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Date:: Thu May 19 07:36:33 2022 UTC
Message:: avoid malloc/free for duplicate check in got_pathlists_insert() 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 	size_t path_len = strlen(path);
228 
229 	if (inserted)
230 		*inserted = NULL;
231 
232 	/*
233 	 * Many callers will provide paths in a somewhat sorted order while
234 	 * constructing a path list from inputs such as tree objects or
235 	 * dirents. Iterating backwards from the tail of the list should
236 	 * be more efficient than traversing through the entire list each
237 	 * time an element is inserted.
238 	 */
239 	pe = TAILQ_LAST(pathlist, got_pathlist_head);
240 	while (pe) {
241 		int cmp = got_path_cmp(pe->path, path, pe->path_len, path_len);
242 		if (cmp == 0)
243 			return NULL;  /* duplicate */
244 		else if (cmp < 0)
245 			break;
246 		pe = TAILQ_PREV(pe, got_pathlist_head, entry);
247 	}
248 
249 	new = malloc(sizeof(*new));
250 	if (new == NULL)
251 		return got_error_from_errno("malloc");
252 	new->path = path;
253 	new->path_len = path_len;
254 	new->data = data;
255 	if (pe)
256 		TAILQ_INSERT_AFTER(pathlist, pe, new, entry);
257 	else
258 		TAILQ_INSERT_HEAD(pathlist, new, entry);
259 	if (inserted)
260 		*inserted = new;
261 	return NULL;
262 }
263 
264 const struct got_error *
265 got_pathlist_append(struct got_pathlist_head *pathlist,
266     const char *path, void *data)
267 {
268 	struct got_pathlist_entry *new;
269 
270 	new = malloc(sizeof(*new));
271 	if (new == NULL)
272 		return got_error_from_errno("malloc");
273 	new->path = path;
274 	new->path_len = strlen(path);
275 	new->data = data;
276 	TAILQ_INSERT_TAIL(pathlist, new, entry);
277 	return NULL;
278 }
279 
280 void
281 got_pathlist_free(struct got_pathlist_head *pathlist)
282 {
283 	struct got_pathlist_entry *pe;
284 
285 	while ((pe = TAILQ_FIRST(pathlist)) != NULL) {
286 		TAILQ_REMOVE(pathlist, pe, entry);
287 		free(pe);
288 	}
289 }
290 
291 static const struct got_error *
292 make_parent_dirs(const char *abspath)
293 {
294 	const struct got_error *err = NULL;
295 	char *parent;
296 
297 	err = got_path_dirname(&parent, abspath);
298 	if (err)
299 		return err;
300 
301 	if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
302 		if (errno == ENOENT) {
303 			err = make_parent_dirs(parent);
304 			if (err)
305 				goto done;
306 			if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
307 				err = got_error_from_errno2("mkdir", parent);
308 				goto done;
309 			}
310 		} else
311 			err = got_error_from_errno2("mkdir", parent);
312 	}
313 done:
314 	free(parent);
315 	return err;
316 }
317 
318 const struct got_error *
319 got_path_mkdir(const char *abspath)
320 {
321 	const struct got_error *err = NULL;
322 
323 	if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1) {
324 		if (errno == ENOENT) {
325 			err = make_parent_dirs(abspath);
326 			if (err)
327 				goto done;
328 			if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1)
329 				err = got_error_from_errno2("mkdir", abspath);
330 		} else
331 			err = got_error_from_errno2("mkdir", abspath);
332 	}
333 
334 done:
335 	return err;
336 }
337 
338 int
339 got_path_dir_is_empty(const char *dir)
340 {
341 	DIR *d;
342 	struct dirent *dent;
343 	int empty = 1;
344 
345 	d = opendir(dir);
346 	if (d == NULL)
347 		return 1;
348 
349 	while ((dent = readdir(d)) != NULL) {
350 		if (strcmp(dent->d_name, ".") == 0 ||
351 		    strcmp(dent->d_name, "..") == 0)
352 			continue;
353 
354 		empty = 0;
355 		break;
356 	}
357 
358 	closedir(d);
359 	return empty;
360 }
361 
362 const struct got_error *
363 got_path_dirname(char **parent, const char *path)
364 {
365 	char buf[PATH_MAX];
366 	char *p;
367 
368 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
369 		return got_error(GOT_ERR_NO_SPACE);
370 
371 	p = dirname(buf);
372 	if (p == NULL)
373 		return got_error_from_errno2("dirname", path);
374 
375 	if (p[0] == '.' && p[1] == '\0')
376 		return got_error_path(path, GOT_ERR_BAD_PATH);
377 
378 	*parent = strdup(p);
379 	if (*parent == NULL)
380 		return got_error_from_errno("strdup");
381 
382 	return NULL;
383 }
384 
385 const struct got_error *
386 got_path_dirent_type(int *type, const char *path_parent, struct dirent *dent)
387 {
388 	const struct got_error *err = NULL;
389 	char *path_child;
390 	struct stat sb;
391 
392 	if (dent->d_type != DT_UNKNOWN) {
393 		*type = dent->d_type;
394 		return NULL;
395 	}
396 
397 	*type = DT_UNKNOWN;
398 
399 	/*
400 	 * This is a fallback to accommodate filesystems which do not
401 	 * provide directory entry type information. DT_UNKNOWN directory
402 	 * entries occur on NFS mounts without "readdir plus" RPC.
