1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2013 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 #include "canonicalize.h"
27 #include "areadlink.h"
29 #include "hash-triple.h"
35 #define MULTIPLE_BITS_SET(i) (((i) & ((i) - 1)) != 0)
37 /* In this file, we cannot handle file names longer than PATH_MAX.
38 On systems with no file name length limit, use a fallback. */
40 # define PATH_MAX 8192
43 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
44 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
48 # define SLASHES "/\\"
53 #if !((HAVE_CANONICALIZE_FILE_NAME && FUNC_REALPATH_WORKS) \
54 || GNULIB_CANONICALIZE_LGPL)
55 /* Return the canonical absolute name of file NAME. A canonical name
56 does not contain any ".", ".." components nor any repeated file name
57 separators ('/') or symlinks. All components must exist.
58 The result is malloc'd. */
61 canonicalize_file_name (const char *name)
63 return canonicalize_filename_mode (name, CAN_EXISTING);
65 #endif /* !HAVE_CANONICALIZE_FILE_NAME */
67 /* Return true if we've already seen the triple, <FILENAME, dev, ino>.
68 If *HT is not initialized, initialize it. */
70 seen_triple (Hash_table **ht, char const *filename, struct stat const *st)
74 size_t initial_capacity = 7;
75 *ht = hash_initialize (initial_capacity,
78 triple_compare_ino_str,
84 if (seen_file (*ht, filename, st))
87 record_file (*ht, filename, st);
91 /* Return the canonical absolute name of file NAME, while treating
92 missing elements according to CAN_MODE. A canonical name
93 does not contain any ".", ".." components nor any repeated file name
94 separators ('/') or, depending on other CAN_MODE flags, symlinks.
95 Whether components must exist or not depends on canonicalize mode.
96 The result is malloc'd. */
99 canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode)
101 char *rname, *dest, *extra_buf = NULL;
104 char const *rname_limit;
105 size_t extra_len = 0;
106 Hash_table *ht = NULL;
108 int can_flags = can_mode & ~CAN_MODE_MASK;
109 bool logical = can_flags & CAN_NOLINKS;
112 can_mode &= CAN_MODE_MASK;
114 if (MULTIPLE_BITS_SET (can_mode))
132 /* This is always zero for Posix hosts, but can be 2 for MS-Windows
133 and MS-DOS X:/foo/bar file names. */
134 prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
136 if (!IS_ABSOLUTE_FILE_NAME (name))
141 dest = strchr (rname, '\0');
142 if (dest - rname < PATH_MAX)
144 char *p = xrealloc (rname, PATH_MAX);
145 dest = p + (dest - rname);
147 rname_limit = rname + PATH_MAX;
154 prefix_len = FILE_SYSTEM_PREFIX_LEN (rname);
158 rname = xmalloc (PATH_MAX);
159 rname_limit = rname + PATH_MAX;
163 memcpy (rname, name, prefix_len);
167 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
169 if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
173 start = name + prefix_len;
176 for ( ; *start; start = end)
178 /* Skip sequence of multiple file name separators. */
179 while (ISSLASH (*start))
182 /* Find end of component. */
183 for (end = start; *end && !ISSLASH (*end); ++end)
186 if (end - start == 0)
188 else if (end - start == 1 && start[0] == '.')
190 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
192 /* Back up to previous component, ignore if at root already. */
193 if (dest > rname + prefix_len + 1)
194 for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
196 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1
197 && !prefix_len && ISSLASH (*dest) && !ISSLASH (dest[1]))
204 if (!ISSLASH (dest[-1]))
207 if (dest + (end - start) >= rname_limit)
209 ptrdiff_t dest_offset = dest - rname;
210 size_t new_size = rname_limit - rname;
212 if (end - start + 1 > PATH_MAX)
213 new_size += end - start + 1;
215 new_size += PATH_MAX;
216 rname = xrealloc (rname, new_size);
217 rname_limit = rname + new_size;
219 dest = rname + dest_offset;
222 dest = memcpy (dest, start, end - start);
226 if (logical && (can_mode == CAN_MISSING))
228 /* Avoid the stat in this case as it's inconsequential.
229 i.e. we're neither resolving symlinks or testing
230 component existence. */
233 else if ((logical ? stat (rname, &st) : lstat (rname, &st)) != 0)
236 if (can_mode == CAN_EXISTING)
238 if (can_mode == CAN_ALL_BUT_LAST)
240 if (end[strspn (end, SLASHES)] || saved_errno != ENOENT)
247 if (S_ISLNK (st.st_mode))
252 /* Detect loops. We cannot use the cycle-check module here,
253 since it's actually possible to encounter the same symlink
254 more than once in a given traversal. However, encountering
255 the same symlink,NAME pair twice does indicate a loop. */
256 if (seen_triple (&ht, name, &st))
258 if (can_mode == CAN_MISSING)
264 buf = areadlink_with_size (rname, st.st_size);
267 if (can_mode == CAN_MISSING && errno != ENOMEM)
279 ((n + len + 1) > PATH_MAX) ? (n + len + 1) : PATH_MAX;
280 extra_buf = xmalloc (extra_len);
282 else if ((n + len + 1) > extra_len)
284 extra_len = n + len + 1;
285 extra_buf = xrealloc (extra_buf, extra_len);
288 /* Careful here, end may be a pointer into extra_buf... */
289 memmove (&extra_buf[n], end, len + 1);
290 name = end = memcpy (extra_buf, buf, n);
292 if (IS_ABSOLUTE_FILE_NAME (buf))
294 size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
297 memcpy (rname, buf, pfxlen);
298 dest = rname + pfxlen;
299 *dest++ = '/'; /* It's an absolute symlink */
300 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
302 if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
306 /* Install the new prefix to be in effect hereafter. */
311 /* Back up to previous component, ignore if at root
313 if (dest > rname + prefix_len + 1)
314 for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
316 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1
317 && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
325 if (!S_ISDIR (st.st_mode) && *end && (can_mode != CAN_MISSING))
327 saved_errno = ENOTDIR;
333 if (dest > rname + prefix_len + 1 && ISSLASH (dest[-1]))
335 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1 && !prefix_len
336 && ISSLASH (*dest) && !ISSLASH (dest[1]))
339 if (rname_limit != dest + 1)
340 rname = xrealloc (rname, dest - rname + 1);