lib/strcase.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#include <curl/curl.h>

#include "strcase.h"

static char raw_tolower(char in);

/* Portable, consistent toupper (remember EBCDIC). Do not use toupper() because
   its behavior is altered by the current locale. */
char Curl_raw_toupper(char in)
{
#if !defined(CURL_DOES_CONVERSIONS)
  if(in >= 'a' && in <= 'z')
    return (char)('A' + in - 'a');
#else
  switch(in) {
  case 'a':
    return 'A';
  case 'b':
    return 'B';
  case 'c':
    return 'C';
  case 'd':
    return 'D';
  case 'e':
    return 'E';
  case 'f':
    return 'F';
  case 'g':
    return 'G';
  case 'h':
    return 'H';
  case 'i':
    return 'I';
  case 'j':
    return 'J';
  case 'k':
    return 'K';
  case 'l':
    return 'L';
  case 'm':
    return 'M';
  case 'n':
    return 'N';
  case 'o':
    return 'O';
  case 'p':
    return 'P';
  case 'q':
    return 'Q';
  case 'r':
    return 'R';
  case 's':
    return 'S';
  case 't':
    return 'T';
  case 'u':
    return 'U';
  case 'v':
    return 'V';
  case 'w':
    return 'W';
  case 'x':
    return 'X';
  case 'y':
    return 'Y';
  case 'z':
    return 'Z';
  }
#endif

  return in;
}


/* Portable, consistent tolower (remember EBCDIC). Do not use tolower() because
   its behavior is altered by the current locale. */
static char raw_tolower(char in)
{
#if !defined(CURL_DOES_CONVERSIONS)
  if(in >= 'A' && in <= 'Z')
    return (char)('a' + in - 'A');
#else
  switch(in) {
  case 'A':
    return 'a';
  case 'B':
    return 'b';
  case 'C':
    return 'c';
  case 'D':
    return 'd';
  case 'E':
    return 'e';
  case 'F':
    return 'f';
  case 'G':
    return 'g';
  case 'H':
    return 'h';
  case 'I':
    return 'i';
  case 'J':
    return 'j';
  case 'K':
    return 'k';
  case 'L':
    return 'l';
  case 'M':
    return 'm';
  case 'N':
    return 'n';
  case 'O':
    return 'o';
  case 'P':
    return 'p';
  case 'Q':
    return 'q';
  case 'R':
    return 'r';
  case 'S':
    return 's';
  case 'T':
    return 't';
  case 'U':
    return 'u';
  case 'V':
    return 'v';
  case 'W':
    return 'w';
  case 'X':
    return 'x';
  case 'Y':
    return 'y';
  case 'Z':
    return 'z';
  }
#endif

  return in;
}


/*
 * Curl_strcasecompare() is for doing "raw" case insensitive strings. This is
 * meant to be locale independent and only compare strings we know are safe
 * for this.  See
 * https://daniel.haxx.se/blog/2008/10/15/strcasecmp-in-turkish/ for some
 * further explanation to why this function is necessary.
 *
 * The function is capable of comparing a-z case insensitively even for
 * non-ascii.
 *
 * @unittest: 1301
 */

int Curl_strcasecompare(const char *first, const char *second)
{
  while(*first && *second) {
    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second))
      /* get out of the loop as soon as they don't match */
      break;
    first++;
    second++;
  }
  /* we do the comparison here (possibly again), just to make sure that if the
     loop above is skipped because one of the strings reached zero, we must not
     return this as a successful match */
  return (Curl_raw_toupper(*first) == Curl_raw_toupper(*second));
}

int Curl_safe_strcasecompare(const char *first, const char *second)
{
  if(first && second)
    /* both pointers point to something then compare them */
    return Curl_strcasecompare(first, second);

  /* if both pointers are NULL then treat them as equal */
  return (NULL == first && NULL == second);
}

/*
 * @unittest: 1301
 */
int Curl_strncasecompare(const char *first, const char *second, size_t max)
{
  while(*first && *second && max) {
    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second)) {
      break;
    }
    max--;
    first++;
    second++;
  }
  if(0 == max)
    return 1; /* they are equal this far */

  return Curl_raw_toupper(*first) == Curl_raw_toupper(*second);
}

/* Copy an upper case version of the string from src to dest.  The
 * strings may overlap.  No more than n characters of the string are copied
 * (including any NUL) and the destination string will NOT be
 * NUL-terminated if that limit is reached.
 */
void Curl_strntoupper(char *dest, const char *src, size_t n)
{
  if(n < 1)
    return;

  do {
    *dest++ = Curl_raw_toupper(*src);
  } while(*src++ && --n);
}

/* Copy a lower case version of the string from src to dest.  The
 * strings may overlap.  No more than n characters of the string are copied
 * (including any NUL) and the destination string will NOT be
 * NUL-terminated if that limit is reached.
 */
void Curl_strntolower(char *dest, const char *src, size_t n)
{
  if(n < 1)
    return;

  do {
    *dest++ = raw_tolower(*src);
  } while(*src++ && --n);
}

/* --- public functions --- */

int curl_strequal(const char *first, const char *second)
{
  return Curl_strcasecompare(first, second);
}
int curl_strnequal(const char *first, const char *second, size_t max)
{
  return Curl_strncasecompare(first, second, max);
}