diff options
| -rw-r--r-- | udevd.c | 39 |
1 files changed, 39 insertions, 0 deletions
@@ -32,6 +32,7 @@ #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <fcntl.h> #include "udev.h" #include "udevd.h" @@ -157,6 +158,9 @@ static void add_queue(struct hotplug_msg *pmsg) dump_queue(); } +static int lock_file = -1; +static char *lock_filename = ".udevd_lock"; + static int process_queue(void) { int msgid; @@ -203,6 +207,10 @@ static int process_queue(void) expect_seqnum = head->seqnum; } else { info("we have nothing to do, so daemon exits..."); + if (lock_file >= 0) { + close(lock_file); + unlink(lock_filename); + } exit(0); } check_queue(); @@ -221,6 +229,10 @@ static void sig_handler(int signum) case SIGINT: case SIGTERM: case SIGKILL: + if (lock_file >= 0) { + close(lock_file); + unlink(lock_filename); + } exit(20 + signum); break; @@ -229,8 +241,35 @@ static void sig_handler(int signum) } } +static int one_and_only(void) +{ + char string[100]; + + lock_file = open(lock_filename, O_RDWR | O_CREAT, 0x640); + + /* see if we can open */ + if (lock_file < 0) + return -EINVAL; + + /* see if we can lock */ + if (lockf(lock_file, F_TLOCK, 0) < 0) { + close(lock_file); + unlink(lock_filename); + return -EINVAL; + } + + snprintf(string, sizeof(string), "%d\n", getpid()); + write(lock_file, string, strlen(string)); + + return 0; +} + int main(int argc, char *argv[]) { + /* only let one version of the daemon run at any one time */ + if (one_and_only() != 0) + exit(0); + /* set up signal handler */ signal(SIGINT, sig_handler); signal(SIGTERM, sig_handler); |