31596ddd36c3a3314daa2de1db6db19690b7800a
[lttng-tools.git] / src / common / utils.c
1 /*
2 * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2013 - Raphaël Beamonte <raphael.beamonte@gmail.com>
4 * Copyright (C) 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License, version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #define _GNU_SOURCE
21 #include <assert.h>
22 #include <ctype.h>
23 #include <fcntl.h>
24 #include <limits.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <sys/stat.h>
28 #include <sys/types.h>
29 #include <unistd.h>
30 #include <inttypes.h>
31 #include <regex.h>
32 #include <grp.h>
33 #include <pwd.h>
34
35 #include <common/common.h>
36 #include <common/runas.h>
37
38 #include "utils.h"
39 #include "defaults.h"
40
41 /*
42 * Return a partial realpath(3) of the path even if the full path does not
43 * exist. For instance, with /tmp/test1/test2/test3, if test2/ does not exist
44 * but the /tmp/test1 does, the real path for /tmp/test1 is concatened with
45 * /test2/test3 then returned. In normal time, realpath(3) fails if the end
46 * point directory does not exist.
47 * In case resolved_path is NULL, the string returned was allocated in the
48 * function and thus need to be freed by the caller. The size argument allows
49 * to specify the size of the resolved_path argument if given, or the size to
50 * allocate.
51 */
52 LTTNG_HIDDEN
53 char *utils_partial_realpath(const char *path, char *resolved_path, size_t size)
54 {
55 char *cut_path, *try_path = NULL, *try_path_prev = NULL;
56 const char *next, *prev, *end;
57
58 /* Safety net */
59 if (path == NULL) {
60 goto error;
61 }
62
63 /*
64 * Identify the end of the path, we don't want to treat the
65 * last char if it is a '/', we will just keep it on the side
66 * to be added at the end, and return a value coherent with
67 * the path given as argument
68 */
69 end = path + strlen(path);
70 if (*(end-1) == '/') {
71 end--;
72 }
73
74 /* Initiate the values of the pointers before looping */
75 next = path;
76 prev = next;
77 /* Only to ensure try_path is not NULL to enter the while */
78 try_path = (char *)next;
79
80 /* Resolve the canonical path of the first part of the path */
81 while (try_path != NULL && next != end) {
82 /*
83 * If there is not any '/' left, we want to try with
84 * the full path
85 */
86 next = strpbrk(next + 1, "/");
87 if (next == NULL) {
88 next = end;
89 }
90
91 /* Cut the part we will be trying to resolve */
92 cut_path = strndup(path, next - path);
93
94 /* Try to resolve this part */
95 try_path = realpath((char *)cut_path, NULL);
96 if (try_path == NULL) {
97 /*
98 * There was an error, we just want to be assured it
99 * is linked to an unexistent directory, if it's another
100 * reason, we spawn an error
101 */
102 switch (errno) {
103 case ENOENT:
104 /* Ignore the error */
105 break;
106 default:
107 PERROR("realpath (partial_realpath)");
108 goto error;
109 break;
110 }
111 } else {
112 /* Save the place we are before trying the next step */
113 free(try_path_prev);
114 try_path_prev = try_path;
115 prev = next;
116 }
117
118 /* Free the allocated memory */
119 free(cut_path);
120 };
121
122 /* Allocate memory for the resolved path if necessary */
123 if (resolved_path == NULL) {
124 resolved_path = zmalloc(size);
125 if (resolved_path == NULL) {
126 PERROR("zmalloc resolved path");
127 goto error;
128 }
129 }
130
131 /*
132 * If we were able to solve at least partially the path, we can concatenate
133 * what worked and what didn't work
134 */
135 if (try_path_prev != NULL) {
136 /* If we risk to concatenate two '/', we remove one of them */
137 if (try_path_prev[strlen(try_path_prev) - 1] == '/' && prev[0] == '/') {
138 try_path_prev[strlen(try_path_prev) - 1] = '\0';
139 }
140
141 /*
142 * Duplicate the memory used by prev in case resolved_path and
143 * path are pointers for the same memory space
144 */
145 cut_path = strdup(prev);
146
147 /* Concatenate the strings */
148 snprintf(resolved_path, size, "%s%s", try_path_prev, cut_path);
149
150 /* Free the allocated memory */
151 free(cut_path);
152 free(try_path_prev);
153 /*
154 * Else, we just copy the path in our resolved_path to
155 * return it as is
156 */
157 } else {
158 strncpy(resolved_path, path, size);
159 }
160
161 /* Then we return the 'partially' resolved path */
162 return resolved_path;
163
164 error:
165 free(resolved_path);
166 return NULL;
167 }
168
169 /*
170 * Make a full resolution of the given path even if it doesn't exist.
