tar/util.c - third_party/libarchive - Git at Google

 /*-
  * Copyright (c) 2003-2007 Tim Kientzle
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "bsdtar_platform.h"
 __FBSDID("$FreeBSD: src/usr.bin/tar/util.c,v 1.23 2008/12/15 06:00:25 kientzle Exp $");

 #ifdef HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>  /* Linux doesn't define mode_t, etc. in sys/stat.h. */
 #endif
 #include <ctype.h>
 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
 #ifdef HAVE_IO_H
 #include <io.h>
 #endif
 #ifdef HAVE_STDARG_H
 #include <stdarg.h>
 #endif
 #ifdef HAVE_STDINT_H
 #include <stdint.h>
 #endif
 #include <stdio.h>
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif
 #ifdef HAVE_WCTYPE_H
 #include <wctype.h>
 #else
 /* If we don't have wctype, we need to hack up some version of iswprint(). */
 #define iswprint isprint
 #endif

 #include "bsdtar.h"
 #include "err.h"

 static size_t	bsdtar_expand_char(char *, size_t, char);
 static const char *strip_components(const char *path, int elements);

 #if defined(_WIN32) && !defined(__CYGWIN__)
 #define read _read
 #endif

 /* TODO:  Hack up a version of mbtowc for platforms with no wide
  * character support at all.  I think the following might suffice,
  * but it needs careful testing.
  * #if !HAVE_MBTOWC
  * #define mbtowc(wcp, p, n) ((*wcp = *p), 1)
  * #endif
  */

 /*
  * Print a string, taking care with any non-printable characters.
  *
  * Note that we use a stack-allocated buffer to receive the formatted
  * string if we can.  This is partly performance (avoiding a call to
  * malloc()), partly out of expedience (we have to call vsnprintf()
  * before malloc() anyway to find out how big a buffer we need; we may
  * as well point that first call at a small local buffer in case it
  * works), but mostly for safety (so we can use this to print messages
  * about out-of-memory conditions).
  */

 void
 safe_fprintf(FILE *f, const char *fmt, ...)
 {
 	char fmtbuff_stack[256]; /* Place to format the printf() string. */
 	char outbuff[256]; /* Buffer for outgoing characters. */
 	char *fmtbuff_heap; /* If fmtbuff_stack is too small, we use malloc */
 	char *fmtbuff;  /* Pointer to fmtbuff_stack or fmtbuff_heap. */
 	int fmtbuff_length;
 	int length, n;
 	va_list ap;
 	const char *p;
 	unsigned i;
 	wchar_t wc;
 	char try_wc;

 	/* Use a stack-allocated buffer if we can, for speed and safety. */
 	fmtbuff_heap = NULL;
 	fmtbuff_length = sizeof(fmtbuff_stack);
 	fmtbuff = fmtbuff_stack;

 	/* Try formatting into the stack buffer. */
 	va_start(ap, fmt);
 	length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
 	va_end(ap);

 	/* If the result was too large, allocate a buffer on the heap. */
 	if (length >= fmtbuff_length) {
 		fmtbuff_length = length+1;
 		fmtbuff_heap = malloc(fmtbuff_length);

 		/* Reformat the result into the heap buffer if we can. */
 		if (fmtbuff_heap != NULL) {
 			fmtbuff = fmtbuff_heap;
 			va_start(ap, fmt);
 			length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
 			va_end(ap);
 		} else {
 			/* Leave fmtbuff pointing to the truncated
 			 * string in fmtbuff_stack. */
 			length = sizeof(fmtbuff_stack) - 1;
 		}
 	}

 	/* Note: mbrtowc() has a cleaner API, but mbtowc() seems a bit
 	 * more portable, so we use that here instead. */
 	n = mbtowc(NULL, NULL, 1); /* Reset the shift state. */

 	/* Write data, expanding unprintable characters. */
 	p = fmtbuff;
 	i = 0;
 	try_wc = 1;
 	while (*p != '\0') {

