sbase/flock.c

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1.2 KiB
C
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/* See LICENSE file for copyright and license details. */
#include <sys/file.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include "util.h"
static void
usage(void)
{
eprintf("usage: %s [-nsux] file cmd [arg ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
int fd, status, savederrno, flags = LOCK_EX, nonblk = 0;
pid_t pid;
ARGBEGIN {
case 'n':
nonblk = LOCK_NB;
break;
case 's':
flags = LOCK_SH;
break;
case 'u':
flags = LOCK_UN;
break;
case 'x':
flags = LOCK_EX;
break;
default:
usage();
} ARGEND;
if (argc < 2)
usage();
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if ((fd = open(*argv, O_RDONLY | O_CREAT, 0644)) < 0)
eprintf("open %s:", *argv);
if (flock(fd, flags | nonblk)) {
if (nonblk && errno == EWOULDBLOCK)
return 1;
eprintf("flock:");
}
switch ((pid = fork())) {
case -1:
eprintf("fork:");
case 0:
argv++;
execvp(*argv, argv);
savederrno = errno;
weprintf("execvp %s:", *argv);
_exit(126 + (savederrno == ENOENT));
default:
break;
}
waitpid(pid, &status, 0);
if (WIFSIGNALED(status))
return 128 + WTERMSIG(status);
if (WIFEXITED(status))
return WEXITSTATUS(status);
if (close(fd) < 0)
eprintf("close:");
return 0;
}