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	flock.c - sbase - suckless unix tools
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	---
	flock.c (1358B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <sys/file.h>
	3 #include <sys/wait.h>
	4
	5 #include <errno.h>
	6 #include <fcntl.h>
	7 #include <stdio.h>
	8 #include <unistd.h>
	9
	10 #include "util.h"
	11
	12 static void
	13 usage(void)
	14 {
	15 eprintf("usage: %s [-nosux] file cmd [arg ...]\n", argv0);
	16 }
	17
	18 int
	19 main(int argc, char *argv[])
	20 {
	21 int fd, status, savederrno, flags = LOCK_EX, nonblk = 0, oflag =…
	22 pid_t pid;
	23
	24 ARGBEGIN {
	25 case 'n':
	26 nonblk = LOCK_NB;
	27 break;
	28 case 'o':
	29 oflag = 1;
	30 break;
	31 case 's':
	32 flags = LOCK_SH;
	33 break;
	34 case 'u':
	35 flags = LOCK_UN;
	36 break;
	37 case 'x':
	38 flags = LOCK_EX;
	39 break;
	40 default:
	41 usage();
	42 } ARGEND
	43
	44 if (argc < 2)
	45 usage();
	46
	47 if ((fd = open(*argv, O_RDONLY \| O_CREAT, 0644)) < 0)
	48 eprintf("open %s:", *argv);
	49
	50 if (flock(fd, flags \| nonblk)) {
	51 if (nonblk && errno == EWOULDBLOCK)
	52 return 1;
	53 eprintf("flock:");
	54 }
	55
	56 switch ((pid = fork())) {
	57 case -1:
	58 eprintf("fork:");
	59 case 0:
	60 if (oflag && close(fd) < 0)
	61 eprintf("close:");
	62 argv++;
	63 execvp(*argv, argv);
	64 savederrno = errno;
	65 weprintf("execvp %s:", *argv);
	66 _exit(126 + (savederrno == ENOENT));
	67 default:
	68 break;
	69 }
	70 if (waitpid(pid, &status, 0) < 0)
	71 eprintf("waitpid:");
	72
	73 if (close(fd) < 0)
	74 eprintf("close:");
	75
	76 if (WIFSIGNALED(status))
	77 return 128 + WTERMSIG(status);
	78 if (WIFEXITED(status))
	79 return WEXITSTATUS(status);
	80
	81 return 0;
	82 }