171 * This function uses the utils_partial_realpath function to resolve
172 * symlinks and relatives paths at the start of the string, and
173 * implements functionnalities to resolve the './' and '../' strings
174 * in the middle of a path. This function is only necessary because
175 * realpath(3) does not accept to resolve unexistent paths.
176 * The returned string was allocated in the function, it is thus of
177 * the responsibility of the caller to free this memory.
178 */
179 LTTNG_HIDDEN
180 char *utils_expand_path(const char *path)
181 {
182 char *next, *previous, *slash, *start_path, *absolute_path = NULL;
183 char *last_token;
184 int is_dot, is_dotdot;
185
186 /* Safety net */
187 if (path == NULL) {
188 goto error;
189 }
190
191 /* Allocate memory for the absolute_path */
192 absolute_path = zmalloc(PATH_MAX);
193 if (absolute_path == NULL) {
194 PERROR("zmalloc expand path");
195 goto error;
196 }
197
198 /*
199 * If the path is not already absolute nor explicitly relative,
200 * consider we're in the current directory
201 */
202 if (*path != '/' && strncmp(path, "./", 2) != 0 &&
203 strncmp(path, "../", 3) != 0) {
204 snprintf(absolute_path, PATH_MAX, "./%s", path);
205 /* Else, we just copy the path */
206 } else {
207 strncpy(absolute_path, path, PATH_MAX);
208 }
209
210 /* Resolve partially our path */
211 absolute_path = utils_partial_realpath(absolute_path,
212 absolute_path, PATH_MAX);
213
214 /* As long as we find '/./' in the working_path string */
215 while ((next = strstr(absolute_path, "/./"))) {
216
217 /* We prepare the start_path not containing it */
218 start_path = strndup(absolute_path, next - absolute_path);
219
220 /* And we concatenate it with the part after this string */
221 snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2);
222
223 free(start_path);
224 }
225
226 /* As long as we find '/../' in the working_path string */
227 while ((next = strstr(absolute_path, "/../"))) {
228 /* We find the last level of directory */
229 previous = absolute_path;
230 while ((slash = strpbrk(previous, "/")) && slash != next) {
231 previous = slash + 1;
232 }
233
234 /* Then we prepare the start_path not containing it */
235 start_path = strndup(absolute_path, previous - absolute_path);
236
237 /* And we concatenate it with the part after the '/../' */
238 snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 4);
239
240 /* We can free the memory used for the start path*/
241 free(start_path);
242
243 /* Then we verify for symlinks using partial_realpath */
244 absolute_path = utils_partial_realpath(absolute_path,
245 absolute_path, PATH_MAX);
246 }
247
248 /* Identify the last token */
249 last_token = strrchr(absolute_path, '/');
250
251 /* Verify that this token is not a relative path */
252 is_dotdot = (strcmp(last_token, "/..") == 0);
253 is_dot = (strcmp(last_token, "/.") == 0);
254
255 /* If it is, take action */
256 if (is_dot || is_dotdot) {
257 /* For both, remove this token */
258 *last_token = '\0';
259
260 /* If it was a reference to parent directory, go back one more time */
261 if (is_dotdot) {
262 last_token = strrchr(absolute_path, '/');
263
264 /* If there was only one level left, we keep the first '/' */
265 if (last_token == absolute_path) {
266 last_token++;
267 }
268
269 *last_token = '\0';
270 }
271 }
272
273 return absolute_path;
274
275 error:
276 free(absolute_path);
277 return NULL;
278 }
279
280 /*
281 * Create a pipe in dst.
282 */
283 LTTNG_HIDDEN
284 int utils_create_pipe(int *dst)
285 {
286 int ret;
287
288 if (dst == NULL) {
289 return -1;
290 }
291
292 ret = pipe(dst);
293 if (ret < 0) {
294 PERROR("create pipe");
295 }
296
297 return ret;
298 }
299
300 /*
301 * Create pipe and set CLOEXEC flag to both fd.
302 *
303 * Make sure the pipe opened by this function are closed at some point. Use
304 * utils_close_pipe().
