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Date:: Thu Apr 7 12:04:42 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/queue.h>
20 #include <sys/stat.h>
21 
22 #include <errno.h>
23 #include <fcntl.h>
24 #include <limits.h>
25 #include <libgen.h>
26 #include <stdlib.h>
27 #include <unistd.h>
28 #include <stdio.h>
29 #include <string.h>
30 #include <dirent.h>
31 #include <paths.h>
32 
33 #include "got_error.h"
34 #include "got_path.h"
35 
36 #ifndef MIN
37 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
38 #endif
39 
40 int
41 got_path_is_absolute(const char *path)
42 {
43 	return path[0] == '/';
44 }
45 
46 /* based on canonpath() from kern_pledge.c */
47 const struct got_error *
48 got_canonpath(const char *input, char *buf, size_t bufsize)
49 {
50 	const char *p;
51 	char *q;
52 
53 	/* can't canon relative paths, don't bother */
54 	if (!got_path_is_absolute(input)) {
55 		if (strlcpy(buf, input, bufsize) >= bufsize)
56 			return got_error(GOT_ERR_NO_SPACE);
57 		return NULL;
58 	}
59 
60 	p = input;
61 	q = buf;
62 	while (*p && (q - buf < bufsize)) {
63 		if (p[0] == '/' && (p[1] == '/' || p[1] == '\0')) {
64 			p += 1;
65 
66 		} else if (p[0] == '/' && p[1] == '.' &&
67 		    (p[2] == '/' || p[2] == '\0')) {
68 			p += 2;
69 
70 		} else if (p[0] == '/' && p[1] == '.' && p[2] == '.' &&
71 		    (p[3] == '/' || p[3] == '\0')) {
72 			p += 3;
73 			if (q != buf)	/* "/../" at start of buf */
74 				while (*--q != '/')
75 					continue;
76 
77 		} else {
78 			*q++ = *p++;
79 		}
80 	}
81 	if ((*p == '\0') && (q - buf < bufsize)) {
82 		*q = 0;
83 		return NULL;
84 	} else
85 		return got_error(GOT_ERR_NO_SPACE);
86 }
87 
88 const struct got_error *
89 got_path_skip_common_ancestor(char **child, const char *parent_abspath,
90     const char *abspath)
91 {
92 	const struct got_error *err = NULL;
93 	size_t len_parent, len, bufsize;
94 
95 	*child = NULL;
96 
97 	len_parent = strlen(parent_abspath);
98 	len = strlen(abspath);
99 	if (len_parent >= len)
100 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
101 	if (strncmp(parent_abspath, abspath, len_parent) != 0)
102 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
103 	if (!got_path_is_root_dir(parent_abspath) && abspath[len_parent] != '/')
104 		return got_error_path(abspath, GOT_ERR_BAD_PATH);
105 	while (abspath[len_parent] == '/')
106 		abspath++;
107 	bufsize = len - len_parent + 1;
108 	*child = malloc(bufsize);
109 	if (*child == NULL)
110 		return got_error_from_errno("malloc");
111 	if (strlcpy(*child, abspath + len_parent, bufsize) >= bufsize) {
112 		err = got_error_from_errno("strlcpy");
113 		free(*child);
114 		*child = NULL;
115 		return err;
116 	}
117 	return NULL;
118 }
119 
120 const struct got_error *
121 got_path_strip(char **out, const char *path, int n)
122 {
123 	const char *p, *c;
124 
125 	p = path;
126 	*out = NULL;
127 
128 	while (n > 0 && (c = strchr(p, '/')) != NULL) {
129 		p = c + 1;
130 		n--;
131 	}
132 
133 	if (n > 0)
134 		return got_error_fmt(GOT_ERR_BAD_PATH,