 		/* Convert to wide char, test if the wide
 		 * char is printable in the current locale. */
 		if (try_wc && (n = mbtowc(&wc, p, length)) != -1) {
 			length -= n;
 			if (iswprint(wc) && wc != L'\\') {
 				/* Printable, copy the bytes through. */
 				while (n-- > 0)
 					outbuff[i++] = *p++;
 			} else {
 				/* Not printable, format the bytes. */
 				while (n-- > 0)
 					i += (unsigned)bsdtar_expand_char(
 					    outbuff, i, *p++);
 			}
 		} else {
 			/* After any conversion failure, don't bother
 			 * trying to convert the rest. */
 			i += (unsigned)bsdtar_expand_char(outbuff, i, *p++);
 			try_wc = 0;
 		}

 		/* If our output buffer is full, dump it and keep going. */
 		if (i > (sizeof(outbuff) - 20)) {
 			outbuff[i] = '\0';
 			fprintf(f, "%s", outbuff);
 			i = 0;
 		}
 	}
 	outbuff[i] = '\0';
 	fprintf(f, "%s", outbuff);

 	/* If we allocated a heap-based formatting buffer, free it now. */
 	if (fmtbuff_heap != NULL)
 		free(fmtbuff_heap);
 }

 /*
  * Render an arbitrary sequence of bytes into printable ASCII characters.
  */
 static size_t
 bsdtar_expand_char(char *buff, size_t offset, char c)
 {
 	size_t i = offset;

 	if (isprint((unsigned char)c) && c != '\\')
 		buff[i++] = c;
 	else {
 		buff[i++] = '\\';
 		switch (c) {
 		case '\a': buff[i++] = 'a'; break;
 		case '\b': buff[i++] = 'b'; break;
 		case '\f': buff[i++] = 'f'; break;
 		case '\n': buff[i++] = 'n'; break;
 #if '\r' != '\n'
 		/* On some platforms, \n and \r are the same. */
 		case '\r': buff[i++] = 'r'; break;
 #endif
 		case '\t': buff[i++] = 't'; break;
 		case '\v': buff[i++] = 'v'; break;
 		case '\\': buff[i++] = '\\'; break;
 		default:
 			sprintf(buff + i, "%03o", 0xFF & (int)c);
 			i += 3;
 		}
 	}

 	return (i - offset);
 }

 int
 yes(const char *fmt, ...)
 {
 	char buff[32];
 	char *p;
 	ssize_t l;

 	va_list ap;
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
 	fprintf(stderr, " (y/N)? ");
 	fflush(stderr);

 	l = read(2, buff, sizeof(buff) - 1);
 	if (l <= 0)
 		return (0);
 	buff[l] = 0;

 	for (p = buff; *p != '\0'; p++) {
 		if (isspace((unsigned char)*p))
 			continue;
 		switch(*p) {
 		case 'y': case 'Y':
 			return (1);
 		case 'n': case 'N':
 			return (0);
 		default:
 			return (0);
 		}
 	}

 	return (0);
 }

 /*-
  * The logic here for -C <dir> attempts to avoid
  * chdir() as long as possible.  For example:
  * "-C /foo -C /bar file"          needs chdir("/bar") but not chdir("/foo")
  * "-C /foo -C bar file"           needs chdir("/foo/bar")
  * "-C /foo -C bar /file1"         does not need chdir()
  * "-C /foo -C bar /file1 file2"   needs chdir("/foo/bar") before file2
  *
  * The only correct way to handle this is to record a "pending" chdir
  * request and combine multiple requests intelligently until we
  * need to process a non-absolute file.  set_chdir() adds the new dir
  * to the pending list; do_chdir() actually executes any pending chdir.
  *
  * This way, programs that build tar command lines don't have to worry
  * about -C with non-existent directories; such requests will only
  * fail if the directory must be accessed.
  *
  * TODO: Make this handle Windows paths correctly.
  */
 void
 set_chdir(struct bsdtar *bsdtar, const char *newdir)
 {
 	if (newdir[0] == '/') {
 		/* The -C /foo -C /bar case; dump first one. */
 		free(bsdtar->pending_chdir);
 		bsdtar->pending_chdir = NULL;
 	}
 	if (bsdtar->pending_chdir == NULL)
 		/* Easy case: no previously-saved dir. */
 		bsdtar->pending_chdir = strdup(newdir);
 	else {
 		/* The -C /foo -C bar case; concatenate */
 		char *old_pending = bsdtar->pending_chdir;
 		size_t old_len = strlen(old_pending);
 		bsdtar->pending_chdir = malloc(old_len + strlen(newdir) + 2);
 		if (old_pending[old_len - 1] == '/')
 			old_pending[old_len - 1] = '\0';
 		if (bsdtar->pending_chdir != NULL)
 			sprintf(bsdtar->pending_chdir, "%s/%s",
 			    old_pending, newdir);
 		free(old_pending);
 	}
 	if (bsdtar->pending_chdir == NULL)
 		lafe_errc(1, errno, "No memory");
 }

