dedup

deduplicating backup program
git clone git://git.2f30.org/dedup.git
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lock.c (686B)


      1 #include <fcntl.h>
      2 #include <limits.h>
      3 #include <stdio.h>
      4 #include <unistd.h>
      5 
      6 int
      7 lockrepo(char *repo)
      8 {
      9 	char path[PATH_MAX];
     10 	struct flock fl;
     11 	int fd;
     12 
     13 	if (snprintf(path, sizeof(path), "%s/lock", repo) >=
     14 	    sizeof(path))
     15 		return -1;
     16 
     17 	fd = open(path, O_RDWR | O_CREAT, 0600);
     18 	if (fd < 0)
     19 		return -1;
     20 	fl.l_type = F_WRLCK;
     21 	fl.l_whence = SEEK_SET;
     22 	fl.l_start = 0;
     23 	fl.l_len = 0;
     24 	if (fcntl(fd, F_SETLK, &fl) < 0) {
     25 		close(fd);
     26 		return -1;
     27 	}
     28 	return fd;
     29 }
     30 
     31 int
     32 unlockrepo(int fd)
     33 {
     34 	struct flock fl;
     35 
     36 	fl.l_type = F_UNLCK;
     37 	fl.l_whence = SEEK_SET;
     38 	fl.l_start = 0;
     39 	fl.l_len = 0;
     40 	if (fcntl(fd, F_SETLK, &fl) < 0)
     41 		return -1;
     42 	if (close(fd) < 0)
     43 		return -1;
     44 	return 0;
     45 }