centralize sessiond config option handling
[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 _LGPL_SOURCE
21 #include <assert.h>
22 #include <ctype.h>
23 #include <fcntl.h>
24 #include <limits.h>
25 #include <stdlib.h>
26 #include <sys/stat.h>
27 #include <sys/types.h>
28 #include <unistd.h>
29 #include <inttypes.h>
30 #include <grp.h>
31 #include <pwd.h>
32 #include <sys/file.h>
33 #include <unistd.h>
34
35 #include <common/common.h>
36 #include <common/runas.h>
37 #include <common/compat/getenv.h>
38 #include <common/compat/string.h>
39 #include <common/compat/dirent.h>
40 #include <lttng/constant.h>
41
42 #include "utils.h"
43 #include "defaults.h"
44
45 /*
46 * Return a partial realpath(3) of the path even if the full path does not
47 * exist. For instance, with /tmp/test1/test2/test3, if test2/ does not exist
48 * but the /tmp/test1 does, the real path for /tmp/test1 is concatened with
49 * /test2/test3 then returned. In normal time, realpath(3) fails if the end
50 * point directory does not exist.
51 * In case resolved_path is NULL, the string returned was allocated in the
52 * function and thus need to be freed by the caller. The size argument allows
53 * to specify the size of the resolved_path argument if given, or the size to
54 * allocate.
55 */
56 LTTNG_HIDDEN
57 char *utils_partial_realpath(const char *path, char *resolved_path, size_t size)
58 {
59 char *cut_path = NULL, *try_path = NULL, *try_path_prev = NULL;
60 const char *next, *prev, *end;
61
62 /* Safety net */
63 if (path == NULL) {
64 goto error;
65 }
66
67 /*
68 * Identify the end of the path, we don't want to treat the
69 * last char if it is a '/', we will just keep it on the side
70 * to be added at the end, and return a value coherent with
71 * the path given as argument
72 */
73 end = path + strlen(path);
74 if (*(end-1) == '/') {
75 end--;
76 }
77
78 /* Initiate the values of the pointers before looping */
79 next = path;
80 prev = next;
81 /* Only to ensure try_path is not NULL to enter the while */
82 try_path = (char *)next;
83
84 /* Resolve the canonical path of the first part of the path */
85 while (try_path != NULL && next != end) {
86 char *try_path_buf = NULL;
87
88 /*
89 * If there is not any '/' left, we want to try with
90 * the full path
91 */
92 next = strpbrk(next + 1, "/");
93 if (next == NULL) {
94 next = end;
95 }
96
97 /* Cut the part we will be trying to resolve */
98 cut_path = lttng_strndup(path, next - path);
99 if (cut_path == NULL) {
100 PERROR("lttng_strndup");
101 goto error;
102 }
103
104 try_path_buf = zmalloc(LTTNG_PATH_MAX);
105 if (!try_path_buf) {
106 PERROR("zmalloc");
107 goto error;
108 }
109
110 /* Try to resolve this part */
111 try_path = realpath((char *) cut_path, try_path_buf);
112 if (try_path == NULL) {
113 free(try_path_buf);
114 /*
115 * There was an error, we just want to be assured it
116 * is linked to an unexistent directory, if it's another
117 * reason, we spawn an error
118 */
119 switch (errno) {
120 case ENOENT:
121 /* Ignore the error */
122 break;
123 default:
124 PERROR("realpath (partial_realpath)");
125 goto error;
126 break;
127 }
128 } else {
129 /* Save the place we are before trying the next step */
130 try_path_buf = NULL;
131 free(try_path_prev);
132 try_path_prev = try_path;
133 prev = next;
134 }
135
136 /* Free the allocated memory */
137 free(cut_path);
138 cut_path = NULL;
139 }
140
141 /* Allocate memory for the resolved path if necessary */
142 if (resolved_path == NULL) {
143 resolved_path = zmalloc(size);
144 if (resolved_path == NULL) {
145 PERROR("zmalloc resolved path");
146 goto error;
147 }
148 }
149
150 /*
151 * If we were able to solve at least partially the path, we can concatenate
152 * what worked and what didn't work
153 */
154 if (try_path_prev != NULL) {
155 /* If we risk to concatenate two '/', we remove one of them */
156 if (try_path_prev[strlen(try_path_prev) - 1] == '/' && prev[0] == '/') {
157 try_path_prev[strlen(try_path_prev) - 1] = '\0';
158 }
159
160 /*
161 * Duplicate the memory used by prev in case resolved_path and
162 * path are pointers for the same memory space
163 */
164 cut_path = strdup(prev);
165 if (cut_path == NULL) {
166 PERROR("strdup");
167 goto error;
168 }
169
170 /* Concatenate the strings */
171 snprintf(resolved_path, size, "%s%s", try_path_prev, cut_path);
172
173 /* Free the allocated memory */
174 free(cut_path);
175 free(try_path_prev);
176 cut_path = NULL;
177 try_path_prev = NULL;
178 /*
179 * Else, we just copy the path in our resolved_path to
180 * return it as is
181 */
182 } else {
183 strncpy(resolved_path, path, size);
184 }
185
186 /* Then we return the 'partially' resolved path */
187 return resolved_path;
188
189 error:
190 free(resolved_path);
191 free(cut_path);
192 free(try_path);
193 if (try_path_prev != try_path) {
194 free(try_path_prev);
195 }
196 return NULL;
197 }
198
199 /*
200 * Make a full resolution of the given path even if it doesn't exist.