 void
 do_chdir(struct bsdtar *bsdtar)
 {
 	if (bsdtar->pending_chdir == NULL)
 		return;

 	if (chdir(bsdtar->pending_chdir) != 0) {
 		lafe_errc(1, 0, "could not chdir to '%s'\n",
 		    bsdtar->pending_chdir);
 	}
 	free(bsdtar->pending_chdir);
 	bsdtar->pending_chdir = NULL;
 }

 static const char *
 strip_components(const char *p, int elements)
 {
 	/* Skip as many elements as necessary. */
 	while (elements > 0) {
 		switch (*p++) {
 		case '/':
 #if defined(_WIN32) && !defined(__CYGWIN__)
 		case '\\': /* Support \ path sep on Windows ONLY. */
 #endif
 			elements--;
 			break;
 		case '\0':
 			/* Path is too short, skip it. */
 			return (NULL);
 		}
 	}

 	/* Skip any / characters.  This handles short paths that have
 	 * additional / termination.  This also handles the case where
 	 * the logic above stops in the middle of a duplicate //
 	 * sequence (which would otherwise get converted to an
 	 * absolute path). */
 	for (;;) {
 		switch (*p) {
 		case '/':
 #if defined(_WIN32) && !defined(__CYGWIN__)
 		case '\\': /* Support \ path sep on Windows ONLY. */
 #endif
 			++p;
 			break;
 		case '\0':
 			return (NULL);
 		default:
 			return (p);
 		}
 	}
 }

 /*
  * Handle --strip-components and any future path-rewriting options.
  * Returns non-zero if the pathname should not be extracted.
  *
  * TODO: Support pax-style regex path rewrites.
  */
 int
 edit_pathname(struct bsdtar *bsdtar, struct archive_entry *entry)
 {
 	const char *name = archive_entry_pathname(entry);
 #if HAVE_REGEX_H
 	char *subst_name;
 	int r;
 #endif

 #if HAVE_REGEX_H
 	r = apply_substitution(bsdtar, name, &subst_name, 0);
 	if (r == -1) {
 		lafe_warnc(0, "Invalid substitution, skipping entry");
 		return 1;
 	}
 	if (r == 1) {
 		archive_entry_copy_pathname(entry, subst_name);
 		if (*subst_name == '\0') {
 			free(subst_name);
 			return -1;
 		} else
 			free(subst_name);
 		name = archive_entry_pathname(entry);
 	}

 	if (archive_entry_hardlink(entry)) {
 		r = apply_substitution(bsdtar, archive_entry_hardlink(entry), &subst_name, 1);
 		if (r == -1) {
 			lafe_warnc(0, "Invalid substitution, skipping entry");
 			return 1;
 		}
 		if (r == 1) {
 			archive_entry_copy_hardlink(entry, subst_name);
 			free(subst_name);
 		}
 	}
 	if (archive_entry_symlink(entry) != NULL) {
 		r = apply_substitution(bsdtar, archive_entry_symlink(entry), &subst_name, 1);
 		if (r == -1) {
 			lafe_warnc(0, "Invalid substitution, skipping entry");
 			return 1;
 		}
 		if (r == 1) {
 			archive_entry_copy_symlink(entry, subst_name);
 			free(subst_name);
 		}
 	}
 #endif

 	/* Strip leading dir names as per --strip-components option. */
 	if (bsdtar->strip_components > 0) {
 		const char *linkname = archive_entry_hardlink(entry);

 		name = strip_components(name, bsdtar->strip_components);
 		if (name == NULL)
 			return (1);

 		if (linkname != NULL) {
 			linkname = strip_components(linkname,
 			    bsdtar->strip_components);
 			if (linkname == NULL)
 				return (1);
 			archive_entry_copy_hardlink(entry, linkname);
 		}
 	}

 	/* By default, don't write or restore absolute pathnames. */
 	if (!bsdtar->option_absolute_paths) {
 		const char *rp, *p = name;
 		int slashonly = 1;

