canonicalize-lgpl.c

/* canonicalize-lgpl.c: Return the canonical absolute name of a given file.
 * Copyright (C) 1996-2012 Free Software Foundation, Inc.
 * This file is part of the GNU C Library.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _LIBC
# if defined(__GNUC__) && defined(__GNUC_MINOR__)
#  if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 1))
#   pragma GCC diagnostic ignored "-Wunused-macros"
#  endif /* GCC 4.1+ */
# endif /* gcc */
# ifndef _GL_USE_STDLIB_ALLOC
#  define _GL_USE_STDLIB_ALLOC 1
# endif /* !_GL_USE_STDLIB_ALLOC */
# include <config.h>
#endif /* !_LIBC */

#if (!defined(HAVE_CANONICALIZE_FILE_NAME) || (defined(HAVE_CANONICALIZE_FILE_NAME) && !HAVE_CANONICALIZE_FILE_NAME)) \
    || !FUNC_REALPATH_WORKS || defined _LIBC

/* Do NOT use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
 * optimizes away the name == NULL test below.  */
#define _GL_ARG_NONNULL(params)

/* Specification.  */
#include <stdlib.h>

#include "canonicalize.h"

#include <alloca.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#if HAVE_SYS_PARAM_H || defined _LIBC
# include <sys/param.h>
#endif /* HAVE_SYS_PARAM_H || _LIBC */
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>

#ifdef _LIBC
# include <shlib-compat.h>
#else
# define SHLIB_COMPAT(lib, introduced, obsoleted) 0
# define versioned_symbol(lib, local, symbol, version) extern int dummy
# define compat_symbol(lib, local, symbol, version)
# define weak_alias(local, symbol)
# define __canonicalize_file_name canonicalize_file_name
# define __realpath realpath
# include "pathmax.h"
# include "malloca.h"
# if HAVE_GETCWD
#  if defined(IN_RELOCWRAPPER) && IN_RELOCWRAPPER
 /* When building the relocatable program wrapper, use the system's getcwd
  * function, not the gnulib override, otherwise we would get a link error.
  */
#   undef getcwd
#  endif /* IN_RELOCWRAPPER */
#  ifdef VMS
    /* We want the directory in Unix syntax, not in VMS syntax.  */
#   define __getcwd(buf, max) getcwd(buf, max, 0)
#  else
#   define __getcwd getcwd
#  endif /* VMS */
# else
#  define __getcwd(buf, max) getwd(buf)
# endif /* HAVE_GETCWD */
# define __readlink readlink
# define __set_errno(e) errno = (e)
# ifndef MAXSYMLINKS
#  ifdef SYMLOOP_MAX
#   define MAXSYMLINKS SYMLOOP_MAX
#  else
#   define MAXSYMLINKS 20
#  endif /* SYMLOOP_MAX */
# endif /* !MAXSYMLINKS */
#endif /* _LIBC */

#ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
# define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
#endif /* !DOUBLE_SLASH_IS_DISTINCT_ROOT */

#if (!defined(FUNC_REALPATH_WORKS) || (defined(FUNC_REALPATH_WORKS) && !FUNC_REALPATH_WORKS)) || defined _LIBC
/* Return the canonical absolute name of file NAME. A canonical name
 * does not contain any ".", ".." components nor any repeated path
 * separators ('/') or symlinks. All path components must exist. If
 * RESOLVED is null, the result is malloc'd; otherwise, if the
 * canonical name is PATH_MAX chars or more, returns null with 'errno'
 * set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
 * returns the name in RESOLVED. If the name cannot be resolved and
 * RESOLVED is non-NULL, it contains the path of the first component
 * that cannot be resolved. If the path can be resolved, RESOLVED
 * holds the same value as the value returned.
 */
char *__realpath(const char *name, char *resolved)
{
  char *rpath, *dest, *extra_buf = NULL;
  const char *start, *end, *rpath_limit;
  long int path_max;
  int num_links = 0;

  if (name == NULL) {
      /* As per Single Unix Specification V2 we must return an error if
       * either parameter is a null pointer.  We extend this to allow
       * the RESOLVED parameter to be NULL in case the we are expected to
       * allocate the room for the return value.  */
      __set_errno(EINVAL);
      return NULL;
  }

  if (name[0] == '\0') {
      /* As per Single Unix Specification V2 we must return an error if
       * the name argument points to an empty string.  */
      __set_errno(ENOENT);
      return NULL;
  }