201 * This function uses the utils_partial_realpath function to resolve
202 * symlinks and relatives paths at the start of the string, and
203 * implements functionnalities to resolve the './' and '../' strings
204 * in the middle of a path. This function is only necessary because
205 * realpath(3) does not accept to resolve unexistent paths.
206 * The returned string was allocated in the function, it is thus of
207 * the responsibility of the caller to free this memory.
208 */
209 LTTNG_HIDDEN
210 char *utils_expand_path(const char *path)
211 {
212 char *next, *previous, *slash, *start_path, *absolute_path = NULL;
213 char *last_token;
214 int is_dot, is_dotdot;
215
216 /* Safety net */
217 if (path == NULL) {
218 goto error;
219 }
220
221 /* Allocate memory for the absolute_path */
222 absolute_path = zmalloc(PATH_MAX);
223 if (absolute_path == NULL) {
224 PERROR("zmalloc expand path");
225 goto error;
226 }
227
228 /*
229 * If the path is not already absolute nor explicitly relative,
230 * consider we're in the current directory
231 */
232 if (*path != '/' && strncmp(path, "./", 2) != 0 &&
233 strncmp(path, "../", 3) != 0) {
234 snprintf(absolute_path, PATH_MAX, "./%s", path);
235 /* Else, we just copy the path */
236 } else {
237 strncpy(absolute_path, path, PATH_MAX);
238 }
239
240 /* Resolve partially our path */
241 absolute_path = utils_partial_realpath(absolute_path,
242 absolute_path, PATH_MAX);
243
244 /* As long as we find '/./' in the working_path string */
245 while ((next = strstr(absolute_path, "/./"))) {
246
247 /* We prepare the start_path not containing it */
248 start_path = lttng_strndup(absolute_path, next - absolute_path);
249 if (!start_path) {
250 PERROR("lttng_strndup");
251 goto error;
252 }
253 /* And we concatenate it with the part after this string */
254 snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2);
255
256 free(start_path);
257 }
258
259 /* As long as we find '/../' in the working_path string */
260 while ((next = strstr(absolute_path, "/../"))) {
261 /* We find the last level of directory */
262 previous = absolute_path;
263 while ((slash = strpbrk(previous, "/")) && slash != next) {
264 previous = slash + 1;
265 }
266
267 /* Then we prepare the start_path not containing it */
268 start_path = lttng_strndup(absolute_path, previous - absolute_path);
269 if (!start_path) {
270 PERROR("lttng_strndup");
271 goto error;
272 }
273
274 /* And we concatenate it with the part after the '/../' */
275 snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 4);
276
277 /* We can free the memory used for the start path*/
278 free(start_path);
279
280 /* Then we verify for symlinks using partial_realpath */
281 absolute_path = utils_partial_realpath(absolute_path,
282 absolute_path, PATH_MAX);
283 }
284
285 /* Identify the last token */
286 last_token = strrchr(absolute_path, '/');
287
288 /* Verify that this token is not a relative path */
289 is_dotdot = (strcmp(last_token, "/..") == 0);
290 is_dot = (strcmp(last_token, "/.") == 0);
291
292 /* If it is, take action */
293 if (is_dot || is_dotdot) {
294 /* For both, remove this token */
295 *last_token = '\0';
296
297 /* If it was a reference to parent directory, go back one more time */
298 if (is_dotdot) {
299 last_token = strrchr(absolute_path, '/');
300
301 /* If there was only one level left, we keep the first '/' */
302 if (last_token == absolute_path) {
303 last_token++;
304 }
305
306 *last_token = '\0';
307 }
308 }
309
310 return absolute_path;
311
312 error:
313 free(absolute_path);
314 return NULL;
315 }
316
317 /*
318 * Create a pipe in dst.
319 */
320 LTTNG_HIDDEN
321 int utils_create_pipe(int *dst)
322 {
323 int ret;
324
325 if (dst == NULL) {
326 return -1;
327 }
328
329 ret = pipe(dst);
330 if (ret < 0) {
331 PERROR("create pipe");
332 }
333
334 return ret;
335 }
336
337 /*
338 * Create pipe and set CLOEXEC flag to both fd.
339 *
340 * Make sure the pipe opened by this function are closed at some point. Use
341 * utils_close_pipe().
342 */
343 LTTNG_HIDDEN
344 int utils_create_pipe_cloexec(int *dst)
345 {
346 int ret, i;
347
348 if (dst == NULL) {
349 return -1;
350 }
351
352 ret = utils_create_pipe(dst);
353 if (ret < 0) {
354 goto error;
355 }
356
357 for (i = 0; i < 2; i++) {
358 ret = fcntl(dst[i], F_SETFD, FD_CLOEXEC);
359 if (ret < 0) {
360 PERROR("fcntl pipe cloexec");
361 goto error;
362 }
363 }
364
365 error:
366 return ret;
367 }
368
369 /*
370 * Create pipe and set fd flags to FD_CLOEXEC and O_NONBLOCK.