305 */
306 LTTNG_HIDDEN
307 int utils_create_pipe_cloexec(int *dst)
308 {
309 int ret, i;
310
311 if (dst == NULL) {
312 return -1;
313 }
314
315 ret = utils_create_pipe(dst);
316 if (ret < 0) {
317 goto error;
318 }
319
320 for (i = 0; i < 2; i++) {
321 ret = fcntl(dst[i], F_SETFD, FD_CLOEXEC);
322 if (ret < 0) {
323 PERROR("fcntl pipe cloexec");
324 goto error;
325 }
326 }
327
328 error:
329 return ret;
330 }
331
332 /*
333 * Create pipe and set fd flags to FD_CLOEXEC and O_NONBLOCK.
334 *
335 * Make sure the pipe opened by this function are closed at some point. Use
336 * utils_close_pipe(). Using pipe() and fcntl rather than pipe2() to
337 * support OSes other than Linux 2.6.23+.
338 */
339 LTTNG_HIDDEN
340 int utils_create_pipe_cloexec_nonblock(int *dst)
341 {
342 int ret, i;
343
344 if (dst == NULL) {
345 return -1;
346 }
347
348 ret = utils_create_pipe(dst);
349 if (ret < 0) {
350 goto error;
351 }
352
353 for (i = 0; i < 2; i++) {
354 ret = fcntl(dst[i], F_SETFD, FD_CLOEXEC);
355 if (ret < 0) {
356 PERROR("fcntl pipe cloexec");
357 goto error;
358 }
359 /*
360 * Note: we override any flag that could have been
361 * previously set on the fd.
362 */
363 ret = fcntl(dst[i], F_SETFL, O_NONBLOCK);
364 if (ret < 0) {
365 PERROR("fcntl pipe nonblock");
366 goto error;
367 }
368 }
369
370 error:
371 return ret;
372 }
373
374 /*
375 * Close both read and write side of the pipe.
376 */
377 LTTNG_HIDDEN
378 void utils_close_pipe(int *src)
379 {
380 int i, ret;
381
382 if (src == NULL) {
383 return;
384 }
385
386 for (i = 0; i < 2; i++) {
387 /* Safety check */
388 if (src[i] < 0) {
389 continue;
390 }
391
392 ret = close(src[i]);
393 if (ret) {
394 PERROR("close pipe");
395 }
396 }
397 }
398
399 /*
400 * Create a new string using two strings range.
401 */
402 LTTNG_HIDDEN
403 char *utils_strdupdelim(const char *begin, const char *end)
404 {
405 char *str;
406
407 str = zmalloc(end - begin + 1);
408 if (str == NULL) {
409 PERROR("zmalloc strdupdelim");
410 goto error;
411 }
412
413 memcpy(str, begin, end - begin);
414 str[end - begin] = '\0';
415
416 error:
417 return str;
418 }
419
420 /*
421 * Set CLOEXEC flag to the give file descriptor.
422 */
423 LTTNG_HIDDEN
424 int utils_set_fd_cloexec(int fd)
425 {
426 int ret;
427
428 if (fd < 0) {
429 ret = -EINVAL;
430 goto end;
431 }
432
433 ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
434 if (ret < 0) {
435 PERROR("fcntl cloexec");
436 ret = -errno;
437 }
438
439 end:
440 return ret;
441 }
442
443 /*
444 * Create pid file to the given path and filename.
445 */
446 LTTNG_HIDDEN
447 int utils_create_pid_file(pid_t pid, const char *filepath)
448 {
449 int ret;
450 FILE *fp;
451
452 assert(filepath);
453
454 fp = fopen(filepath, "w");
455 if (fp == NULL) {
456 PERROR("open pid file %s", filepath);
457 ret = -1;
458 goto error;
459 }
460
461 ret = fprintf(fp, "%d\n", pid);
462 if (ret < 0) {
463 PERROR("fprintf pid file");
464 }
465
466 fclose(fp);
467 DBG("Pid %d written in file %s", pid, filepath);
468 error:
469 return ret;
470 }
471
472 /*
473 * Recursively create directory using the given path and mode.
474 *
475 * On success, return 0 else a negative error code.