#ifdef PATH_MAX
  path_max = PATH_MAX;
#else
  path_max = pathconf(name, _PC_PATH_MAX);
  if (path_max <= 0) {
	  path_max = 8192;
  }
#endif /* PATH_MAX */

  if (resolved == NULL) {
      rpath = (char *)malloc((size_t)path_max);
      if (rpath == NULL) {
          /* It is easier to set errno to ENOMEM than to rely on the
           * 'malloc-posix' gnulib module.  */
          errno = ENOMEM;
          return NULL;
	  }
  } else {
	  rpath = resolved;
  }
  rpath_limit = (rpath + path_max);

  if (name[0] != '/') {
      if (!__getcwd(rpath, (size_t)path_max)) {
          rpath[0] = '\0';
          goto error;
	  }
      dest = strchr(rpath, '\0');
  } else {
      rpath[0] = '/';
      dest = (rpath + 1);
      if (DOUBLE_SLASH_IS_DISTINCT_ROOT) {
          if ((name[1] == '/') && (name[2] != '/')) {
			  *dest++ = '/';
		  }
          *dest = '\0';
	  }
  }

  for ((start = end = name); *start; (start = end)) {
#ifdef _LIBC
      struct stat64 st;
#else
      struct stat st;
#endif /* _LIBC */
      int n;

      /* dummy condition to use value stored to 'end': */
	  if (start == end) {
		  ;
	  }

      /* Skip sequence of multiple path-separators. */
      while (*start == '/') {
		  ++start;
	  }

      /* Find end of path component.  */
      for ((end = start); (*end && (*end != '/')); ++end) {
		  /* Nothing.  */;
	  }

      if ((end - start) == 0) {
		  break;
      } else if (((end - start) == 1) && (start[0] == '.')) {
		  /* nothing */;
      } else if (end - start == 2 && start[0] == '.' && start[1] == '.') {
          /* Back up to previous component, ignore if at root already.  */
          if (dest > (rpath + 1)) {
			  while ((--dest)[-1] != '/') {
				  /* nothing (?) */;
			  }
		  }
          if (DOUBLE_SLASH_IS_DISTINCT_ROOT && (dest == (rpath + 1))
              && (*dest == '/') && (dest[1] != '/')) {
			  dest++;
		  }
	  } else {
          size_t new_size;

          if (dest[-1] != '/') {
			  *dest++ = '/';
		  }

          if ((dest + (end - start)) >= rpath_limit) {
              ptrdiff_t dest_offset = (dest - rpath);
              char *new_rpath;

              if (resolved) {
                  __set_errno(ENAMETOOLONG);
                  if (dest > (rpath + 1)) {
					  dest--;
				  }
                  *dest = '\0';
                  goto error;
			  }
              new_size = (size_t)(rpath_limit - rpath);
              if ((end - start + 1) > path_max) {
				  new_size += (size_t)(end - start + 1);
              } else {
				  new_size += (size_t)path_max;
			  }
              new_rpath = (char *)realloc(rpath, new_size);
              if (new_rpath == NULL) {
                  /* It is easier to set errno to ENOMEM than to rely on the
                   * 'realloc-posix' gnulib module.  */
                  errno = ENOMEM;
                  goto error;
			  }
              rpath = new_rpath;
              rpath_limit = (rpath + new_size);

              dest = (rpath + dest_offset);
		  }

#ifdef _LIBC
          dest = __mempcpy(dest, start, (end - start));
#else
          memcpy(dest, start, (size_t)(end - start));
          dest += (end - start);
#endif /* _LIBC */
          *dest = '\0';