371 *
372 * Make sure the pipe opened by this function are closed at some point. Use
373 * utils_close_pipe(). Using pipe() and fcntl rather than pipe2() to
374 * support OSes other than Linux 2.6.23+.
375 */
376 LTTNG_HIDDEN
377 int utils_create_pipe_cloexec_nonblock(int *dst)
378 {
379 int ret, i;
380
381 if (dst == NULL) {
382 return -1;
383 }
384
385 ret = utils_create_pipe(dst);
386 if (ret < 0) {
387 goto error;
388 }
389
390 for (i = 0; i < 2; i++) {
391 ret = fcntl(dst[i], F_SETFD, FD_CLOEXEC);
392 if (ret < 0) {
393 PERROR("fcntl pipe cloexec");
394 goto error;
395 }
396 /*
397 * Note: we override any flag that could have been
398 * previously set on the fd.
399 */
400 ret = fcntl(dst[i], F_SETFL, O_NONBLOCK);
401 if (ret < 0) {
402 PERROR("fcntl pipe nonblock");
403 goto error;
404 }
405 }
406
407 error:
408 return ret;
409 }
410
411 /*
412 * Close both read and write side of the pipe.
413 */
414 LTTNG_HIDDEN
415 void utils_close_pipe(int *src)
416 {
417 int i, ret;
418
419 if (src == NULL) {
420 return;
421 }
422
423 for (i = 0; i < 2; i++) {
424 /* Safety check */
425 if (src[i] < 0) {
426 continue;
427 }
428
429 ret = close(src[i]);
430 if (ret) {
431 PERROR("close pipe");
432 }
433 }
434 }
435
436 /*
437 * Create a new string using two strings range.
438 */
439 LTTNG_HIDDEN
440 char *utils_strdupdelim(const char *begin, const char *end)
441 {
442 char *str;
443
444 str = zmalloc(end - begin + 1);
445 if (str == NULL) {
446 PERROR("zmalloc strdupdelim");
447 goto error;
448 }
449
450 memcpy(str, begin, end - begin);
451 str[end - begin] = '\0';
452
453 error:
454 return str;
455 }
456
457 /*
458 * Set CLOEXEC flag to the give file descriptor.
459 */
460 LTTNG_HIDDEN
461 int utils_set_fd_cloexec(int fd)
462 {
463 int ret;
464
465 if (fd < 0) {
466 ret = -EINVAL;
467 goto end;
468 }
469
470 ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
471 if (ret < 0) {
472 PERROR("fcntl cloexec");
473 ret = -errno;
474 }
475
476 end:
477 return ret;
478 }
479
480 /*
481 * Create pid file to the given path and filename.
482 */
483 LTTNG_HIDDEN
484 int utils_create_pid_file(pid_t pid, const char *filepath)
485 {
486 int ret;
487 FILE *fp;
488
489 assert(filepath);
490
491 fp = fopen(filepath, "w");
492 if (fp == NULL) {
493 PERROR("open pid file %s", filepath);
494 ret = -1;
495 goto error;
496 }
497
498 ret = fprintf(fp, "%d\n", (int) pid);
499 if (ret < 0) {
500 PERROR("fprintf pid file");
501 goto error;
502 }
503
504 if (fclose(fp)) {
505 PERROR("fclose");
506 }
507 DBG("Pid %d written in file %s", (int) pid, filepath);
508 ret = 0;
509 error:
510 return ret;
511 }
512
513 /*
514 * Create lock file to the given path and filename.
515 * Returns the associated file descriptor, -1 on error.
516 */
517 LTTNG_HIDDEN
518 int utils_create_lock_file(const char *filepath)
519 {
520 int ret;
521 int fd;
522 struct flock lock;
523
524 assert(filepath);
525
526 memset(&lock, 0, sizeof(lock));
527 fd = open(filepath, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR |
528 S_IRGRP | S_IWGRP);
529 if (fd < 0) {
530 PERROR("open lock file %s", filepath);
531 fd = -1;
532 goto error;
533 }
534
535 /*
536 * Attempt to lock the file. If this fails, there is
537 * already a process using the same lock file running
538 * and we should exit.
539 */
540 lock.l_whence = SEEK_SET;
541 lock.l_type = F_WRLCK;
542
543 ret = fcntl(fd, F_SETLK, &lock);
544 if (ret == -1) {
545 PERROR("fcntl lock file");
546 ERR("Could not get lock file %s, another instance is running.",
547 filepath);
548 if (close(fd)) {
549 PERROR("close lock file");
550 }
551 fd = ret;
552 goto error;
553 }
554
555 error:
556 return fd;
557 }
558
559 /*
560 * On some filesystems (e.g. nfs), mkdir will validate access rights before
561 * checking for the existence of the path element. This means that on a setup
562 * where "/home/" is a mounted NFS share, and running as an unpriviledged user,
563 * recursively creating a path of the form "/home/my_user/trace/" will fail with
564 * EACCES on mkdir("/home", ...).
