWD, filename.c_str(), nullptr, 0) < 0) {
    return Status::POSIX_errno();
  }
#else
  // fall back to utimes
  if (utimes(filename.c_str(), nullptr) < 0) {
    return Status::POSIX_errno();
  }
#endif
  return Status::Success();
}

Status SystemTools::FileTimeCompare(std::string const& f1,
                                    std::string const& f2, int* result)
{
  // Default to same time.
  *result = 0;
#if !defined(_WIN32) || defined(__CYGWIN__)
  // POSIX version.  Use stat function to get file modification time.
  struct stat s1;
  if (stat(f1.c_str(), &s1) != 0) {
    return Status::POSIX_errno();
  }
  struct stat s2;
  if (stat(f2.c_str(), &s2) != 0) {
    return Status::POSIX_errno();
  }
#  if KWSYS_CXX_STAT_HAS_ST_MTIM
  // Compare using nanosecond resolution.
  if (s1.st_mtim.tv_sec < s2.st_mtim.tv_sec) {
    *result = -1;
  } else if (s1.st_mtim.tv_sec > s2.st_mtim.tv_sec) {
    *result = 1;
  } else if (s1.st_mtim.tv_nsec < s2.st_mtim.tv_nsec) {
    *result = -1;
  } else if (s1.st_mtim.tv_nsec > s2.st_mtim.tv_nsec) {
    *result = 1;
  }
#  elif KWSYS_CXX_STAT_HAS_ST_MTIMESPEC
  // Compare using nanosecond resolution.
  if (s1.st_mtimespec.tv_sec < s2.st_mtimespec.tv_sec) {
    *result = -1;
  } else if (s1.st_mtimespec.tv_sec > s2.st_mtimespec.tv_sec) {
    *result = 1;
  } else if (s1.st_mtimespec.tv_nsec < s2.st_mtimespec.tv_nsec) {
    *result = -1;
  } else if (s1.st_mtimespec.tv_nsec > s2.st_mtimespec.tv_nsec) {
    *result = 1;
  }
#  else
  // Compare using 1 second resolution.
  if (s1.st_mtime < s2.st_mtime) {
    *result = -1;
  } else if (s1.st_mtime > s2.st_mtime) {
    *result = 1;
  }
#  endif
#else
  // Windows version.  Get the modification time from extended file attributes.
  WIN32_FILE_ATTRIBUTE_DATA f1d;
  WIN32_FILE_ATTRIBUTE_DATA f2d;
  if (!GetFileAttributesExW(Encoding::ToWindowsExtendedPath(f1).c_str(),
                            GetFileExInfoStandard, &f1d)) {
    return Status::Windows_GetLastError();
  }
  if (!GetFileAttributesExW(Encoding::ToWindowsExtendedPath(f2).c_str(),
                            GetFileExInfoStandard, &f2d)) {
    return Status::Windows_GetLastError();
  }

  // Compare the file times using resolution provided by system call.
  *result = (int)CompareFileTime(&f1d.ftLastWriteTime, &f2d.ftLastWriteTime);
#endif
  return Status::Success();
}

// Return a capitalized string (i.e the first letter is uppercased, all other
// are lowercased)
std::string SystemTools::Capitalized(std::string const& s)
{
  std::string n;
  if (s.empty()) {
    return n;
  }
  n.resize(s.size());
  n[0] = static_cast<std::string::value_type>(kwsysString_toupper(s[0]));
  for (size_t i = 1; i < s.size(); i++) {
    n[i] = static_cast<std::string::value_type>(kwsysString_tolower(s[i]));
  }
  return n;
}

// Return capitalized words
std::string SystemTools::CapitalizedWords(std::string const& s)
{
  std::string n(s);
  for (size_t i = 0; i < s.size(); i++) {
    if (kwsysString_isalpha(s[i]) &&
        (i == 0 || kwsysString_isspace(s[i - 1]))) {
      n[i] = static_cast<std::string::value_type>(kwsysString_toupper(s[i]));
    }
  }
  return n;
}

// Return uncapitalized words
std::string SystemTools::UnCapitalizedWords(std::string const& s)
{
  std::string n(s);
  for (size_t i = 0; i < s.size(); i++) {
    if (kwsysString_isalpha(s[i]) &&
        (i == 0 || kwsysString_isspace(s[i - 1]))) {
      n[i] = static_cast<std::string::value_type>(kwsysString_tolower(s[i]));
    }
  }
  return n;
}

// only works for words with at least two letters
std::string SystemTools::AddSpaceBetweenCapitalizedWords(std::string const& s)
{
  std::string n;
  if (!s.empty()) {
    n.reserve(s.size());
    n += s[0];
    for (size_t i = 1; i < s.size(); i++) {
      if (kwsysString_isupper(s[i]) && !kwsysString_isspace(s[i - 1]) &&
          !kwsysString_isupper(s[i - 1])) {
        n += ' ';
      }
      n += s[i];
    }
  }
  return n;
}

char* SystemTools::AppendStrings(char const* str1, char const* str2)
{
  if (!str1) {
    return SystemTools::DuplicateString(str2);
  }
  if (!str2) {
    return SystemTools::DuplicateString(str1);
  }
  size_t len1 = strlen(str1);
  char* newstr = new char[len1 + strlen(str2) + 1];
  if (!newstr) {
    return nullptr;
  }
  strcpy(newstr, str1);
  strcat(newstr + len1, str2);
  return newstr;
}

char* SystemTools::AppendStrings(char const* str1, char const* str2,
                                 char const* str3)
{
  if (!str1) {
    return SystemTools::AppendStrings(str2, str3);
  }
  if (!str2) {
    return SystemTools::AppendStrings(str1, str3);
  }
  if (!str3) {
    return SystemTools::AppendStrings(str1, str2);
  }

  size_t len1 = strlen(str1), len2 = strlen(str2);
  char* newstr = new char[len1 + len2 + strlen(str3) + 1];
  if (!newstr) {
    return nullptr;
  }
  strcpy(newstr, str1);
  strcat(newstr + len1, str2);
  strcat(newstr + len1 + len2, str3);
  return newstr;
}

std::string SystemTools::LowerCase(std::string s)
{
  std::transform(s.begin(), s.end(), s.begin(), kwsysString_tolower);
  return s;
}

std::string SystemTools::UpperCase(std::string s)
{
  std::transform(s.begin(), s.end(), s.begin(), kwsysString_toupper);
  return s;
}

// Count char in string
size_t SystemTools::CountChar(char const* str, char c)
{
  size_t count = 0;

  if (str) {
    while (*str) {
      if (*str == c) {
        ++count;
      }
      ++str;
    }
  }
  return count;
}

// Remove chars in string
char* SystemTools::RemoveChars(char const* str, char const* toremove)
{
  if (!str) {
    return nullptr;
  }
  char* clean_str = new char[strlen(str) + 1];
  char* ptr = clean_str;
  while (*str) {
    char const* str2 = toremove;
    while (*str2 && *str != *str2) {
      ++str2;
    }
    if (!*str2) {
      *ptr++ = *str;
    }
    ++str;
  }
  *ptr = '\0';
  return clean_str;
}

// Remove chars in string
char* SystemTools::RemoveCharsButUpperHex(char const* str)
{
  if (!str) {
    return nullptr;
  }
  char* clean_str = new char[strlen(str) + 1];
  char* ptr = clean_str;
  while (*str) {
    if ((*str >= '0' && *str <= '9') || (*str >= 'A' && *str <= 'F')) {
      *ptr++ = *str;
    }
    ++str;
  }
  *ptr = '\0';
  return clean_str;
}

// Replace chars in string
char* SystemTools::ReplaceChars(char* str, char const* toreplace,
                                char replacement)
{
  if (str) {
    char* ptr = str;
    while (*ptr) {
      char const* ptr2 = toreplace;
      while (*ptr2) {
        if (*ptr == *ptr2) {
          *ptr = replacement;
        }
        ++ptr2;
      }
      ++ptr;
    }
  }
  return str;
}

// Returns if string starts with another string
bool SystemTools::StringStartsWith(char const* str1, char const* str2)
{
  if (!str1 || !str2) {
    return false;
  }
  size_t len1 = strlen(str1), len2 = strlen(str2);
  return len1 >= len2 && !strncmp(str1, str2, len2) ? true : false;
}

// Returns if string starts with another string
bool SystemTools::StringStartsWith(std::string const& str1, char const* str2)
{
  if (!str2) {
    return false;
  }
  size_t len1 = str1.size(), len2 = strlen(str2);
  return len1 >= len2 && !strncmp(str1.c_str(), str2, len2) ? true : false;
}

// Returns if string ends with another string
bool SystemTools::StringEndsWith(char const* str1, char const* str2)
{
  if (!str1 || !str2) {
    return false;
  }
  size_t len1 = strlen(str1), len2 = strlen(str2);
  return len1 >= len2 && !strncmp(str1 + (len1 - len2), str2, len2) ? true
                                                                    : false;
}

// Returns if string ends with another string
bool SystemTools::StringEndsWith(std::string const& str1, char const* str2)
{
  if (!str2) {
    return false;
  }
  size_t len1 = str1.size(), len2 = strlen(str2);
  return len1 >= len2 && !strncmp(str1.c_str() + (len1 - len2), str2, len2)
    ? true
    : false;
}

// Returns a pointer to the last occurrence of str2 in str1
char const* SystemTools::FindLastString(char const* str1, char const* str2)
{
  if (!str1 || !str2) {
    return nullptr;
  }

  size_t len1 = strlen(str1), len2 = strlen(str2);
  if (len1 >= len2) {
    char const* ptr = str1 + len1 - len2;
    do {
      if (!strncmp(ptr, str2, len2)) {
        return ptr;
      }
    } while (ptr-- != str1);
  }

  return nullptr;
}

// Duplicate string
char* SystemTools::DuplicateString(char const* str)
{
  if (str) {
    char* newstr = new char[strlen(str) + 1];
    return strcpy(newstr, str);
  }
  return nullptr;
}

// Return a cropped string
std::string SystemTools::CropString(std::string const& s, size_t max_len)
{
  if (s.empty() || max_len == 0 || max_len >= s.size()) {
    return s;
  }

  std::string n;
  n.reserve(max_len);

  size_t middle = max_len / 2;

  n.assign(s, 0, middle);
  n += s.substr(s.size() - (max_len - middle));

  if (max_len > 2) {
    n[middle] = '.';
    if (max_len > 3) {
      n[middle - 1] = '.';
      if (max_len > 4) {
        n[middle + 1] = '.';
      }
    }
  }

  return n;
}

std::vector<std::string> SystemTools::SplitString(std::string const& p,
                                                  char sep, bool isPath)
{
  std::string path = p;
  std::vector<std::string> paths;
  if (path.empty()) {
    return paths;
  }
  if (isPath && path[0] == '/') {
    path.erase(path.begin());
    paths.emplace_back("/");
  }
  std::string::size_type pos1 = 0;
  std::string::size_type pos2 = path.find(sep, pos1);
  while (pos2 != std::string::npos) {
    paths.push_back(path.substr(pos1, pos2 - pos1));
    pos1 = pos2 + 1;
    pos2 = path.find(sep, pos1 + 1);
  }
  paths.push_back(path.substr(pos1, pos2 - pos1));

  return paths;
}

int SystemTools::EstimateFormatLength(char const* format, va_list ap)
{
  if (!format) {
    return 0;
  }

  // Quick-hack attempt at estimating the length of the string.
  // Should never under-estimate.