135 		    "can't strip %d path-components from %s", n, path);
136 
137 	if ((*out = strdup(p)) == NULL)
138 		return got_error_from_errno("strdup");
139 	return NULL;
140 }
141 
142 int
143 got_path_is_root_dir(const char *path)
144 {
145 	while (*path == '/')
146 		path++;
147 	return (*path == '\0');
148 }
149 
150 int
151 got_path_is_current_dir(const char *path)
152 {
153 	return (path[0] == '.' && path[1] == '\0');
154 }
155 
156 int
157 got_path_is_child(const char *child, const char *parent, size_t parent_len)
158 {
159 	if (parent_len == 0 || got_path_is_root_dir(parent))
160 		return 1;
161 
162 	if (strncmp(parent, child, parent_len) != 0)
163 		return 0;
164 	if (child[parent_len] != '/')
165 		return 0;
166 
167 	return 1;
168 }
169 
170 int
171 got_path_cmp(const char *path1, const char *path2, size_t len1, size_t len2)
172 {
173 	size_t min_len;
174 	size_t i = 0;
175 
176 	/* Leading directory separators are insignificant. */
177 	while (path1[0] == '/') {
178 		path1++;
179 		len1--;
180 	}
181 	while (path2[0] == '/') {
182 		path2++;
183 		len2--;
184 	}
185 
186 	min_len = MIN(len1, len2);
187 
188 	/* Skip over common prefix. */
189 	while (i < min_len && path1[i] == path2[i])
190 		i++;
191 
192 	/* Are the paths exactly equal (besides path separators)? */
193 	if (len1 == len2 && i >= min_len)
194 		return 0;
195 
196 	/* Skip over redundant trailing path seperators. */
197 	while (path1[i] == '/' && path1[i + 1] == '/')
198 		path1++;
199 	while (path2[i] == '/' && path2[i + 1] == '/')
200 		path2++;
201 
202 	/* Trailing path separators are insignificant. */
203 	if (path1[i] == '/' && path1[i + 1] == '\0' && path2[i] == '\0')
204 		return 0;
205 	if (path2[i] == '/' && path2[i + 1] == '\0' && path1[i] == '\0')
206 		return 0;
207 
208 	/* Order children in subdirectories directly after their parents. */
209 	if (path1[i] == '/' && path2[i] == '\0')
210 		return 1;
211 	if (path2[i] == '/' && path1[i] == '\0')
212 		return -1;
213 	if (path1[i] == '/' && path2[i] != '\0')
214 		return -1;
215 	if (path2[i] == '/' && path1[i] != '\0')
216 		return 1;
217 
218 	/* Next character following the common prefix determines order. */
219 	return (unsigned char)path1[i] < (unsigned char)path2[i] ? -1 : 1;
220 }
221 
222 const struct got_error *
223 got_pathlist_insert(struct got_pathlist_entry **inserted,
224     struct got_pathlist_head *pathlist, const char *path, void *data)
225 {
226 	struct got_pathlist_entry *new, *pe;
227 
228 	if (inserted)
229 		*inserted = NULL;
230 
231 	new = malloc(sizeof(*new));
232 	if (new == NULL)
233 		return got_error_from_errno("malloc");
234 	new->path = path;
235 	new->path_len = strlen(path);
236 	new->data = data;
237 
238 	/*
239 	 * Many callers will provide paths in a somewhat sorted order while
240 	 * constructing a path list from inputs such as tree objects or
241 	 * dirents. Iterating backwards from the tail of the list should
242 	 * be more efficient than traversing through the entire list each
243 	 * time an element is inserted.