565 *
566 * Performing a stat(...) on the path to check for existence allows us to
567 * work around this behaviour.
568 */
569 static
570 int mkdir_check_exists(const char *path, mode_t mode)
571 {
572 int ret = 0;
573 struct stat st;
574
575 ret = stat(path, &st);
576 if (ret == 0) {
577 if (S_ISDIR(st.st_mode)) {
578 /* Directory exists, skip. */
579 goto end;
580 } else {
581 /* Exists, but is not a directory. */
582 errno = ENOTDIR;
583 ret = -1;
584 goto end;
585 }
586 }
587
588 /*
589 * Let mkdir handle other errors as the caller expects mkdir
590 * semantics.
591 */
592 ret = mkdir(path, mode);
593 end:
594 return ret;
595 }
596
597 /*
598 * Create directory using the given path and mode.
599 *
600 * On success, return 0 else a negative error code.
601 */
602 LTTNG_HIDDEN
603 int utils_mkdir(const char *path, mode_t mode, int uid, int gid)
604 {
605 int ret;
606
607 if (uid < 0 || gid < 0) {
608 ret = mkdir_check_exists(path, mode);
609 } else {
610 ret = run_as_mkdir(path, mode, uid, gid);
611 }
612 if (ret < 0) {
613 if (errno != EEXIST) {
614 PERROR("mkdir %s, uid %d, gid %d", path ? path : "NULL",
615 uid, gid);
616 } else {
617 ret = 0;
618 }
619 }
620
621 return ret;
622 }
623
624 /*
625 * Internal version of mkdir_recursive. Runs as the current user.
626 * Don't call directly; use utils_mkdir_recursive().
627 *
628 * This function is ominously marked as "unsafe" since it should only
629 * be called by a caller that has transitioned to the uid and gid under which
630 * the directory creation should occur.
631 */
632 LTTNG_HIDDEN
633 int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode)
634 {
635 char *p, tmp[PATH_MAX];
636 size_t len;
637 int ret;
638
639 assert(path);
640
641 ret = snprintf(tmp, sizeof(tmp), "%s", path);
642 if (ret < 0) {
643 PERROR("snprintf mkdir");
644 goto error;
645 }
646
647 len = ret;
648 if (tmp[len - 1] == '/') {
649 tmp[len - 1] = 0;
650 }
651
652 for (p = tmp + 1; *p; p++) {
653 if (*p == '/') {
654 *p = 0;
655 if (tmp[strlen(tmp) - 1] == '.' &&
656 tmp[strlen(tmp) - 2] == '.' &&
657 tmp[strlen(tmp) - 3] == '/') {
658 ERR("Using '/../' is not permitted in the trace path (%s)",
659 tmp);
660 ret = -1;
661 goto error;
662 }
663 ret = mkdir_check_exists(tmp, mode);
664 if (ret < 0) {
665 if (errno != EACCES) {
666 PERROR("mkdir recursive");
667 ret = -errno;
668 goto error;
669 }
670 }
671 *p = '/';
672 }
673 }
674
675 ret = mkdir_check_exists(tmp, mode);
676 if (ret < 0) {
677 PERROR("mkdir recursive last element");
678 ret = -errno;
679 }
680
681 error:
682 return ret;
683 }
684
685 /*
686 * Recursively create directory using the given path and mode, under the
687 * provided uid and gid.
688 *
689 * On success, return 0 else a negative error code.
690 */
691 LTTNG_HIDDEN
692 int utils_mkdir_recursive(const char *path, mode_t mode, int uid, int gid)
693 {
694 int ret;
695
696 if (uid < 0 || gid < 0) {
697 /* Run as current user. */
698 ret = _utils_mkdir_recursive_unsafe(path, mode);
699 } else {
700 ret = run_as_mkdir_recursive(path, mode, uid, gid);
701 }
702 if (ret < 0) {
703 PERROR("mkdir %s, uid %d, gid %d", path ? path : "NULL",
704 uid, gid);
705 }
706
707 return ret;
708 }
709
710 /*
711 * path is the output parameter. It needs to be PATH_MAX len.
712 *
713 * Return 0 on success or else a negative value.
714 */
715 static int utils_stream_file_name(char *path,
716 const char *path_name, const char *file_name,
717 uint64_t size, uint64_t count,
718 const char *suffix)
719 {
720 int ret;
721 char full_path[PATH_MAX];
722 char *path_name_suffix = NULL;
723 char *extra = NULL;
724
725 ret = snprintf(full_path, sizeof(full_path), "%s/%s",
726 path_name, file_name);
727 if (ret < 0) {
728 PERROR("snprintf create output file");
729 goto error;
730 }
731
732 /* Setup extra string if suffix or/and a count is needed. */
733 if (size > 0 && suffix) {
734 ret = asprintf(&extra, "_%" PRIu64 "%s", count, suffix);
735 } else if (size > 0) {
736 ret = asprintf(&extra, "_%" PRIu64, count);
737 } else if (suffix) {
738 ret = asprintf(&extra, "%s", suffix);
739 }
740 if (ret < 0) {
741 PERROR("Allocating extra string to name");
742 goto error;
743 }
744
745 /*
746 * If we split the trace in multiple files, we have to add the count at
747 * the end of the tracefile name.