476 */
477 LTTNG_HIDDEN
478 int utils_mkdir_recursive(const char *path, mode_t mode)
479 {
480 char *p, tmp[PATH_MAX];
481 size_t len;
482 int ret;
483
484 assert(path);
485
486 ret = snprintf(tmp, sizeof(tmp), "%s", path);
487 if (ret < 0) {
488 PERROR("snprintf mkdir");
489 goto error;
490 }
491
492 len = ret;
493 if (tmp[len - 1] == '/') {
494 tmp[len - 1] = 0;
495 }
496
497 for (p = tmp + 1; *p; p++) {
498 if (*p == '/') {
499 *p = 0;
500 if (tmp[strlen(tmp) - 1] == '.' &&
501 tmp[strlen(tmp) - 2] == '.' &&
502 tmp[strlen(tmp) - 3] == '/') {
503 ERR("Using '/../' is not permitted in the trace path (%s)",
504 tmp);
505 ret = -1;
506 goto error;
507 }
508 ret = mkdir(tmp, mode);
509 if (ret < 0) {
510 if (errno != EEXIST) {
511 PERROR("mkdir recursive");
512 ret = -errno;
513 goto error;
514 }
515 }
516 *p = '/';
517 }
518 }
519
520 ret = mkdir(tmp, mode);
521 if (ret < 0) {
522 if (errno != EEXIST) {
523 PERROR("mkdir recursive last piece");
524 ret = -errno;
525 } else {
526 ret = 0;
527 }
528 }
529
530 error:
531 return ret;
532 }
533
534 /*
535 * Create the stream tracefile on disk.
536 *
537 * Return 0 on success or else a negative value.
538 */
539 LTTNG_HIDDEN
540 int utils_create_stream_file(const char *path_name, char *file_name, uint64_t size,
541 uint64_t count, int uid, int gid, char *suffix)
542 {
543 int ret, out_fd, flags, mode;
544 char full_path[PATH_MAX], *path_name_suffix = NULL, *path;
545 char *extra = NULL;
546
547 assert(path_name);
548 assert(file_name);
549
550 ret = snprintf(full_path, sizeof(full_path), "%s/%s",
551 path_name, file_name);
552 if (ret < 0) {
553 PERROR("snprintf create output file");
554 goto error;
555 }
556
557 /* Setup extra string if suffix or/and a count is needed. */
558 if (size > 0 && suffix) {
559 ret = asprintf(&extra, "_%" PRIu64 "%s", count, suffix);
560 } else if (size > 0) {
561 ret = asprintf(&extra, "_%" PRIu64, count);
562 } else if (suffix) {
563 ret = asprintf(&extra, "%s", suffix);
564 }
565 if (ret < 0) {
566 PERROR("Allocating extra string to name");
567 goto error;
568 }
569
570 /*
571 * If we split the trace in multiple files, we have to add the count at the
572 * end of the tracefile name
573 */
574 if (extra) {
575 ret = asprintf(&path_name_suffix, "%s%s", full_path, extra);
576 if (ret < 0) {
577 PERROR("Allocating path name with extra string");
578 goto error_free_suffix;
579 }
580 path = path_name_suffix;
581 } else {
582 path = full_path;
583 }
584
585 flags = O_WRONLY | O_CREAT | O_TRUNC;
586 /* Open with 660 mode */
587 mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
588
589 if (uid < 0 || gid < 0) {
590 out_fd = open(path, flags, mode);
591 } else {
592 out_fd = run_as_open(path, flags, mode, uid, gid);
593 }
594 if (out_fd < 0) {
595 PERROR("open stream path %s", path);
596 goto error_open;
597 }
598 ret = out_fd;
599
600 error_open:
601 free(path_name_suffix);
602 error_free_suffix:
603 free(extra);
604 error:
605 return ret;
606 }
607
608 /*
609 * Change the output tracefile according to the given size and count The
610 * new_count pointer is set during this operation.
611 *
612 * From the consumer, the stream lock MUST be held before calling this function
613 * because we are modifying the stream status.
614 *
615 * Return 0 on success or else a negative value.
616 */
617 LTTNG_HIDDEN
618 int utils_rotate_stream_file(char *path_name, char *file_name, uint64_t size,
619 uint64_t count, int uid, int gid, int out_fd, uint64_t *new_count,
620 int *stream_fd)
621 {
622 int ret;
623
624 assert(new_count);
625 assert(stream_fd);
626
627 ret = close(out_fd);
628 if (ret < 0) {
629 PERROR("Closing tracefile");
630 goto error;
631 }
632
633 if (count > 0) {
634 *new_count = (*new_count + 1) % count;
635 } else {
636 (*new_count)++;
637 }
638
639 ret = utils_create_stream_file(path_name, file_name, size, *new_count,
640 uid, gid, 0);
641 if (ret < 0) {
642 goto error;
643 }
644 *stream_fd = ret;
645
646 /* Success. */
647 ret = 0;
648
649 error:
650 return ret;
651 }
652
653 /**
654 * Prints the error message corresponding to a regex error code.