  // Start with the length of the format string itself.

  size_t length = strlen(format);

  // Increase the length for every argument in the format.

  char const* cur = format;
  while (*cur) {
    if (*cur++ == '%') {
      // Skip "%%" since it doesn't correspond to a va_arg.
      if (*cur != '%') {
        while (!kwsysString_isalpha(*cur)) {
          ++cur;
        }
        switch (*cur) {
          case 's': {
            // Check the length of the string.
            char* s = va_arg(ap, char*);
            if (s) {
              length += strlen(s);
            }
          } break;
          case 'e':
          case 'f':
          case 'g': {
            // Assume the argument contributes no more than 64 characters.
            length += 64;

            // Eat the argument.
            static_cast<void>(va_arg(ap, double));
          } break;
          default: {
            // Assume the argument contributes no more than 64 characters.
            length += 64;

            // Eat the argument.
            static_cast<void>(va_arg(ap, int));
          } break;
        }
      }

      // Move past the characters just tested.
      ++cur;
    }
  }

  return static_cast<int>(length);
}

std::string SystemTools::EscapeChars(char const* str,
                                     char const* chars_to_escape,
                                     char escape_char)
{
  std::string n;
  if (str) {
    if (!chars_to_escape || !*chars_to_escape) {
      n.append(str);
    } else {
      n.reserve(strlen(str));
      while (*str) {
        char const* ptr = chars_to_escape;
        while (*ptr) {
          if (*str == *ptr) {
            n += escape_char;
            break;
          }
          ++ptr;
        }
        n += *str;
        ++str;
      }
    }
  }
  return n;
}

#ifdef __VMS
static void ConvertVMSToUnix(std::string& path)
{
  std::string::size_type rootEnd = path.find(":[");
  std::string::size_type pathEnd = path.find(']');
  if (rootEnd != std::string::npos) {
    std::string root = path.substr(0, rootEnd);
    std::string pathPart = path.substr(rootEnd + 2, pathEnd - rootEnd - 2);
    char const* pathCString = pathPart.c_str();
    char const* pos0 = pathCString;
    for (std::string::size_type pos = 0; *pos0; ++pos) {
      if (*pos0 == '.') {
        pathPart[pos] = '/';
      }
      pos0++;
    }
    path = '/' + root + '/' + pathPart;
  }
}
#endif

// convert windows slashes to unix slashes
void SystemTools::ConvertToUnixSlashes(std::string& path)
{
  if (path.empty()) {
    return;
  }

#ifdef __VMS
  ConvertVMSToUnix(path);
#else
  // replace backslashes
  std::replace(path.begin(), path.end(), '\\', '/');

  // collapse repeated slashes, except exactly two leading slashes are
  // meaningful and must be preserved.
  bool hasDoubleSlash = path[0] == '/' && path[1] == '/' && path[2] != '/';
  auto uniqueEnd = std::unique(
    path.begin() + hasDoubleSlash, path.end(),
    [](char c1, char c2) -> bool { return c1 == '/' && c1 == c2; });
  path.erase(uniqueEnd, path.end());
#endif

  // if there is a tilda ~ then replace it with HOME
  if (path[0] == '~' && (path[1] == '/' || path[1] == '\0')) {
    std::string homeEnv;
    if (SystemTools::GetEnv("HOME", homeEnv)) {
      path.replace(0, 1, homeEnv);
    }
  }
#ifdef HAVE_GETPWNAM
  else if (path[0] == '~') {
    std::string::size_type idx = path.find('/');
    std::string user = path.substr(1, idx - 1);
    passwd* pw = getpwnam(user.c_str());
    if (pw) {
      path.replace(0, idx, pw->pw_dir);
    }
  }
#endif
  // remove trailing slash, but preserve the root slash and the slash
  // after windows drive letter (c:/).
  size_t size = path.size();
  if (size > 1 && path.back() == '/') {
    if (!(size == 3 && path[1] == ':') && path[size - 2] != '/') {
      path.resize(size - 1);
    }
  }
}

#ifdef _WIN32
std::wstring SystemTools::ConvertToWindowsExtendedPath(
  std::string const& source)
{
  return Encoding::ToWindowsExtendedPath(source);
}
#endif

// change // to /, and escape any spaces in the path
std::string SystemTools::ConvertToUnixOutputPath(std::string const& path)
{
  std::string ret = path;

  // remove // except at the beginning might be a cygwin drive
  std::string::size_type pos = 1;
  while ((pos = ret.find("//", pos)) != std::string::npos) {
    ret.erase(pos, 1);
  }
  // escape spaces and () in the path
  if (ret.find_first_of(' ') != std::string::npos) {
    std::string result;
    char lastch = 1;
    for (char const* ch = ret.c_str(); *ch != '\0'; ++ch) {
      // if it is already escaped then don't try to escape it again
      if ((*ch == ' ') && lastch != '\\') {
        result += '\\';
      }
      result += *ch;
      lastch = *ch;
    }
    ret = result;
  }
  return ret;
}

std::string SystemTools::ConvertToOutputPath(std::string const& path)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
  return SystemTools::ConvertToWindowsOutputPath(path);
#else
  return SystemTools::ConvertToUnixOutputPath(path);
#endif
}

// remove double slashes not at the start
std::string SystemTools::ConvertToWindowsOutputPath(std::string const& path)
{
  std::string ret;
  // make it big enough for all of path and double quotes
  ret.reserve(path.size() + 3);
  // put path into the string
  ret = path;
  std::string::size_type pos = 0;
  // first convert all of the slashes
  while ((pos = ret.find('/', pos)) != std::string::npos) {
    ret[pos] = '\\';
    pos++;
  }
  // check for really small paths
  if (ret.size() < 2) {
    return ret;
  }
  // now clean up a bit and remove double slashes
  // Only if it is not the first position in the path which is a network
  // path on windows
  pos = 1; // start at position 1
  if (ret[0] == '\"') {
    pos = 2; // if the string is already quoted then start at 2
    if (ret.size() < 3) {
      return ret;
    }
  }
  while ((pos = ret.find("\\\\", pos)) != std::string::npos) {
    ret.erase(pos, 1);
  }
  // now double quote the path if it has spaces in it
  // and is not already double quoted
  if (ret.find(' ') != std::string::npos && ret[0] != '\"') {
    ret.insert(static_cast<std::string::size_type>(0),
               static_cast<std::string::size_type>(1), '\"');
    ret.append(1, '\"');
  }
  return ret;
}

/**
 * Append the filename from the path source to the directory name dir.
 */
static std::string FileInDir(std::string const& source, std::string const& dir)
{
  std::string new_destination = dir;
  SystemTools::ConvertToUnixSlashes(new_destination);
  return new_destination + '/' + SystemTools::GetFilenameName(source);
}

SystemTools::CopyStatus SystemTools::CopyFileIfDifferent(
  std::string const& source, std::string const& destination)
{
  // special check for a destination that is a directory
  // FilesDiffer does not handle file to directory compare
  if (SystemTools::FileIsDirectory(destination)) {
    std::string const new_destination = FileInDir(source, destination);
    if (!SystemTools::ComparePath(new_destination, destination)) {
      return SystemTools::CopyFileIfDifferent(source, new_destination);
    }
  } else {
    // source and destination are files so do a copy if they
    // are different
    if (SystemTools::FilesDiffer(source, destination)) {
      return SystemTools::CopyFileAlways(source, destination);
    }
  }
  // at this point the files must be the same so return true
  return CopyStatus{ Status::Success(), CopyStatus::NoPath };
}

SystemTools::CopyStatus SystemTools::CopyFileIfNewer(
  std::string const& source, std::string const& destination)
{
  // special check for a destination that is a directory
  // FileTimeCompare does not handle file to directory compare
  if (SystemTools::FileIsDirectory(destination)) {
    std::string const new_destination = FileInDir(source, destination);
    if (!SystemTools::ComparePath(new_destination, destination)) {
      return SystemTools::CopyFileIfNewer(source, new_destination);
    }
    // If source and destination are the same path, don't copy
    return CopyStatus{ Status::Success(), CopyStatus::NoPath };
  }

  // source and destination are files so do a copy if source is newer
  // Check if source file exists first
  if (!SystemTools::FileExists(source)) {
    return CopyStatus{ Status::POSIX(ENOENT), CopyStatus::SourcePath };
  }
  // If destination doesn't exist, always copy
  if (!SystemTools::FileExists(destination)) {
    return SystemTools::CopyFileAlways(source, destination);
  }
  // Check if source is newer than destination
  int timeResult;
  Status timeStatus =
    SystemTools::FileTimeCompare(source, destination, &timeResult);
  if (timeStatus.IsSuccess()) {
    if (timeResult > 0) {
      // Source is newer, copy it
      return SystemTools::CopyFileAlways(source, destination);
    } else {
      // Source is not newer, no need to copy
      return CopyStatus{ Status::Success(), CopyStatus::NoPath };
    }
  } else {
    // Time comparison failed, be conservative and copy to ensure updates are
    // not missed
    return SystemTools::CopyFileAlways(source, destination);
  }
}

// 4 KiB. This value is historical.
#define KWSYS_ST_STACK_BUFFER (1 << 12)
// 1 MiB. This seems to be the maximum value that modern Windows CopyFile uses.
#define KWSYS_ST_HEAP_BUFFER (1 << 20)
// 16 KiB. This seems roughly appropriate.
#define KWSYS_ST_HEAP_SWITCHOVER (1 << 14)

bool SystemTools::FilesDiffer(std::string const& source,
                              std::string const& destination)
{
  // Get the size of the files. If they are different sizes, they differ.

#if defined(_WIN32)
  WIN32_FILE_ATTRIBUTE_DATA statSource;
  if (GetFileAttributesExW(Encoding::ToWindowsExtendedPath(source).c_str(),
                           GetFileExInfoStandard, &statSource) == 0) {
    return true;
  }

  WIN32_FILE_ATTRIBUTE_DATA statDestination;
  if (GetFileAttributesExW(
        Encoding::ToWindowsExtendedPath(destination).c_str(),
        GetFileExInfoStandard, &statDestination) == 0) {
    return true;
  }

  if (statSource.nFileSizeHigh != statDestination.nFileSizeHigh ||
      statSource.nFileSizeLow != statDestination.nFileSizeLow) {
    return true;
  }

  if (statSource.nFileSizeHigh == 0 && statSource.nFileSizeLow == 0) {
    return false;
  }
  auto const fileSize =
    (static_cast<unsigned long long>(statSource.nFileSizeHigh) << 32) +
    statSource.nFileSizeLow;

#else

  struct stat statSource;
  if (stat(source.c_str(), &statSource) != 0) {
    return true;
  }

  struct stat statDestination;
  if (stat(destination.c_str(), &statDestination) != 0) {
    return true;
  }

  if (statSource.st_size != statDestination.st_size) {
    return true;
  }

  if (statSource.st_size == 0) {
    return false;
  }
  auto const fileSize = static_cast<unsigned long long>(statSource.st_size);
#endif

  // Open the files using C I/O to avoid `fstream`'s internal buffer.
  FILE* const fSource = Fopen(source.c_str(), "rb");
  if (!fSource) {
    return true;
  }
  FILE* const fDestination = Fopen(destination.c_str(), "rb");
  if (!fDestination) {
    fclose(fSource);
    return true;
  }

  // Prepare the buffers for reading the files. Use stack buffers for the first
  // comparison regardless of file size for a quick exit for early differences.
  char* heapBuffer = nullptr;
  bool triedHeapBuffer = false;
  char sourceStackBuffer[KWSYS_ST_STACK_BUFFER];
  char destStackBuffer[KWSYS_ST_STACK_BUFFER];
  char* source_buf = sourceStackBuffer;
  char* dest_buf = destStackBuffer;
  size_t bufferSize = KWSYS_ST_STACK_BUFFER;

  // Compare the files a block at a time.
  auto blockSize = bufferSize;
  auto nleft = fileSize;
  while (true) {
    // Read a block from each file.
    // If either failed to read assume they are different.
    auto nnext = static_cast<size_t>(nleft > blockSize ? blockSize : nleft);
    if (fread(source_buf, 1, nnext, fSource) != nnext) {
      break;
    }
    if (fread(dest_buf, 1, nnext, fDestination) != nnext) {
      break;
    }

    // If this block differs the file differs.
    if (memcmp(static_cast<void const*>(source_buf),
               static_cast<void const*>(dest_buf), nnext) != 0) {
      break;
    }

    // Update the byte count remaining.
    nleft -= nnext;

    // If no bytes remain, the files are the same.
    if (nleft == 0) {
      break;
    }

    // Switch from stack buffers to heap buffers if we haven't already tried,
    // enough file size remains, and the allocation succeeds.
    if (!triedHeapBuffer && nleft > KWSYS_ST_HEAP_SWITCHOVER) {
      triedHeapBuffer = true;
      auto heapBufferSize = 2 *
        static_cast<size_t>(nleft < KWSYS_ST_HEAP_BUFFER
                              ? nleft
                              : KWSYS_ST_HEAP_BUFFER);
      heapBuffer = static_cast<char*>(malloc(heapBufferSize));
      if (heapBuffer) {
        bufferSize = heapBufferSize / 2;
        source_buf = heapBuffer;
        dest_buf = source_buf + bufferSize;
      }
    }

