1/*
2 * I'm tired of doing "vsnprintf()" etc just to open a
3 * file, so here's a "return static buffer with printf"
4 * interface for paths.
5 *
6 * It's obviously not thread-safe. Sue me. But it's quite
7 * useful for doing things like
8 *
9 * f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
10 *
11 * which is what it's designed for.
12 */
13#include "cache.h"
14#include "strbuf.h"
15static char bad_path[] = "/bad-path/";
17static char *get_pathname(void)
19{
20 static char pathname_array[4][PATH_MAX];
21 static int index;
22 return pathname_array[3 & ++index];
23}
24static char *cleanup_path(char *path)
26{
27 /* Clean it up */
28 if (!memcmp(path, "./", 2)) {
29 path += 2;
30 while (*path == '/')
31 path++;
32 }
33 return path;
34}
35char *mksnpath(char *buf, size_t n, const char *fmt, ...)
37{
38 va_list args;
39 unsigned len;
40 va_start(args, fmt);
42 len = vsnprintf(buf, n, fmt, args);
43 va_end(args);
44 if (len >= n) {
45 strlcpy(buf, bad_path, n);
46 return buf;
47 }
48 return cleanup_path(buf);
49}
50static char *git_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
52{
53 const char *git_dir = get_git_dir();
54 size_t len;
55 len = strlen(git_dir);
57 if (n < len + 1)
58 goto bad;
59 memcpy(buf, git_dir, len);
60 if (len && !is_dir_sep(git_dir[len-1]))
61 buf[len++] = '/';
62 len += vsnprintf(buf + len, n - len, fmt, args);
63 if (len >= n)
64 goto bad;
65 return cleanup_path(buf);
66bad:
67 strlcpy(buf, bad_path, n);
68 return buf;
69}
70char *git_snpath(char *buf, size_t n, const char *fmt, ...)
72{
73 va_list args;
74 va_start(args, fmt);
75 (void)git_vsnpath(buf, n, fmt, args);
76 va_end(args);
77 return buf;
78}
79char *git_pathdup(const char *fmt, ...)
81{
82 char path[PATH_MAX];
83 va_list args;
84 va_start(args, fmt);
85 (void)git_vsnpath(path, sizeof(path), fmt, args);
86 va_end(args);
87 return xstrdup(path);
88}
89char *mkpath(const char *fmt, ...)
91{
92 va_list args;
93 unsigned len;
94 char *pathname = get_pathname();
95 va_start(args, fmt);
97 len = vsnprintf(pathname, PATH_MAX, fmt, args);
98 va_end(args);
99 if (len >= PATH_MAX)
100 return bad_path;
101 return cleanup_path(pathname);
102}
103char *git_path(const char *fmt, ...)
105{
106 const char *git_dir = get_git_dir();
107 char *pathname = get_pathname();
108 va_list args;
109 unsigned len;
110 len = strlen(git_dir);
112 if (len > PATH_MAX-100)
113 return bad_path;
114 memcpy(pathname, git_dir, len);
115 if (len && git_dir[len-1] != '/')
116 pathname[len++] = '/';
117 va_start(args, fmt);
118 len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
119 va_end(args);
120 if (len >= PATH_MAX)
121 return bad_path;
122 return cleanup_path(pathname);
123}
124/* git_mkstemp() - create tmp file honoring TMPDIR variable */
127int git_mkstemp(char *path, size_t len, const char *template)
128{
129 const char *tmp;
130 size_t n;
131 tmp = getenv("TMPDIR");
133 if (!tmp)
134 tmp = "/tmp";
135 n = snprintf(path, len, "%s/%s", tmp, template);
136 if (len <= n) {
137 errno = ENAMETOOLONG;
138 return -1;
139 }
140 return mkstemp(path);
141}
142/* git_mkstemps() - create tmp file with suffix honoring TMPDIR variable. */
144int git_mkstemps(char *path, size_t len, const char *template, int suffix_len)
145{
146 const char *tmp;
147 size_t n;
148 tmp = getenv("TMPDIR");
150 if (!tmp)
151 tmp = "/tmp";
152 n = snprintf(path, len, "%s/%s", tmp, template);
153 if (len <= n) {
154 errno = ENAMETOOLONG;
155 return -1;
156 }
157 return mkstemps(path, suffix_len);
158}
159/* Adapted from libiberty's mkstemp.c. */
161#undef TMP_MAX
163#define TMP_MAX 16384
164int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
166{
167 static const char letters[] =
168 "abcdefghijklmnopqrstuvwxyz"
169 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
170 "0123456789";
171 static const int num_letters = 62;
172 uint64_t value;
173 struct timeval tv;
174 char *template;
175 size_t len;
176 int fd, count;
177 len = strlen(pattern);
179 if (len < 6 + suffix_len) {
181 errno = EINVAL;
182 return -1;
183 }
184 if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
186 errno = EINVAL;
187 return -1;
188 }
189 /*
191 * Replace pattern's XXXXXX characters with randomness.