748 */
749 if (extra) {
750 ret = asprintf(&path_name_suffix, "%s%s", full_path, extra);
751 if (ret < 0) {
752 PERROR("Allocating path name with extra string");
753 goto error_free_suffix;
754 }
755 strncpy(path, path_name_suffix, PATH_MAX - 1);
756 path[PATH_MAX - 1] = '\0';
757 } else {
758 strncpy(path, full_path, PATH_MAX - 1);
759 }
760 path[PATH_MAX - 1] = '\0';
761 ret = 0;
762
763 free(path_name_suffix);
764 error_free_suffix:
765 free(extra);
766 error:
767 return ret;
768 }
769
770 /*
771 * Create the stream file on disk.
772 *
773 * Return 0 on success or else a negative value.
774 */
775 LTTNG_HIDDEN
776 int utils_create_stream_file(const char *path_name, char *file_name, uint64_t size,
777 uint64_t count, int uid, int gid, char *suffix)
778 {
779 int ret, flags, mode;
780 char path[PATH_MAX];
781
782 ret = utils_stream_file_name(path, path_name, file_name,
783 size, count, suffix);
784 if (ret < 0) {
785 goto error;
786 }
787
788 flags = O_WRONLY | O_CREAT | O_TRUNC;
789 /* Open with 660 mode */
790 mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
791
792 if (uid < 0 || gid < 0) {
793 ret = open(path, flags, mode);
794 } else {
795 ret = run_as_open(path, flags, mode, uid, gid);
796 }
797 if (ret < 0) {
798 PERROR("open stream path %s", path);
799 }
800 error:
801 return ret;
802 }
803
804 /*
805 * Unlink the stream tracefile from disk.
806 *
807 * Return 0 on success or else a negative value.
808 */
809 LTTNG_HIDDEN
810 int utils_unlink_stream_file(const char *path_name, char *file_name, uint64_t size,
811 uint64_t count, int uid, int gid, char *suffix)
812 {
813 int ret;
814 char path[PATH_MAX];
815
816 ret = utils_stream_file_name(path, path_name, file_name,
817 size, count, suffix);
818 if (ret < 0) {
819 goto error;
820 }
821 if (uid < 0 || gid < 0) {
822 ret = unlink(path);
823 } else {
824 ret = run_as_unlink(path, uid, gid);
825 }
826 if (ret < 0) {
827 goto error;
828 }
829 error:
830 DBG("utils_unlink_stream_file %s returns %d", path, ret);
831 return ret;
832 }
833
834 /*
835 * Change the output tracefile according to the given size and count The
836 * new_count pointer is set during this operation.
837 *
838 * From the consumer, the stream lock MUST be held before calling this function
839 * because we are modifying the stream status.
840 *
841 * Return 0 on success or else a negative value.
842 */
843 LTTNG_HIDDEN
844 int utils_rotate_stream_file(char *path_name, char *file_name, uint64_t size,
845 uint64_t count, int uid, int gid, int out_fd, uint64_t *new_count,
846 int *stream_fd)
847 {
848 int ret;
849
850 assert(stream_fd);
851
852 ret = close(out_fd);
853 if (ret < 0) {
854 PERROR("Closing tracefile");
855 goto error;
856 }
857 *stream_fd = -1;
858
859 if (count > 0) {
860 /*
861 * In tracefile rotation, for the relay daemon we need
862 * to unlink the old file if present, because it may
863 * still be open in reading by the live thread, and we
864 * need to ensure that we do not overwrite the content
865 * between get_index and get_packet. Since we have no
866 * way to verify integrity of the data content compared
867 * to the associated index, we need to ensure the reader
868 * has exclusive access to the file content, and that
869 * the open of the data file is performed in get_index.
870 * Unlinking the old file rather than overwriting it
871 * achieves this.
872 */
873 if (new_count) {
874 *new_count = (*new_count + 1) % count;
875 }
876 ret = utils_unlink_stream_file(path_name, file_name, size,
877 new_count ? *new_count : 0, uid, gid, 0);
878 if (ret < 0 && errno != ENOENT) {
879 goto error;
880 }
881 } else {
882 if (new_count) {
883 (*new_count)++;
884 }
885 }
886
887 ret = utils_create_stream_file(path_name, file_name, size,
888 new_count ? *new_count : 0, uid, gid, 0);
889 if (ret < 0) {
890 goto error;
891 }
892 *stream_fd = ret;
893
894 /* Success. */
895 ret = 0;
896
897 error:
898 return ret;
899 }
900
901
902 /**
903 * Parse a string that represents a size in human readable format. It
904 * supports decimal integers suffixed by 'k', 'K', 'M' or 'G'.
905 *
906 * The suffix multiply the integer by:
907 * 'k': 1024
908 * 'M': 1024^2
909 * 'G': 1024^3
910 *
911 * @param str The string to parse.
912 * @param size Pointer to a uint64_t that will be filled with the
913 * resulting size.
914 *
915 * @return 0 on success, -1 on failure.
