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fa0bc87c | 1 | /* Return the canonical absolute name of a given file. |
581c785b | 2 | Copyright (C) 1996-2022 Free Software Foundation, Inc. |
a18f587d | 3 | This file is part of the GNU C Library. |
fa0bc87c | 4 | |
a18f587d | 5 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
fa0bc87c | 9 | |
a18f587d UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
fa0bc87c | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
fa0bc87c | 18 | |
c6e0b0b5 AZ |
19 | #ifndef _LIBC |
20 | /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc | |
21 | optimizes away the name == NULL test below. */ | |
22 | # define _GL_ARG_NONNULL(params) | |
23 | ||
24 | # define _GL_USE_STDLIB_ALLOC 1 | |
25 | # include <libc-config.h> | |
26 | #endif | |
27 | ||
28 | /* Specification. */ | |
fa0bc87c | 29 | #include <stdlib.h> |
c6e0b0b5 AZ |
30 | |
31 | #include <errno.h> | |
32 | #include <fcntl.h> | |
fa0bc87c | 33 | #include <limits.h> |
c6e0b0b5 AZ |
34 | #include <stdbool.h> |
35 | #include <string.h> | |
fa0bc87c | 36 | #include <sys/stat.h> |
c6e0b0b5 | 37 | #include <unistd.h> |
fa0bc87c | 38 | |
4f75b7a0 | 39 | #include <eloop-threshold.h> |
c6e0b0b5 AZ |
40 | #include <filename.h> |
41 | #include <idx.h> | |
42 | #include <intprops.h> | |
43 | #include <scratch_buffer.h> | |
44 | ||
45 | #ifdef _LIBC | |
46 | # include <shlib-compat.h> | |
47 | # define GCC_LINT 1 | |
48 | # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__)) | |
49 | #else | |
50 | # define __canonicalize_file_name canonicalize_file_name | |
51 | # define __realpath realpath | |
52 | # include "pathmax.h" | |
53 | # define __faccessat faccessat | |
54 | # if defined _WIN32 && !defined __CYGWIN__ | |
55 | # define __getcwd _getcwd | |
56 | # elif HAVE_GETCWD | |
57 | # if IN_RELOCWRAPPER | |
58 | /* When building the relocatable program wrapper, use the system's getcwd | |
59 | function, not the gnulib override, otherwise we would get a link error. | |
60 | */ | |
61 | # undef getcwd | |
62 | # endif | |
63 | # if defined VMS && !defined getcwd | |
64 | /* We want the directory in Unix syntax, not in VMS syntax. | |
65 | The gnulib override of 'getcwd' takes 2 arguments; the original VMS | |
66 | 'getcwd' takes 3 arguments. */ | |
67 | # define __getcwd(buf, max) getcwd (buf, max, 0) | |
68 | # else | |
69 | # define __getcwd getcwd | |
70 | # endif | |
71 | # else | |
72 | # define __getcwd(buf, max) getwd (buf) | |
73 | # endif | |
74 | # define __mempcpy mempcpy | |
75 | # define __pathconf pathconf | |
76 | # define __rawmemchr rawmemchr | |
77 | # define __readlink readlink | |
78 | # define __stat stat | |
79 | #endif | |
3e0dd85b | 80 | |
c6e0b0b5 AZ |
81 | /* Suppress bogus GCC -Wmaybe-uninitialized warnings. */ |
82 | #if defined GCC_LINT || defined lint | |
83 | # define IF_LINT(Code) Code | |
84 | #else | |
85 | # define IF_LINT(Code) /* empty */ | |
86 | #endif | |
fa0bc87c | 87 | |
c6e0b0b5 AZ |
88 | #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT |
89 | # define DOUBLE_SLASH_IS_DISTINCT_ROOT false | |
90 | #endif | |
91 | ||
92 | #if defined _LIBC || !FUNC_REALPATH_WORKS | |
93 | ||
94 | /* Return true if FILE's existence can be shown, false (setting errno) | |
95 | otherwise. Follow symbolic links. */ | |
96 | static bool | |
97 | file_accessible (char const *file) | |
98 | { | |
99 | # if defined _LIBC || HAVE_FACCESSAT | |
100 | return __faccessat (AT_FDCWD, file, F_OK, AT_EACCESS) == 0; | |