 		/* Remove leading "//./" or "//?/" or "//?/UNC/"
 		 * (absolute path prefixes used by Windows API) */
 		if ((p[0] == '/' || p[0] == '\\') &&
 		    (p[1] == '/' || p[1] == '\\') &&
 		    (p[2] == '.' || p[2] == '?') &&
 		    (p[3] == '/' || p[3] == '\\'))
 		{
 			if (p[2] == '?' &&
 			    (p[4] == 'U' || p[4] == 'u') &&
 			    (p[5] == 'N' || p[5] == 'n') &&
 			    (p[6] == 'C' || p[6] == 'c') &&
 			    (p[7] == '/' || p[7] == '\\'))
 				p += 8;
 			else
 				p += 4;
 			slashonly = 0;
 		}
 		do {
 			rp = p;
 			/* Remove leading drive letter from archives created
 			 * on Windows. */
 			if (((p[0] >= 'a' && p[0] <= 'z') ||
 			     (p[0] >= 'A' && p[0] <= 'Z')) &&
 				 p[1] == ':') {
 				p += 2;
 				slashonly = 0;
 			}
 			/* Remove leading "/../", "//", etc. */
 			while (p[0] == '/' || p[0] == '\\') {
 				if (p[1] == '.' && p[2] == '.' &&
 					(p[3] == '/' || p[3] == '\\')) {
 					p += 3; /* Remove "/..", leave "/"
 							 * for next pass. */
 					slashonly = 0;
 				} else
 					p += 1; /* Remove "/". */
 			}
 		} while (rp != p);

 		if (p != name && !bsdtar->warned_lead_slash) {
 			/* Generate a warning the first time this happens. */
 			if (slashonly)
 				lafe_warnc(0,
 				    "Removing leading '%c' from member names",
 				    name[0]);
 			else
 				lafe_warnc(0,
 				    "Removing leading drive letter from "
 				    "member names");
 			bsdtar->warned_lead_slash = 1;
 		}

 		/* Special case: Stripping everything yields ".". */
 		if (*p == '\0')
 			name = ".";
 		else
 			name = p;
 	} else {
 		/* Strip redundant leading '/' characters. */
 		while (name[0] == '/' && name[1] == '/')
 			name++;
 	}

 	/* Safely replace name in archive_entry. */
 	if (name != archive_entry_pathname(entry)) {
 		char *q = strdup(name);
 		archive_entry_copy_pathname(entry, q);
 		free(q);
 	}
 	return (0);
 }

 /*
  * It would be nice to just use printf() for formatting large numbers,
  * but the compatibility problems are quite a headache.  Hence the
  * following simple utility function.
  */
 const char *
 tar_i64toa(int64_t n0)
 {
 	static char buff[24];
 	int64_t n = n0 < 0 ? -n0 : n0;
 	char *p = buff + sizeof(buff);

 	*--p = '\0';
 	do {
 		*--p = '0' + (int)(n % 10);
 		n /= 10;
 	} while (n > 0);
 	if (n0 < 0)
 		*--p = '-';
 	return p;
 }

 /*
  * Like strcmp(), but try to be a little more aware of the fact that
  * we're comparing two paths.  Right now, it just handles leading
  * "./" and trailing '/' specially, so that "a/b/" == "./a/b"
  *
  * TODO: Make this better, so that "./a//b/./c/" == "a/b/c"
  * TODO: After this works, push it down into libarchive.
  * TODO: Publish the path normalization routines in libarchive so
  * that bsdtar can normalize paths and use fast strcmp() instead
  * of this.
  *
  * Note: This is currently only used within write.c, so should
  * not handle \ path separators.
  */

 int
 pathcmp(const char *a, const char *b)
 {
 	/* Skip leading './' */
 	if (a[0] == '.' && a[1] == '/' && a[2] != '\0')
 		a += 2;
 	if (b[0] == '.' && b[1] == '/' && b[2] != '\0')
 		b += 2;
 	/* Find the first difference, or return (0) if none. */
 	while (*a == *b) {
 		if (*a == '\0')
 			return (0);
 		a++;
 		b++;
 	}
 	/*
 	 * If one ends in '/' and the other one doesn't,
 	 * they're the same.
 	 */
 	if (a[0] == '/' && a[1] == '\0' && b[0] == '\0')
 		return (0);
 	if (a[0] == '\0' && b[0] == '/' && b[1] == '\0')
 		return (0);
 	/* They're really different, return the correct sign. */
 	return (*(const unsigned char *)a - *(const unsigned char *)b);
 }
	/*-
	* Copyright (c) 2003-2007 Tim Kientzle
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "bsdtar_platform.h"
	__FBSDID("$FreeBSD: src/usr.bin/tar/util.c,v 1.23 2008/12/15 06:00:25 kientzle Exp $");