192 * Try TMP_MAX different filenames.
193 */
194 gettimeofday(&tv, NULL);
195 value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
196 template = &pattern[len - 6 - suffix_len];
197 for (count = 0; count < TMP_MAX; ++count) {
198 uint64_t v = value;
199 /* Fill in the random bits. */
200 template[0] = letters[v % num_letters]; v /= num_letters;
201 template[1] = letters[v % num_letters]; v /= num_letters;
202 template[2] = letters[v % num_letters]; v /= num_letters;
203 template[3] = letters[v % num_letters]; v /= num_letters;
204 template[4] = letters[v % num_letters]; v /= num_letters;
205 template[5] = letters[v % num_letters]; v /= num_letters;
206 fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
208 if (fd > 0)
209 return fd;
210 /*
211 * Fatal error (EPERM, ENOSPC etc).
212 * It doesn't make sense to loop.
213 */
214 if (errno != EEXIST)
215 break;
216 /*
217 * This is a random value. It is only necessary that
218 * the next TMP_MAX values generated by adding 7777 to
219 * VALUE are different with (module 2^32).
220 */
221 value += 7777;
222 }
223 /* We return the null string if we can't find a unique file name. */
224 pattern[0] = '\0';
225 return -1;
226}
227int git_mkstemp_mode(char *pattern, int mode)
229{
230 /* mkstemp is just mkstemps with no suffix */
231 return git_mkstemps_mode(pattern, 0, mode);
232}
233int gitmkstemps(char *pattern, int suffix_len)
235{
236 return git_mkstemps_mode(pattern, suffix_len, 0600);
237}
238int validate_headref(const char *path)
240{
241 struct stat st;
242 char *buf, buffer[256];
243 unsigned char sha1[20];
244 int fd;
245 ssize_t len;
246 if (lstat(path, &st) < 0)
248 return -1;
249 /* Make sure it is a "refs/.." symlink */
251 if (S_ISLNK(st.st_mode)) {
252 len = readlink(path, buffer, sizeof(buffer)-1);
253 if (len >= 5 && !memcmp("refs/", buffer, 5))
254 return 0;
255 return -1;
256 }
257 /*
259 * Anything else, just open it and try to see if it is a symbolic ref.
260 */
261 fd = open(path, O_RDONLY);
262 if (fd < 0)
263 return -1;
264 len = read_in_full(fd, buffer, sizeof(buffer)-1);
265 close(fd);
266 /*
268 * Is it a symbolic ref?
269 */
270 if (len < 4)
271 return -1;
272 if (!memcmp("ref:", buffer, 4)) {
273 buf = buffer + 4;
274 len -= 4;
275 while (len && isspace(*buf))
276 buf++, len--;
277 if (len >= 5 && !memcmp("refs/", buf, 5))
278 return 0;
279 }
280 /*
282 * Is this a detached HEAD?
283 */
284 if (!get_sha1_hex(buffer, sha1))
285 return 0;
286 return -1;
288}
289static struct passwd *getpw_str(const char *username, size_t len)
291{
292 struct passwd *pw;
293 char *username_z = xmalloc(len + 1);
294 memcpy(username_z, username, len);
295 username_z[len] = '\0';
296 pw = getpwnam(username_z);
297 free(username_z);
298 return pw;
299}
300/*
302 * Return a string with ~ and ~user expanded via getpw*. If buf != NULL,
303 * then it is a newly allocated string. Returns NULL on getpw failure or
304 * if path is NULL.