101 | # else | |
102 | struct stat st; | |
103 | return __stat (file, &st) == 0 || errno == EOVERFLOW; | |
104 | # endif | |
105 | } | |
106 | ||
107 | /* True if concatenating END as a suffix to a file name means that the | |
108 | code needs to check that the file name is that of a searchable | |
109 | directory, since the canonicalize_filename_mode_stk code won't | |
110 | check this later anyway when it checks an ordinary file name | |
111 | component within END. END must either be empty, or start with a | |
112 | slash. */ | |
113 | ||
114 | static bool _GL_ATTRIBUTE_PURE | |
115 | suffix_requires_dir_check (char const *end) | |
116 | { | |
117 | /* If END does not start with a slash, the suffix is OK. */ | |
118 | while (ISSLASH (*end)) | |
119 | { | |
120 | /* Two or more slashes act like a single slash. */ | |
121 | do | |
122 | end++; | |
123 | while (ISSLASH (*end)); | |
124 | ||
125 | switch (*end++) | |
126 | { | |
127 | default: return false; /* An ordinary file name component is OK. */ | |
128 | case '\0': return true; /* Trailing "/" is trouble. */ | |
129 | case '.': break; /* Possibly "." or "..". */ | |
130 | } | |
131 | /* Trailing "/.", or "/.." even if not trailing, is trouble. */ | |
132 | if (!*end || (*end == '.' && (!end[1] || ISSLASH (end[1])))) | |
133 | return true; | |
134 | } | |
135 | ||
136 | return false; | |
137 | } | |
138 | ||
139 | /* Append this to a file name to test whether it is a searchable directory. | |
140 | On POSIX platforms "/" suffices, but "/./" is sometimes needed on | |
141 | macOS 10.13 <https://bugs.gnu.org/30350>, and should also work on | |
142 | platforms like AIX 7.2 that need at least "/.". */ | |
143 | ||
144 | #if defined _LIBC || defined LSTAT_FOLLOWS_SLASHED_SYMLINK | |
145 | static char const dir_suffix[] = "/"; | |
146 | #else | |
147 | static char const dir_suffix[] = "/./"; | |
148 | #endif | |
149 | ||
150 | /* Return true if DIR is a searchable dir, false (setting errno) otherwise. | |
151 | DIREND points to the NUL byte at the end of the DIR string. | |
152 | Store garbage into DIREND[0 .. strlen (dir_suffix)]. */ | |
153 | ||
154 | static bool | |
155 | dir_check (char *dir, char *dirend) | |
156 | { | |
157 | strcpy (dirend, dir_suffix); | |
158 | return file_accessible (dir); | |
159 | } | |
160 | ||
161 | static idx_t | |
162 | get_path_max (void) | |
163 | { | |
164 | # ifdef PATH_MAX | |
165 | long int path_max = PATH_MAX; | |
166 | # else | |
167 | /* The caller invoked realpath with a null RESOLVED, even though | |
168 | PATH_MAX is not defined as a constant. The glibc manual says | |
169 | programs should not do this, and POSIX says the behavior is undefined. | |
170 | Historically, glibc here used the result of pathconf, or 1024 if that | |
171 | failed; stay consistent with this (dubious) historical practice. */ | |
172 | int err = errno; | |
173 | long int path_max = __pathconf ("/", _PC_PATH_MAX); | |
174 | __set_errno (err); | |
175 | # endif | |
176 | return path_max < 0 ? 1024 : path_max <= IDX_MAX ? path_max : IDX_MAX; | |
177 | } | |
178 | ||
179 | /* Act like __realpath (see below), with an additional argument | |
180 | rname_buf that can be used as temporary storage. | |
181 | ||
182 | If GCC_LINT is defined, do not inline this function with GCC 10.1 | |
183 | and later, to avoid creating a pointer to the stack that GCC | |
184 | -Wreturn-local-addr incorrectly complains about. See: | |
185 | https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644 | |