916 */
917 LTTNG_HIDDEN
918 int utils_parse_size_suffix(const char * const str, uint64_t * const size)
919 {
920 int ret;
921 uint64_t base_size;
922 long shift = 0;
923 const char *str_end;
924 char *num_end;
925
926 if (!str) {
927 DBG("utils_parse_size_suffix: received a NULL string.");
928 ret = -1;
929 goto end;
930 }
931
932 /* strtoull will accept a negative number, but we don't want to. */
933 if (strchr(str, '-') != NULL) {
934 DBG("utils_parse_size_suffix: invalid size string, should not contain '-'.");
935 ret = -1;
936 goto end;
937 }
938
939 /* str_end will point to the \0 */
940 str_end = str + strlen(str);
941 errno = 0;
942 base_size = strtoull(str, &num_end, 0);
943 if (errno != 0) {
944 PERROR("utils_parse_size_suffix strtoull");
945 ret = -1;
946 goto end;
947 }
948
949 if (num_end == str) {
950 /* strtoull parsed nothing, not good. */
951 DBG("utils_parse_size_suffix: strtoull had nothing good to parse.");
952 ret = -1;
953 goto end;
954 }
955
956 /* Check if a prefix is present. */
957 switch (*num_end) {
958 case 'G':
959 shift = GIBI_LOG2;
960 num_end++;
961 break;
962 case 'M': /* */
963 shift = MEBI_LOG2;
964 num_end++;
965 break;
966 case 'K':
967 case 'k':
968 shift = KIBI_LOG2;
969 num_end++;
970 break;
971 case '\0':
972 break;
973 default:
974 DBG("utils_parse_size_suffix: invalid suffix.");
975 ret = -1;
976 goto end;
977 }
978
979 /* Check for garbage after the valid input. */
980 if (num_end != str_end) {
981 DBG("utils_parse_size_suffix: Garbage after size string.");
982 ret = -1;
983 goto end;
984 }
985
986 *size = base_size << shift;
987
988 /* Check for overflow */
989 if ((*size >> shift) != base_size) {
990 DBG("utils_parse_size_suffix: oops, overflow detected.");
991 ret = -1;
992 goto end;
993 }
994
995 ret = 0;
996 end:
997 return ret;
998 }
999
1000 /*
1001 * fls: returns the position of the most significant bit.
1002 * Returns 0 if no bit is set, else returns the position of the most
1003 * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
1004 */
1005 #if defined(__i386) || defined(__x86_64)
1006 static inline unsigned int fls_u32(uint32_t x)
1007 {
1008 int r;
1009
1010 asm("bsrl %1,%0\n\t"
1011 "jnz 1f\n\t"
1012 "movl $-1,%0\n\t"
1013 "1:\n\t"
1014 : "=r" (r) : "rm" (x));
1015 return r + 1;
1016 }
1017 #define HAS_FLS_U32
1018 #endif
1019
1020 #if defined(__x86_64)
1021 static inline
1022 unsigned int fls_u64(uint64_t x)
1023 {
1024 long r;
1025
1026 asm("bsrq %1,%0\n\t"
1027 "jnz 1f\n\t"
1028 "movq $-1,%0\n\t"
1029 "1:\n\t"
1030 : "=r" (r) : "rm" (x));
1031 return r + 1;
1032 }
1033 #define HAS_FLS_U64
1034 #endif
1035
1036 #ifndef HAS_FLS_U64
1037 static __attribute__((unused))
1038 unsigned int fls_u64(uint64_t x)
1039 {
1040 unsigned int r = 64;
1041
1042 if (!x)
1043 return 0;
1044
1045 if (!(x & 0xFFFFFFFF00000000ULL)) {
1046 x <<= 32;
1047 r -= 32;
1048 }
1049 if (!(x & 0xFFFF000000000000ULL)) {
1050 x <<= 16;
1051 r -= 16;
1052 }
1053 if (!(x & 0xFF00000000000000ULL)) {
1054 x <<= 8;
1055 r -= 8;
1056 }
1057 if (!(x & 0xF000000000000000ULL)) {
1058 x <<= 4;
1059 r -= 4;
1060 }
1061 if (!(x & 0xC000000000000000ULL)) {
1062 x <<= 2;
1063 r -= 2;
1064 }
1065 if (!(x & 0x8000000000000000ULL)) {
1066 x <<= 1;
1067 r -= 1;
1068 }
1069 return r;
1070 }
1071 #endif
1072
1073 #ifndef HAS_FLS_U32
1074 static __attribute__((unused)) unsigned int fls_u32(uint32_t x)
1075 {
1076 unsigned int r = 32;
1077
1078 if (!x) {
1079 return 0;
1080 }
1081 if (!(x & 0xFFFF0000U)) {
1082 x <<= 16;
1083 r -= 16;
1084 }
1085 if (!(x & 0xFF000000U)) {
1086 x <<= 8;
1087 r -= 8;
1088 }
1089 if (!(x & 0xF0000000U)) {
1090 x <<= 4;
1091 r -= 4;
1092 }
1093 if (!(x & 0xC0000000U)) {
1094 x <<= 2;
1095 r -= 2;
1096 }
1097 if (!(x & 0x80000000U)) {
1098 x <<= 1;
1099 r -= 1;
1100 }
1101 return r;
1102 }
1103 #endif
1104
1105 /*
1106 * Return the minimum order for which x <= (1UL << order).