	#ifdef HAVE_SYS_STAT_H
	#include <sys/stat.h>
	#endif
	#ifdef HAVE_SYS_TYPES_H
	#include <sys/types.h> /* Linux doesn't define mode_t, etc. in sys/stat.h. */
	#endif
	#include <ctype.h>
	#ifdef HAVE_ERRNO_H
	#include <errno.h>
	#endif
	#ifdef HAVE_IO_H
	#include <io.h>
	#endif
	#ifdef HAVE_STDARG_H
	#include <stdarg.h>
	#endif
	#ifdef HAVE_STDINT_H
	#include <stdint.h>
	#endif
	#include <stdio.h>
	#ifdef HAVE_STDLIB_H
	#include <stdlib.h>
	#endif
	#ifdef HAVE_STRING_H
	#include <string.h>
	#endif
	#ifdef HAVE_WCTYPE_H
	#include <wctype.h>
	#else
	/* If we don't have wctype, we need to hack up some version of iswprint(). */
	#define iswprint isprint
	#endif

	#include "bsdtar.h"
	#include "err.h"

	static size_t bsdtar_expand_char(char *, size_t, char);
	static const char strip_components(const char path, int elements);

	#if defined(_WIN32) && !defined(__CYGWIN__)
	#define read _read
	#endif

	/* TODO: Hack up a version of mbtowc for platforms with no wide
	* character support at all. I think the following might suffice,
	* but it needs careful testing.
	* #if !HAVE_MBTOWC
	* #define mbtowc(wcp, p, n) ((wcp = p), 1)
	* #endif
	*/

	/*
	* Print a string, taking care with any non-printable characters.
	*
	* Note that we use a stack-allocated buffer to receive the formatted
	* string if we can. This is partly performance (avoiding a call to
	* malloc()), partly out of expedience (we have to call vsnprintf()
	* before malloc() anyway to find out how big a buffer we need; we may
	* as well point that first call at a small local buffer in case it
	* works), but mostly for safety (so we can use this to print messages
	* about out-of-memory conditions).
	*/

	void
	safe_fprintf(FILE f, const char fmt, ...)
	{
	char fmtbuff_stack[256]; /* Place to format the printf() string. */
	char outbuff[256]; /* Buffer for outgoing characters. */
	char fmtbuff_heap; / If fmtbuff_stack is too small, we use malloc */
	char fmtbuff; / Pointer to fmtbuff_stack or fmtbuff_heap. */
	int fmtbuff_length;
	int length, n;
	va_list ap;
	const char *p;
	unsigned i;
	wchar_t wc;
	char try_wc;

	/* Use a stack-allocated buffer if we can, for speed and safety. */
	fmtbuff_heap = NULL;
	fmtbuff_length = sizeof(fmtbuff_stack);
	fmtbuff = fmtbuff_stack;

	/* Try formatting into the stack buffer. */
	va_start(ap, fmt);
	length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
	va_end(ap);

	/* If the result was too large, allocate a buffer on the heap. */
	if (length >= fmtbuff_length) {
	fmtbuff_length = length+1;
	fmtbuff_heap = malloc(fmtbuff_length);

	/* Reformat the result into the heap buffer if we can. */
	if (fmtbuff_heap != NULL) {
	fmtbuff = fmtbuff_heap;
	va_start(ap, fmt);
	length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
	va_end(ap);
	} else {
	/* Leave fmtbuff pointing to the truncated
	* string in fmtbuff_stack. */
	length = sizeof(fmtbuff_stack) - 1;
	}
	}

	/* Note: mbrtowc() has a cleaner API, but mbtowc() seems a bit
	* more portable, so we use that here instead. */
	n = mbtowc(NULL, NULL, 1); /* Reset the shift state. */