186 | Although the noinline attribute can hurt performance a bit, no better way | |
187 | to pacify GCC is known; even an explicit #pragma does not pacify GCC. | |
188 | When the GCC bug is fixed this workaround should be limited to the | |
189 | broken GCC versions. */ | |
190 | #if __GNUC_PREREQ (10, 1) | |
191 | # if defined GCC_LINT || defined lint | |
192 | __attribute__ ((__noinline__)) | |
193 | # elif __OPTIMIZE__ && !__NO_INLINE__ | |
194 | # define GCC_BOGUS_WRETURN_LOCAL_ADDR | |
195 | # endif | |
196 | #endif | |
197 | static char * | |
198 | realpath_stk (const char *name, char *resolved, | |
199 | struct scratch_buffer *rname_buf) | |
fa0bc87c | 200 | { |
c6e0b0b5 AZ |
201 | char *dest; |
202 | char const *start; | |
203 | char const *end; | |
394f4f17 | 204 | int num_links = 0; |
fa0bc87c | 205 | |
310b3460 | 206 | if (name == NULL) |
86187531 UD |
207 | { |
208 | /* As per Single Unix Specification V2 we must return an error if | |
c6e0b0b5 AZ |
209 | either parameter is a null pointer. We extend this to allow |
210 | the RESOLVED parameter to be NULL in case the we are expected to | |
211 | allocate the room for the return value. */ | |
86187531 UD |
212 | __set_errno (EINVAL); |
213 | return NULL; | |
214 | } | |
215 | ||
216 | if (name[0] == '\0') | |
217 | { | |
218 | /* As per Single Unix Specification V2 we must return an error if | |
c6e0b0b5 | 219 | the name argument points to an empty string. */ |
86187531 UD |
220 | __set_errno (ENOENT); |
221 | return NULL; | |
222 | } | |
223 | ||
c6e0b0b5 AZ |
224 | struct scratch_buffer extra_buffer, link_buffer; |
225 | scratch_buffer_init (&extra_buffer); | |
226 | scratch_buffer_init (&link_buffer); | |
227 | scratch_buffer_init (rname_buf); | |
228 | char *rname_on_stack = rname_buf->data; | |
229 | char *rname = rname_on_stack; | |
230 | bool end_in_extra_buffer = false; | |
231 | bool failed = true; | |
fa0bc87c | 232 | |
c6e0b0b5 AZ |
233 | /* This is always zero for Posix hosts, but can be 2 for MS-Windows |
234 | and MS-DOS X:/foo/bar file names. */ | |
235 | idx_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name); | |
fa0bc87c | 236 | |
c6e0b0b5 | 237 | if (!IS_ABSOLUTE_FILE_NAME (name)) |
a18f587d | 238 | { |
c6e0b0b5 AZ |
239 | while (!__getcwd (rname, rname_buf->length)) |
240 | { | |
241 | if (errno != ERANGE) | |
242 | { | |
243 | dest = rname; | |
244 | goto error; | |
245 | } | |
246 | if (!scratch_buffer_grow (rname_buf)) | |
247 | goto error_nomem; | |
248 | rname = rname_buf->data; | |
249 | } | |
250 | dest = __rawmemchr (rname, '\0'); | |
251 | start = name; | |
252 | prefix_len = FILE_SYSTEM_PREFIX_LEN (rname); | |
a18f587d UD |
253 | } |
254 | else | |
255 | { | |
c6e0b0b5 AZ |
256 | dest = __mempcpy (rname, name, prefix_len); |
257 | *dest++ = '/'; | |
258 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT) | |
259 | { | |
260 | if (prefix_len == 0 /* implies ISSLASH (name[0]) */ | |
261 | && ISSLASH (name[1]) && !ISSLASH (name[2])) | |
262 | *dest++ = '/'; | |
263 | *dest = '\0'; | |
264 | } | |
265 | start = name + prefix_len; | |
a18f587d | 266 | } |
fa0bc87c | 267 | |
c6e0b0b5 | 268 | for ( ; *start; start = end) |
fa0bc87c | 269 | { |
c6e0b0b5 AZ |
270 | /* Skip sequence of multiple file name separators. */ |
271 | while (ISSLASH (*start)) | |
272 | ++start; | |
273 | ||
274 | /* Find end of component. */ | |
275 | for (end = start; *end && !ISSLASH (*end); ++end) | |
276 | /* Nothing. */; | |
277 | ||
