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Date:: Sat Apr 16 08:06:59 2022 UTC
Message:: rename variables in got_path_strip() for clarity; ok op@
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1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2015 Theo de Raadt <deraadt@openbsd.org>
4  * Copyright (c) 1997 Todd C. Miller <millert@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <sys/stat.h>
20 
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <limits.h>
24 #include <libgen.h>
25 #include <stdlib.h>
26 #include <unistd.h>
27 #include <stdio.h>
28 #include <string.h>
29 #include <dirent.h>
30 #include <paths.h>
31 
32 #include "got_compat.h"
33 
34 #include "got_error.h"
35 #include "got_path.h"
36 
37 #ifndef MIN
38 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
39 #endif
40 
41 int
42 got_path_is_absolute(const char *path)
43 {
44 	return path[0] == '/';
45 }
46 
47 /* based on canonpath() from kern_pledge.c */
48 const struct got_error *
49 got_canonpath(const char *input, char *buf, size_t bufsize)
50 {
51 	const char *p;
52 	char *q;
53 
54 	/* can't canon relative paths, don't bother */
55 	if (!got_path_is_absolute(input)) {
56 		if (strlcpy(buf, input, bufsize) >= bufsize)
57 			return got_error(GOT_ERR_NO_SPACE);
58 		return NULL;
59 	}
60 
61 	p = input;
62 	q = buf;
63 	while (*p && (q - buf < bufsize)) {
64 		if (p[0] == '/' && (p[1] == '/' || p[1] == '\0')) {
65 			p += 1;
66 
67 		} else if (p[0] == '/' && p[1] == '.' &&
68 		    (p[2] == '/' || p[2] == '\0')) {
69 			p += 2;
70 
71 		} else if (p[0] == '/' && p[1] == '.' && p[2] == '.' &&
72 		    (p[3] == '/' || p[3] == '\0')) {
73 			p += 3;
74 			if (q != buf)	/* "/../" at start of buf */
75 				while (*--q != '/')
76 					continue;
77 
78 		} else {
79 			*q++ = *p++;
80 		}
81 	}
82 	if ((*p == '\0') && (q - buf < bufsize)) {
83 		*q = 0;
84 		return NULL;
85 	} else
86 		return got_error(GOT_ERR_NO_SPACE);
87 }
88 
89 const struct got_error *
90 got_path_skip_common_ancestor(char **child, const char *parent_abspath,
91     const char *abspath)
92 {
93 	const struct got_error *err = NULL;
94 	size_t len_parent, len, bufsize;
95 
96 	*child = NULL;
97 
98 	len_parent = strlen(parent_abspath);
99 	len = strlen(abspath);
100 	if (len_parent >= len)
101 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
102 	if (strncmp(parent_abspath, abspath, len_parent) != 0)
103 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
104 	if (!got_path_is_root_dir(parent_abspath) && abspath[len_parent] != '/')
105 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
106 	while (abspath[len_parent] == '/')
107 		abspath++;
108 	bufsize = len - len_parent + 1;
109 	*child = malloc(bufsize);
110 	if (*child == NULL)
111 		return got_error_from_errno("malloc");
112 	if (strlcpy(*child, abspath + len_parent, bufsize) >= bufsize) {
113 		err = got_error_from_errno("strlcpy");
114 		free(*child);
115 		*child = NULL;
116 		return err;
117 	}
118 	return NULL;
119 }
120 
121 const struct got_error *
122 got_path_strip(char **out, const char *path, int n)
123 {
124 	const char *p, *c;
125 
126 	p = path;
127 	*out = NULL;
128 
