1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2013 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
28 #include <eloop-threshold.h>
29 #include <shlib-compat.h>
31 /* Return the canonical absolute name of file NAME. A canonical name
32 does not contain any `.', `..' components nor any repeated path
33 separators ('/') or symlinks. All path components must exist. If
34 RESOLVED is null, the result is malloc'd; otherwise, if the
35 canonical name is PATH_MAX chars or more, returns null with `errno'
36 set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
37 returns the name in RESOLVED. If the name cannot be resolved and
38 RESOLVED is non-NULL, it contains the path of the first component
39 that cannot be resolved. If the path can be resolved, RESOLVED
40 holds the same value as the value returned. */
43 __realpath (const char *name, char *resolved)
45 char *rpath, *dest, *extra_buf = NULL;
46 const char *start, *end, *rpath_limit;
52 /* As per Single Unix Specification V2 we must return an error if
53 either parameter is a null pointer. We extend this to allow
54 the RESOLVED parameter to be NULL in case the we are expected to
55 allocate the room for the return value. */
62 /* As per Single Unix Specification V2 we must return an error if
63 the name argument points to an empty string. */
71 path_max = pathconf (name, _PC_PATH_MAX);
78 rpath = malloc (path_max);
84 rpath_limit = rpath + path_max;
88 if (!__getcwd (rpath, path_max))
93 dest = __rawmemchr (rpath, '\0');
101 for (start = end = name; *start; start = end)
106 /* Skip sequence of multiple path-separators. */
107 while (*start == '/')
110 /* Find end of path component. */
111 for (end = start; *end && *end != '/'; ++end)
114 if (end - start == 0)
116 else if (end - start == 1 && start[0] == '.')
118 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
120 /* Back up to previous component, ignore if at root already. */
121 if (dest > rpath + 1)
122 while ((--dest)[-1] != '/');
131 if (dest + (end - start) >= rpath_limit)
133 ptrdiff_t dest_offset = dest - rpath;
138 __set_errno (ENAMETOOLONG);
139 if (dest > rpath + 1)
144 new_size = rpath_limit - rpath;
145 if (end - start + 1 > path_max)
146 new_size += end - start + 1;
148 new_size += path_max;
149 new_rpath = (char *) realloc (rpath, new_size);
150 if (new_rpath == NULL)
153 rpath_limit = rpath + new_size;
155 dest = rpath + dest_offset;
158 dest = __mempcpy (dest, start, end - start);
161 if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
164 if (S_ISLNK (st.st_mode))
166 char *buf = __alloca (path_max);
169 if (++num_links > __eloop_threshold ())
175 n = __readlink (rpath, buf, path_max - 1);
181 extra_buf = __alloca (path_max);
184 if ((long int) (n + len) >= path_max)
186 __set_errno (ENAMETOOLONG);
190 /* Careful here, end may be a pointer into extra_buf... */
191 memmove (&extra_buf[n], end, len + 1);
192 name = end = memcpy (extra_buf, buf, n);
195 dest = rpath + 1; /* It's an absolute symlink */
197 /* Back up to previous component, ignore if at root already: */
198 if (dest > rpath + 1)
199 while ((--dest)[-1] != '/');
201 else if (!S_ISDIR (st.st_mode) && *end != '\0')
203 __set_errno (ENOTDIR);
208 if (dest > rpath + 1 && dest[-1] == '/')
212 assert (resolved == NULL || resolved == rpath);
216 assert (resolved == NULL || resolved == rpath);
217 if (resolved == NULL)
221 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
224 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
226 attribute_compat_text_section
227 __old_realpath (const char *name, char *resolved)
229 if (resolved == NULL)
231 __set_errno (EINVAL);
235 return __realpath (name, resolved);
237 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
242 __canonicalize_file_name (const char *name)
244 return __realpath (name, NULL);
246 weak_alias (__canonicalize_file_name, canonicalize_file_name)