    // Buffer size allowing, scale up the block size. The more bytes we've seen
    // without difference, the less likely the following bytes will differ, so
    // the larger the optimal block size that balances the number of reads with
    // the number of wasted bytes read beyond the first difference.
    blockSize = bufferSize < blockSize * 2 ? bufferSize : blockSize * 2;
  }

  // Free resources.
  free(heapBuffer);
  fclose(fDestination);
  fclose(fSource);

  return nleft > 0;
}

bool SystemTools::TextFilesDiffer(std::string const& path1,
                                  std::string const& path2)
{
  kwsys::ifstream if1(path1.c_str());
  kwsys::ifstream if2(path2.c_str());
  if (!if1 || !if2) {
    return true;
  }

  for (;;) {
    std::string line1, line2;
    bool hasData1 = GetLineFromStream(if1, line1);
    bool hasData2 = GetLineFromStream(if2, line2);
    if (hasData1 != hasData2) {
      return true;
    }
    if (!hasData1) {
      break;
    }
    if (line1 != line2) {
      return true;
    }
  }
  return false;
}

SystemTools::CopyStatus SystemTools::CopyFileContentBlockwise(
  std::string const& source, std::string const& destination)
{
  // try and remove the destination file so that read only destination files
  // can be written to.
  // If the remove fails continue so that files in read only directories
  // that do not allow file removal can be modified.
  SystemTools::RemoveFile(destination);

  // Open the files using C I/O to avoid `fstream`'s internal buffer.
  FILE* const fin = Fopen(source.c_str(), "rb");
  if (!fin) {
    return CopyStatus{ Status::POSIX_errno(), CopyStatus::SourcePath };
  }
  FILE* const fout = Fopen(destination.c_str(), "wb");
  if (!fout) {
    auto status = Status::POSIX_errno();
    fclose(fin);
    return CopyStatus{ status, CopyStatus::DestPath };
  }

  // Attempt to get the size of the source file. Failure (0) is tolerated.
  auto const fileSize = FileLength(source);

  // Prepare the buffer for reading the file. Use a stack buffer for small
  // files and a heap buffer for large files if the allocation succeeds.
  char* heapBuffer = nullptr;
  char stackBuffer[KWSYS_ST_STACK_BUFFER];
  char* buffer = stackBuffer;
  size_t bufferSize = KWSYS_ST_STACK_BUFFER;
  if (fileSize > KWSYS_ST_HEAP_SWITCHOVER) {
    auto heapBufferSize = static_cast<size_t>(
      fileSize < KWSYS_ST_HEAP_BUFFER ? fileSize : KWSYS_ST_HEAP_BUFFER);
    heapBuffer = static_cast<char*>(malloc(heapBufferSize));
    if (heapBuffer) {
      bufferSize = heapBufferSize;
      buffer = heapBuffer;
    }
  }

  auto status = Status::Success();
  auto path = CopyStatus::NoPath;

  // Copy the file a block at a time and detect short reads/writes.
  while (status.IsSuccess()) {
    auto bytesRead = fread(buffer, 1, bufferSize, fin);
    if (bytesRead > 0 && fwrite(buffer, 1, bytesRead, fout) != bytesRead) {
      status = Status::POSIX_errno();
      path = CopyStatus::DestPath;
      break;
    }

    if (bytesRead < bufferSize) {
      if (ferror(fin)) {
        status = Status::POSIX_errno();
        path = CopyStatus::SourcePath;
      }
      break;
    }
  }

  // Make sure the operating system has finished writing the file.
  if (status.IsSuccess() && fflush(fout) != 0) {
    status = Status::POSIX_errno();
    path = CopyStatus::DestPath;
  }

  // Free resources.
  free(heapBuffer);
  if (fclose(fout) != 0 && status.IsSuccess()) {
    status = Status::POSIX_errno();
    path = CopyStatus::DestPath;
  }
  if (fclose(fin) != 0 && status.IsSuccess()) {
    status = Status::POSIX_errno();
    path = CopyStatus::SourcePath;
  }

  return CopyStatus{ status, path };
}

/**
 * Attempt to copy source file to the destination file using
 * operating system mechanisms.
 *
 * If available, copy-on-write/clone will be used.
 * On Linux, the FICLONE ioctl is used to create a clone of the source file.
 * On macOS, the copyfile() call is used to make a clone of the file, and
 * it will fall back to a regular copy if that's not possible.
 *
 * This function will follow symlinks (ie copy the file being
 * pointed-to, not the symlink itself), and the resultant
 * file will be owned by the uid of this process. It will overwrite
 * an existing destination file.
 *
 * Examples of why this method may fail -
 * - We're running on an OS for which this method is not implemented.
 * - The underlying OS won't do a copy for us, and -
 *   - The source and destination are on different file systems
 *     thus a clone is not possible.
 *   - The underlying filesystem does not support file cloning.
 */
SystemTools::CopyStatus SystemTools::CloneFileContent(
  std::string const& source, std::string const& destination)
{
#if defined(__linux) && defined(FICLONE)
  int in = open(source.c_str(), O_RDONLY);
  if (in < 0) {
    return CopyStatus{ Status::POSIX_errno(), CopyStatus::SourcePath };
  }

  SystemTools::RemoveFile(destination);

  int out =
    open(destination.c_str(), O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
  if (out < 0) {
    CopyStatus status{ Status::POSIX_errno(), CopyStatus::DestPath };
    close(in);
    return status;
  }

  CopyStatus status{ Status::Success(), CopyStatus::NoPath };
  if (ioctl(out, FICLONE, in) < 0) {
    status = CopyStatus{ Status::POSIX_errno(), CopyStatus::NoPath };
  }
  close(in);
  close(out);

  return status;
#elif defined(__APPLE__) &&                                                   \
  defined(KWSYS_SYSTEMTOOLS_HAVE_MACOS_COPYFILE_CLONE)
  // When running as root, copyfile() copies more metadata than we
  // want, such as ownership.  Pretend it is not available.
  if (getuid() == 0) {
    return CopyStatus{ Status::POSIX(ENOSYS), CopyStatus::NoPath };
  }

  // NOTE: we cannot use `clonefile` as the {a,c,m}time for the file needs to
  // be updated by `copy_file_if_different` and `copy_file`.
  //
  // COPYFILE_CLONE forces COPYFILE_NOFOLLOW_SRC and that violates the
  // invariant that this should result in a file. We used to manually specify
  // COPYFILE_EXCL | COPYFILE_STAT | COPYFILE_XATTR | COPYFILE_DATA here, but
  // what the copyfile() manpage does not tell you is that COPYFILE_DATA
  // appears to disable cloning all together. Instead, explicitly reject
  // copying symlinks here.
  //
  // COPYFILE_CLONE implies a few flags, including COPYFILE_EXCL.
  // We add COPYFILE_UNLINK to be consistent with the Linux implementation
  // above, as well as CopyFileContentBlockwise(). This will remove the
  // destination file before cloning, allowing this call to complete
  // if the destination file already exists.
  //
  if (SystemTools::FileIsSymlink(source)) {
    return CopyStatus{ Status::POSIX(ENOSYS), CopyStatus::NoPath };
  }

  if (copyfile(source.c_str(), destination.c_str(), nullptr,
               COPYFILE_METADATA | COPYFILE_CLONE | COPYFILE_UNLINK) < 0) {
    return CopyStatus{ Status::POSIX_errno(), CopyStatus::NoPath };
  }
#  if KWSYS_CXX_HAS_UTIMENSAT
  // utimensat is only available on newer Unixes and macOS 10.13+
  if (utimensat(AT_FDCWD, destination.c_str(), nullptr, 0) < 0) {
    return CopyStatus{ Status::POSIX_errno(), CopyStatus::DestPath };
  }
#  else
  // fall back to utimes
  if (utimes(destination.c_str(), nullptr) < 0) {
    return CopyStatus{ Status::POSIX_errno(), CopyStatus::DestPath };
  }
#  endif
  return CopyStatus{ Status::Success(), CopyStatus::NoPath };
#else
  (void)source;
  (void)destination;
  return CopyStatus{ Status::POSIX(ENOSYS), CopyStatus::NoPath };
#endif
}

/**
 * Copy a file named by "source" to the file named by "destination".
 */
SystemTools::CopyStatus SystemTools::CopyFileAlways(
  std::string const& source, std::string const& destination)
{
  CopyStatus status;
  mode_t perm = 0;
  Status perms = SystemTools::GetPermissions(source, perm);
  std::string real_destination = destination;

  if (SystemTools::FileIsDirectory(source)) {
    status = CopyStatus{ SystemTools::MakeDirectory(destination),
                         CopyStatus::DestPath };
    if (!status.IsSuccess()) {
      return status;
    }
  } else {
    // If destination is a directory, try to create a file with the same
    // name as the source in that directory.

    std::string destination_dir;
    if (SystemTools::FileIsDirectory(destination)) {
      destination_dir = real_destination;
      SystemTools::ConvertToUnixSlashes(real_destination);
      real_destination += '/';
      std::string source_name = source;
      real_destination += SystemTools::GetFilenameName(source_name);
    } else {
      destination_dir = SystemTools::GetFilenamePath(destination);
    }
    // If files are the same do not copy
    if (SystemTools::SameFile(source, real_destination)) {
      return status;
    }

    // Create destination directory
    if (!destination_dir.empty()) {
      status = CopyStatus{ SystemTools::MakeDirectory(destination_dir),
                           CopyStatus::DestPath };
      if (!status.IsSuccess()) {
        return status;
      }
    }

    status = SystemTools::CloneFileContent(source, real_destination);
    // if cloning did not succeed, fall back to blockwise copy
    if (!status.IsSuccess()) {
      status = SystemTools::CopyFileContentBlockwise(source, real_destination);
    }
    if (!status.IsSuccess()) {
      return status;
    }
  }
  if (perms) {
    status = CopyStatus{ SystemTools::SetPermissions(real_destination, perm),
                         CopyStatus::DestPath };
  }
  return status;
}

SystemTools::CopyStatus SystemTools::CopyAFile(std::string const& source,
                                               std::string const& destination,
                                               SystemTools::CopyWhen when)
{
  switch (when) {
    case SystemTools::CopyWhen::Unconditional:
      return SystemTools::CopyFileAlways(source, destination);
    case SystemTools::CopyWhen::OnlyIfDifferent:
      return SystemTools::CopyFileIfDifferent(source, destination);
    case SystemTools::CopyWhen::OnlyIfNewer:
      return SystemTools::CopyFileIfNewer(source, destination);
    default:
      break;
  }
  // Should not reach here
  return CopyStatus{ Status::POSIX_errno(), CopyStatus::NoPath };
}

SystemTools::CopyStatus SystemTools::CopyAFile(std::string const& source,
                                               std::string const& destination,
                                               bool always)
{
  return SystemTools::CopyAFile(source, destination,
                                always ? CopyWhen::Unconditional
                                       : CopyWhen::OnlyIfDifferent);
}

/**
 * Copy a directory content from "source" directory to the directory named by
 * "destination".
 */
Status SystemTools::CopyADirectory(std::string const& source,
                                   std::string const& destination,
                                   SystemTools::CopyWhen when)
{
  Status status;
  Directory dir;
  status = dir.Load(source);
  if (!status.IsSuccess()) {
    return status;
  }
  status = SystemTools::MakeDirectory(destination);
  if (!status.IsSuccess()) {
    return status;
  }

  for (size_t fileNum = 0; fileNum < dir.GetNumberOfFiles(); ++fileNum) {
    std::string const& filename = dir.GetFileName(fileNum);
    if (filename != "." && filename != "..") {
      std::string fullPath = source;
      fullPath += '/';
      fullPath += filename;
      if (SystemTools::FileIsDirectory(fullPath)) {
        std::string fullDestPath = destination;
        fullDestPath += '/';
        fullDestPath += filename;
        status = SystemTools::CopyADirectory(fullPath, fullDestPath, when);
        if (!status.IsSuccess()) {
          return status;
        }
      } else {
        status = SystemTools::CopyAFile(fullPath, destination, when);
        if (!status.IsSuccess()) {
          return status;
        }
      }
    }
  }

  return status;
}

Status SystemTools::CopyADirectory(std::string const& source,
                                   std::string const& destination, bool always)
{
  return SystemTools::CopyADirectory(source, destination,
                                     always ? CopyWhen::Unconditional
                                            : CopyWhen::OnlyIfDifferent);
}