129 	while (n > 0 && (c = strchr(p, '/')) != NULL) {
130 		p = c + 1;
131 		n--;
132 	}
133 
134 	if (n > 0)
135 		return got_error_fmt(GOT_ERR_BAD_PATH,
136 		    "can't strip %d path-components from %s", n, path);
137 
138 	if ((*out = strdup(p)) == NULL)
139 		return got_error_from_errno("strdup");
140 	return NULL;
141 }
142 
143 int
144 got_path_is_root_dir(const char *path)
145 {
146 	while (*path == '/')
147 		path++;
148 	return (*path == '\0');
149 }
150 
151 int
152 got_path_is_current_dir(const char *path)
153 {
154 	return (path[0] == '.' && path[1] == '\0');
155 }
156 
157 int
158 got_path_is_child(const char *child, const char *parent, size_t parent_len)
159 {
160 	if (parent_len == 0 || got_path_is_root_dir(parent))
161 		return 1;
162 
163 	if (strncmp(parent, child, parent_len) != 0)
164 		return 0;
165 	if (child[parent_len] != '/')
166 		return 0;
167 
168 	return 1;
169 }
170 
171 int
172 got_path_cmp(const char *path1, const char *path2, size_t len1, size_t len2)
173 {
174 	size_t min_len;
175 	size_t i = 0;
176 
177 	/* Leading directory separators are insignificant. */
178 	while (path1[0] == '/') {
179 		path1++;
180 		len1--;
181 	}
182 	while (path2[0] == '/') {
183 		path2++;
184 		len2--;
185 	}
186 
187 	min_len = MIN(len1, len2);
188 
189 	/* Skip over common prefix. */
190 	while (i < min_len && path1[i] == path2[i])
191 		i++;
192 
193 	/* Are the paths exactly equal (besides path separators)? */
194 	if (len1 == len2 && i >= min_len)
195 		return 0;
196 
197 	/* Skip over redundant trailing path seperators. */
198 	while (path1[i] == '/' && path1[i + 1] == '/')
199 		path1++;
200 	while (path2[i] == '/' && path2[i + 1] == '/')
201 		path2++;
202 
203 	/* Trailing path separators are insignificant. */
204 	if (path1[i] == '/' && path1[i + 1] == '\0' && path2[i] == '\0')
205 		return 0;
206 	if (path2[i] == '/' && path2[i + 1] == '\0' && path1[i] == '\0')
207 		return 0;
208 
209 	/* Order children in subdirectories directly after their parents. */
210 	if (path1[i] == '/' && path2[i] == '\0')
211 		return 1;
212 	if (path2[i] == '/' && path1[i] == '\0')
213 		return -1;
214 	if (path1[i] == '/' && path2[i] != '\0')
215 		return -1;
216 	if (path2[i] == '/' && path1[i] != '\0')
217 		return 1;
218 
219 	/* Next character following the common prefix determines order. */
220 	return (unsigned char)path1[i] < (unsigned char)path2[i] ? -1 : 1;
221 }
222 
223 const struct got_error *
224 got_pathlist_insert(struct got_pathlist_entry **inserted,
225     struct got_pathlist_head *pathlist, const char *path, void *data)
226 {
227 	struct got_pathlist_entry *new, *pe;
228 
229 	if (inserted)
230 		*inserted = NULL;
231 
232 	new = malloc(sizeof(*new));
233 	if (new == NULL)
234 		return got_error_from_errno("malloc");
235 	new->path = path;
236 	new->path_len = strlen(path);
237 	new->data = data;
238 
239 	/*
240 	 * Many callers will provide paths in a somewhat sorted order while
241 	 * constructing a path list from inputs such as tree objects or
242 	 * dirents. Iterating backwards from the tail of the list should
243 	 * be more efficient than traversing through the entire list each
244 	 * time an element is inserted.
