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Date:: Thu May 19 13:34:05 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/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 	size_t path_len = strlen(path);
229 
230 	if (inserted)
231 		*inserted = NULL;
232 
233 	/*
234 	 * Many callers will provide paths in a somewhat sorted order while
235 	 * constructing a path list from inputs such as tree objects or
236 	 * dirents. Iterating backwards from the tail of the list should
237 	 * be more efficient than traversing through the entire list each
238 	 * time an element is inserted.
239 	 */
240 	pe = TAILQ_LAST(pathlist, got_pathlist_head);
241 	while (pe) {
242 		int cmp = got_path_cmp(pe->path, path, pe->path_len, path_len);
243 		if (cmp == 0)
244 			return NULL;  /* duplicate */
245 		else if (cmp < 0)
246 			break;
247 		pe = TAILQ_PREV(pe, got_pathlist_head, entry);
248 	}
249 
250 	new = malloc(sizeof(*new));
251 	if (new == NULL)
252 		return got_error_from_errno("malloc");
253 	new->path = path;
254 	new->path_len = path_len;
255 	new->data = data;
256 	if (pe)
257 		TAILQ_INSERT_AFTER(pathlist, pe, new, entry);
258 	else
259 		TAILQ_INSERT_HEAD(pathlist, new, entry);
260 	if (inserted)
261 		*inserted = new;
262 	return NULL;
263 }
264 
265 const struct got_error *
266 got_pathlist_append(struct got_pathlist_head *pathlist,
267     const char *path, void *data)
268 {
269 	struct got_pathlist_entry *new;
270 
271 	new = malloc(sizeof(*new));
272 	if (new == NULL)
273 		return got_error_from_errno("malloc");
274 	new->path = path;
275 	new->path_len = strlen(path);
276 	new->data = data;
277 	TAILQ_INSERT_TAIL(pathlist, new, entry);
278 	return NULL;
279 }
280 
281 void
282 got_pathlist_free(struct got_pathlist_head *pathlist)
283 {
284 	struct got_pathlist_entry *pe;
285 
286 	while ((pe = TAILQ_FIRST(pathlist)) != NULL) {
287 		TAILQ_REMOVE(pathlist, pe, entry);
288 		free(pe);
289 	}
290 }
291 
292 static const struct got_error *
293 make_parent_dirs(const char *abspath)
294 {
295 	const struct got_error *err = NULL;
296 	char *parent;
297 
298 	err = got_path_dirname(&parent, abspath);
299 	if (err)
300 		return err;
301 
302 	if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
303 		if (errno == ENOENT) {
304 			err = make_parent_dirs(parent);
305 			if (err)
306 				goto done;
307 			if (mkdir(parent, GOT_DEFAULT_DIR_MODE) == -1) {
308 				err = got_error_from_errno2("mkdir", parent);
309 				goto done;
310 			}
311 		} else
312 			err = got_error_from_errno2("mkdir", parent);
313 	}
314 done:
315 	free(parent);
316 	return err;
317 }
318 
319 const struct got_error *
320 got_path_mkdir(const char *abspath)
321 {
322 	const struct got_error *err = NULL;
323 
324 	if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1) {
325 		if (errno == ENOENT) {
326 			err = make_parent_dirs(abspath);
327 			if (err)
328 				goto done;
329 			if (mkdir(abspath, GOT_DEFAULT_DIR_MODE) == -1)
330 				err = got_error_from_errno2("mkdir", abspath);
331 		} else
332 			err = got_error_from_errno2("mkdir", abspath);
333 	}
334 
335 done:
336 	return err;
337 }
338 
339 int
340 got_path_dir_is_empty(const char *dir)
341 {
342 	DIR *d;
343 	struct dirent *dent;
344 	int empty = 1;
345 
346 	d = opendir(dir);
347 	if (d == NULL)
348 		return 1;
349 
350 	while ((dent = readdir(d)) != NULL) {
351 		if (strcmp(dent->d_name, ".") == 0 ||
352 		    strcmp(dent->d_name, "..") == 0)
353 			continue;
354 
355 		empty = 0;
356 		break;
357 	}
358 
359 	closedir(d);
360 	return empty;
361 }
362 
363 const struct got_error *
364 got_path_dirname(char **parent, const char *path)
365 {
366 	char buf[PATH_MAX];
367 	char *p;
368 
369 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
370 		return got_error(GOT_ERR_NO_SPACE);
371 
372 	p = dirname(buf);
373 	if (p == NULL)
374 		return got_error_from_errno2("dirname", path);
375 
376 	if (p[0] == '.' && p[1] == '\0')
377 		return got_error_path(path, GOT_ERR_BAD_PATH);
378 
379 	*parent = strdup(p);
380 	if (*parent == NULL)
381 		return got_error_from_errno("strdup");
382 
383 	return NULL;
384 }
385 
386 const struct got_error *
387 got_path_dirent_type(int *type, const char *path_parent, struct dirent *dent)
388 {
389 	const struct got_error *err = NULL;
390 	char *path_child;
391 	struct stat sb;
392 
393 	if (dent->d_type != DT_UNKNOWN) {
394 		*type = dent->d_type;
395 		return NULL;
396 	}
397 
398 	*type = DT_UNKNOWN;
399 
400 	/*
401 	 * This is a fallback to accommodate filesystems which do not
402 	 * provide directory entry type information. DT_UNKNOWN directory
403 	 * entries occur on NFS mounts without "readdir plus" RPC.