305 */
306char *expand_user_path(const char *path)
307{
308 struct strbuf user_path = STRBUF_INIT;
309 const char *first_slash = strchrnul(path, '/');
310 const char *to_copy = path;
311 if (path == NULL)
313 goto return_null;
314 if (path[0] == '~') {
315 const char *username = path + 1;
316 size_t username_len = first_slash - username;
317 if (username_len == 0) {
318 const char *home = getenv("HOME");
319 strbuf_add(&user_path, home, strlen(home));
320 } else {
321 struct passwd *pw = getpw_str(username, username_len);
322 if (!pw)
323 goto return_null;
324 strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
325 }
326 to_copy = first_slash;
327 }
328 strbuf_add(&user_path, to_copy, strlen(to_copy));
329 return strbuf_detach(&user_path, NULL);
330return_null:
331 strbuf_release(&user_path);
332 return NULL;
333}
334/*
336 * First, one directory to try is determined by the following algorithm.
337 *
338 * (0) If "strict" is given, the path is used as given and no DWIM is
339 * done. Otherwise:
340 * (1) "~/path" to mean path under the running user's home directory;
341 * (2) "~user/path" to mean path under named user's home directory;
342 * (3) "relative/path" to mean cwd relative directory; or
343 * (4) "/absolute/path" to mean absolute directory.
344 *
345 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
346 * "%s/.git", "%s.git", "%s" in this order. The first one that exists is
347 * what we try.
348 *
349 * Second, we try chdir() to that. Upon failure, we return NULL.
350 *
351 * Then, we try if the current directory is a valid git repository.
352 * Upon failure, we return NULL.
353 *
354 * If all goes well, we return the directory we used to chdir() (but
355 * before ~user is expanded), avoiding getcwd() resolving symbolic
356 * links. User relative paths are also returned as they are given,
357 * except DWIM suffixing.
358 */
359char *enter_repo(char *path, int strict)
360{
361 static char used_path[PATH_MAX];
362 static char validated_path[PATH_MAX];
363 if (!path)
365 return NULL;
366 if (!strict) {
368 static const char *suffix[] = {
369 ".git/.git", "/.git", ".git", "", NULL,
370 };
371 int len = strlen(path);
372 int i;
373 while ((1 < len) && (path[len-1] == '/')) {
374 path[len-1] = 0;
375 len--;
376 }
377 if (PATH_MAX <= len)
378 return NULL;
379 if (path[0] == '~') {
380 char *newpath = expand_user_path(path);
381 if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
382 free(newpath);
383 return NULL;
384 }
385 /*
386 * Copy back into the static buffer. A pity
387 * since newpath was not bounded, but other
388 * branches of the if are limited by PATH_MAX
389 * anyway.
390 */
391 strcpy(used_path, newpath); free(newpath);
392 strcpy(validated_path, path);
393 path = used_path;
394 }
395 else if (PATH_MAX - 10 < len)
396 return NULL;
397 else {
398 path = strcpy(used_path, path);
399 strcpy(validated_path, path);
400 }
401 len = strlen(path);
402 for (i = 0; suffix[i]; i++) {
403 strcpy(path + len, suffix[i]);
404 if (!access(path, F_OK)) {
405 strcat(validated_path, suffix[i]);
406 break;
407 }
408 }
409 if (!suffix[i] || chdir(path))
410 return NULL;
411 path = validated_path;
412 }
413 else if (chdir(path))
414 return NULL;
415 if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
417 validate_headref("HEAD") == 0) {
418 setenv(GIT_DIR_ENVIRONMENT, ".", 1);
419 check_repository_format();
420 return path;
421 }
422 return NULL;
424}
425int set_shared_perm(const char *path, int mode)
427{
428 struct stat st;
429 int tweak, shared, orig_mode;
430 if (!shared_repository) {
432 if (mode)
433 return chmod(path, mode & ~S_IFMT);
434 return 0;
435 }