// return size of file; also returns zero if no file exists
unsigned long long SystemTools::FileLength(std::string const& filename)
{
  unsigned long long length = 0;
#ifdef _WIN32
  WIN32_FILE_ATTRIBUTE_DATA fs;
  if (GetFileAttributesExW(Encoding::ToWindowsExtendedPath(filename).c_str(),
                           GetFileExInfoStandard, &fs) != 0) {
    length = (static_cast<unsigned long long>(fs.nFileSizeHigh) << 32) +
      fs.nFileSizeLow;
  }
#else
  struct stat fs;
  if (stat(filename.c_str(), &fs) == 0) {
    length = static_cast<unsigned long long>(fs.st_size);
  }
#endif
  return length;
}

int SystemTools::Strucmp(char const* l, char const* r)
{
  int lc;
  int rc;
  do {
    lc = kwsysString_tolower(*l++);
    rc = kwsysString_tolower(*r++);
  } while (lc == rc && lc);
  return lc - rc;
}

// return file's modified time
long int SystemTools::ModifiedTime(std::string const& filename)
{
  long int mt = 0;
#ifdef _WIN32
  WIN32_FILE_ATTRIBUTE_DATA fs;
  if (GetFileAttributesExW(Encoding::ToWindowsExtendedPath(filename).c_str(),
                           GetFileExInfoStandard, &fs) != 0) {
    mt = windows_filetime_to_posix_time(fs.ftLastWriteTime);
  }
#else
  struct stat fs;
  if (stat(filename.c_str(), &fs) == 0) {
    mt = static_cast<long int>(fs.st_mtime);
  }
#endif
  return mt;
}

// return file's creation time
long int SystemTools::CreationTime(std::string const& filename)
{
  long int ct = 0;
#ifdef _WIN32
  WIN32_FILE_ATTRIBUTE_DATA fs;
  if (GetFileAttributesExW(Encoding::ToWindowsExtendedPath(filename).c_str(),
                           GetFileExInfoStandard, &fs) != 0) {
    ct = windows_filetime_to_posix_time(fs.ftCreationTime);
  }
#else
  struct stat fs;
  if (stat(filename.c_str(), &fs) == 0) {
    ct = fs.st_ctime >= 0 ? static_cast<long int>(fs.st_ctime) : 0;
  }
#endif
  return ct;
}

std::string SystemTools::GetLastSystemError()
{
  int e = errno;
  return strerror(e);
}

Status SystemTools::RemoveFile(std::string const& source)
{
#ifdef _WIN32
  std::wstring const& ws = Encoding::ToWindowsExtendedPath(source);
  if (DeleteFileW(ws.c_str())) {
    return Status::Success();
  }
  DWORD err = GetLastError();
  if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) {
    return Status::Success();
  }
  if (err != ERROR_ACCESS_DENIED) {
    return Status::Windows(err);
  }
  /* The file may be read-only.  Try adding write permission.  */
  mode_t mode;
  if (!SystemTools::GetPermissions(source, mode) ||
      !SystemTools::SetPermissions(source, S_IWRITE)) {
    SetLastError(err);
    return Status::Windows(err);
  }

  const DWORD DIRECTORY_SOFT_LINK_ATTRS =
    FILE_ATTRIBUTE_DIRECTORY | FILE_ATTRIBUTE_REPARSE_POINT;
  DWORD attrs = GetFileAttributesW(ws.c_str());
  if (attrs != INVALID_FILE_ATTRIBUTES &&
      (attrs & DIRECTORY_SOFT_LINK_ATTRS) == DIRECTORY_SOFT_LINK_ATTRS &&
      RemoveDirectoryW(ws.c_str())) {
    return Status::Success();
  }
  if (DeleteFileW(ws.c_str()) || GetLastError() == ERROR_FILE_NOT_FOUND ||
      GetLastError() == ERROR_PATH_NOT_FOUND) {
    return Status::Success();
  }
  /* Try to restore the original permissions.  */
  SystemTools::SetPermissions(source, mode);
  SetLastError(err);
  return Status::Windows(err);
#else
  if (unlink(source.c_str()) != 0 && errno != ENOENT) {
    return Status::POSIX_errno();
  }
  return Status::Success();
#endif
}

Status SystemTools::RemoveADirectory(std::string const& source)
{
  // Add read and write permission to the directory so we can read
  // and modify its content to remove files and directories from it.
  mode_t mode = 0;
  if (SystemTools::GetPermissions(source, mode)) {
#if defined(_WIN32) && !defined(__CYGWIN__)
    mode |= S_IREAD | S_IWRITE;
#else
    mode |= S_IRUSR | S_IWUSR;
#endif
    SystemTools::SetPermissions(source, mode);
  }

  Status status;
  Directory dir;
  status = dir.Load(source);
  if (!status.IsSuccess()) {
    return status;
  }

  size_t fileNum;
  for (fileNum = 0; fileNum < dir.GetNumberOfFiles(); ++fileNum) {
    std::string const& filename = dir.GetFileName(fileNum);
    if (filename != "." && filename != "..") {
      std::string fullPath = source;
      fullPath += '/';
      fullPath += filename;
      if (SystemTools::FileIsDirectory(fullPath) &&
          !SystemTools::FileIsSymlink(fullPath)) {
        status = SystemTools::RemoveADirectory(fullPath);
        if (!status.IsSuccess()) {
          return status;
        }
      } else {
        status = SystemTools::RemoveFile(fullPath);
        if (!status.IsSuccess()) {
          return status;
        }
      }
    }
  }

  if (Rmdir(source) != 0) {
    status = Status::POSIX_errno();
  }
  return status;
}

/**
 */
size_t SystemTools::GetMaximumFilePathLength()
{
  return KWSYS_SYSTEMTOOLS_MAXPATH;
}

/**
 * Find the file the given name.  Searches the given path and then
 * the system search path.  Returns the full path to the file if it is
 * found.  Otherwise, the empty string is returned.
 */
std::string SystemTools::FindNameImpl(
  std::string const& name, std::vector<std::string> const& userPaths,
  bool no_system_path)
{
  // Add the system search path to our path first
  std::vector<std::string> path;
  if (!no_system_path) {
    SystemTools::GetPath(path, "CMAKE_FILE_PATH");
    SystemTools::GetPath(path);
  }
  // now add the additional paths
  path.reserve(path.size() + userPaths.size());
  path.insert(path.end(), userPaths.begin(), userPaths.end());
  // now look for the file
  for (std::string const& p : path) {
    std::string tryPath = p;
    if (tryPath.empty() || tryPath.back() != '/') {
      tryPath += '/';
    }
    tryPath += name;
    if (SystemTools::FileExists(tryPath)) {
      return tryPath;
    }
  }
  // Couldn't find the file.
  return "";
}

/**
 * Find the file the given name.  Searches the given path and then
 * the system search path.  Returns the full path to the file if it is
 * found.  Otherwise, the empty string is returned.
 */
std::string SystemTools::FindFile(std::string const& name,
                                  std::vector<std::string> const& userPaths,
                                  bool no_system_path)
{
  std::string tryPath =
    SystemTools::FindNameImpl(name, userPaths, no_system_path);
  if (!tryPath.empty() && !SystemTools::FileIsDirectory(tryPath)) {
    return SystemTools::CollapseFullPath(tryPath);
  }
  // Couldn't find the file.
  return "";
}

/**
 * Find the directory the given name.  Searches the given path and then
 * the system search path.  Returns the full path to the directory if it is
 * found.  Otherwise, the empty string is returned.
 */
std::string SystemTools::FindDirectory(
  std::string const& name, std::vector<std::string> const& userPaths,
  bool no_system_path)
{
  std::string tryPath =
    SystemTools::FindNameImpl(name, userPaths, no_system_path);
  if (!tryPath.empty() && SystemTools::FileIsDirectory(tryPath)) {
    return SystemTools::CollapseFullPath(tryPath);
  }
  // Couldn't find the file.
  return "";
}

/**
 * Find the executable with the given name.  Searches the given path and then
 * the system search path.  Returns the full path to the executable if it is
 * found.  Otherwise, the empty string is returned.
 */
std::string SystemTools::FindProgram(std::string const& name,
                                     std::vector<std::string> const& userPaths,
                                     bool no_system_path)
{
#if defined(_WIN32) || defined(__CYGWIN__) || defined(__MINGW32__)
  std::vector<std::string> extensions;
  // check to see if the name already has a .xxx at
  // the end of it
  // on windows try .com then .exe
  if (name.size() <= 3 || name[name.size() - 4] != '.') {
    extensions.emplace_back(".com");
    extensions.emplace_back(".exe");

    // first try with extensions if the os supports them
    for (std::string const& ext : extensions) {
      std::string tryPath = name;
      tryPath += ext;
      if (SystemTools::FileIsExecutable(tryPath)) {
        return SystemTools::CollapseFullPath(tryPath);
      }
    }
  }
#endif

  // now try just the name
  if (SystemTools::FileIsExecutable(name)) {
    return SystemTools::CollapseFullPath(name);
  }
  // now construct the path
  std::vector<std::string> path;
  // Add the system search path to our path.
  if (!no_system_path) {
    SystemTools::GetPath(path);
  }
  // now add the additional paths
  path.reserve(path.size() + userPaths.size());
  path.insert(path.end(), userPaths.begin(), userPaths.end());
  // Add a trailing slash to all paths to aid the search process.
  for (std::string& p : path) {
    if (p.empty() || p.back() != '/') {
      p += '/';
    }
  }
  // Try each path
  for (std::string& p : path) {
#ifdef _WIN32
    // Remove double quotes from the path on windows
    SystemTools::ReplaceString(p, "\"", "");
#endif
#if defined(_WIN32) || defined(__CYGWIN__) || defined(__MINGW32__)
    // first try with extensions
    for (std::string const& ext : extensions) {
      std::string tryPath = p;
      tryPath += name;
      tryPath += ext;
      if (SystemTools::FileIsExecutable(tryPath)) {
        return SystemTools::CollapseFullPath(tryPath);
      }
    }
#endif
    // now try it without them
    std::string tryPath = p;
    tryPath += name;
    if (SystemTools::FileIsExecutable(tryPath)) {
      return SystemTools::CollapseFullPath(tryPath);
    }
  }
  // Couldn't find the program.
  return "";
}

std::string SystemTools::GetRealPath(std::string const& path,
                                     std::string* errorMessage)
{
  std::string ret;
  Realpath(path, ret, errorMessage);
  return ret;
}

// Remove any trailing slash from the name except in a root component.
static char const* RemoveTrailingSlashes(
  std::string const& inName, char (&local_buffer)[KWSYS_SYSTEMTOOLS_MAXPATH],
  std::string& string_buffer)
{
  size_t length = inName.size();
  char const* name = inName.c_str();

  if (length == 0) {
    return name;
  }

  size_t last = length - 1;
  if (last > 0 && (name[last] == '/' || name[last] == '\\') &&
      name[last - 1] != ':') {
    if (last < sizeof(local_buffer)) {
      memcpy(local_buffer, name, last);
      local_buffer[last] = '\0';
      name = local_buffer;
    } else {
      string_buffer.append(name, last);
      name = string_buffer.c_str();
    }
  }

  return name;
}

bool SystemTools::FileIsDirectory(std::string const& inName)
{
  if (inName.empty()) {
    return false;
  }

  char local_buffer[KWSYS_SYSTEMTOOLS_MAXPATH];
  std::string string_buffer;
  auto const name = RemoveTrailingSlashes(inName, local_buffer, string_buffer);

// Now check the file node type.
#if defined(_WIN32)
  DWORD attr =
    GetFileAttributesW(Encoding::ToWindowsExtendedPath(name).c_str());
  return (attr != INVALID_FILE_ATTRIBUTES) &&
    (attr & FILE_ATTRIBUTE_DIRECTORY);
#else
  struct stat fs;

  return (stat(name, &fs) == 0) && S_ISDIR(fs.st_mode);
#endif
}

bool SystemTools::FileIsExecutable(std::string const& inName)
{
  if (inName.empty()) {
    return false;
  }

#ifdef _WIN32
  char local_buffer[KWSYS_SYSTEMTOOLS_MAXPATH];
  std::string string_buffer;
  auto const name = RemoveTrailingSlashes(inName, local_buffer, string_buffer);
  auto const attr =
    GetFileAttributesW(Encoding::ToWindowsExtendedPath(name).c_str());

  // On Windows any file that exists and is not a directory is considered
  // readable and therefore also executable:
  return attr != INVALID_FILE_ATTRIBUTES && !(attr & FILE_ATTRIBUTE_DIRECTORY);
#else
  return !FileIsDirectory(inName) && TestFileAccess(inName, TEST_FILE_EXECUTE);
#endif
}

