blob: 4b1f6cb40ffbc9cd112331d1ce3af0b318431cec [file] [log] [blame]
/* Return the canonical absolute name of a given file.
Copyright (C) 1996-2016 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
/* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
optimizes away the name == NULL test below. */
# define _GL_ARG_NONNULL(params)
# define _GL_USE_STDLIB_ALLOC 1
# include <config.h>
#endif
#if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
/* Specification. */
#include <stdlib.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
#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"
# include "dosname.h"
# if HAVE_GETCWD
# if 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
# 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
# else
# define __getcwd(buf, max) getwd (buf)
# endif
# define __readlink readlink
# define __set_errno(e) errno = (e)
# ifndef MAXSYMLINKS
# ifdef SYMLOOP_MAX
# define MAXSYMLINKS SYMLOOP_MAX
# else
# define MAXSYMLINKS 20
# endif
# endif
#endif
#ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
# define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
#endif
/* Define this independently so that stdint.h is not a prerequisite. */
#ifndef SIZE_MAX
# define SIZE_MAX ((size_t) -1)
#endif
#if !FUNC_REALPATH_WORKS || defined _LIBC
static void
alloc_failed (void)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Avoid errno problem without using the malloc or realloc modules; see:
http://lists.gnu.org/archive/html/bug-gnulib/2016-08/msg00025.html */
errno = ENOMEM;
#endif
}
/* 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;
size_t prefix_len;
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
if (resolved == NULL)
{
rpath = malloc (path_max);
if (rpath == NULL)
{
alloc_failed ();
return NULL;
}
}
else
rpath = resolved;
rpath_limit = rpath + path_max;
/* This is always zero for Posix hosts, but can be 2 for MS-Windows
and MS-DOS X:/foo/bar file names. */
prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
if (!IS_ABSOLUTE_FILE_NAME (name))
{
if (!__getcwd (rpath, path_max))
{
rpath[0] = '\0';
goto error;
}
dest = strchr (rpath, '\0');
start = name;
prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
}
else
{
dest = rpath;
if (prefix_len)
{
memcpy (rpath, name, prefix_len);
dest += prefix_len;
}
*dest++ = '/';
if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
{
if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
*dest++ = '/';
*dest = '\0';
}
start = name + prefix_len;
}
for (end = start; *start; start = end)
{
#ifdef _LIBC
struct stat64 st;
#else
struct stat st;
#endif
/* Skip sequence of multiple path-separators. */
while (ISSLASH (*start))
++start;
/* Find end of path component. */
for (end = start; *end && !ISSLASH (*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 + prefix_len + 1)
for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
continue;
if (DOUBLE_SLASH_IS_DISTINCT_ROOT
&& dest == rpath + 1 && !prefix_len
&& ISSLASH (*dest) && !ISSLASH (dest[1]))
dest++;
}
else
{
size_t new_size;
if (!ISSLASH (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 + prefix_len + 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)
{
alloc_failed ();
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, end - start);
dest += end - start;
#endif
*dest = '\0';
#ifdef _LIBC
if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
#else
if (lstat (rpath, &st) < 0)
#endif
goto error;
if (S_ISLNK (st.st_mode))
{
char *buf;
size_t len;
ssize_t n;
if (++num_links > MAXSYMLINKS)
{
__set_errno (ELOOP);
goto error;
}
buf = malloca (path_max);
if (!buf)
{
__set_errno (ENOMEM);
goto error;
}
n = __readlink (rpath, buf, path_max - 1);
if (n < 0)
{
int saved_errno = errno;
freea (buf);
__set_errno (saved_errno);
goto error;
}
buf[n] = '\0';
if (!extra_buf)
{
extra_buf = malloca (path_max);
if (!extra_buf)
{
freea (buf);
__set_errno (ENOMEM);
goto error;
}
}
len = strlen (end);
/* Check that n + len + 1 doesn't overflow and is <= path_max. */
if (n >= SIZE_MAX - len || 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 = memcpy (extra_buf, buf, n);
if (IS_ABSOLUTE_FILE_NAME (buf))
{
size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
if (pfxlen)
memcpy (rpath, buf, pfxlen);
dest = rpath + pfxlen;
*dest++ = '/'; /* It's an absolute symlink */
if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
{
if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
*dest++ = '/';
*dest = '\0';
}
/* Install the new prefix to be in effect hereafter. */
prefix_len = pfxlen;
}
else
{
/* Back up to previous component, ignore if at root
already: */
if (dest > rpath + prefix_len + 1)
for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
continue;
if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
&& ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
dest++;
}
}
else if (!S_ISDIR (st.st_mode) && *end != '\0')
{
__set_errno (ENOTDIR);
goto error;
}
}
}
if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
--dest;
if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
&& ISSLASH (*dest) && !ISSLASH (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);
__set_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
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 dummy;
#endif