436 if (!mode) {
437 if (lstat(path, &st) < 0)
438 return -1;
439 mode = st.st_mode;
440 orig_mode = mode;
441 } else
442 orig_mode = 0;
443 if (shared_repository < 0)
444 shared = -shared_repository;
445 else
446 shared = shared_repository;
447 tweak = shared;
448 if (!(mode & S_IWUSR))
450 tweak &= ~0222;
451 if (mode & S_IXUSR)
452 /* Copy read bits to execute bits */
453 tweak |= (tweak & 0444) >> 2;
454 if (shared_repository < 0)
455 mode = (mode & ~0777) | tweak;
456 else
457 mode |= tweak;
458 if (S_ISDIR(mode)) {
460 /* Copy read bits to execute bits */
461 mode |= (shared & 0444) >> 2;
462 mode |= FORCE_DIR_SET_GID;
463 }
464 if (((shared_repository < 0
466 ? (orig_mode & (FORCE_DIR_SET_GID | 0777))
467 : (orig_mode & mode)) != mode) &&
468 chmod(path, (mode & ~S_IFMT)) < 0)
469 return -2;
470 return 0;
471}
472const char *make_relative_path(const char *abs, const char *base)
474{
475 static char buf[PATH_MAX + 1];
476 int i = 0, j = 0;
477 if (!base || !base[0])
479 return abs;
480 while (base[i]) {
481 if (is_dir_sep(base[i])) {
482 if (!is_dir_sep(abs[j]))
483 return abs;
484 while (is_dir_sep(base[i]))
485 i++;
486 while (is_dir_sep(abs[j]))
487 j++;
488 continue;
489 } else if (abs[j] != base[i]) {
490 return abs;
491 }
492 i++;
493 j++;
494 }
495 if (
496 /* "/foo" is a prefix of "/foo" */
497 abs[j] &&
498 /* "/foo" is not a prefix of "/foobar" */
499 !is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
500 )
501 return abs;
502 while (is_dir_sep(abs[j]))
503 j++;
504 if (!abs[j])
505 strcpy(buf, ".");
506 else
507 strcpy(buf, abs + j);
508 return buf;
509}
510/*
512 * It is okay if dst == src, but they should not overlap otherwise.
513 *
514 * Performs the following normalizations on src, storing the result in dst:
515 * - Ensures that components are separated by '/' (Windows only)
516 * - Squashes sequences of '/'.
517 * - Removes "." components.
518 * - Removes ".." components, and the components the precede them.
519 * Returns failure (non-zero) if a ".." component appears as first path
520 * component anytime during the normalization. Otherwise, returns success (0).
521 *
522 * Note that this function is purely textual. It does not follow symlinks,
523 * verify the existence of the path, or make any system calls.
524 */
525int normalize_path_copy(char *dst, const char *src)
526{
527 char *dst0;
528 if (has_dos_drive_prefix(src)) {
530 *dst++ = *src++;
531 *dst++ = *src++;
532 }
533 dst0 = dst;
534 if (is_dir_sep(*src)) {
536 *dst++ = '/';
537 while (is_dir_sep(*src))
538 src++;
539 }
540 for (;;) {
542 char c = *src;
543 /*
545 * A path component that begins with . could be
546 * special:
547 * (1) "." and ends -- ignore and terminate.
548 * (2) "./" -- ignore them, eat slash and continue.
549 * (3) ".." and ends -- strip one and terminate.
550 * (4) "../" -- strip one, eat slash and continue.
551 */
552 if (c == '.') {
553 if (!src[1]) {
554 /* (1) */
555 src++;
556 } else if (is_dir_sep(src[1])) {
557 /* (2) */
558 src += 2;
559 while (is_dir_sep(*src))
560 src++;
561 continue;
562 } else if (src[1] == '.') {
563 if (!src[2]) {
564 /* (3) */
565 src += 2;
566 goto up_one;
567 } else if (is_dir_sep(src[2])) {
568 /* (4) */
569 src += 3;
570 while (is_dir_sep(*src))
571 src++;
572 goto up_one;
573 }
574 }
575 }
576 /* copy up to the next '/', and eat all '/' */
578 while ((c = *src++) != '\0' && !is_dir_sep(c))
579 *dst++ = c;
580 if (is_dir_sep(c)) {
581 *dst++ = '/';
582 while (is_dir_sep(c))
583 c = *src++;
584 src--;
585 } else if (!c)
586 break;
587 continue;
588 up_one:
590 /*
591 * dst0..dst is prefix portion, and dst[-1] is '/';
592 * go up one level.
