1 01b7ba6b 2019-03-11 stsp /*
  2 01b7ba6b 2019-03-11 stsp  * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
  3 01b7ba6b 2019-03-11 stsp  *
  4 01b7ba6b 2019-03-11 stsp  * Permission to use, copy, modify, and distribute this software for any
  5 01b7ba6b 2019-03-11 stsp  * purpose with or without fee is hereby granted, provided that the above
  6 01b7ba6b 2019-03-11 stsp  * copyright notice and this permission notice appear in all copies.
  7 01b7ba6b 2019-03-11 stsp  *
  8 01b7ba6b 2019-03-11 stsp  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  9 01b7ba6b 2019-03-11 stsp  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 10 01b7ba6b 2019-03-11 stsp  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 11 01b7ba6b 2019-03-11 stsp  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 12 01b7ba6b 2019-03-11 stsp  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 13 01b7ba6b 2019-03-11 stsp  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 14 01b7ba6b 2019-03-11 stsp  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 15 01b7ba6b 2019-03-11 stsp  */
 16 01b7ba6b 2019-03-11 stsp 
 17 01b7ba6b 2019-03-11 stsp #include <sys/stat.h>
 18 01b7ba6b 2019-03-11 stsp #include <sys/queue.h>
 19 01b7ba6b 2019-03-11 stsp 
 20 01b7ba6b 2019-03-11 stsp #include <errno.h>
 21 01b7ba6b 2019-03-11 stsp #include <fcntl.h>
 22 01b7ba6b 2019-03-11 stsp #include <stdlib.h>
 23 01b7ba6b 2019-03-11 stsp #include <unistd.h>
 24 01b7ba6b 2019-03-11 stsp #include <string.h>
 25 01b7ba6b 2019-03-11 stsp #include <stdio.h>
 26 01b7ba6b 2019-03-11 stsp #include <time.h>
 27 01b7ba6b 2019-03-11 stsp 
 28 01b7ba6b 2019-03-11 stsp #include "got_error.h"
 29 324d37e7 2019-05-11 stsp #include "got_path.h"
 30 01b7ba6b 2019-03-11 stsp 
 31 01b7ba6b 2019-03-11 stsp #include "got_lib_lockfile.h"
 32 01b7ba6b 2019-03-11 stsp 
 33 01b7ba6b 2019-03-11 stsp const struct got_error *
 34 5345b4c7 2021-07-06 stsp got_lockfile_lock(struct got_lockfile **lf, const char *path, int dir_fd)
 35 01b7ba6b 2019-03-11 stsp {
 36 01b7ba6b 2019-03-11 stsp 	const struct got_error *err = NULL;
 37 01b7ba6b 2019-03-11 stsp 	int attempts = 5;
 38 01b7ba6b 2019-03-11 stsp 
 39 47112f60 2019-03-11 stsp 	*lf = calloc(1, sizeof(**lf));
 40 01b7ba6b 2019-03-11 stsp 	if (*lf == NULL)
 41 638f9024 2019-05-13 stsp 		return got_error_from_errno("calloc");
 42 01b7ba6b 2019-03-11 stsp 	(*lf)->fd = -1;
 43 01b7ba6b 2019-03-11 stsp 
 44 01b7ba6b 2019-03-11 stsp 	(*lf)->locked_path = strdup(path);
 45 01b7ba6b 2019-03-11 stsp 	if ((*lf)->locked_path == NULL) {
 46 638f9024 2019-05-13 stsp 		err = got_error_from_errno("strdup");
 47 01b7ba6b 2019-03-11 stsp 		goto done;
 48 01b7ba6b 2019-03-11 stsp 	}
 49 01b7ba6b 2019-03-11 stsp 