#if defined(_WIN32)
bool SystemTools::FileIsSymlinkWithAttr(std::wstring const& path,
                                        unsigned long attr)
{
  if (attr != INVALID_FILE_ATTRIBUTES) {
    if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) != 0) {
      // FILE_ATTRIBUTE_REPARSE_POINT means:
      // * a file or directory that has an associated reparse point, or
      // * a file that is a symbolic link.
      HANDLE hFile = CreateFileW(
        path.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING,
        FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, nullptr);
      if (hFile == INVALID_HANDLE_VALUE) {
        return false;
      }
      BYTE buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
      DWORD bytesReturned = 0;
      if (!DeviceIoControl(hFile, FSCTL_GET_REPARSE_POINT, nullptr, 0, buffer,
                           MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &bytesReturned,
                           nullptr)) {
        CloseHandle(hFile);
        // Since FILE_ATTRIBUTE_REPARSE_POINT is set this file must be
        // a symbolic link if it is not a reparse point.
        return GetLastError() == ERROR_NOT_A_REPARSE_POINT;
      }
      CloseHandle(hFile);
      ULONG reparseTag =
        reinterpret_cast<PREPARSE_DATA_BUFFER>(&buffer[0])->ReparseTag;
      return (reparseTag == IO_REPARSE_TAG_SYMLINK) ||
        (reparseTag == IO_REPARSE_TAG_MOUNT_POINT);
    }
    return false;
  }

  return false;
}
#endif

bool SystemTools::FileIsSymlink(std::string const& name)
{
#if defined(_WIN32)
  std::wstring path = Encoding::ToWindowsExtendedPath(name);
  return FileIsSymlinkWithAttr(path, GetFileAttributesW(path.c_str()));
#else
  struct stat fs;
  return (lstat(name.c_str(), &fs) == 0) && S_ISLNK(fs.st_mode);
#endif
}

bool SystemTools::FileIsFIFO(std::string const& name)
{
#if defined(_WIN32)
  HANDLE hFile =
    CreateFileW(Encoding::ToWide(name).c_str(), GENERIC_READ, FILE_SHARE_READ,
                nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
  if (hFile == INVALID_HANDLE_VALUE) {
    return false;
  }
  const DWORD type = GetFileType(hFile);
  CloseHandle(hFile);
  return type == FILE_TYPE_PIPE;
#else
  struct stat fs;
  return (lstat(name.c_str(), &fs) == 0) && S_ISFIFO(fs.st_mode);
#endif
}

Status SystemTools::ReadSymlink(std::string const& newName,
                                std::string& origName)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
  std::wstring newPath = Encoding::ToWindowsExtendedPath(newName);
  // FILE_ATTRIBUTE_REPARSE_POINT means:
  // * a file or directory that has an associated reparse point, or
  // * a file that is a symbolic link.
  HANDLE hFile = CreateFileW(
    newPath.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING,
    FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, nullptr);
  if (hFile == INVALID_HANDLE_VALUE) {
    return Status::Windows_GetLastError();
  }
  BYTE buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
  DWORD bytesReturned = 0;
  Status status;
  if (!DeviceIoControl(hFile, FSCTL_GET_REPARSE_POINT, nullptr, 0, buffer,
                       MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &bytesReturned,
                       nullptr)) {
    status = Status::Windows_GetLastError();
  }
  CloseHandle(hFile);
  if (!status.IsSuccess()) {
    return status;
  }
  PREPARSE_DATA_BUFFER data =
    reinterpret_cast<PREPARSE_DATA_BUFFER>(&buffer[0]);
  USHORT substituteNameLength;
  PCWSTR substituteNameData;
  if (data->ReparseTag == IO_REPARSE_TAG_SYMLINK) {
    substituteNameLength =
      data->SymbolicLinkReparseBuffer.SubstituteNameLength / sizeof(WCHAR);
    substituteNameData = data->SymbolicLinkReparseBuffer.PathBuffer +
      data->SymbolicLinkReparseBuffer.SubstituteNameOffset / sizeof(WCHAR);
  } else if (data->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT) {
    substituteNameLength =
      data->MountPointReparseBuffer.SubstituteNameLength / sizeof(WCHAR);
    substituteNameData = data->MountPointReparseBuffer.PathBuffer +
      data->MountPointReparseBuffer.SubstituteNameOffset / sizeof(WCHAR);
  } else if (data->ReparseTag == IO_REPARSE_TAG_APPEXECLINK) {
    // The reparse buffer is a list of 0-terminated non-empty strings,
    // terminated by an empty string (0-0).  We need the third string.
    size_t destLen;
    substituteNameData = GetAppExecLink(data, destLen);
    if (!substituteNameData || destLen == 0) {
      return Status::Windows(ERROR_SYMLINK_NOT_SUPPORTED);
    }
    substituteNameLength = static_cast<USHORT>(destLen);
  } else {
    return Status::Windows(ERROR_REPARSE_TAG_MISMATCH);
  }
  std::wstring substituteName(substituteNameData, substituteNameLength);
  origName = Encoding::ToNarrow(substituteName);
  // Symbolic links to absolute paths may use a NT Object Path prefix.
  // If the path begins with "\??\UNC\", replace it with "\\".
  // Otherwise, if the path begins with "\??\", remove the prefix.
  if (origName.compare(0, 8, "\\??\\UNC\\") == 0) {
    origName.erase(1, 6);
  } else if (origName.compare(0, 4, "\\??\\") == 0) {
    origName.erase(0, 4);
  }
#else
  char buf[KWSYS_SYSTEMTOOLS_MAXPATH + 1];
  int count = static_cast<int>(
    readlink(newName.c_str(), buf, KWSYS_SYSTEMTOOLS_MAXPATH));
  if (count < 0) {
    return Status::POSIX_errno();
  }
  // Add null-terminator.
  buf[count] = 0;
  origName = buf;
#endif
  return Status::Success();
}

Status SystemTools::ChangeDirectory(std::string const& dir)
{
  if (Chdir(dir) < 0) {
    return Status::POSIX_errno();
  }
  return Status::Success();
}

std::string SystemTools::GetCurrentWorkingDirectory()
{
  char buf[2048];
  char const* cwd = Getcwd(buf, 2048);
  std::string path;
  if (cwd) {
    path = cwd;
    SystemTools::ConvertToUnixSlashes(path);
  }
  return path;
}

std::string SystemTools::GetProgramPath(std::string const& in_name)
{
  std::string dir, file;
  SystemTools::SplitProgramPath(in_name, dir, file);
  return dir;
}

bool SystemTools::SplitProgramPath(std::string const& in_name,
                                   std::string& dir, std::string& file, bool)
{
  dir = in_name;
  file.clear();
  SystemTools::ConvertToUnixSlashes(dir);

  if (!SystemTools::FileIsDirectory(dir)) {
    std::string::size_type slashPos = dir.rfind('/');
    if (slashPos != std::string::npos) {
      file = dir.substr(slashPos + 1);
      dir.resize(slashPos);
    } else {
      file = dir;
      dir.clear();
    }
  }
  if (!(dir.empty()) && !SystemTools::FileIsDirectory(dir)) {
    std::string oldDir = in_name;
    SystemTools::ConvertToUnixSlashes(oldDir);
    dir = in_name;
    return false;
  }
  return true;
}

static void SystemToolsAppendComponents(
  std::vector<std::string>& out_components,
  std::vector<std::string>::iterator first,
  std::vector<std::string>::iterator last)
{
  static std::string const up = "..";
  static std::string const cur = ".";
  for (std::vector<std::string>::const_iterator i = first; i != last; ++i) {
    if (*i == up) {
      // Remove the previous component if possible.  Ignore ../ components
      // that try to go above the root.  Keep ../ components if they are
      // at the beginning of a relative path (base path is relative).
      if (out_components.size() > 1 && out_components.back() != up) {
        out_components.resize(out_components.size() - 1);
      } else if (!out_components.empty() && out_components[0].empty()) {
        out_components.emplace_back(std::move(*i));
      }
    } else if (!i->empty() && *i != cur) {
      out_components.emplace_back(std::move(*i));
    }
  }
}

namespace {

std::string CollapseFullPathImpl(std::string const& in_path,
                                 std::string const* in_base)
{
  // Collect the output path components.
  std::vector<std::string> out_components;

  // Split the input path components.
  std::vector<std::string> path_components;
  SystemTools::SplitPath(in_path, path_components);
  out_components.reserve(path_components.size());

  // If the input path is relative, start with a base path.
  if (path_components[0].empty()) {
    std::vector<std::string> base_components;

    if (in_base) {
      // Use the given base path.
      SystemTools::SplitPath(*in_base, base_components);
    } else {
      // Use the current working directory as a base path.
      std::string cwd = SystemTools::GetCurrentWorkingDirectory();
      SystemTools::SplitPath(cwd, base_components);
    }

    // Append base path components to the output path.
    out_components.push_back(base_components[0]);
    SystemToolsAppendComponents(out_components, base_components.begin() + 1,
                                base_components.end());
  }

  // Append input path components to the output path.
  SystemToolsAppendComponents(out_components, path_components.begin(),
                              path_components.end());

  // Transform the path back to a string.
  std::string newPath = SystemTools::JoinPath(out_components);

#ifdef _WIN32
  SystemTools::ConvertToUnixSlashes(newPath);
#endif
  // Return the reconstructed path.
  return newPath;
}
}

std::string SystemTools::CollapseFullPath(std::string const& in_path)
{
  return CollapseFullPathImpl(in_path, nullptr);
}

std::string SystemTools::CollapseFullPath(std::string const& in_path,
                                          char const* in_base)
{
  if (!in_base) {
    return CollapseFullPathImpl(in_path, nullptr);
  }
  std::string tmp_base = in_base;
  return CollapseFullPathImpl(in_path, &tmp_base);
}

std::string SystemTools::CollapseFullPath(std::string const& in_path,
                                          std::string const& in_base)
{
  return CollapseFullPathImpl(in_path, &in_base);
}

// compute the relative path from here to there
std::string SystemTools::RelativePath(std::string const& local,
                                      std::string const& remote)
{
  if (!SystemTools::FileIsFullPath(local)) {
    return "";
  }
  if (!SystemTools::FileIsFullPath(remote)) {
    return "";
  }

  std::string l = SystemTools::CollapseFullPath(local);
  std::string r = SystemTools::CollapseFullPath(remote);

  // split up both paths into arrays of strings using / as a separator
  std::vector<std::string> localSplit = SystemTools::SplitString(l, '/', true);
  std::vector<std::string> remoteSplit =
    SystemTools::SplitString(r, '/', true);
  std::vector<std::string>
    commonPath; // store shared parts of path in this array
  std::vector<std::string> finalPath; // store the final relative path here
  // count up how many matching directory names there are from the start
  unsigned int sameCount = 0;
  while (((sameCount <= (localSplit.size() - 1)) &&
          (sameCount <= (remoteSplit.size() - 1))) &&
// for Windows and Apple do a case insensitive string compare
#if defined(_WIN32) || defined(__APPLE__)
         SystemTools::Strucmp(localSplit[sameCount].c_str(),
                              remoteSplit[sameCount].c_str()) == 0
#else
         localSplit[sameCount] == remoteSplit[sameCount]
#endif
  ) {
    // put the common parts of the path into the commonPath array
    commonPath.push_back(localSplit[sameCount]);
    // erase the common parts of the path from the original path arrays
    localSplit[sameCount] = "";
    remoteSplit[sameCount] = "";
    sameCount++;
  }

  // If there is nothing in common at all then just return the full
  // path.  This is the case only on windows when the paths have
  // different drive letters.  On unix two full paths always at least
  // have the root "/" in common so we will return a relative path
  // that passes through the root directory.
  if (sameCount == 0) {
    return remote;
  }

