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#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/file.h>
#include "lock.h"
// Maximum path length for the lock file
#define MAX_PATH_SIZE 512
/**
* Calculate the path to use for the lock file and store it in
* path.
*
* Return false if no path could be determined.
*/
bool get_lockfile_path(char path[MAX_PATH_SIZE]) {
char *runtime_dir = getenv("XDG_RUNTIME_DIR");
if (!runtime_dir) {
// Use the /tmp directory if we couldn't get a normal runtime dir
runtime_dir = "/tmp";
}
char *display = getenv("WAYLAND_DISPLAY");
if (!display) {
fprintf(stderr, "No wayland session found\n");
return false;
}
if (snprintf(path, MAX_PATH_SIZE, "%s/slurp-%s.lock", runtime_dir, display) >= MAX_PATH_SIZE) {
fprintf(stderr, "lockfile path was too long\n");
return false;
}
return true;
}
bool acquire_lock() {
char lockfile[MAX_PATH_SIZE];
if (!get_lockfile_path(lockfile)) {
return false;
}
// Open the lock file for write, creating with user read/write if necessary
int fd = open(lockfile, O_WRONLY|O_CREAT, 00600);
if (fd == -1) {
fprintf(stderr, "failed to open lock file\n");
return false;
}
if (flock(fd, LOCK_EX|LOCK_NB)) {
fprintf(stderr, "another slurp process is running for this wayland session\n");
return false;
}
return true;
}
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