278 | /* Length of this file name component; it can be zero if a file | |
279 | name ends in '/'. */ | |
280 | idx_t startlen = end - start; | |
281 | ||
282 | if (startlen == 0) | |
283 | break; | |
284 | else if (startlen == 1 && start[0] == '.') | |
285 | /* nothing */; | |
286 | else if (startlen == 2 && start[0] == '.' && start[1] == '.') | |
287 | { | |
288 | /* Back up to previous component, ignore if at root already. */ | |
289 | if (dest > rname + prefix_len + 1) | |
290 | for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest) | |
291 | continue; | |
292 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT | |
293 | && dest == rname + 1 && !prefix_len | |
294 | && ISSLASH (*dest) && !ISSLASH (dest[1])) | |
295 | dest++; | |
296 | } | |
86187531 | 297 | else |
c6e0b0b5 AZ |
298 | { |
299 | if (!ISSLASH (dest[-1])) | |
300 | *dest++ = '/'; | |
301 | ||
302 | while (rname + rname_buf->length - dest | |
303 | < startlen + sizeof dir_suffix) | |
304 | { | |
305 | idx_t dest_offset = dest - rname; | |
306 | if (!scratch_buffer_grow_preserve (rname_buf)) | |
307 | goto error_nomem; | |
308 | rname = rname_buf->data; | |
309 | dest = rname + dest_offset; | |
310 | } | |
311 | ||
312 | dest = __mempcpy (dest, start, startlen); | |
313 | *dest = '\0'; | |
314 | ||
315 | char *buf; | |
316 | ssize_t n; | |
317 | while (true) | |
318 | { | |
319 | buf = link_buffer.data; | |
320 | idx_t bufsize = link_buffer.length; | |
321 | n = __readlink (rname, buf, bufsize - 1); | |
322 | if (n < bufsize - 1) | |
323 | break; | |
324 | if (!scratch_buffer_grow (&link_buffer)) | |
325 | goto error_nomem; | |
326 | } | |
327 | if (0 <= n) | |
328 | { | |
329 | if (++num_links > __eloop_threshold ()) | |
330 | { | |
331 | __set_errno (ELOOP); | |
332 | goto error; | |
333 | } | |
334 | ||
335 | buf[n] = '\0'; | |
336 | ||
337 | char *extra_buf = extra_buffer.data; | |
338 | idx_t end_idx IF_LINT (= 0); | |
339 | if (end_in_extra_buffer) | |
340 | end_idx = end - extra_buf; | |
341 | size_t len = strlen (end); | |
342 | if (INT_ADD_OVERFLOW (len, n)) | |
343 | { | |
344 | __set_errno (ENOMEM); | |
345 | goto error_nomem; | |
346 | } | |
347 | while (extra_buffer.length <= len + n) | |
348 | { | |
349 | if (!scratch_buffer_grow_preserve (&extra_buffer)) | |
350 | goto error_nomem; | |
351 | extra_buf = extra_buffer.data; | |
352 | } | |
353 | if (end_in_extra_buffer) | |
354 | end = extra_buf + end_idx; | |
355 | ||
356 | /* Careful here, end may be a pointer into extra_buf... */ | |
357 | memmove (&extra_buf[n], end, len + 1); | |
358 | name = end = memcpy (extra_buf, buf, n); | |
359 | end_in_extra_buffer = true; | |
360 | ||
361 | if (IS_ABSOLUTE_FILE_NAME (buf)) | |
362 | { | |
363 | idx_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf); | |
364 | ||
365 | dest = __mempcpy (rname, buf, pfxlen); | |
366 | *dest++ = '/'; /* It's an absolute symlink */ | |
367 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT) | |
368 | { | |
369 | if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen) | |
370 | *dest++ = '/'; | |
371 | *dest = '\0'; | |
372 | } | |
373 | /* Install the new prefix to be in effect hereafter. */ | |
374 | prefix_len = pfxlen; | |
375 | } | |
376 | else | |
377 | { | |
378 | /* Back up to previous component, ignore if at root | |
379 | already: */ | |
380 | if (dest > rname + prefix_len + 1) | |
381 | for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest) | |
382 | continue; | |
383 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1 | |