245 	 */
246 	pe = TAILQ_LAST(pathlist, got_pathlist_head);
247 	while (pe) {
248 		int cmp = got_path_cmp(pe->path, new->path,
249 		    pe->path_len, new->path_len);
250 		if (cmp == 0) {
251 			free(new); /* duplicate */
252 			return NULL;
253 		} else if (cmp < 0) {
254 			TAILQ_INSERT_AFTER(pathlist, pe, new, entry);
255 			if (inserted)
256 				*inserted = new;
257 			return NULL;
258 		}
259 		pe = TAILQ_PREV(pe, got_pathlist_head, entry);
260 	}
261 
262 	TAILQ_INSERT_HEAD(pathlist, new, entry);
263 	if (inserted)
264 		*inserted = new;
265 	return NULL;
266 }
267 
268 const struct got_error *
269 got_pathlist_append(struct got_pathlist_head *pathlist,
270     const char *path, void *data)
271 {
272 	struct got_pathlist_entry *new;
273 
274 	new = malloc(sizeof(*new));
275 	if (new == NULL)
276 		return got_error_from_errno("malloc");
277 	new->path = path;
278 	new->path_len = strlen(path);
279 	new->data = data;
280 	TAILQ_INSERT_TAIL(pathlist, new, entry);
281 	return NULL;
282 }
283 
284 void
285 got_pathlist_free(struct got_pathlist_head *pathlist)
286 {
287 	struct got_pathlist_entry *pe;
288 
289 	while ((pe = TAILQ_FIRST(pathlist)) != NULL) {
290 		TAILQ_REMOVE(pathlist, pe, entry);
291 		free(pe);
292 	}
293 }
294 
295 static const struct got_error *
296 make_parent_dirs(const char *abspath)
297 {
298 	const struct got_error *err = NULL;
299 	char *parent;
300 
301 	err = got_path_dirname(&parent, abspath);
302 	if (err)
303 		return err;
304 
305 	if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
306 		if (errno == ENOENT) {
307 			err = make_parent_dirs(parent);
308 			if (err)
309 				goto done;
310 			if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
311 				err = got_error_from_errno2("mkdir", parent);
312 				goto done;
313 			}
314 		} else
315 			err = got_error_from_errno2("mkdir", parent);
316 	}
317 done:
318 	free(parent);
319 	return err;
320 }
321 
322 const struct got_error *
323 got_path_mkdir(const char *abspath)
324 {
325 	const struct got_error *err = NULL;
326 
327 	if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1) {
328 		if (errno == ENOENT) {
329 			err = make_parent_dirs(abspath);
330 			if (err)
331 				goto done;
332 			if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1)
333 				err = got_error_from_errno2("mkdir", abspath);
334 		} else
335 			err = got_error_from_errno2("mkdir", abspath);
336 	}
337 
338 done:
339 	return err;
340 }
341 
342 int
343 got_path_dir_is_empty(const char *dir)
344 {
345 	DIR *d;
346 	struct dirent *dent;
347 	int empty = 1;
348 
349 	d = opendir(dir);
350 	if (d == NULL)
351 		return 1;
352 
353 	while ((dent = readdir(d)) != NULL) {
354 		if (strcmp(dent->d_name, ".") == 0 ||
355 		    strcmp(dent->d_name, "..") == 0)
356 			continue;
357 
358 		empty = 0;
359 		break;
360 	}
361 
362 	closedir(d);
363 	return empty;
364 }
365 
366 const struct got_error *
367 got_path_dirname(char **parent, const char *path)
368 {
369 	char buf[PATH_MAX];
370 	char *p;
371 
372 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
373 		return got_error(GOT_ERR_NO_SPACE);
374 
375 	p = dirname(buf);
376 	if (p == NULL)
377 		return got_error_from_errno2("dirname", path);
378 
379 	if (p[0] == '.' && p[1] == '\0')
380 		return got_error_path(path, GOT_ERR_BAD_PATH);
381 
382 	*parent = strdup(p);
383 	if (*parent == NULL)
384 		return got_error_from_errno("strdup");
385 
386 	return NULL;
387 }
388 
389 const struct got_error *
390 got_path_dirent_type(int *type, const char *path_parent, struct dirent *dent)
391 {
392 	const struct got_error *err = NULL;
393 	char *path_child;
394 	struct stat sb;
395 
396 	if (dent->d_type != DT_UNKNOWN) {
397 		*type = dent->d_type;
398 		return NULL;
399 	}
400 
401 	*type = DT_UNKNOWN;
402 
403 	/*
404 	 * This is a fallback to accommodate filesystems which do not
405 	 * provide directory entry type information. DT_UNKNOWN directory
406 	 * entries occur on NFS mounts without "readdir plus" RPC.