244 	 */
245 	pe = TAILQ_LAST(pathlist, got_pathlist_head);
246 	while (pe) {
247 		int cmp = got_path_cmp(pe->path, new->path,
248 		    pe->path_len, new->path_len);
249 		if (cmp == 0) {
250 			free(new); /* duplicate */
251 			return NULL;
252 		} else if (cmp < 0) {
253 			TAILQ_INSERT_AFTER(pathlist, pe, new, entry);
254 			if (inserted)
255 				*inserted = new;
256 			return NULL;
257 		}
258 		pe = TAILQ_PREV(pe, got_pathlist_head, entry);
259 	}
260 
261 	TAILQ_INSERT_HEAD(pathlist, new, entry);
262 	if (inserted)
263 		*inserted = new;
264 	return NULL;
265 }
266 
267 const struct got_error *
268 got_pathlist_append(struct got_pathlist_head *pathlist,
269     const char *path, void *data)
270 {
271 	struct got_pathlist_entry *new;
272 
273 	new = malloc(sizeof(*new));
274 	if (new == NULL)
275 		return got_error_from_errno("malloc");
276 	new->path = path;
277 	new->path_len = strlen(path);
278 	new->data = data;
279 	TAILQ_INSERT_TAIL(pathlist, new, entry);
280 	return NULL;
281 }
282 
283 void
284 got_pathlist_free(struct got_pathlist_head *pathlist)
285 {
286 	struct got_pathlist_entry *pe;
287 
288 	while ((pe = TAILQ_FIRST(pathlist)) != NULL) {
289 		TAILQ_REMOVE(pathlist, pe, entry);
290 		free(pe);
291 	}
292 }
293 
294 static const struct got_error *
295 make_parent_dirs(const char *abspath)
296 {
297 	const struct got_error *err = NULL;
298 	char *parent;
299 
300 	err = got_path_dirname(&parent, abspath);
301 	if (err)
302 		return err;
303 
304 	if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
305 		if (errno == ENOENT) {
306 			err = make_parent_dirs(parent);
307 			if (err)
308 				goto done;
309 			if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
310 				err = got_error_from_errno2("mkdir", parent);
311 				goto done;
312 			}
313 		} else
314 			err = got_error_from_errno2("mkdir", parent);
315 	}
316 done:
317 	free(parent);
318 	return err;
319 }
320 
321 const struct got_error *
322 got_path_mkdir(const char *abspath)
323 {
324 	const struct got_error *err = NULL;
325 
326 	if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1) {
327 		if (errno == ENOENT) {
328 			err = make_parent_dirs(abspath);
329 			if (err)
330 				goto done;
331 			if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1)
332 				err = got_error_from_errno2("mkdir", abspath);
333 		} else
334 			err = got_error_from_errno2("mkdir", abspath);
335 	}
336 
337 done:
338 	return err;
339 }
340 
341 int
342 got_path_dir_is_empty(const char *dir)
343 {
344 	DIR *d;
345 	struct dirent *dent;
346 	int empty = 1;
347 
348 	d = opendir(dir);
349 	if (d == NULL)
350 		return 1;
351 
352 	while ((dent = readdir(d)) != NULL) {
353 		if (strcmp(dent->d_name, ".") == 0 ||
354 		    strcmp(dent->d_name, "..") == 0)
355 			continue;
356 
357 		empty = 0;
358 		break;
359 	}
360 
361 	closedir(d);
362 	return empty;
363 }
364 
365 const struct got_error *
366 got_path_dirname(char **parent, const char *path)
367 {
368 	char buf[PATH_MAX];
369 	char *p;
370 
371 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
372 		return got_error(GOT_ERR_NO_SPACE);
373 
374 	p = dirname(buf);
375 	if (p == NULL)
376 		return got_error_from_errno2("dirname", path);
377 
378 	if (p[0] == '.' && p[1] == '\0')
379 		return got_error_path(path, GOT_ERR_BAD_PATH);
380 
381 	*parent = strdup(p);
382 	if (*parent == NULL)
383 		return got_error_from_errno("strdup");
384 
385 	return NULL;
386 }
387 
388 const struct got_error *
389 got_path_dirent_type(int *type, const char *path_parent, struct dirent *dent)
390 {
391 	const struct got_error *err = NULL;
392 	char *path_child;
393 	struct stat sb;
394 
395 	if (dent->d_type != DT_UNKNOWN) {
396 		*type = dent->d_type;
397 		return NULL;
398 	}
399 
400 	*type = DT_UNKNOWN;
401 
402 	/*
403 	 * This is a fallback to accommodate filesystems which do not
404 	 * provide directory entry type information. DT_UNKNOWN directory
405 	 * entries occur on NFS mounts without "readdir plus" RPC.