404 	 */
405 
406 	if (asprintf(&path_child, "%s/%s", path_parent, dent->d_name) == -1)
407 		return got_error_from_errno("asprintf");
408 
409 	if (lstat(path_child, &sb) == -1) {
410 		err = got_error_from_errno2("lstat", path_child);
411 		goto done;
412 	}
413 
414 	if (S_ISFIFO(sb.st_mode))
415 		*type = DT_FIFO;
416 	else if (S_ISCHR(sb.st_mode))
417 		*type = DT_CHR;
418 	else if (S_ISDIR(sb.st_mode))
419 		*type = DT_DIR;
420 	else if (S_ISBLK(sb.st_mode))
421 		*type = DT_BLK;
422 	else if (S_ISLNK(sb.st_mode))
423 		*type = DT_LNK;
424 	else if (S_ISREG(sb.st_mode))
425 		*type = DT_REG;
426 	else if (S_ISSOCK(sb.st_mode))
427 		*type = DT_SOCK;
428 done:
429 	free(path_child);
430 	return err;
431 }
432 
433 const struct got_error *
434 got_path_basename(char **s, const char *path)
435 {
436 	char buf[PATH_MAX];
437 	char *base;
438 
439 	if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf))
440 		return got_error(GOT_ERR_NO_SPACE);
441 
442 	base = basename(buf);
443 	if (base == NULL)
444 		return got_error_from_errno2("basename", path);
445 
446 	*s = strdup(base);
447 	if (*s == NULL)
448 		return got_error_from_errno("strdup");
449 
450 	return NULL;
451 }
452 
453 void
454 got_path_strip_trailing_slashes(char *path)
455 {
456 	size_t x;
457 
458 	x = strlen(path);
459 	while (x-- > 0 && path[x] == '/')
460 		path[x] = '\0';
461 }
462 
463 /* based on findprog() from usr.bin/which/which.c */
464 const struct got_error *
465 got_path_find_prog(char **filename, const char *prog)
466 {
467 	const struct got_error *err = NULL;
468 	char *p;
469 	int len;
470 	struct stat sbuf;
471 	char *path, *pathcpy;
472 
473 	*filename = NULL;
474 
475 	path = getenv("PATH");
476 	if (path == NULL)
477 		path = _PATH_DEFPATH;
478 
479 	/* Special case if prog contains '/' */
480 	if (strchr(prog, '/')) {
481 		if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
482 		    access(prog, X_OK) == 0) {
483 			*filename = strdup(prog);
484 			if (*filename == NULL)
485 				return got_error_from_errno("strdup");
486 		}
487 		return NULL;
488 	}
489 
490 	if ((path = strdup(path)) == NULL)
491 		return got_error_from_errno("strdup");
492 	pathcpy = path;
493 
494 	while ((p = strsep(&pathcpy, ":")) != NULL) {
495 		if (*p == '\0')
496 			p = ".";
497 
498 		len = strlen(p);
499 		while (len > 0 && p[len-1] == '/')
500 			p[--len] = '\0';	/* strip trailing '/' */
501 
502 		if (asprintf(filename, "%s/%s", p, prog) == -1) {
503 			err = got_error_from_errno("asprintf");
504 			break;
505 		}
506 		if ((stat(*filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
507 		    access(*filename, X_OK) == 0)
508 			break;
509 		free(*filename);
510 		*filename = NULL;
511 		continue;
512 	}
513 	free(path);
514 	return err;
515 }
516 
517 const struct got_error *
518 got_path_create_file(const char *path, const char *content)
519 {
520 	const struct got_error *err = NULL;
521 	int fd = -1;
522 
523 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW | O_CLOEXEC,
524 	    GOT_DEFAULT_FILE_MODE);
525 	if (fd == -1) {
526 		err = got_error_from_errno2("open", path);
527 		goto done;
528 	}
529 
530 	if (content) {
531 		int len = dprintf(fd, "%s\n", content);
532 		if (len != strlen(content) + 1) {
533 			err = got_error_from_errno("dprintf");
534 			goto done;
535 		}
536 	}
537 
538 done:
539 	if (fd != -1 && close(fd) == -1 && err == NULL)
540 		err = got_error_from_errno("close");
541 	return err;
542 }