diff options
Diffstat (limited to 'src/daemon.c')
| -rw-r--r-- | src/daemon.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/src/daemon.c b/src/daemon.c index 88ce785..596b863 100644 --- a/src/daemon.c +++ b/src/daemon.c @@ -224,6 +224,57 @@ void drop_privileges(void) #endif } +void write_pid_file(void) +{ + FILE* fp; + int fd, flags; + struct flock lock; + + if (!options.pid_file) + return; + + if ((fd = open(options.pid_file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR)) == -1) { + fprintf(stderr, "unable to open PID file %s: %s", options.pid_file, strerror(errno)); + exit(1); + } + + if ((flags = fcntl(fd, F_GETFD)) == -1) { + fprintf(stderr, "unable to get PID file flags: %s", strerror(errno)); + exit(1); + } + flags |= FD_CLOEXEC; + if (fcntl(fd, F_SETFD, flags) == 1) { + fprintf(stderr, "unable to set PID file flags: %s", strerror(errno)); + exit(1); + } + + lock.l_type = F_WRLCK; + lock.l_whence = SEEK_SET; + lock.l_start = 0; + lock.l_len = 0; + + if (fcntl(fd, F_SETLK, &lock) == -1) { + if (errno == EACCES || errno == EAGAIN) { + fprintf(stderr, "PID file locked by other process"); + exit(1); + } + + fprintf(stderr, "unable to lock PID file: %s", strerror(errno)); + exit(1); + } + + if (ftruncate(fd, 0) == -1) { + fprintf(stderr, "unable to truncate PID file: %s", strerror(errno)); + exit(1); + } + + fp = fdopen(fd, "w"); + if (!fp || fprintf(fp, "%d\n", getpid()) < 1 || fflush(fp)) { + fprintf(stderr, "unable to write to PID file: %s", strerror(errno)); + exit(1); + } +} + void daemonize(void) { pid_t pid; @@ -235,6 +286,7 @@ void daemonize(void) exit(1); } else if (pid > 0) exit(0); + write_pid_file(); openlog("dnscap", 0, LOG_DAEMON); if (setsid() < 0) { logerr("setsid failed: %s", strerror(errno)); |