406 	 */
407 
408 	if (asprintf(&path_child, "%s/%s", path_parent, dent->d_name) == -1)
409 		return got_error_from_errno("asprintf");
410 
411 	if (lstat(path_child, &sb) == -1) {
412 		err = got_error_from_errno2("lstat", path_child);
413 		goto done;
414 	}
415 
416 	if (S_ISFIFO(sb.st_mode))
417 		*type = DT_FIFO;
418 	else if (S_ISCHR(sb.st_mode))
419 		*type = DT_CHR;
420 	else if (S_ISDIR(sb.st_mode))
421 		*type = DT_DIR;
422 	else if (S_ISBLK(sb.st_mode))
423 		*type = DT_BLK;
424 	else if (S_ISLNK(sb.st_mode))
425 		*type = DT_LNK;
426 	else if (S_ISREG(sb.st_mode))
427 		*type = DT_REG;
428 	else if (S_ISSOCK(sb.st_mode))
429 		*type = DT_SOCK;
430 done:
431 	free(path_child);
432 	return err;
433 }
434 
435 const struct got_error *
436 got_path_basename(char **s, const char *path)
437 {
438 	char buf[PATH_MAX];
439 	char *base;
440 
441 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
442 		return got_error(GOT_ERR_NO_SPACE);
443 
444 	base = basename(buf);
445 	if (base == NULL)
446 		return got_error_from_errno2("basename", path);
447 
448 	*s = strdup(base);
449 	if (*s == NULL)
450 		return got_error_from_errno("strdup");
451 
452 	return NULL;
453 }
454 
455 void
456 got_path_strip_trailing_slashes(char *path)
457 {
458 	size_t x;
459 
460 	x = strlen(path);
461 	while (x-- > 0 && path[x] == '/')
462 		path[x] = '\0';
463 }
464 
465 /* based on findprog() from usr.bin/which/which.c */
466 const struct got_error *
467 got_path_find_prog(char **filename, const char *prog)
468 {
469 	const struct got_error *err = NULL;
470 	char *p;
471 	int len;
472 	struct stat sbuf;
473 	char *path, *pathcpy;
474 
475 	*filename = NULL;
476 
477 	path = getenv("PATH");
478 	if (path == NULL)
479 		path = _PATH_DEFPATH;
480 
481 	/* Special case if prog contains '/' */
482 	if (strchr(prog, '/')) {
483 		if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
484 		    access(prog, X_OK) == 0) {
485 			*filename = strdup(prog);
486 			if (*filename == NULL)
487 				return got_error_from_errno("strdup");
488 		}
489 		return NULL;
490 	}
491 
492 	if ((path = strdup(path)) == NULL)
493 		return got_error_from_errno("strdup");
494 	pathcpy = path;
495 
496 	while ((p = strsep(&pathcpy, ":")) != NULL) {
497 		if (*p == '\0')
498 			p = ".";
499 
500 		len = strlen(p);
501 		while (len > 0 && p[len-1] == '/')
502 			p[--len] = '\0';	/* strip trailing '/' */
503 
504 		if (asprintf(filename, "%s/%s", p, prog) == -1) {
505 			err = got_error_from_errno("asprintf");
506 			break;
507 		}
508 		if ((stat(*filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
509 		    access(*filename, X_OK) == 0)
510 			break;
511 		free(*filename);
512 		*filename = NULL;
513 		continue;
514 	}
515 	free(path);
516 	return err;
517 }
518 
519 const struct got_error *
520 got_path_create_file(const char *path, const char *content)
521 {
522 	const struct got_error *err = NULL;
523 	int fd = -1;
524 
525 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC,
526 	    GOT_DEFAULT_FILE_MODE);
527 	if (fd == -1) {
528 		err = got_error_from_errno2("open", path);
529 		goto done;
530 	}
531 
532 	if (content) {
533 		int len = dprintf(fd, "%s\n", content);
534 		if (len != strlen(content) + 1) {
535 			err = got_error_from_errno("dprintf");
536 			goto done;
537 		}
538 	}
539 
540 done:
541 	if (fd != -1 && close(fd) == -1 && err == NULL)
542 		err = got_error_from_errno("close");
543 	return err;
544 }