 50 01b7ba6b 2019-03-11 stsp 	if (asprintf(&(*lf)->path, "%s%s", path, GOT_LOCKFILE_SUFFIX) == -1) {
 51 638f9024 2019-05-13 stsp 		err = got_error_from_errno("asprintf");
 52 01b7ba6b 2019-03-11 stsp 		goto done;
 53 01b7ba6b 2019-03-11 stsp 	}
 54 01b7ba6b 2019-03-11 stsp 
 55 01b7ba6b 2019-03-11 stsp 	do {
 56 5345b4c7 2021-07-06 stsp 		if (dir_fd != -1) {
 57 5345b4c7 2021-07-06 stsp 			(*lf)->fd = openat(dir_fd, (*lf)->path,
 58 e7ae0baf 2021-12-31 stsp 			    O_RDONLY | O_CREAT | O_EXCL | O_EXLOCK | O_CLOEXEC,
 59 5345b4c7 2021-07-06 stsp 			    GOT_DEFAULT_FILE_MODE);
 60 5345b4c7 2021-07-06 stsp 		} else {
 61 5345b4c7 2021-07-06 stsp 			(*lf)->fd = open((*lf)->path,
 62 8bd0cdad 2021-12-31 stsp 			    O_RDONLY | O_CREAT | O_EXCL | O_EXLOCK | O_CLOEXEC,
 63 5345b4c7 2021-07-06 stsp 			    GOT_DEFAULT_FILE_MODE);
 64 5345b4c7 2021-07-06 stsp 		}
 65 c789dbac 2019-03-11 stsp 		if ((*lf)->fd != -1)
 66 c789dbac 2019-03-11 stsp 			break;
 67 c789dbac 2019-03-11 stsp 		if (errno != EEXIST) {
 68 638f9024 2019-05-13 stsp 			err = got_error_from_errno2("open", (*lf)->path);
 69 c789dbac 2019-03-11 stsp 			goto done;
 70 01b7ba6b 2019-03-11 stsp 		}
 71 c789dbac 2019-03-11 stsp 		sleep(1);
 72 01b7ba6b 2019-03-11 stsp 	} while (--attempts > 0);
 73 01b7ba6b 2019-03-11 stsp 
 74 01b7ba6b 2019-03-11 stsp 	if ((*lf)->fd == -1)
 75 01b7ba6b 2019-03-11 stsp 		err = got_error(GOT_ERR_LOCKFILE_TIMEOUT);
 76 01b7ba6b 2019-03-11 stsp done:
 77 01b7ba6b 2019-03-11 stsp 	if (err) {
 78 5345b4c7 2021-07-06 stsp 		got_lockfile_unlock(*lf, dir_fd);
 79 01b7ba6b 2019-03-11 stsp 		*lf = NULL;
 80 01b7ba6b 2019-03-11 stsp 	}
 81 01b7ba6b 2019-03-11 stsp 	return err;
 82 01b7ba6b 2019-03-11 stsp }
 83 01b7ba6b 2019-03-11 stsp 
 84 01b7ba6b 2019-03-11 stsp const struct got_error *
 85 5345b4c7 2021-07-06 stsp got_lockfile_unlock(struct got_lockfile *lf, int dir_fd)
 86 01b7ba6b 2019-03-11 stsp {
 87 01b7ba6b 2019-03-11 stsp 	const struct got_error *err = NULL;
 88 01b7ba6b 2019-03-11 stsp 
 89 5345b4c7 2021-07-06 stsp 	if (dir_fd != -1) {
 90 5345b4c7 2021-07-06 stsp 		if (lf->path && lf->fd != -1 &&
 91 5345b4c7 2021-07-06 stsp 		    unlinkat(dir_fd, lf->path, 0) != 0)
 92 5345b4c7 2021-07-06 stsp 			err = got_error_from_errno("unlinkat");
 93 5345b4c7 2021-07-06 stsp 	} else if (lf->path && lf->fd != -1 && unlink(lf->path) != 0)
 94 638f9024 2019-05-13 stsp 		err = got_error_from_errno("unlink");
 95 08578a35 2021-01-22 stsp 	if (lf->fd != -1 && close(lf->fd) == -1 && err == NULL)
 96 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");
 97 01b7ba6b 2019-03-11 stsp 	free(lf->path);
 98 01b7ba6b 2019-03-11 stsp 	free(lf->locked_path);
 99 01b7ba6b 2019-03-11 stsp 	free(lf);
100 01b7ba6b 2019-03-11 stsp 	return err;
101 01b7ba6b 2019-03-11 stsp }