  // for each entry that is not common in the local path
  // add a ../ to the finalpath array, this gets us out of the local
  // path into the remote dir
  for (std::string const& lp : localSplit) {
    if (!lp.empty()) {
      finalPath.emplace_back("../");
    }
  }
  // for each entry that is not common in the remote path add it
  // to the final path.
  for (std::string const& rp : remoteSplit) {
    if (!rp.empty()) {
      finalPath.push_back(rp);
    }
  }
  std::string relativePath; // result string
  // now turn the array of directories into a unix path by puttint /
  // between each entry that does not already have one
  for (std::string const& fp : finalPath) {
    if (!relativePath.empty() && relativePath.back() != '/') {
      relativePath += '/';
    }
    relativePath += fp;
  }
  return relativePath;
}

char const* SystemTools::SplitPathRootComponent(std::string const& p,
                                                std::string* root)
{
  // Identify the root component.
  char const* c = p.c_str();
  if ((c[0] == '/' && c[1] == '/') || (c[0] == '\\' && c[1] == '\\')) {
    // Network path.
    if (root) {
      *root = "//";
    }
    c += 2;
  } else if (c[0] == '/' || c[0] == '\\') {
    // Unix path (or Windows path w/out drive letter).
    if (root) {
      *root = "/";
    }
    c += 1;
  } else if (c[0] && c[1] == ':' && (c[2] == '/' || c[2] == '\\')) {
    // Windows path.
    if (root) {
      (*root) = "_:/";
      (*root)[0] = c[0];
    }
    c += 3;
  } else if (c[0] && c[1] == ':') {
    // Path relative to a windows drive working directory.
    if (root) {
      (*root) = "_:";
      (*root)[0] = c[0];
    }
    c += 2;
  } else if (c[0] == '~') {
    // Home directory.  The returned root should always have a
    // trailing slash so that appending components as
    // c[0]c[1]/c[2]/... works.  The remaining path returned should
    // skip the first slash if it exists:
    //
    //   "~"    : root = "~/" , return ""
    //   "~/    : root = "~/" , return ""
    //   "~/x   : root = "~/" , return "x"
    //   "~u"   : root = "~u/", return ""
    //   "~u/"  : root = "~u/", return ""
    //   "~u/x" : root = "~u/", return "x"
    size_t n = 1;
    while (c[n] && c[n] != '/') {
      ++n;
    }
    if (root) {
      root->assign(c, n);
      *root += '/';
    }
    if (c[n] == '/') {
      ++n;
    }
    c += n;
  } else {
    // Relative path.
    if (root) {
      *root = "";
    }
  }

  // Return the remaining path.
  return c;
}

void SystemTools::SplitPath(std::string const& p,
                            std::vector<std::string>& components,
                            bool expand_home_dir)
{
  char const* c;
  components.clear();

  // Identify the root component.
  {
    std::string root;
    c = SystemTools::SplitPathRootComponent(p, &root);

    // Expand home directory references if requested.
    if (expand_home_dir && !root.empty() && root[0] == '~') {
      std::string homedir;
      root.resize(root.size() - 1);
      if (root.size() == 1) {
#if defined(_WIN32) && !defined(__CYGWIN__)
        if (!SystemTools::GetEnv("USERPROFILE", homedir))
#endif
          SystemTools::GetEnv("HOME", homedir);
      }
#ifdef HAVE_GETPWNAM
      else if (passwd* pw = getpwnam(root.c_str() + 1)) {
        if (pw->pw_dir) {
          homedir = pw->pw_dir;
        }
      }
#endif
      if (!homedir.empty() &&
          (homedir.back() == '/' || homedir.back() == '\\')) {
        homedir.resize(homedir.size() - 1);
      }
      SystemTools::SplitPath(homedir, components);
    } else {
      components.push_back(root);
    }
  }

  // Parse the remaining components.
  char const* first = c;
  char const* last = first;
  for (; *last; ++last) {
    if (*last == '/' || *last == '\\') {
      // End of a component.  Save it.
      components.emplace_back(first, last);
      first = last + 1;
    }
  }

  // Save the last component unless there were no components.
  if (last != c) {
    components.emplace_back(first, last);
  }
}

std::string SystemTools::JoinPath(std::vector<std::string> const& components)
{
  return SystemTools::JoinPath(components.begin(), components.end());
}

std::string SystemTools::JoinPath(
  std::vector<std::string>::const_iterator first,
  std::vector<std::string>::const_iterator last)
{
  // Construct result in a single string.
  std::string result;
  size_t len = 0;
  for (auto i = first; i != last; ++i) {
    len += 1 + i->size();
  }
  result.reserve(len);

  // The first two components do not add a slash.
  if (first != last) {
    result.append(*first++);
  }
  if (first != last) {
    result.append(*first++);
  }

  // All remaining components are always separated with a slash.
  while (first != last) {
    result.push_back('/');
    result.append((*first++));
  }

  // Return the concatenated result.
  return result;
}

bool SystemTools::ComparePath(std::string const& c1, std::string const& c2)
{
#if defined(_WIN32) || defined(__APPLE__)
#  ifdef _MSC_VER
  return _stricmp(c1.c_str(), c2.c_str()) == 0;
#  elif defined(__APPLE__) || defined(__GNUC__)
  return strcasecmp(c1.c_str(), c2.c_str()) == 0;
#  else
  return SystemTools::Strucmp(c1.c_str(), c2.c_str()) == 0;
#  endif
#else
  return c1 == c2;
#endif
}

bool SystemTools::Split(std::string const& str,
                        std::vector<std::string>& lines, char separator)
{
  std::string data(str);
  std::string::size_type lpos = 0;
  while (lpos < data.length()) {
    std::string::size_type rpos = data.find_first_of(separator, lpos);
    if (rpos == std::string::npos) {
      // String ends at end of string without a separator.
      lines.push_back(data.substr(lpos));
      return false;
    } else {
      // String ends in a separator, remove the character.
      lines.push_back(data.substr(lpos, rpos - lpos));
    }
    lpos = rpos + 1;
  }
  return true;
}

bool SystemTools::Split(std::string const& str,
                        std::vector<std::string>& lines)
{
  std::string data(str);
  std::string::size_type lpos = 0;
  while (lpos < data.length()) {
    std::string::size_type rpos = data.find_first_of('\n', lpos);
    if (rpos == std::string::npos) {
      // Line ends at end of string without a newline.
      lines.push_back(data.substr(lpos));
      return false;
    }
    if ((rpos > lpos) && (data[rpos - 1] == '\r')) {
      // Line ends in a "\r\n" pair, remove both characters.
      lines.push_back(data.substr(lpos, (rpos - 1) - lpos));
    } else {
      // Line ends in a "\n", remove the character.
      lines.push_back(data.substr(lpos, rpos - lpos));
    }
    lpos = rpos + 1;
  }
  return true;
}

std::string SystemTools::Join(std::vector<std::string> const& list,
                              std::string const& separator)
{
  std::string result;
  if (list.empty()) {
    return result;
  }

  size_t total_size = separator.size() * (list.size() - 1);
  for (std::string const& string : list) {
    total_size += string.size();
  }

  result.reserve(total_size);
  bool needs_separator = false;
  for (std::string const& string : list) {
    if (needs_separator) {
      result += separator;
    }
    result += string;
    needs_separator = true;
  }

  return result;
}

/**
 * Return path of a full filename (no trailing slashes).
 * Warning: returned path is converted to Unix slashes format.
 */
std::string SystemTools::GetFilenamePath(std::string const& filename)
{
  std::string fn = filename;
  SystemTools::ConvertToUnixSlashes(fn);

  std::string::size_type slash_pos = fn.rfind('/');
  if (slash_pos == 0) {
    return "/";
  }
  if (slash_pos == 2 && fn[1] == ':') {
    // keep the / after a drive letter
    fn.resize(3);
    return fn;
  }
  if (slash_pos == std::string::npos) {
    return "";
  }
  fn.resize(slash_pos);
  return fn;
}

/**
 * Return file name of a full filename (i.e. file name without path).
 */
std::string SystemTools::GetFilenameName(std::string const& filename)
{
#if defined(_WIN32) || defined(KWSYS_SYSTEMTOOLS_SUPPORT_WINDOWS_SLASHES)
  char const* separators = "/\\";
#else
  char separators = '/';
#endif
  std::string::size_type slash_pos = filename.find_last_of(separators);
  if (slash_pos != std::string::npos) {
    return filename.substr(slash_pos + 1);
  } else {
    return filename;
  }
}

/**
 * Return file extension of a full filename (dot included).
 * Warning: this is the longest extension (for example: .tar.gz)
 */
std::string SystemTools::GetFilenameExtension(std::string const& filename)
{
  std::string name = SystemTools::GetFilenameName(filename);
  std::string::size_type dot_pos = name.find('.');
  if (dot_pos != std::string::npos) {
    name.erase(0, dot_pos);
    return name;
  } else {
    return "";
  }
}

/**
 * Return file extension of a full filename (dot included).
 * Warning: this is the shortest extension (for example: .gz of .tar.gz)
 */
std::string SystemTools::GetFilenameLastExtension(std::string const& filename)
{
  std::string name = SystemTools::GetFilenameName(filename);
  std::string::size_type dot_pos = name.rfind('.');
  if (dot_pos != std::string::npos) {
    name.erase(0, dot_pos);
    return name;
  } else {
    return "";
  }
}

/**
 * Return file name without extension of a full filename (i.e. without path).
 * Warning: it considers the longest extension (for example: .tar.gz)
 */
std::string SystemTools::GetFilenameWithoutExtension(
  std::string const& filename)
{
  std::string name = SystemTools::GetFilenameName(filename);
  std::string::size_type dot_pos = name.find('.');
  if (dot_pos != std::string::npos) {
    name.resize(dot_pos);
  }
  return name;
}

/**
 * Return file name without extension of a full filename (i.e. without path).
 * Warning: it considers the last extension (for example: removes .gz
 * from .tar.gz)
 */
std::string SystemTools::GetFilenameWithoutLastExtension(
  std::string const& filename)
{
  std::string name = SystemTools::GetFilenameName(filename);
  std::string::size_type dot_pos = name.rfind('.');
  if (dot_pos != std::string::npos) {
    name.resize(dot_pos);
  }
  return name;
}

bool SystemTools::FileHasSignature(char const* filename, char const* signature,
                                   long offset)
{
  if (!filename || !signature) {
    return false;
  }

  FILE* fp = Fopen(filename, "rb");
  if (!fp) {
    return false;
  }

  fseek(fp, offset, SEEK_SET);

  bool res = false;
  size_t signature_len = strlen(signature);
  char* buffer = new char[signature_len];

  if (fread(buffer, 1, signature_len, fp) == signature_len) {
    res = (!strncmp(buffer, signature, signature_len) ? true : false);
  }

  delete[] buffer;

  fclose(fp);
  return res;
}

SystemTools::FileTypeEnum SystemTools::DetectFileType(char const* filename,
                                                      unsigned long length,
                                                      double percent_bin)
{
  if (!filename || percent_bin < 0) {
    return SystemTools::FileTypeUnknown;
  }

  if (SystemTools::FileIsDirectory(filename)) {
    return SystemTools::FileTypeUnknown;
  }

  FILE* fp = Fopen(filename, "rb");
  if (!fp) {
    return SystemTools::FileTypeUnknown;
  }

  // Allocate buffer and read bytes

  auto* buffer = new unsigned char[length];
  size_t read_length = fread(buffer, 1, length, fp);
  fclose(fp);
  if (read_length == 0) {
    delete[] buffer;
    return SystemTools::FileTypeUnknown;
  }

  // Loop over contents and count

  size_t text_count = 0;

  unsigned char const* ptr = buffer;
  unsigned char const* buffer_end = buffer + read_length;

  while (ptr != buffer_end) {
    if ((*ptr >= 0x20 && *ptr <= 0x7F) || *ptr == '\n' || *ptr == '\r' ||
        *ptr == '\t') {
      text_count++;
    }
    ptr++;
  }

  delete[] buffer;

  double current_percent_bin = (static_cast<double>(read_length - text_count) /
                                static_cast<double>(read_length));

  if (current_percent_bin >= percent_bin) {
    return SystemTools::FileTypeBinary;
  }

  return SystemTools::FileTypeText;
}

bool SystemTools::LocateFileInDir(char const* filename, char const* dir,
                                  std::string& filename_found,
                                  int try_filename_dirs)
{
  if (!filename || !dir) {
    return false;
  }

  // Get the basename of 'filename'

  std::string filename_base = SystemTools::GetFilenameName(filename);

  // Check if 'dir' is really a directory
  // If win32 and matches something like C:, accept it as a dir

  std::string real_dir;
  if (!SystemTools::FileIsDirectory(dir)) {
#if defined(_WIN32)
    size_t dir_len = strlen(dir);
    if (dir_len < 2 || dir[dir_len - 1] != ':') {
#endif
      real_dir = SystemTools::GetFilenamePath(dir);
      dir = real_dir.c_str();
#if defined(_WIN32)
    }
#endif
  }