407 	 */
408 
409 	if (asprintf(&path_child, "%s/%s", path_parent, dent->d_name) == -1)
410 		return got_error_from_errno("asprintf");
411 
412 	if (lstat(path_child, &sb) == -1) {
413 		err = got_error_from_errno2("lstat", path_child);
414 		goto done;
415 	}
416 
417 	if (S_ISFIFO(sb.st_mode))
418 		*type = DT_FIFO;
419 	else if (S_ISCHR(sb.st_mode))
420 		*type = DT_CHR;
421 	else if (S_ISDIR(sb.st_mode))
422 		*type = DT_DIR;
423 	else if (S_ISBLK(sb.st_mode))
424 		*type = DT_BLK;
425 	else if (S_ISLNK(sb.st_mode))
426 		*type = DT_LNK;
427 	else if (S_ISREG(sb.st_mode))
428 		*type = DT_REG;
429 	else if (S_ISSOCK(sb.st_mode))
430 		*type = DT_SOCK;
431 done:
432 	free(path_child);
433 	return err;
434 }
435 
436 const struct got_error *
437 got_path_basename(char **s, const char *path)
438 {
439 	char buf[PATH_MAX];
440 	char *base;
441 
442 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
443 		return got_error(GOT_ERR_NO_SPACE);
444 
445 	base = basename(buf);
446 	if (base == NULL)
447 		return got_error_from_errno2("basename", path);
448 
449 	*s = strdup(base);
450 	if (*s == NULL)
451 		return got_error_from_errno("strdup");
452 
453 	return NULL;
454 }
455 
456 void
457 got_path_strip_trailing_slashes(char *path)
458 {
459 	size_t x;
460 
461 	x = strlen(path);
462 	while (x-- > 0 && path[x] == '/')
463 		path[x] = '\0';
464 }
465 
466 /* based on findprog() from usr.bin/which/which.c */
467 const struct got_error *
468 got_path_find_prog(char **filename, const char *prog)
469 {
470 	const struct got_error *err = NULL;
471 	char *p;
472 	int len;
473 	struct stat sbuf;
474 	char *path, *pathcpy;
475 
476 	*filename = NULL;
477 
478 	path = getenv("PATH");
479 	if (path == NULL)
480 		path = _PATH_DEFPATH;
481 
482 	/* Special case if prog contains '/' */
483 	if (strchr(prog, '/')) {
484 		if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
485 		    access(prog, X_OK) == 0) {
486 			*filename = strdup(prog);
487 			if (*filename == NULL)
488 				return got_error_from_errno("strdup");
489 		}
490 		return NULL;
491 	}
492 
493 	if ((path = strdup(path)) == NULL)
494 		return got_error_from_errno("strdup");
495 	pathcpy = path;
496 
497 	while ((p = strsep(&pathcpy, ":")) != NULL) {
498 		if (*p == '\0')
499 			p = ".";
500 
501 		len = strlen(p);
502 		while (len > 0 && p[len-1] == '/')
503 			p[--len] = '\0';	/* strip trailing '/' */
504 
505 		if (asprintf(filename, "%s/%s", p, prog) == -1) {
506 			err = got_error_from_errno("asprintf");
507 			break;
508 		}
509 		if ((stat(*filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
510 		    access(*filename, X_OK) == 0)
511 			break;
512 		free(*filename);
513 		*filename = NULL;
514 		continue;
515 	}
516 	free(path);
517 	return err;
518 }
519 
520 const struct got_error *
521 got_path_create_file(const char *path, const char *content)
522 {
523 	const struct got_error *err = NULL;
524 	int fd = -1;
525 
526 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC,
527 	    GOT_DEFAULT_FILE_MODE);
528 	if (fd == -1) {
529 		err = got_error_from_errno2("open", path);
530 		goto done;
531 	}
532 
533 	if (content) {
534 		int len = dprintf(fd, "%s\n", content);
535 		if (len != strlen(content) + 1) {
536 			err = got_error_from_errno("dprintf");
537 			goto done;
538 		}
539 	}
540 
541 done:
542 	if (fd != -1 && close(fd) == -1 && err == NULL)
543 		err = got_error_from_errno("close");
544 	return err;
545 }