1107 * Return -1 if x is 0.
1108 */
1109 LTTNG_HIDDEN
1110 int utils_get_count_order_u32(uint32_t x)
1111 {
1112 if (!x) {
1113 return -1;
1114 }
1115
1116 return fls_u32(x - 1);
1117 }
1118
1119 /*
1120 * Return the minimum order for which x <= (1UL << order).
1121 * Return -1 if x is 0.
1122 */
1123 LTTNG_HIDDEN
1124 int utils_get_count_order_u64(uint64_t x)
1125 {
1126 if (!x) {
1127 return -1;
1128 }
1129
1130 return fls_u64(x - 1);
1131 }
1132
1133 /**
1134 * Obtain the value of LTTNG_HOME environment variable, if exists.
1135 * Otherwise returns the value of HOME.
1136 */
1137 LTTNG_HIDDEN
1138 char *utils_get_home_dir(void)
1139 {
1140 char *val = NULL;
1141 struct passwd *pwd;
1142
1143 val = lttng_secure_getenv(DEFAULT_LTTNG_HOME_ENV_VAR);
1144 if (val != NULL) {
1145 goto end;
1146 }
1147 val = lttng_secure_getenv(DEFAULT_LTTNG_FALLBACK_HOME_ENV_VAR);
1148 if (val != NULL) {
1149 goto end;
1150 }
1151
1152 /* Fallback on the password file entry. */
1153 pwd = getpwuid(getuid());
1154 if (!pwd) {
1155 goto end;
1156 }
1157 val = pwd->pw_dir;
1158
1159 DBG3("Home directory is '%s'", val);
1160
1161 end:
1162 return val;
1163 }
1164
1165 /**
1166 * Get user's home directory. Dynamically allocated, must be freed
1167 * by the caller.
1168 */
1169 LTTNG_HIDDEN
1170 char *utils_get_user_home_dir(uid_t uid)
1171 {
1172 struct passwd pwd;
1173 struct passwd *result;
1174 char *home_dir = NULL;
1175 char *buf = NULL;
1176 long buflen;
1177 int ret;
1178
1179 buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
1180 if (buflen == -1) {
1181 goto end;
1182 }
1183 retry:
1184 buf = zmalloc(buflen);
1185 if (!buf) {
1186 goto end;
1187 }
1188
1189 ret = getpwuid_r(uid, &pwd, buf, buflen, &result);
1190 if (ret || !result) {
1191 if (ret == ERANGE) {
1192 free(buf);
1193 buflen *= 2;
1194 goto retry;
1195 }
1196 goto end;
1197 }
1198
1199 home_dir = strdup(pwd.pw_dir);
1200 end:
1201 free(buf);
1202 return home_dir;
1203 }
1204
1205 /*
1206 * With the given format, fill dst with the time of len maximum siz.
1207 *
1208 * Return amount of bytes set in the buffer or else 0 on error.
1209 */
1210 LTTNG_HIDDEN
1211 size_t utils_get_current_time_str(const char *format, char *dst, size_t len)
1212 {
1213 size_t ret;
1214 time_t rawtime;
1215 struct tm *timeinfo;
1216
1217 assert(format);
1218 assert(dst);
1219
1220 /* Get date and time for session path */
1221 time(&rawtime);
1222 timeinfo = localtime(&rawtime);
1223 ret = strftime(dst, len, format, timeinfo);
1224 if (ret == 0) {
1225 ERR("Unable to strftime with format %s at dst %p of len %zu", format,
1226 dst, len);
1227 }
1228
1229 return ret;
1230 }
1231
1232 /*
1233 * Return the group ID matching name, else 0 if it cannot be found.
1234 */
1235 LTTNG_HIDDEN
1236 gid_t utils_get_group_id(const char *name)
1237 {
1238 struct group *grp;
1239
1240 grp = getgrnam(name);
1241 if (!grp) {
1242 static volatile int warn_once;
1243
1244 if (!warn_once) {
1245 WARN("No tracing group detected");
1246 warn_once = 1;
1247 }
1248 return 0;
1249 }
1250 return grp->gr_gid;
1251 }
1252
1253 /*
1254 * Return a newly allocated option string. This string is to be used as the
1255 * optstring argument of getopt_long(), see GETOPT(3). opt_count is the number
1256 * of elements in the long_options array. Returns NULL if the string's
1257 * allocation fails.
1258 */
1259 LTTNG_HIDDEN
1260 char *utils_generate_optstring(const struct option *long_options,
1261 size_t opt_count)
1262 {
1263 int i;
1264 size_t string_len = opt_count, str_pos = 0;
1265 char *optstring;
1266
1267 /*
1268 * Compute the necessary string length. One letter per option, two when an
1269 * argument is necessary, and a trailing NULL.
