1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
20 optimizes away the name == NULL test below. */
21 # define _GL_ARG_NONNULL(params)
23 # define _GL_USE_STDLIB_ALLOC 1
27 #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
36 #if HAVE_SYS_PARAM_H || defined _LIBC
37 # include <sys/param.h>
44 # include <shlib-compat.h>
46 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
47 # define versioned_symbol(lib, local, symbol, version) extern int dummy
48 # define compat_symbol(lib, local, symbol, version)
49 # define weak_alias(local, symbol)
50 # define __canonicalize_file_name canonicalize_file_name
51 # define __realpath realpath
57 /* When building the relocatable program wrapper, use the system's getcwd
58 function, not the gnulib override, otherwise we would get a link error.
63 /* We want the directory in Unix syntax, not in VMS syntax. */
64 # define __getcwd(buf, max) getcwd (buf, max, 0)
66 # define __getcwd getcwd
69 # define __getcwd(buf, max) getwd (buf)
71 # define __readlink readlink
72 # define __set_errno(e) errno = (e)
75 # define MAXSYMLINKS SYMLOOP_MAX
77 # define MAXSYMLINKS 20
82 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
83 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
86 #if !FUNC_REALPATH_WORKS || defined _LIBC
91 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
92 /* Avoid errno problem without using the malloc or realloc modules; see:
93 http://lists.gnu.org/archive/html/bug-gnulib/2016-08/msg00025.html */
98 /* Return the canonical absolute name of file NAME. A canonical name
99 does not contain any ".", ".." components nor any repeated path
100 separators ('/') or symlinks. All path components must exist. If
101 RESOLVED is null, the result is malloc'd; otherwise, if the
102 canonical name is PATH_MAX chars or more, returns null with 'errno'
103 set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
104 returns the name in RESOLVED. If the name cannot be resolved and
105 RESOLVED is non-NULL, it contains the path of the first component
106 that cannot be resolved. If the path can be resolved, RESOLVED
107 holds the same value as the value returned. */
110 __realpath (const char *name, char *resolved)
112 char *rpath, *dest, *extra_buf = NULL;
113 const char *start, *end, *rpath_limit;
120 /* As per Single Unix Specification V2 we must return an error if
121 either parameter is a null pointer. We extend this to allow
122 the RESOLVED parameter to be NULL in case the we are expected to
123 allocate the room for the return value. */
124 __set_errno (EINVAL);
130 /* As per Single Unix Specification V2 we must return an error if
131 the name argument points to an empty string. */
132 __set_errno (ENOENT);
139 path_max = pathconf (name, _PC_PATH_MAX);
144 if (resolved == NULL)
146 rpath = malloc (path_max);
155 rpath_limit = rpath + path_max;
157 /* This is always zero for Posix hosts, but can be 2 for MS-Windows
158 and MS-DOS X:/foo/bar file names. */
159 prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
161 if (!IS_ABSOLUTE_FILE_NAME (name))
163 if (!__getcwd (rpath, path_max))
168 dest = strchr (rpath, '\0');
170 prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
177 memcpy (rpath, name, prefix_len);
181 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
183 if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
187 start = name + prefix_len;
190 for (end = start; *start; start = end)
199 /* Skip sequence of multiple path-separators. */
200 while (ISSLASH (*start))
203 /* Find end of path component. */
204 for (end = start; *end && !ISSLASH (*end); ++end)
207 if (end - start == 0)
209 else if (end - start == 1 && start[0] == '.')
211 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
213 /* Back up to previous component, ignore if at root already. */
214 if (dest > rpath + prefix_len + 1)
215 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
217 if (DOUBLE_SLASH_IS_DISTINCT_ROOT
218 && dest == rpath + 1 && !prefix_len
219 && ISSLASH (*dest) && !ISSLASH (dest[1]))
226 if (!ISSLASH (dest[-1]))
229 if (dest + (end - start) >= rpath_limit)
231 ptrdiff_t dest_offset = dest - rpath;
236 __set_errno (ENAMETOOLONG);
237 if (dest > rpath + prefix_len + 1)
242 new_size = rpath_limit - rpath;
243 if (end - start + 1 > path_max)
244 new_size += end - start + 1;
246 new_size += path_max;
247 new_rpath = (char *) realloc (rpath, new_size);
248 if (new_rpath == NULL)
254 rpath_limit = rpath + new_size;
256 dest = rpath + dest_offset;
260 dest = __mempcpy (dest, start, end - start);
262 memcpy (dest, start, end - start);
268 if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
270 if (lstat (rpath, &st) < 0)
274 if (S_ISLNK (st.st_mode))
279 if (++num_links > MAXSYMLINKS)
285 buf = malloca (path_max);
288 __set_errno (ENOMEM);
292 n = __readlink (rpath, buf, path_max - 1);
295 int saved_errno = errno;
297 __set_errno (saved_errno);
304 extra_buf = malloca (path_max);
308 __set_errno (ENOMEM);
314 if ((long int) (n + len) >= path_max)
317 __set_errno (ENAMETOOLONG);
321 /* Careful here, end may be a pointer into extra_buf... */
322 memmove (&extra_buf[n], end, len + 1);
323 name = end = memcpy (extra_buf, buf, n);
325 if (IS_ABSOLUTE_FILE_NAME (buf))
327 size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
330 memcpy (rpath, buf, pfxlen);
331 dest = rpath + pfxlen;
332 *dest++ = '/'; /* It's an absolute symlink */
333 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
335 if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
339 /* Install the new prefix to be in effect hereafter. */
344 /* Back up to previous component, ignore if at root
346 if (dest > rpath + prefix_len + 1)
347 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
349 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
350 && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
354 else if (!S_ISDIR (st.st_mode) && *end != '\0')
356 __set_errno (ENOTDIR);
361 if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
363 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
364 && ISSLASH (*dest) && !ISSLASH (dest[1]))
375 int saved_errno = errno;
378 if (resolved == NULL)
380 __set_errno (saved_errno);
384 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
385 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
388 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
390 attribute_compat_text_section
391 __old_realpath (const char *name, char *resolved)
393 if (resolved == NULL)
395 __set_errno (EINVAL);
399 return __realpath (name, resolved);
401 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
406 __canonicalize_file_name (const char *name)
408 return __realpath (name, NULL);
410 weak_alias (__canonicalize_file_name, canonicalize_file_name)
414 /* This declaration is solely to ensure that after preprocessing
415 this file is never empty. */