403 	 */
404 
405 	if (asprintf(&path_child, "%s/%s", path_parent, dent->d_name) == -1)
406 		return got_error_from_errno("asprintf");
407 
408 	if (lstat(path_child, &sb) == -1) {
409 		err = got_error_from_errno2("lstat", path_child);
410 		goto done;
411 	}
412 
413 	if (S_ISFIFO(sb.st_mode))
414 		*type = DT_FIFO;
415 	else if (S_ISCHR(sb.st_mode))
416 		*type = DT_CHR;
417 	else if (S_ISDIR(sb.st_mode))
418 		*type = DT_DIR;
419 	else if (S_ISBLK(sb.st_mode))
420 		*type = DT_BLK;
421 	else if (S_ISLNK(sb.st_mode))
422 		*type = DT_LNK;
423 	else if (S_ISREG(sb.st_mode))
424 		*type = DT_REG;
425 	else if (S_ISSOCK(sb.st_mode))
426 		*type = DT_SOCK;
427 done:
428 	free(path_child);
429 	return err;
430 }
431 
432 const struct got_error *
433 got_path_basename(char **s, const char *path)
434 {
435 	char buf[PATH_MAX];
436 	char *base;
437 
438 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
439 		return got_error(GOT_ERR_NO_SPACE);
440 
441 	base = basename(buf);
442 	if (base == NULL)
443 		return got_error_from_errno2("basename", path);
444 
445 	*s = strdup(base);
446 	if (*s == NULL)
447 		return got_error_from_errno("strdup");
448 
449 	return NULL;
450 }
451 
452 void
453 got_path_strip_trailing_slashes(char *path)
454 {
455 	size_t x;
456 
457 	x = strlen(path);
458 	while (x-- > 0 && path[x] == '/')
459 		path[x] = '\0';
460 }
461 
462 /* based on findprog() from usr.bin/which/which.c */
463 const struct got_error *
464 got_path_find_prog(char **filename, const char *prog)
465 {
466 	const struct got_error *err = NULL;
467 	char *p;
468 	int len;
469 	struct stat sbuf;
470 	char *path, *pathcpy;
471 
472 	*filename = NULL;
473 
474 	path = getenv("PATH");
475 	if (path == NULL)
476 		path = _PATH_DEFPATH;
477 
478 	/* Special case if prog contains '/' */
479 	if (strchr(prog, '/')) {
480 		if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
481 		    access(prog, X_OK) == 0) {
482 			*filename = strdup(prog);
483 			if (*filename == NULL)
484 				return got_error_from_errno("strdup");
485 		}
486 		return NULL;
487 	}
488 
489 	if ((path = strdup(path)) == NULL)
490 		return got_error_from_errno("strdup");
491 	pathcpy = path;
492 
493 	while ((p = strsep(&pathcpy, ":")) != NULL) {
494 		if (*p == '\0')
495 			p = ".";
496 
497 		len = strlen(p);
498 		while (len > 0 && p[len-1] == '/')
499 			p[--len] = '\0';	/* strip trailing '/' */
500 
501 		if (asprintf(filename, "%s/%s", p, prog) == -1) {
502 			err = got_error_from_errno("asprintf");
503 			break;
504 		}
505 		if ((stat(*filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
506 		    access(*filename, X_OK) == 0)
507 			break;
508 		free(*filename);
509 		*filename = NULL;
510 		continue;
511 	}
512 	free(path);
513 	return err;
514 }
515 
516 const struct got_error *
517 got_path_create_file(const char *path, const char *content)
518 {
519 	const struct got_error *err = NULL;
520 	int fd = -1;
521 
522 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC,
523 	    GOT_DEFAULT_FILE_MODE);
524 	if (fd == -1) {
525 		err = got_error_from_errno2("open", path);
526 		goto done;
527 	}
528 
529 	if (content) {
530 		int len = dprintf(fd, "%s\n", content);
531 		if (len != strlen(content) + 1) {
532 			err = got_error_from_errno("dprintf");
533 			goto done;
534 		}
535 	}
536 
537 done:
538 	if (fd != -1 && close(fd) == -1 && err == NULL)
539 		err = got_error_from_errno("close");
540 	return err;
541 }