	/* Write data, expanding unprintable characters. */
	p = fmtbuff;
	i = 0;
	try_wc = 1;
	while (*p != '\0') {

	/* Convert to wide char, test if the wide
	* char is printable in the current locale. */
	if (try_wc && (n = mbtowc(&wc, p, length)) != -1) {
	length -= n;
	if (iswprint(wc) && wc != L'\\') {
	/* Printable, copy the bytes through. */
	while (n-- > 0)
	outbuff[i++] = *p++;
	} else {
	/* Not printable, format the bytes. */
	while (n-- > 0)
	i += (unsigned)bsdtar_expand_char(
	outbuff, i, *p++);
	}
	} else {
	/* After any conversion failure, don't bother
	* trying to convert the rest. */
	i += (unsigned)bsdtar_expand_char(outbuff, i, *p++);
	try_wc = 0;
	}

	/* If our output buffer is full, dump it and keep going. */
	if (i > (sizeof(outbuff) - 20)) {
	outbuff[i] = '\0';
	fprintf(f, "%s", outbuff);
	i = 0;
	}
	}
	outbuff[i] = '\0';
	fprintf(f, "%s", outbuff);

	/* If we allocated a heap-based formatting buffer, free it now. */
	if (fmtbuff_heap != NULL)
	free(fmtbuff_heap);
	}

	/*
	* Render an arbitrary sequence of bytes into printable ASCII characters.
	*/
	static size_t
	bsdtar_expand_char(char *buff, size_t offset, char c)
	{
	size_t i = offset;

	if (isprint((unsigned char)c) && c != '\\')
	buff[i++] = c;
	else {
	buff[i++] = '\\';
	switch (c) {
	case '\a': buff[i++] = 'a'; break;
	case '\b': buff[i++] = 'b'; break;
	case '\f': buff[i++] = 'f'; break;
	case '\n': buff[i++] = 'n'; break;
	#if '\r' != '\n'
	/* On some platforms, \n and \r are the same. */
	case '\r': buff[i++] = 'r'; break;
	#endif
	case '\t': buff[i++] = 't'; break;
	case '\v': buff[i++] = 'v'; break;
	case '\\': buff[i++] = '\\'; break;
	default:
	sprintf(buff + i, "%03o", 0xFF & (int)c);
	i += 3;
	}
	}

	return (i - offset);
	}

	int
	yes(const char *fmt, ...)
	{
	char buff[32];
	char *p;
	ssize_t l;

	va_list ap;
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fprintf(stderr, " (y/N)? ");
	fflush(stderr);

	l = read(2, buff, sizeof(buff) - 1);
	if (l <= 0)
	return (0);
	buff[l] = 0;

	for (p = buff; *p != '\0'; p++) {
	if (isspace((unsigned char)*p))
	continue;
	switch(*p) {
	case 'y': case 'Y':
	return (1);
	case 'n': case 'N':
	return (0);
	default:
	return (0);
	}
	}

	return (0);
	}

	/*-
	* The logic here for -C <dir> attempts to avoid
	* chdir() as long as possible. For example:
	* "-C /foo -C /bar file" needs chdir("/bar") but not chdir("/foo")
	* "-C /foo -C bar file" needs chdir("/foo/bar")
	* "-C /foo -C bar /file1" does not need chdir()
	* "-C /foo -C bar /file1 file2" needs chdir("/foo/bar") before file2
	*
	* The only correct way to handle this is to record a "pending" chdir
	* request and combine multiple requests intelligently until we
	* need to process a non-absolute file. set_chdir() adds the new dir
	* to the pending list; do_chdir() actually executes any pending chdir.
	*
	* This way, programs that build tar command lines don't have to worry
	* about -C with non-existent directories; such requests will only
	* fail if the directory must be accessed.
	*
	* TODO: Make this handle Windows paths correctly.
	*/
	void
	set_chdir(struct bsdtar bsdtar, const char newdir)
	{
	if (newdir[0] == '/') {
	/* The -C /foo -C /bar case; dump first one. */
	free(bsdtar->pending_chdir);
	bsdtar->pending_chdir = NULL;
	}
	if (bsdtar->pending_chdir == NULL)
	/* Easy case: no previously-saved dir. */
	bsdtar->pending_chdir = strdup(newdir);
	else {
	/* The -C /foo -C bar case; concatenate */
	char *old_pending = bsdtar->pending_chdir;
	size_t old_len = strlen(old_pending);
	bsdtar->pending_chdir = malloc(old_len + strlen(newdir) + 2);
	if (old_pending[old_len - 1] == '/')
	old_pending[old_len - 1] = '\0';
	if (bsdtar->pending_chdir != NULL)
	sprintf(bsdtar->pending_chdir, "%s/%s",
	old_pending, newdir);
	free(old_pending);
	}
	if (bsdtar->pending_chdir == NULL)
	lafe_errc(1, errno, "No memory");
	}