655 *
656 * @param errcode The error code.
657 * @param regex The regex object that produced the error code.
658 */
659 static void regex_print_error(int errcode, regex_t *regex)
660 {
661 /* Get length of error message and allocate accordingly */
662 size_t length;
663 char *buffer;
664
665 assert(regex != NULL);
666
667 length = regerror(errcode, regex, NULL, 0);
668 if (length == 0) {
669 ERR("regerror returned a length of 0");
670 return;
671 }
672
673 buffer = zmalloc(length);
674 if (!buffer) {
675 ERR("regex_print_error: zmalloc failed");
676 return;
677 }
678
679 /* Get and print error message */
680 regerror(errcode, regex, buffer, length);
681 ERR("regex error: %s\n", buffer);
682 free(buffer);
683
684 }
685
686 /**
687 * Parse a string that represents a size in human readable format. It
688 * supports decimal integers suffixed by 'k', 'M' or 'G'.
689 *
690 * The suffix multiply the integer by:
691 * 'k': 1024
692 * 'M': 1024^2
693 * 'G': 1024^3
694 *
695 * @param str The string to parse.
696 * @param size Pointer to a size_t that will be filled with the
697 * resulting size.
698 *
699 * @return 0 on success, -1 on failure.
700 */
701 LTTNG_HIDDEN
702 int utils_parse_size_suffix(char *str, uint64_t *size)
703 {
704 regex_t regex;
705 int ret;
706 const int nmatch = 3;
707 regmatch_t suffix_match, matches[nmatch];
708 unsigned long long base_size;
709 long shift = 0;
710
711 if (!str) {
712 return 0;
713 }
714
715 /* Compile regex */
716 ret = regcomp(&regex, "^\\(0x\\)\\{0,1\\}[0-9][0-9]*\\([kKMG]\\{0,1\\}\\)$", 0);
717 if (ret != 0) {
718 regex_print_error(ret, &regex);
719 ret = -1;
720 goto end;
721 }
722
723 /* Match regex */
724 ret = regexec(&regex, str, nmatch, matches, 0);
725 if (ret != 0) {
726 ret = -1;
727 goto free;
728 }
729
730 /* There is a match ! */
731 errno = 0;
732 base_size = strtoull(str, NULL, 0);
733 if (errno != 0) {
734 PERROR("strtoull");
735 ret = -1;
736 goto free;
737 }
738
739 /* Check if there is a suffix */
740 suffix_match = matches[2];
741 if (suffix_match.rm_eo - suffix_match.rm_so == 1) {
742 switch (*(str + suffix_match.rm_so)) {
743 case 'K':
744 case 'k':
745 shift = KIBI_LOG2;
746 break;
747 case 'M':
748 shift = MEBI_LOG2;
749 break;
750 case 'G':
751 shift = GIBI_LOG2;
752 break;
753 default:
754 ERR("parse_human_size: invalid suffix");
755 ret = -1;
756 goto free;
757 }
758 }
759
760 *size = base_size << shift;
761
762 /* Check for overflow */
763 if ((*size >> shift) != base_size) {
764 ERR("parse_size_suffix: oops, overflow detected.");
765 ret = -1;
766 goto free;
767 }
768
769 ret = 0;
770
771 free:
772 regfree(&regex);
773 end:
774 return ret;
775 }
776
777 /*
778 * fls: returns the position of the most significant bit.
779 * Returns 0 if no bit is set, else returns the position of the most
780 * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
781 */
782 #if defined(__i386) || defined(__x86_64)
783 static inline unsigned int fls_u32(uint32_t x)
784 {
785 int r;
786
787 asm("bsrl %1,%0\n\t"
788 "jnz 1f\n\t"
789 "movl $-1,%0\n\t"
790 "1:\n\t"
791 : "=r" (r) : "rm" (x));
792 return r + 1;
793 }
794 #define HAS_FLS_U32
795 #endif
796
797 #ifndef HAS_FLS_U32
798 static __attribute__((unused)) unsigned int fls_u32(uint32_t x)
799 {
800 unsigned int r = 32;
801
802 if (!x) {
803 return 0;
804 }
805 if (!(x & 0xFFFF0000U)) {
806 x <<= 16;
807 r -= 16;
808 }
809 if (!(x & 0xFF000000U)) {
810 x <<= 8;
811 r -= 8;
812 }
813 if (!(x & 0xF0000000U)) {
814 x <<= 4;
815 r -= 4;
816 }
817 if (!(x & 0xC0000000U)) {
818 x <<= 2;
819 r -= 2;
820 }
821 if (!(x & 0x80000000U)) {
822 x <<= 1;
823 r -= 1;
824 }
825 return r;
826 }
827 #endif
828
829 /*
830 * Return the minimum order for which x <= (1UL << order).