  // Try to find the file in 'dir'

  bool res = false;
  if (!filename_base.empty() && dir) {
    size_t dir_len = strlen(dir);
    int need_slash =
      (dir_len && dir[dir_len - 1] != '/' && dir[dir_len - 1] != '\\');

    std::string temp = dir;
    if (need_slash) {
      temp += '/';
    }
    temp += filename_base;

    if (SystemTools::FileExists(temp)) {
      res = true;
      filename_found = temp;
    }

    // If not found, we can try harder by appending part of the file to
    // to the directory to look inside.
    // Example: if we were looking for /foo/bar/yo.txt in /d1/d2, then
    // try to find yo.txt in /d1/d2/bar, then /d1/d2/foo/bar, etc.

    else if (try_filename_dirs) {
      std::string filename_dir(filename);
      std::string filename_dir_base;
      std::string filename_dir_bases;
      do {
        filename_dir = SystemTools::GetFilenamePath(filename_dir);
        filename_dir_base = SystemTools::GetFilenameName(filename_dir);
#if defined(_WIN32)
        if (filename_dir_base.empty() || filename_dir_base.back() == ':')
#else
        if (filename_dir_base.empty())
#endif
        {
          break;
        }

        filename_dir_bases = filename_dir_base + '/' + filename_dir_bases;

        temp = dir;
        if (need_slash) {
          temp += '/';
        }
        temp += filename_dir_bases;

        res = SystemTools::LocateFileInDir(filename_base.c_str(), temp.c_str(),
                                           filename_found, 0);

      } while (!res && !filename_dir_base.empty());
    }
  }

  return res;
}

namespace {
bool FileIsFullPathImpl(char const* in_name, size_t len)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
  // On Windows, the name must be at least two characters long.
  if (len < 2) {
    return false;
  }
  if (in_name[1] == ':') {
    return true;
  }
  if (in_name[0] == '\\') {
    return true;
  }
#else
  // On UNIX, the name must be at least one character long.
  if (len < 1) {
    return false;
  }
#endif
#if !defined(_WIN32)
  if (in_name[0] == '~') {
    return true;
  }
#endif
  // On UNIX, the name must begin in a '/'.
  // On Windows, if the name begins in a '/', then it is a full
  // network path.
  if (in_name[0] == '/') {
    return true;
  }
  return false;
}
}

bool SystemTools::FileIsFullPath(std::string const& in_name)
{
  return FileIsFullPathImpl(in_name.c_str(), in_name.size());
}

bool SystemTools::FileIsFullPath(char const* in_name)
{
  return FileIsFullPathImpl(in_name, in_name[0] ? (in_name[1] ? 2 : 1) : 0);
}

Status SystemTools::GetShortPath(std::string const& path,
                                 std::string& shortPath)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
  std::string tempPath = path; // create a buffer

  // if the path passed in has quotes around it, first remove the quotes
  if (!path.empty() && path[0] == '"' && path.back() == '"') {
    tempPath.resize(path.length() - 1);
    tempPath.erase(0, 1);
  }

  std::wstring wtempPath = Encoding::ToWide(tempPath);
  DWORD ret = GetShortPathNameW(wtempPath.c_str(), nullptr, 0);
  std::vector<wchar_t> buffer(ret);
  if (ret != 0) {
    ret = GetShortPathNameW(wtempPath.c_str(), &buffer[0],
                            static_cast<DWORD>(buffer.size()));
  }

  if (ret == 0) {
    return Status::Windows_GetLastError();
  } else {
    shortPath = Encoding::ToNarrow(&buffer[0]);
    return Status::Success();
  }
#else
  shortPath = path;
  return Status::Success();
#endif
}

std::tm SystemTools::LocalTime(std::time_t timep)
{
  std::tm out;
#if defined(_WIN32) && !defined(__CYGWIN__)
  localtime_s(&out, &timep);
#else
  localtime_r(&timep, &out);
#endif
  return out;
}

std::tm SystemTools::GMTime(std::time_t timep)
{
  std::tm out;
#if defined(_WIN32) && !defined(__CYGWIN__)
  gmtime_s(&out, &timep);
#else
  gmtime_r(&timep, &out);
#endif
  return out;
}

std::string SystemTools::GetCurrentDateTime(char const* format)
{
  char buf[1024];
  tm const t = LocalTime(std::time(nullptr));
  strftime(buf, sizeof(buf), format, &t);
  return std::string(buf);
}

std::string SystemTools::MakeCidentifier(std::string const& s)
{
  std::string str(s);
  if (str.find_first_of("0123456789") == 0) {
    str = '_' + str;
  }

  std::string permited_chars("_"
                             "abcdefghijklmnopqrstuvwxyz"
                             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                             "0123456789");
  std::string::size_type pos = 0;
  while ((pos = str.find_first_not_of(permited_chars, pos)) !=
         std::string::npos) {
    str[pos] = '_';
  }
  return str;
}

// Convenience function around std::getline which removes a trailing carriage
// return and can truncate the buffer as needed.  Returns true
// if any data were read before the end-of-file was reached.
bool SystemTools::GetLineFromStream(
  std::istream& is, std::string& line, bool* has_newline /* = 0 */,
  std::string::size_type sizeLimit /* = std::string::npos */)
{
  // Start with an empty line.
  line = "";

  // Early short circuit return if stream is no good. Just return
  // false and the empty line. (Probably means caller tried to
  // create a file stream with a non-existent file name...)
  //
  if (!is) {
    if (has_newline) {
      *has_newline = false;
    }
    return false;
  }

  std::getline(is, line);
  bool haveData = !line.empty() || !is.eof();
  if (!line.empty()) {
    // Avoid storing a carriage return character.
    if (line.back() == '\r') {
      line.resize(line.size() - 1);
    }

    // if we read too much then truncate the buffer
    if (sizeLimit != std::string::npos && line.size() > sizeLimit) {
      line.resize(sizeLimit);
    }
  }

  // Return the results.
  if (has_newline) {
    *has_newline = !is.eof();
  }
  return haveData;
}

int SystemTools::GetTerminalWidth()
{
  int width = -1;
#ifdef HAVE_TTY_INFO
  struct winsize ws;
  std::string columns; /* Unix98 environment variable */
  if (ioctl(1, TIOCGWINSZ, &ws) != -1 && ws.ws_col > 0 && ws.ws_row > 0) {
    width = ws.ws_col;
  }
  if (!isatty(STDOUT_FILENO)) {
    width = -1;
  }
  if (SystemTools::GetEnv("COLUMNS", columns) && !columns.empty()) {
    long t;
    char* endptr;
    t = strtol(columns.c_str(), &endptr, 0);
    if (endptr && !*endptr && (t > 0) && (t < 1000)) {
      width = static_cast<int>(t);
    }
  }
  if (width < 9) {
    width = -1;
  }
#endif
  return width;
}

Status SystemTools::GetPermissions(char const* file, mode_t& mode)
{
  if (!file) {
    return Status::POSIX(EINVAL);
  }
  return SystemTools::GetPermissions(std::string(file), mode);
}

Status SystemTools::GetPermissions(std::string const& file, mode_t& mode)
{
#if defined(_WIN32)
  DWORD attr =
    GetFileAttributesW(Encoding::ToWindowsExtendedPath(file).c_str());
  if (attr == INVALID_FILE_ATTRIBUTES) {
    return Status::Windows_GetLastError();
  }
  if ((attr & FILE_ATTRIBUTE_READONLY) != 0) {
    mode = (_S_IREAD | (_S_IREAD >> 3) | (_S_IREAD >> 6));
  } else {
    mode = (_S_IWRITE | (_S_IWRITE >> 3) | (_S_IWRITE >> 6)) |
      (_S_IREAD | (_S_IREAD >> 3) | (_S_IREAD >> 6));
  }
  if ((attr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
    mode |= S_IFDIR | (_S_IEXEC | (_S_IEXEC >> 3) | (_S_IEXEC >> 6));
  } else {
    mode |= S_IFREG;
  }
  size_t dotPos = file.rfind('.');
  char const* ext = dotPos == std::string::npos ? 0 : (file.c_str() + dotPos);
  if (ext &&
      (Strucmp(ext, ".exe") == 0 || Strucmp(ext, ".com") == 0 ||
       Strucmp(ext, ".cmd") == 0 || Strucmp(ext, ".bat") == 0)) {
    mode |= (_S_IEXEC | (_S_IEXEC >> 3) | (_S_IEXEC >> 6));
  }
#else
  struct stat st;
  if (stat(file.c_str(), &st) < 0) {
    return Status::POSIX_errno();
  }
  mode = st.st_mode;
#endif
  return Status::Success();
}

Status SystemTools::SetPermissions(char const* file, mode_t mode,
                                   bool honor_umask)
{
  if (!file) {
    return Status::POSIX(EINVAL);
  }
  return SystemTools::SetPermissions(std::string(file), mode, honor_umask);
}

Status SystemTools::SetPermissions(std::string const& file, mode_t mode,
                                   bool honor_umask)
{
  if (!SystemTools::PathExists(file)) {
    return Status::POSIX(ENOENT);
  }
  if (honor_umask) {
    mode_t currentMask = umask(0);
    umask(currentMask);
    mode &= ~currentMask;
  }
#ifdef _WIN32
  if (_wchmod(Encoding::ToWindowsExtendedPath(file).c_str(), mode) < 0)
#else
  if (chmod(file.c_str(), mode) < 0)
#endif
  {
    return Status::POSIX_errno();
  }

  return Status::Success();
}

std::string SystemTools::GetParentDirectory(std::string const& fileOrDir)
{
  return SystemTools::GetFilenamePath(fileOrDir);
}

bool SystemTools::IsSubDirectory(std::string const& cSubdir,
                                 std::string const& cDir)
{
  if (cDir.empty()) {
    return false;
  }
  std::string subdir = cSubdir;
  std::string dir = cDir;
  SystemTools::ConvertToUnixSlashes(subdir);
  SystemTools::ConvertToUnixSlashes(dir);
  if (subdir.size() <= dir.size() || dir.empty()) {
    return false;
  }
  bool isRootPath = dir.back() == '/'; // like "/" or "C:/"
  size_t expectedSlashPosition = isRootPath ? dir.size() - 1u : dir.size();
  if (subdir[expectedSlashPosition] != '/') {
    return false;
  }
  subdir.resize(dir.size());
  return SystemTools::ComparePath(subdir, dir);
}

void SystemTools::Delay(unsigned int msec)
{
#ifdef _WIN32
  Sleep(msec);
#else
  // The sleep function gives 1 second resolution and the usleep
  // function gives 1e-6 second resolution but on some platforms has a
  // maximum sleep time of 1 second.  This could be re-implemented to
  // use select with masked signals or pselect to mask signals
  // atomically.  If select is given empty sets and zero as the max
  // file descriptor but a non-zero timeout it can be used to block
  // for a precise amount of time.
  if (msec >= 1000) {
    sleep(msec / 1000);
    usleep((msec % 1000) * 1000);
  } else {
    usleep(msec * 1000);
  }
#endif
}

std::string SystemTools::GetOperatingSystemNameAndVersion()
{
  std::string res;

#ifdef _WIN32
  char buffer[256];

  OSVERSIONINFOEXA osvi;
  BOOL bOsVersionInfoEx;

  ZeroMemory(&osvi, sizeof(osvi));
  osvi.dwOSVersionInfoSize = sizeof(osvi);

#  ifdef KWSYS_WINDOWS_DEPRECATED_GetVersionEx
#    pragma warning(push)
#    ifdef __INTEL_COMPILER
#      pragma warning(disable : 1478)
#    elif defined __clang__
#      pragma clang diagnostic push
#      pragma clang diagnostic ignored "-Wdeprecated-declarations"
#    else
#      pragma warning(disable : 4996)
#    endif
#  endif
  bOsVersionInfoEx = GetVersionExA((OSVERSIONINFOA*)&osvi);
  if (!bOsVersionInfoEx) {
    return "";
  }
#  ifdef KWSYS_WINDOWS_DEPRECATED_GetVersionEx
#    ifdef __clang__
#      pragma clang diagnostic pop
#    else
#      pragma warning(pop)
#    endif
#  endif

  switch (osvi.dwPlatformId) {
      // Test for the Windows NT product family.

    case VER_PLATFORM_WIN32_NT:

      // Test for the specific product family.
      if (osvi.dwMajorVersion == 10 && osvi.dwMinorVersion == 0) {
        if (osvi.wProductType == VER_NT_WORKSTATION) {
          res += "Microsoft Windows 10";
        } else {
          res += "Microsoft Windows Server 2016 family";
        }
      }

      if (osvi.dwMajorVersion == 6 && osvi.dwMinorVersion == 3) {
        if (osvi.wProductType == VER_NT_WORKSTATION) {
          res += "Microsoft Windows 8.1";
        } else {
          res += "Microsoft Windows Server 2012 R2 family";
        }
      }

      if (osvi.dwMajorVersion == 6 && osvi.dwMinorVersion == 2) {
        if (osvi.wProductType == VER_NT_WORKSTATION) {
          res += "Microsoft Windows 8";
        } else {
          res += "Microsoft Windows Server 2012 family";
        }
      }

      if (osvi.dwMajorVersion == 6 && osvi.dwMinorVersion == 1) {
        if (osvi.wProductType == VER_NT_WORKSTATION) {
          res += "Microsoft Windows 7";
        } else {
          res += "Microsoft Windows Server 2008 R2 family";
        }
      }

      if (osvi.dwMajorVersion == 6 && osvi.dwMinorVersion == 0) {
        if (osvi.wProductType == VER_NT_WORKSTATION) {
          res += "Microsoft Windows Vista";
        } else {
          res += "Microsoft Windows Server 2008 family";
        }
      }

      if (osvi.dwMajorVersion == 5 && osvi.dwMinorVersion == 2) {
        res += "Microsoft Windows Server 2003 family";
      }

      if (osvi.dwMajorVersion == 5 && osvi.dwMinorVersion == 1) {
        res += "Microsoft Windows XP";
      }

      if (osvi.dwMajorVersion == 5 && osvi.dwMinorVersion == 0) {
        res += "Microsoft Windows 2000";
      }

      if (osvi.dwMajorVersion <= 4) {
        res += "Microsoft Windows NT";
      }

      // Test for specific product on Windows NT 4.0 SP6 and later.

      if (bOsVersionInfoEx) {
        // Test for the workstation type.

        if (osvi.wProductType == VER_NT_WORKSTATION) {
          if (osvi.dwMajorVersion == 4) {
            res += " Workstation 4.0";
          } else if (osvi.dwMajorVersion == 5) {
            if (osvi.wSuiteMask & VER_SUITE_PERSONAL) {
              res += " Home Edition";
            } else {
              res += " Professional";
            }
          }
        }

        // Test for the server type.

        else if (osvi.wProductType == VER_NT_SERVER) {
          if (osvi.dwMajorVersion == 5 && osvi.dwMinorVersion == 2) {
            if (osvi.wSuiteMask & VER_SUITE_DATACENTER) {
              res += " Datacenter Edition";
            } else if (osvi.wSuiteMask & VER_SUITE_ENTERPRISE) {
              res += " Enterprise Edition";
            } else if (osvi.wSuiteMask == VER_SUITE_BLADE) {
              res += " Web Edition";
            } else {
              res += " Standard Edition";
            }
          }

          else if (osvi.dwMajorVersion == 5 && osvi.dwMinorVersion == 0) {
            if (osvi.wSuiteMask & VER_SUITE_DATACENTER) {
              res += " Datacenter Server";
            } else if (osvi.wSuiteMask & VER_SUITE_ENTERPRISE) {
              res += " Advanced Server";
            } else {
              res += " Server";
            }
          }

          else if (osvi.dwMajorVersion <= 4) // Windows NT 4.0
          {
            if (osvi.wSuiteMask & VER_SUITE_ENTERPRISE) {
              res += " Server 4.0, Enterprise Edition";
            } else {
              res += " Server 4.0";
            }
          }
        }
      }

      // Test for specific product on Windows NT 4.0 SP5 and earlier

      else {
        HKEY hKey;
#  define BUFSIZE 80
        wchar_t szProductType[BUFSIZE];
        DWORD dwBufLen = BUFSIZE;
        LONG lRet;

        lRet =
          RegOpenKeyExW(HKEY_LOCAL_MACHINE,
                        L"SYSTEM\\CurrentControlSet\\Control\\ProductOptions",
                        0, KEY_QUERY_VALUE, &hKey);
        if (lRet != ERROR_SUCCESS) {
          return "";
        }

        lRet = RegQueryValueExW(hKey, L"ProductType", nullptr, nullptr,
                                (LPBYTE)szProductType, &dwBufLen);

        if ((lRet != ERROR_SUCCESS) || (dwBufLen > BUFSIZE)) {
          return "";
        }

        RegCloseKey(hKey);

        if (lstrcmpiW(L"WINNT", szProductType) == 0) {
          res += " Workstation";
        }
        if (lstrcmpiW(L"LANMANNT", szProductType) == 0) {
          res += " Server";
        }
        if (lstrcmpiW(L"SERVERNT", szProductType) == 0) {
          res += " Advanced Server";
        }

        res += ' ';
        snprintf(buffer, sizeof(buffer), "%ld", osvi.dwMajorVersion);
        res += buffer;
        res += '.';
        snprintf(buffer, sizeof(buffer), "%ld", osvi.dwMinorVersion);
        res += buffer;
      }

      // Display service pack (if any) and build number.

      if (osvi.dwMajorVersion == 4 &&
          lstrcmpiA(osvi.szCSDVersion, "Service Pack 6") == 0) {
        HKEY hKey;
        LONG lRet;

        // Test for SP6 versus SP6a.

        lRet = RegOpenKeyExW(
          HKEY_LOCAL_MACHINE,
          L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Hotfix\\Q246009",
          0, KEY_QUERY_VALUE, &hKey);

        if (lRet == ERROR_SUCCESS) {
          res += " Service Pack 6a (Build ";
          snprintf(buffer, sizeof(buffer), "%ld", osvi.dwBuildNumber & 0xFFFF);
          res += buffer;
          res += ')';
        } else // Windows NT 4.0 prior to SP6a
        {
          res += ' ';
          res += osvi.szCSDVersion;
          res += " (Build ";
          snprintf(buffer, sizeof(buffer), "%ld", osvi.dwBuildNumber & 0xFFFF);
          res += buffer;
          res += ')';
        }

        RegCloseKey(hKey);
      } else // Windows NT 3.51 and earlier or Windows 2000 and later
      {
        res += ' ';
        res += osvi.szCSDVersion;
        res += " (Build ";
        snprintf(buffer, sizeof(buffer), "%ld", osvi.dwBuildNumber & 0xFFFF);
        res += buffer;
        res += ')';
      }

      break;

      // Test for the Windows 95 product family.

    case VER_PLATFORM_WIN32_WINDOWS:

      if (osvi.dwMajorVersion == 4 && osvi.dwMinorVersion == 0) {
        res += "Microsoft Windows 95";
        if (osvi.szCSDVersion[1] == 'C' || osvi.szCSDVersion[1] == 'B') {
          res += " OSR2";
        }
      }

      if (osvi.dwMajorVersion == 4 && osvi.dwMinorVersion == 10) {
        res += "Microsoft Windows 98";
        if (osvi.szCSDVersion[1] == 'A') {
          res += " SE";
        }
      }

      if (osvi.dwMajorVersion == 4 && osvi.dwMinorVersion == 90) {
        res += "Microsoft Windows Millennium Edition";
      }
      break;

    case VER_PLATFORM_WIN32s:

      res += "Microsoft Win32s";
      break;
  }
#endif

  return res;
}

bool SystemTools::ParseURLProtocol(std::string const& URL,
                                   std::string& protocol,
                                   std::string& dataglom, bool decode)
{
  // match 0 entire url
  // match 1 protocol
  // match 2 dataglom following protocol://
  kwsys::RegularExpression urlRe(VTK_URL_PROTOCOL_REGEX);

  if (!urlRe.find(URL))
    return false;

  protocol = urlRe.match(1);
  dataglom = urlRe.match(2);

  if (decode) {
    dataglom = DecodeURL(dataglom);
  }

  return true;
}

bool SystemTools::ParseURL(std::string const& URL, std::string& protocol,
                           std::string& username, std::string& password,
                           std::string& hostname, std::string& dataport,
                           std::string& database, bool decode)
{
  kwsys::RegularExpression urlRe(VTK_URL_REGEX);
  if (!urlRe.find(URL))
    return false;

  // match 0 URL
  // match 1 protocol
  // match 2 mangled user
  // match 3 username
  // match 4 mangled password
  // match 5 password
  // match 6 hostname
  // match 7 mangled port
  // match 8 dataport
  // match 9 database name

  protocol = urlRe.match(1);
  username = urlRe.match(3);
  password = urlRe.match(5);
  hostname = urlRe.match(6);
  dataport = urlRe.match(8);
  database = urlRe.match(9);

  if (decode) {
    username = DecodeURL(username);
    password = DecodeURL(password);
    hostname = DecodeURL(hostname);
    dataport = DecodeURL(dataport);
    database = DecodeURL(database);
  }

  return true;
}

// ----------------------------------------------------------------------
std::string SystemTools::DecodeURL(std::string const& url)
{
  kwsys::RegularExpression urlByteRe(VTK_URL_BYTE_REGEX);
  std::string ret;
  for (size_t i = 0; i < url.length(); i++) {
    if (urlByteRe.find(url.substr(i, 3))) {
      char bytes[] = { url[i + 1], url[i + 2], '\0' };
      ret += static_cast<char>(strtoul(bytes, nullptr, 16));
      i += 2;
    } else {
      ret += url[i];
    }
  }
  return ret;
}

#if defined(__VMS) || defined(_WIN32)
#  define KWSYS_NEED_SYSTEM_TOOLS_MANAGER 1
#else
#  define KWSYS_NEED_SYSTEM_TOOLS_MANAGER 0
#endif

#if KWSYS_NEED_SYSTEM_TOOLS_MANAGER
// ----------------------------------------------------------------------
// Do NOT initialize.  Default initialization to zero is necessary.
static unsigned int SystemToolsManagerCount;

// SystemToolsManager manages the SystemTools singleton.
// SystemToolsManager should be included in any translation unit
// that will use SystemTools or that implements the singleton
// pattern. It makes sure that the SystemTools singleton is created
// before and destroyed after all other singletons in CMake.

SystemToolsManager::SystemToolsManager()
{
  if (++SystemToolsManagerCount == 1) {
    SystemTools::ClassInitialize();
  }
}

SystemToolsManager::~SystemToolsManager()
{
  if (--SystemToolsManagerCount == 0) {
    SystemTools::ClassFinalize();
  }
}

#  if defined(__VMS)
// On VMS we configure the run time C library to be more UNIX like.
// https://h71000.www7.hp.com/doc/732final/5763/5763pro_004.html
extern "C" int decc$feature_get_index(char* name);
extern "C" int decc$feature_set_value(int index, int mode, int value);
static int SetVMSFeature(char* name, int value)
{
  int i;
  errno = 0;
  i = decc$feature_get_index(name);
  return i >= 0 && (decc$feature_set_value(i, 1, value) >= 0 || errno == 0);
}
#  endif

void SystemTools::ClassInitialize()
{
#  ifdef __VMS
  SetVMSFeature("DECC$FILENAME_UNIX_ONLY", 1);
#  endif

#  ifdef _WIN32
  // Create statics singleton instance
  SystemToolsStatics = new SystemToolsStatic;
#  endif
}

void SystemTools::ClassFinalize()
{
#  ifdef _WIN32
  delete SystemToolsStatics;
#  endif
}
#endif

} // namespace KWSYS_NAMESPACE

#if defined(_MSC_VER) && defined(_DEBUG)
#  include <crtdbg.h>
#  include <stdio.h>
#  include <stdlib.h>
namespace KWSYS_NAMESPACE {

static int SystemToolsDebugReport(int, char* message, int* ret)
{
  if (ret) {
    // Pretend user clicked on Retry button in popup.
    *ret = 1;
  }
  fprintf(stderr, "%s", message);
  fflush(stderr);
  return 1; // no further reporting required
}

void SystemTools::EnableMSVCDebugHook()
{
  if (SystemTools::HasEnv("DART_TEST_FROM_DART") ||
      SystemTools::HasEnv("DASHBOARD_TEST_FROM_CTEST")) {
    _CrtSetReportHook(SystemToolsDebugReport);
  }
}

} // namespace KWSYS_NAMESPACE
#else
namespace KWSYS_NAMESPACE {
void SystemTools::EnableMSVCDebugHook()
{
}
} // namespace KWSYS_NAMESPACE
#endif