Пример #1
0
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 = 1024;
#endif

  if (resolved == NULL)
    {
      rpath = malloc (path_max);
      if (rpath == NULL)
	return NULL;
    }
  else
    rpath = resolved;
  rpath_limit = rpath + path_max;

  if (name[0] != '/')
    {
      if (!__getcwd (rpath, path_max))
	{
	  rpath[0] = '\0';
	  goto error;
	}
      dest = __rawmemchr (rpath, '\0');
    }
  else
    {
      rpath[0] = '/';
      dest = rpath + 1;
    }

  for (start = end = name; *start; start = end)
    {
      struct stat64 st;
      int n;

      /* 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] != '/');
	}
      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 = rpath_limit - rpath;
	      if (end - start + 1 > path_max)
		new_size += end - start + 1;
	      else
		new_size += path_max;
	      new_rpath = (char *) realloc (rpath, new_size);
	      if (new_rpath == NULL)
		goto error;
	      rpath = new_rpath;
	      rpath_limit = rpath + new_size;

	      dest = rpath + dest_offset;
	    }

	  dest = __mempcpy (dest, start, end - start);
	  *dest = '\0';

	  if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
	    goto error;

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

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

	      n = __readlink (rpath, buf, path_max - 1);
	      if (n < 0)
		goto error;
	      buf[n] = '\0';

	      if (!extra_buf)
		extra_buf = __alloca (path_max);

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

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

	      if (buf[0] == '/')
		dest = rpath + 1;	/* It's an absolute symlink */
	      else
		/* Back up to previous component, ignore if at root already: */
		if (dest > rpath + 1)
		  while ((--dest)[-1] != '/');
	    }
	  else if (!S_ISDIR (st.st_mode) && *end != '\0')
	    {
	      __set_errno (ENOTDIR);
	      goto error;
	    }
	}
    }
  if (dest > rpath + 1 && dest[-1] == '/')
    --dest;
  *dest = '\0';

  assert (resolved == NULL || resolved == rpath);
  return rpath;

error:
  assert (resolved == NULL || resolved == rpath);
  if (resolved == NULL)
    free (rpath);
  return NULL;
}
Пример #2
0
char *
chroot_canon (const char *chroot, const char *name)
{
  char *rpath;
  char *dest;
  char *extra_buf = NULL;
  char *rpath_root;
  const char *start;
  const char *end;
  const char *rpath_limit;
  int num_links = 0;
  size_t chroot_len = strlen (chroot);

  if (chroot_len < 1)
    {
      __set_errno (EINVAL);
      return NULL;
    }

  rpath = xmalloc (chroot_len + PATH_MAX);

  rpath_limit = rpath + chroot_len + PATH_MAX;

  rpath_root = (char *) mempcpy (rpath, chroot, chroot_len) - 1;
  if (*rpath_root != '/')
    *++rpath_root = '/';
  dest = rpath_root + 1;

  for (start = end = name; *start; start = end)
    {
      struct stat64 st;

      /* 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_root + 1)
	    while ((--dest)[-1] != '/');
	}
      else
	{
	  size_t new_size;

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

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

	      new_size = rpath_limit - rpath;
	      if (end - start + 1 > PATH_MAX)
		new_size += end - start + 1;
	      else
		new_size += PATH_MAX;
	      new_rpath = (char *) xrealloc (rpath, new_size);
	      rpath = new_rpath;
	      rpath_limit = rpath + new_size;

	      dest = rpath + dest_offset;
	    }

	  dest = mempcpy (dest, start, end - start);
	  *dest = '\0';

	  if (lstat64 (rpath, &st) < 0)
	    {
	      if (*end == '\0')
		goto done;
	      goto error;
	    }

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

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

	      ssize_t n = readlink (rpath, buf, PATH_MAX - 1);
	      if (n < 0)
		{
		  if (*end == '\0')
		    goto done;
		  goto error;
		}
	      buf[n] = '\0';

	      if (!extra_buf)
		extra_buf = alloca (PATH_MAX);

	      len = strlen (end);
	      if (len >= PATH_MAX - n)
		{
		  __set_errno (ENAMETOOLONG);
		  goto error;
		}

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

	      if (buf[0] == '/')
		dest = rpath_root + 1;	/* It's an absolute symlink */
	      else
		/* Back up to previous component, ignore if at root already: */
		if (dest > rpath_root + 1)
		  while ((--dest)[-1] != '/');
	    }
	}
    }
 done:
  if (dest > rpath_root + 1 && dest[-1] == '/')
    --dest;
  *dest = '\0';

  return rpath;

 error:
  free (rpath);
  return NULL;
}