A simple command that wraps another command, locking a file first. It is similar to flock, just simpler.
#include <stddef.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/file.h>
#include <err.h>
#include <stdlib.h>
void attemptLock(const char *lockFileName)
{
int fd = open(lockFileName, O_CREAT | O_WRONLY, 0666);
if (!fd || flock(fd, LOCK_EX))
warn("Cannot lock %s", lockFileName);
}
int main(int argc, char *argv[])
{
if (argc < 3)
errx(EXIT_FAILURE, "Not enough arguments.\nUsage: %s LOCKFILENAME COMMAND...\n", argv[0]);
attemptLock(argv[1]);
argv += 2; // Skip our own command name and LOCKFILENAME.
execvp(argv[0], argv);
err(EXIT_FAILURE, "Cannot execute %s", argv[0]);
}
Anything fishy? Bogus? Wrong? Anything that can be improved (besides adding options like -h)?