593 */
594 dst--; /* go to trailing '/' */
595 if (dst <= dst0)
596 return -1;
597 /* Windows: dst[-1] cannot be backslash anymore */
598 while (dst0 < dst && dst[-1] != '/')
599 dst--;
600 }
601 *dst = '\0';
602 return 0;
603}
604/*
606 * path = Canonical absolute path
607 * prefix_list = Colon-separated list of absolute paths
608 *
609 * Determines, for each path in prefix_list, whether the "prefix" really
610 * is an ancestor directory of path. Returns the length of the longest
611 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
612 * is an ancestor. (Note that this means 0 is returned if prefix_list is
613 * "/".) "/foo" is not considered an ancestor of "/foobar". Directories
614 * are not considered to be their own ancestors. path must be in a
615 * canonical form: empty components, or "." or ".." components are not
616 * allowed. prefix_list may be null, which is like "".
617 */
618int longest_ancestor_length(const char *path, const char *prefix_list)
619{
620 char buf[PATH_MAX+1];
621 const char *ceil, *colon;
622 int len, max_len = -1;
623 if (prefix_list == NULL || !strcmp(path, "/"))
625 return -1;
626 for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
628 for (colon = ceil; *colon && *colon != PATH_SEP; colon++);
629 len = colon - ceil;
630 if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
631 continue;
632 strlcpy(buf, ceil, len+1);
633 if (normalize_path_copy(buf, buf) < 0)
634 continue;
635 len = strlen(buf);
636 if (len > 0 && buf[len-1] == '/')
637 buf[--len] = '\0';
638 if (!strncmp(path, buf, len) &&
640 path[len] == '/' &&
641 len > max_len) {
642 max_len = len;
643 }
644 }
645 return max_len;
647}
648/* strip arbitrary amount of directory separators at end of path */
650static inline int chomp_trailing_dir_sep(const char *path, int len)
651{
652 while (len && is_dir_sep(path[len - 1]))
653 len--;
654 return len;
655}
656/*
658 * If path ends with suffix (complete path components), returns the
659 * part before suffix (sans trailing directory separators).
660 * Otherwise returns NULL.
661 */
662char *strip_path_suffix(const char *path, const char *suffix)
663{
664 int path_len = strlen(path), suffix_len = strlen(suffix);
665 while (suffix_len) {
667 if (!path_len)
668 return NULL;
669 if (is_dir_sep(path[path_len - 1])) {
671 if (!is_dir_sep(suffix[suffix_len - 1]))
672 return NULL;
673 path_len = chomp_trailing_dir_sep(path, path_len);
674 suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
675 }
676 else if (path[--path_len] != suffix[--suffix_len])
677 return NULL;
678 }
679 if (path_len && !is_dir_sep(path[path_len - 1]))
681 return NULL;
682 return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
683}
684int daemon_avoid_alias(const char *p)
686{
687 int sl, ndot;
688 /*
690 * This resurrects the belts and suspenders paranoia check by HPA
691 * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
692 * does not do getcwd() based path canonicalization.
693 *
694 * sl becomes true immediately after seeing '/' and continues to
695 * be true as long as dots continue after that without intervening
696 * non-dot character.
697 */
698 if (!p || (*p != '/' && *p != '~'))
699 return -1;
700 sl = 1; ndot = 0;
701 p++;
702 while (1) {
704 char ch = *p++;
705 if (sl) {
706 if (ch == '.')
707 ndot++;
708 else if (ch == '/') {
709 if (ndot < 3)
710 /* reject //, /./ and /../ */
711 return -1;
712 ndot = 0;
713 }
714 else if (ch == 0) {
715 if (0 < ndot && ndot < 3)
716 /* reject /.$ and /..$ */
717 return -1;
718 return 0;
719 }
720 else
721 sl = ndot = 0;
722 }
723 else if (ch == 0)
724 return 0;
725 else if (ch == '/') {
726 sl = 1;
727 ndot = 0;
728 }
729 }
730}