	void
	do_chdir(struct bsdtar *bsdtar)
	{
	if (bsdtar->pending_chdir == NULL)
	return;

	if (chdir(bsdtar->pending_chdir) != 0) {
	lafe_errc(1, 0, "could not chdir to '%s'\n",
	bsdtar->pending_chdir);
	}
	free(bsdtar->pending_chdir);
	bsdtar->pending_chdir = NULL;
	}

	static const char *
	strip_components(const char *p, int elements)
	{
	/* Skip as many elements as necessary. */
	while (elements > 0) {
	switch (*p++) {
	case '/':
	#if defined(_WIN32) && !defined(__CYGWIN__)
	case '\\': /* Support \ path sep on Windows ONLY. */
	#endif
	elements--;
	break;
	case '\0':
	/* Path is too short, skip it. */
	return (NULL);
	}
	}

	/* Skip any / characters. This handles short paths that have
	* additional / termination. This also handles the case where
	* the logic above stops in the middle of a duplicate //
	* sequence (which would otherwise get converted to an
	* absolute path). */
	for (;;) {
	switch (*p) {
	case '/':
	#if defined(_WIN32) && !defined(__CYGWIN__)
	case '\\': /* Support \ path sep on Windows ONLY. */
	#endif
	++p;
	break;
	case '\0':
	return (NULL);
	default:
	return (p);
	}
	}
	}

	/*
	* Handle --strip-components and any future path-rewriting options.
	* Returns non-zero if the pathname should not be extracted.
	*
	* TODO: Support pax-style regex path rewrites.
	*/
	int
	edit_pathname(struct bsdtar bsdtar, struct archive_entry entry)
	{
	const char *name = archive_entry_pathname(entry);
	#if HAVE_REGEX_H
	char *subst_name;
	int r;
	#endif

	#if HAVE_REGEX_H
	r = apply_substitution(bsdtar, name, &subst_name, 0);
	if (r == -1) {
	lafe_warnc(0, "Invalid substitution, skipping entry");
	return 1;
	}
	if (r == 1) {
	archive_entry_copy_pathname(entry, subst_name);
	if (*subst_name == '\0') {
	free(subst_name);
	return -1;
	} else
	free(subst_name);
	name = archive_entry_pathname(entry);
	}

	if (archive_entry_hardlink(entry)) {
	r = apply_substitution(bsdtar, archive_entry_hardlink(entry), &subst_name, 1);
	if (r == -1) {
	lafe_warnc(0, "Invalid substitution, skipping entry");
	return 1;
	}
	if (r == 1) {
	archive_entry_copy_hardlink(entry, subst_name);
	free(subst_name);
	}
	}
	if (archive_entry_symlink(entry) != NULL) {
	r = apply_substitution(bsdtar, archive_entry_symlink(entry), &subst_name, 1);
	if (r == -1) {
	lafe_warnc(0, "Invalid substitution, skipping entry");
	return 1;
	}
	if (r == 1) {
	archive_entry_copy_symlink(entry, subst_name);
	free(subst_name);
	}
	}
	#endif

	/* Strip leading dir names as per --strip-components option. */
	if (bsdtar->strip_components > 0) {
	const char *linkname = archive_entry_hardlink(entry);

	name = strip_components(name, bsdtar->strip_components);
	if (name == NULL)
	return (1);

	if (linkname != NULL) {
	linkname = strip_components(linkname,
	bsdtar->strip_components);
	if (linkname == NULL)
	return (1);
	archive_entry_copy_hardlink(entry, linkname);
	}
	}

	/* By default, don't write or restore absolute pathnames. */
	if (!bsdtar->option_absolute_paths) {
	const char rp, p = name;
	int slashonly = 1;