831 * Return -1 if x is 0.
832 */
833 LTTNG_HIDDEN
834 int utils_get_count_order_u32(uint32_t x)
835 {
836 if (!x) {
837 return -1;
838 }
839
840 return fls_u32(x - 1);
841 }
842
843 /**
844 * Obtain the value of LTTNG_HOME environment variable, if exists.
845 * Otherwise returns the value of HOME.
846 */
847 LTTNG_HIDDEN
848 char *utils_get_home_dir(void)
849 {
850 char *val = NULL;
851 val = getenv(DEFAULT_LTTNG_HOME_ENV_VAR);
852 if (val != NULL) {
853 return val;
854 }
855 return getenv(DEFAULT_LTTNG_FALLBACK_HOME_ENV_VAR);
856 }
857
858 /**
859 * Get user's home directory. Dynamically allocated, must be freed
860 * by the caller.
861 */
862 LTTNG_HIDDEN
863 char *utils_get_user_home_dir(uid_t uid)
864 {
865 struct passwd pwd;
866 struct passwd *result;
867 char *home_dir = NULL;
868 char *buf = NULL;
869 long buflen;
870 int ret;
871
872 buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
873 if (buflen == -1) {
874 goto end;
875 }
876 retry:
877 buf = zmalloc(buflen);
878 if (!buf) {
879 goto end;
880 }
881
882 ret = getpwuid_r(uid, &pwd, buf, buflen, &result);
883 if (ret || !result) {
884 if (ret == ERANGE) {
885 free(buf);
886 buflen *= 2;
887 goto retry;
888 }
889 goto end;
890 }
891
892 home_dir = strdup(pwd.pw_dir);
893 end:
894 free(buf);
895 return home_dir;
896 }
897
898 /*
899 * With the given format, fill dst with the time of len maximum siz.
900 *
901 * Return amount of bytes set in the buffer or else 0 on error.
902 */
903 LTTNG_HIDDEN
904 size_t utils_get_current_time_str(const char *format, char *dst, size_t len)
905 {
906 size_t ret;
907 time_t rawtime;
908 struct tm *timeinfo;
909
910 assert(format);
911 assert(dst);
912
913 /* Get date and time for session path */
914 time(&rawtime);
915 timeinfo = localtime(&rawtime);
916 ret = strftime(dst, len, format, timeinfo);
917 if (ret == 0) {
918 ERR("Unable to strftime with format %s at dst %p of len %lu", format,
919 dst, len);
920 }
921
922 return ret;
923 }
924
925 /*
926 * Return the group ID matching name, else 0 if it cannot be found.
927 */
928 LTTNG_HIDDEN
929 gid_t utils_get_group_id(const char *name)
930 {
931 struct group *grp;
932
933 grp = getgrnam(name);
934 if (!grp) {
935 static volatile int warn_once;
936
937 if (!warn_once) {
938 WARN("No tracing group detected");
939 warn_once = 1;
940 }
941 return 0;
942 }
943 return grp->gr_gid;
944 }
945
946 /*
947 * Return a newly allocated option string. This string is to be used as the
948 * optstring argument of getopt_long(), see GETOPT(3). opt_count is the number
949 * of elements in the long_options array. Returns NULL if the string's
950 * allocation fails.
951 */
952 LTTNG_HIDDEN
953 char *utils_generate_optstring(const struct option *long_options,
954 size_t opt_count)
955 {
956 int i;
957 size_t string_len = opt_count, str_pos = 0;
958 char *optstring;
959
960 /*
961 * Compute the necessary string length. One letter per option, two when an
962 * argument is necessary, and a trailing NULL.
963 */
964 for (i = 0; i < opt_count; i++) {
965 string_len += long_options[i].has_arg ? 1 : 0;
966 }
967
968 optstring = zmalloc(string_len);
969 if (!optstring) {
970 goto end;
971 }
972
973 for (i = 0; i < opt_count; i++) {
974 if (!long_options[i].name) {
975 /* Got to the trailing NULL element */
976 break;
977 }
978
979 optstring[str_pos++] = (char)long_options[i].val;
980 if (long_options[i].has_arg) {
981 optstring[str_pos++] = ':';
982 }
983 }
984
985 end:
986 return optstring;
987 }
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