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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
void usage (void)
{
printf ("Usage: testlock <filepath> [R|W]\n");
return;
}
int main (int argc, char *argv[])
{
char *file_path = NULL;
int fd = -1;
struct flock lock = {0};
int ret = -1;
int c = 0;
if (argc != 3) {
usage ();
exit (1);
}
file_path = argv[1];
fd = open (file_path, O_RDWR);
if (-1 == fd) {
printf ("Failed to open file %s. %m\n", file_path);
exit (1);
}
/* TODO: Check for invalid input*/
if (!strcmp (argv[2], "W")) {
lock.l_type = F_WRLCK;
printf("Taking write lock\n");
} else {
lock.l_type = F_RDLCK;
printf("Taking read lock\n");
}
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
lock.l_pid = getpid ();
printf ("Acquiring lock on %s\n", file_path);
ret = fcntl (fd, F_SETLK, &lock);
if (ret) {
printf ("Failed to acquire lock on %s (%m)\n", file_path);
close (fd);
exit (1);
}
sleep(10);
/*Unlock*/
printf ("Releasing lock on %s\n", file_path);
lock.l_type = F_UNLCK;
ret = fcntl (fd, F_SETLK, &lock);
if (ret) {
printf ("Failed to release lock on %s (%m)\n", file_path);
}
close (fd);
return ret;
}
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