1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2018 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 <https://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.
62 # if defined VMS && !defined getcwd
63 /* We want the directory in Unix syntax, not in VMS syntax.
64 The gnulib override of 'getcwd' takes 2 arguments; the original VMS
65 'getcwd' takes 3 arguments. */
66 # define __getcwd(buf, max) getcwd (buf, max, 0)
68 # define __getcwd getcwd
71 # define __getcwd(buf, max) getwd (buf)
73 # define __readlink readlink
74 # define __set_errno(e) errno = (e)
77 # define MAXSYMLINKS SYMLOOP_MAX
79 # define MAXSYMLINKS 20
84 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
85 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
88 /* Define this independently so that stdint.h is not a prerequisite. */
90 # define SIZE_MAX ((size_t) -1)
93 #if !FUNC_REALPATH_WORKS || defined _LIBC
98 #if defined _WIN32 && ! defined __CYGWIN__
99 /* Avoid errno problem without using the malloc or realloc modules; see:
100 https://lists.gnu.org/r/bug-gnulib/2016-08/msg00025.html */
105 /* Return the canonical absolute name of file NAME. A canonical name
106 does not contain any ".", ".." components nor any repeated path
107 separators ('/') or symlinks. All path components must exist. If
108 RESOLVED is null, the result is malloc'd; otherwise, if the
109 canonical name is PATH_MAX chars or more, returns null with 'errno'
110 set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
111 returns the name in RESOLVED. If the name cannot be resolved and
112 RESOLVED is non-NULL, it contains the path of the first component
113 that cannot be resolved. If the path can be resolved, RESOLVED
114 holds the same value as the value returned. */
117 __realpath (const char *name, char *resolved)
119 char *rpath, *dest, *extra_buf = NULL;
120 const char *start, *end, *rpath_limit;
127 /* As per Single Unix Specification V2 we must return an error if
128 either parameter is a null pointer. We extend this to allow
129 the RESOLVED parameter to be NULL in case the we are expected to
130 allocate the room for the return value. */
131 __set_errno (EINVAL);
137 /* As per Single Unix Specification V2 we must return an error if
138 the name argument points to an empty string. */
139 __set_errno (ENOENT);
146 path_max = pathconf (name, _PC_PATH_MAX);
151 if (resolved == NULL)
153 rpath = malloc (path_max);
162 rpath_limit = rpath + path_max;
164 /* This is always zero for Posix hosts, but can be 2 for MS-Windows
165 and MS-DOS X:/foo/bar file names. */
166 prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
168 if (!IS_ABSOLUTE_FILE_NAME (name))
170 if (!__getcwd (rpath, path_max))
175 dest = strchr (rpath, '\0');
177 prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
184 memcpy (rpath, name, prefix_len);
188 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
190 if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
194 start = name + prefix_len;
197 for (end = start; *start; start = end)
205 /* Skip sequence of multiple path-separators. */
206 while (ISSLASH (*start))
209 /* Find end of path component. */
210 for (end = start; *end && !ISSLASH (*end); ++end)
213 if (end - start == 0)
215 else if (end - start == 1 && start[0] == '.')
217 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
219 /* Back up to previous component, ignore if at root already. */
220 if (dest > rpath + prefix_len + 1)
221 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
223 if (DOUBLE_SLASH_IS_DISTINCT_ROOT
224 && dest == rpath + 1 && !prefix_len
225 && ISSLASH (*dest) && !ISSLASH (dest[1]))
232 if (!ISSLASH (dest[-1]))
235 if (dest + (end - start) >= rpath_limit)
237 ptrdiff_t dest_offset = dest - rpath;
242 __set_errno (ENAMETOOLONG);
243 if (dest > rpath + prefix_len + 1)
248 new_size = rpath_limit - rpath;
249 if (end - start + 1 > path_max)
250 new_size += end - start + 1;
252 new_size += path_max;
253 new_rpath = (char *) realloc (rpath, new_size);
254 if (new_rpath == NULL)
260 rpath_limit = rpath + new_size;
262 dest = rpath + dest_offset;
266 dest = __mempcpy (dest, start, end - start);
268 memcpy (dest, start, end - start);
273 /* FIXME: if lstat fails with errno == EOVERFLOW,
276 if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
278 if (lstat (rpath, &st) < 0)
282 if (S_ISLNK (st.st_mode))
288 if (++num_links > MAXSYMLINKS)
294 buf = malloca (path_max);
297 __set_errno (ENOMEM);
301 n = __readlink (rpath, buf, path_max - 1);
304 int saved_errno = errno;
306 __set_errno (saved_errno);
313 extra_buf = malloca (path_max);
317 __set_errno (ENOMEM);
323 /* Check that n + len + 1 doesn't overflow and is <= path_max. */
324 if (n >= SIZE_MAX - len || n + len >= path_max)
327 __set_errno (ENAMETOOLONG);
331 /* Careful here, end may be a pointer into extra_buf... */
332 memmove (&extra_buf[n], end, len + 1);
333 name = end = memcpy (extra_buf, buf, n);
335 if (IS_ABSOLUTE_FILE_NAME (buf))
337 size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
340 memcpy (rpath, buf, pfxlen);
341 dest = rpath + pfxlen;
342 *dest++ = '/'; /* It's an absolute symlink */
343 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
345 if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
349 /* Install the new prefix to be in effect hereafter. */
354 /* Back up to previous component, ignore if at root
356 if (dest > rpath + prefix_len + 1)
357 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
359 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
360 && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
364 else if (!S_ISDIR (st.st_mode) && *end != '\0')
366 __set_errno (ENOTDIR);
371 if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
373 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
374 && ISSLASH (*dest) && !ISSLASH (dest[1]))
385 int saved_errno = errno;
388 if (resolved == NULL)
390 __set_errno (saved_errno);
394 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
395 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
398 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
400 attribute_compat_text_section
401 __old_realpath (const char *name, char *resolved)
403 if (resolved == NULL)
405 __set_errno (EINVAL);
409 return __realpath (name, resolved);
411 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
416 __canonicalize_file_name (const char *name)
418 return __realpath (name, NULL);
420 weak_alias (__canonicalize_file_name, canonicalize_file_name)
424 /* This declaration is solely to ensure that after preprocessing
425 this file is never empty. */