/* Return the canonical absolute name of a given file.
Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Copyright (C) 2002 Red Hat, Inc. (trivial port to GLib)
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <config.h>
#include "canonicalize.h"
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>
/* 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. */
static char*
menu_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. */
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. */
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
rpath = resolved ? g_alloca (path_max) : g_malloc (path_max);
rpath_limit = rpath + path_max;
if (name[0] != G_DIR_SEPARATOR)
{
if (!getcwd (rpath, path_max))
{
rpath[0] = '\0';
goto error;
}
dest = strchr (rpath, '\0');
}
else
{
rpath[0] = G_DIR_SEPARATOR;
dest = rpath + 1;
}
for (start = end = name; *start; start = end)
{
struct stat st;
int n;
/* Skip sequence of multiple path-separators. */
while (*start == G_DIR_SEPARATOR)
++start;
/* Find end of path component. */
for (end = start; *end && *end != G_DIR_SEPARATOR; ++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] != G_DIR_SEPARATOR);
}
else
{
size_t new_size;
if (dest[-1] != G_DIR_SEPARATOR)
*dest++ = G_DIR_SEPARATOR;
if (dest + (end - start) >= rpath_limit)
{
ptrdiff_t dest_offset = dest - rpath;
char *new_rpath;
if (resolved)
{
#ifdef ENAMETOOLONG
errno = ENAMETOOLONG;
#else
/* Uh... just pick something */
errno = EINVAL;
#endif
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;
}
memcpy (dest, start, end - start);
dest = dest + (end - start);
*dest = '\0';
if (stat (rpath, &st) < 0)
goto error;
if (S_ISLNK (st.st_mode))
{
char *buf = alloca (path_max);
size_t len;
if (++num_links > MAXSYMLINKS)
{
errno = ELOOP;
goto error;
}
n = readlink (rpath, buf, path_max);
if (n < 0)
goto error;
buf[n] = '\0';
if (!extra_buf)
extra_buf = g_alloca (path_max);
len = strlen (end);
if ((long int) (n + len) >= path_max)
{
#ifdef ENAMETOOLONG
errno = ENAMETOOLONG;
#else
/* Uh... just pick something */
errno = EINVAL;
#endif
goto error;
}
/* Careful here, end may be a pointer into extra_buf... */
g_memmove (&extra_buf[n], end, len + 1);
name = end = memcpy (extra_buf, buf, n);
if (buf[0] == G_DIR_SEPARATOR)
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] != G_DIR_SEPARATOR);
}
}
}
if (dest > rpath + 1 && dest[-1] == G_DIR_SEPARATOR)
--dest;
*dest = '\0';
return resolved ? memcpy (resolved, rpath, dest - rpath + 1) : rpath;
error:
if (resolved)
strcpy (resolved, rpath);
else
g_free (rpath);
return NULL;
}
char *
menu_canonicalize_file_name (const char *name,
gboolean allow_missing_basename)
{
char *retval;
retval = menu_realpath (name, NULL);
/* We could avoid some system calls by using the second
* argument to realpath() instead of doing realpath
* all over again, but who cares really. we'll see if
* it's ever in a profile.
*/
if (allow_missing_basename && retval == NULL)
{
char *dirname;
char *canonical_dirname;
dirname = g_path_get_dirname (name);
canonical_dirname = menu_realpath (dirname, NULL);
g_free (dirname);
if (canonical_dirname)
{
char *basename;
basename = g_path_get_basename (name);
retval = g_build_filename (canonical_dirname, basename, NULL);
g_free (basename);
g_free (canonical_dirname);
}
}
return retval;
}