384 | && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len) | |
385 | dest++; | |
386 | } | |
387 | } | |
388 | else if (! (suffix_requires_dir_check (end) | |
389 | ? dir_check (rname, dest) | |
390 | : errno == EINVAL)) | |
391 | goto error; | |
392 | } | |
394f4f17 | 393 | } |
c6e0b0b5 | 394 | if (dest > rname + prefix_len + 1 && ISSLASH (dest[-1])) |
394f4f17 | 395 | --dest; |
c6e0b0b5 AZ |
396 | if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1 && !prefix_len |
397 | && ISSLASH (*dest) && !ISSLASH (dest[1])) | |
398 | dest++; | |
399 | failed = false; | |
394f4f17 RM |
400 | |
401 | error: | |
c6e0b0b5 | 402 | *dest++ = '\0'; |
ee8d5e33 SP |
403 | if (resolved != NULL) |
404 | { | |
405 | if (dest - rname <= get_path_max ()) | |
406 | rname = strcpy (resolved, rname); | |
407 | else | |
408 | { | |
409 | failed = true; | |
410 | __set_errno (ENAMETOOLONG); | |
411 | } | |
412 | } | |
c6e0b0b5 AZ |
413 | |
414 | error_nomem: | |
415 | scratch_buffer_free (&extra_buffer); | |
416 | scratch_buffer_free (&link_buffer); | |
417 | ||
418 | if (failed || rname == resolved) | |
419 | { | |
420 | scratch_buffer_free (rname_buf); | |
421 | return failed ? NULL : resolved; | |
422 | } | |
423 | ||
424 | return scratch_buffer_dupfree (rname_buf, dest - rname); | |
425 | } | |
426 | ||
427 | /* Return the canonical absolute name of file NAME. A canonical name | |
428 | does not contain any ".", ".." components nor any repeated file name | |
429 | separators ('/') or symlinks. All file name components must exist. If | |
430 | RESOLVED is null, the result is malloc'd; otherwise, if the | |
431 | canonical name is PATH_MAX chars or more, returns null with 'errno' | |
432 | set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, | |
433 | returns the name in RESOLVED. If the name cannot be resolved and | |
434 | RESOLVED is non-NULL, it contains the name of the first component | |
435 | that cannot be resolved. If the name can be resolved, RESOLVED | |
436 | holds the same value as the value returned. */ | |
437 | ||
438 | char * | |
439 | __realpath (const char *name, char *resolved) | |
440 | { | |
441 | #ifdef GCC_BOGUS_WRETURN_LOCAL_ADDR | |
442 | #warning "GCC might issue a bogus -Wreturn-local-addr warning here." | |
443 | #warning "See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644>." | |
444 | #endif | |
445 | struct scratch_buffer rname_buffer; | |
446 | return realpath_stk (name, resolved, &rname_buffer); | |
fa0bc87c | 447 | } |
8ed3b643 | 448 | libc_hidden_def (__realpath) |
3e0dd85b | 449 | versioned_symbol (libc, __realpath, realpath, GLIBC_2_3); |
c6e0b0b5 | 450 | #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */ |
3e0dd85b UD |
451 | |
452 | ||
453 | #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3) | |
454 | char * | |
4a381a81 | 455 | attribute_compat_text_section |
3e0dd85b UD |
456 | __old_realpath (const char *name, char *resolved) |
457 | { | |
458 | if (resolved == NULL) | |
459 | { | |
460 | __set_errno (EINVAL); | |
461 | return NULL; | |
462 | } | |
463 | ||
464 | return __realpath (name, resolved); | |
465 | } | |
466 | compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0); | |
467 | #endif | |
fa0bc87c | 468 | |
a18f587d | 469 | |
fa0bc87c | 470 | char * |
2ad4fab2 | 471 | __canonicalize_file_name (const char *name) |
fa0bc87c | 472 | { |
f7501ae6 | 473 | return __realpath (name, NULL); |
fa0bc87c | 474 | } |
2ad4fab2 | 475 | weak_alias (__canonicalize_file_name, canonicalize_file_name) |