#ifdef _LIBC
          if (__lxstat64(_STAT_VER, rpath, &st) < 0) {
			  goto error;
		  }
#else
          if (lstat(rpath, &st) < 0) {
			  goto error;
		  }
#endif /* _LIBC */

          if (S_ISLNK (st.st_mode)) {
              char *buf;
              size_t len;

              if (++num_links > MAXSYMLINKS) {
                  __set_errno(ELOOP);
                  goto error;
			  }

              buf = (char *)malloca((size_t)path_max);
              if (!buf) {
                  errno = ENOMEM;
                  goto error;
			  }

              n = (int)__readlink(rpath, buf, (size_t)(path_max - 1));
              if (n < 0) {
                  int saved_errno = errno;
                  freea(buf);
                  errno = saved_errno;
                  goto error;
			  }
              buf[n] = '\0';

              if (!extra_buf) {
                  extra_buf = (char *)malloca((size_t)path_max);
                  if (!extra_buf) {
                      freea(buf);
                      errno = ENOMEM;
                      goto error;
				  }
			  }

              len = strlen(end);
              if ((long int)((size_t)n + len) >= path_max) {
                  freea(buf);
                  __set_errno(ENAMETOOLONG);
                  goto error;
			  }

              /* Careful here, end may be a pointer into extra_buf... */
              memmove(&extra_buf[n], end, (len + 1));
              name = end = (const char *)memcpy(extra_buf, buf, (size_t)n);

			  /* dummy condition to use value stored to 'name': */
			  if (name == end) {
				  ;
			  }

              if (buf[0] == '/') {
                  dest = (rpath + 1);     /* It is an absolute symlink */
                  if (DOUBLE_SLASH_IS_DISTINCT_ROOT) {
                      if ((buf[1] == '/') && (buf[2] != '/')) {
						  *dest++ = '/';
					  }
                      *dest = '\0';
                    }
			  } else {
                  /* Back up to previous component, ignore if at root
                   * already: */
                  if (dest > (rpath + 1)) {
					  while ((--dest)[-1] != '/') {
						  /* nothing (?) */;
					  }
				  }
                  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && (dest == (rpath + 1))
                      && (*dest == '/') && (dest[1] != '/')) {
					  dest++;
				  }
			  }
		  } else if (!S_ISDIR(st.st_mode) && (*end != '\0')) {
              __set_errno(ENOTDIR);
              goto error;
		  }
	  }
  }
  if ((dest > (rpath + 1)) && (dest[-1] == '/')) {
	  --dest;
  }
  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && (dest == (rpath + 1))
      && (*dest == '/') && (dest[1] != '/')) {
	  dest++;
  }
  *dest = '\0';

  if (extra_buf) {
	  freea(extra_buf);
  }

  return rpath;

error:
  {
    int saved_errno = errno;
	if (extra_buf) {
		freea(extra_buf);
	}
	if (resolved == NULL) {
		free(rpath);
	}
    errno = saved_errno;
  }
  return NULL;
}
versioned_symbol(libc, __realpath, realpath, GLIBC_2_3);
#endif /* !FUNC_REALPATH_WORKS || defined _LIBC */


#if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
char *
attribute_compat_text_section
__old_realpath(const char *name, char *resolved)
{
  if (resolved == NULL) {
      __set_errno (EINVAL);
      return NULL;
  }

  return __realpath(name, resolved);
}
compat_symbol(libc, __old_realpath, realpath, GLIBC_2_0);
#endif /* SHLIB_COMPAT check */


char *
__canonicalize_file_name(const char *name)
{
  return __realpath(name, NULL);
}
weak_alias(__canonicalize_file_name, canonicalize_file_name)

#else
/* This declaration is solely to ensure that after preprocessing
 * this file is never empty.  */
typedef int canonicalize_lgpl_c_dummy_t;
#endif /* !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || _LIBC */

#ifdef _GL_USE_STDLIB_ALLOC
# undef _GL_USE_STDLIB_ALLOC
#endif /* _GL_USE_STDLIB_ALLOC */
#ifdef compat_symbol
# undef compat_symbol
#endif /* compat_symbol */

/* EOF */