	/* Remove leading "//./" or "//?/" or "//?/UNC/"
	* (absolute path prefixes used by Windows API) */
	if ((p[0] == '/' \|\| p[0] == '\\') &&
	(p[1] == '/' \|\| p[1] == '\\') &&
	(p[2] == '.' \|\| p[2] == '?') &&
	(p[3] == '/' \|\| p[3] == '\\'))
	{
	if (p[2] == '?' &&
	(p[4] == 'U' \|\| p[4] == 'u') &&
	(p[5] == 'N' \|\| p[5] == 'n') &&
	(p[6] == 'C' \|\| p[6] == 'c') &&
	(p[7] == '/' \|\| p[7] == '\\'))
	p += 8;
	else
	p += 4;
	slashonly = 0;
	}
	do {
	rp = p;
	/* Remove leading drive letter from archives created
	* on Windows. */
	if (((p[0] >= 'a' && p[0] <= 'z') \|\|
	(p[0] >= 'A' && p[0] <= 'Z')) &&
	p[1] == ':') {
	p += 2;
	slashonly = 0;
	}
	/* Remove leading "/../", "//", etc. */
	while (p[0] == '/' \|\| p[0] == '\\') {
	if (p[1] == '.' && p[2] == '.' &&
	(p[3] == '/' \|\| p[3] == '\\')) {
	p += 3; /* Remove "/..", leave "/"
	* for next pass. */
	slashonly = 0;
	} else
	p += 1; /* Remove "/". */
	}
	} while (rp != p);

	if (p != name && !bsdtar->warned_lead_slash) {
	/* Generate a warning the first time this happens. */
	if (slashonly)
	lafe_warnc(0,
	"Removing leading '%c' from member names",
	name[0]);
	else
	lafe_warnc(0,
	"Removing leading drive letter from "
	"member names");
	bsdtar->warned_lead_slash = 1;
	}

	/* Special case: Stripping everything yields ".". */
	if (*p == '\0')
	name = ".";
	else
	name = p;
	} else {
	/* Strip redundant leading '/' characters. */
	while (name[0] == '/' && name[1] == '/')
	name++;
	}

	/* Safely replace name in archive_entry. */
	if (name != archive_entry_pathname(entry)) {
	char *q = strdup(name);
	archive_entry_copy_pathname(entry, q);
	free(q);
	}
	return (0);
	}

	/*
	* It would be nice to just use printf() for formatting large numbers,
	* but the compatibility problems are quite a headache. Hence the
	* following simple utility function.
	*/
	const char *
	tar_i64toa(int64_t n0)
	{
	static char buff[24];
	int64_t n = n0 < 0 ? -n0 : n0;
	char *p = buff + sizeof(buff);

	*--p = '\0';
	do {
	*--p = '0' + (int)(n % 10);
	n /= 10;
	} while (n > 0);
	if (n0 < 0)
	*--p = '-';
	return p;
	}

	/*
	* Like strcmp(), but try to be a little more aware of the fact that
	* we're comparing two paths. Right now, it just handles leading
	* "./" and trailing '/' specially, so that "a/b/" == "./a/b"
	*
	* TODO: Make this better, so that "./a//b/./c/" == "a/b/c"
	* TODO: After this works, push it down into libarchive.
	* TODO: Publish the path normalization routines in libarchive so
	* that bsdtar can normalize paths and use fast strcmp() instead
	* of this.
	*
	* Note: This is currently only used within write.c, so should
	* not handle \ path separators.
	*/

	int
	pathcmp(const char a, const char b)
	{
	/* Skip leading './' */
	if (a[0] == '.' && a[1] == '/' && a[2] != '\0')
	a += 2;
	if (b[0] == '.' && b[1] == '/' && b[2] != '\0')
	b += 2;
	/* Find the first difference, or return (0) if none. */
	while (a == b) {
	if (*a == '\0')
	return (0);
	a++;
	b++;
	}
	/*
	* If one ends in '/' and the other one doesn't,
	* they're the same.
	*/
	if (a[0] == '/' && a[1] == '\0' && b[0] == '\0')
	return (0);
	if (a[0] == '\0' && b[0] == '/' && b[1] == '\0')
	return (0);
	/* They're really different, return the correct sign. */
	return ((const unsigned char )a - (const unsigned char )b);
	}