1270 */
1271 for (i = 0; i < opt_count; i++) {
1272 string_len += long_options[i].has_arg ? 1 : 0;
1273 }
1274
1275 optstring = zmalloc(string_len);
1276 if (!optstring) {
1277 goto end;
1278 }
1279
1280 for (i = 0; i < opt_count; i++) {
1281 if (!long_options[i].name) {
1282 /* Got to the trailing NULL element */
1283 break;
1284 }
1285
1286 if (long_options[i].val != '\0') {
1287 optstring[str_pos++] = (char) long_options[i].val;
1288 if (long_options[i].has_arg) {
1289 optstring[str_pos++] = ':';
1290 }
1291 }
1292 }
1293
1294 end:
1295 return optstring;
1296 }
1297
1298 /*
1299 * Try to remove a hierarchy of empty directories, recursively. Don't unlink
1300 * any file. Try to rmdir any empty directory within the hierarchy.
1301 */
1302 LTTNG_HIDDEN
1303 int utils_recursive_rmdir(const char *path)
1304 {
1305 DIR *dir;
1306 size_t path_len;
1307 int dir_fd, ret = 0, closeret, is_empty = 1;
1308 struct dirent *entry;
1309
1310 /* Open directory */
1311 dir = opendir(path);
1312 if (!dir) {
1313 PERROR("Cannot open '%s' path", path);
1314 return -1;
1315 }
1316 dir_fd = lttng_dirfd(dir);
1317 if (dir_fd < 0) {
1318 PERROR("lttng_dirfd");
1319 return -1;
1320 }
1321
1322 path_len = strlen(path);
1323 while ((entry = readdir(dir))) {
1324 struct stat st;
1325 size_t name_len;
1326 char filename[PATH_MAX];
1327
1328 if (!strcmp(entry->d_name, ".")
1329 || !strcmp(entry->d_name, "..")) {
1330 continue;
1331 }
1332
1333 name_len = strlen(entry->d_name);
1334 if (path_len + name_len + 2 > sizeof(filename)) {
1335 ERR("Failed to remove file: path name too long (%s/%s)",
1336 path, entry->d_name);
1337 continue;
1338 }
1339 if (snprintf(filename, sizeof(filename), "%s/%s",
1340 path, entry->d_name) < 0) {
1341 ERR("Failed to format path.");
1342 continue;
1343 }
1344
1345 if (stat(filename, &st)) {
1346 PERROR("stat");
1347 continue;
1348 }
1349
1350 if (S_ISDIR(st.st_mode)) {
1351 char subpath[PATH_MAX];
1352
1353 strncpy(subpath, path, PATH_MAX);
1354 subpath[PATH_MAX - 1] = '\0';
1355 strncat(subpath, "/",
1356 PATH_MAX - strlen(subpath) - 1);
1357 strncat(subpath, entry->d_name,
1358 PATH_MAX - strlen(subpath) - 1);
1359 if (utils_recursive_rmdir(subpath)) {
1360 is_empty = 0;
1361 }
1362 } else if (S_ISREG(st.st_mode)) {
1363 is_empty = 0;
1364 } else {
1365 ret = -EINVAL;
1366 goto end;
1367 }
1368 }
1369 end:
1370 closeret = closedir(dir);
1371 if (closeret) {
1372 PERROR("closedir");
1373 }
1374 if (is_empty) {
1375 DBG3("Attempting rmdir %s", path);
1376 ret = rmdir(path);
1377 }
1378 return ret;
1379 }
1380
1381 LTTNG_HIDDEN
1382 int utils_truncate_stream_file(int fd, off_t length)
1383 {
1384 int ret;
1385
1386 ret = ftruncate(fd, length);
1387 if (ret < 0) {
1388 PERROR("ftruncate");
1389 goto end;
1390 }
1391 ret = lseek(fd, length, SEEK_SET);
1392 if (ret < 0) {
1393 PERROR("lseek");
1394 goto end;
1395 }
1396 end:
1397 return ret;
1398 }
1399
1400 static const char *get_man_bin_path(void)
1401 {
1402 char *env_man_path = lttng_secure_getenv(DEFAULT_MAN_BIN_PATH_ENV);
1403
1404 if (env_man_path) {
1405 return env_man_path;
1406 }
1407
1408 return DEFAULT_MAN_BIN_PATH;
1409 }
1410
1411 LTTNG_HIDDEN
1412 int utils_show_help(int section, const char *page_name,
1413 const char *help_msg)
1414 {
1415 char section_string[8];
1416 const char *man_bin_path = get_man_bin_path();
1417 int ret = 0;
1418
1419 if (help_msg) {
1420 printf("%s", help_msg);
1421 goto end;
1422 }
1423
1424 /* Section integer -> section string */
1425 ret = sprintf(section_string, "%d", section);
1426 assert(ret > 0 && ret < 8);
1427
1428 /*
1429 * Execute man pager.
1430 *
1431 * We provide -M to man here because LTTng-tools can
1432 * be installed outside /usr, in which case its man pages are
1433 * not located in the default /usr/share/man directory.
1434 */
1435 ret = execlp(man_bin_path, "man", "-M", MANPATH,
1436 section_string, page_name, NULL);
1437
1438 end:
1439 return ret;
1440 }
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