diff options
| -rw-r--r-- | demo-json-rpc-server.c | 55 |
1 files changed, 51 insertions, 4 deletions
diff --git a/demo-json-rpc-server.c b/demo-json-rpc-server.c index 1eebe4d..1b10e9d 100644 --- a/demo-json-rpc-server.c +++ b/demo-json-rpc-server.c @@ -1496,6 +1496,7 @@ static struct config_item g_config_table[] = { "port_fastcgi", "9000", "Port to bind for FastCGI" }, { "port_scgi", NULL, "Port to bind for SCGI" }, { "port_ws", NULL, "Port to bind for WebSockets" }, + { "pid_file", NULL, "Full path for the PID file" }, { "static_root", NULL, "The root for static content" }, { NULL, NULL, NULL } }; @@ -2668,6 +2669,51 @@ setup_listen_fds (struct server_context *ctx, struct error **e) return true; } +static bool +lock_pid_file (struct server_context *ctx, struct error **e) +{ + const char *path = str_map_find (&ctx->config, "pid_file"); + if (!path) + return true; + + int fd = open (path, O_RDWR | O_CREAT, + S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH /* 644 */); + if (fd < 0) + { + error_set (e, "can't open `%s': %s", path, strerror (errno)); + return false; + } + + struct flock lock = + { + .l_type = F_WRLCK, + .l_start = 0, + .l_whence = SEEK_SET, + .l_len = 0, + }; + if (fcntl (fd, F_SETLK, &lock)) + { + error_set (e, "can't lock `%s': %s", path, strerror (errno)); + return false; + } + + struct str pid; + str_init (&pid); + str_append_printf (&pid, "%ld", (long) getpid ()); + + if (ftruncate (fd, 0) + || write (fd, pid.str, pid.len) != (ssize_t) pid.len) + { + error_set (e, "can't write to `%s': %s", path, strerror (errno)); + return false; + } + str_free (&pid); + + // Intentionally not closing the file descriptor; it must stay alive + // for the entire life of the application + return true; +} + // --- Main program ------------------------------------------------------------ static void @@ -2683,9 +2729,6 @@ on_termination_signal (EV_P_ ev_signal *handle, int revents) static void daemonize (void) { - // TODO: create and lock a PID file? - // TODO: add the path for the PID file into "struct server_context", - // see the UNIX bible for more details on how to proceed. print_status ("daemonizing..."); if (chdir ("/")) @@ -2708,7 +2751,10 @@ daemonize (void) openlog (PROGRAM_NAME, LOG_NDELAY | LOG_NOWAIT | LOG_PID, 0); g_log_message_real = log_message_syslog; - // XXX: we may close our own descriptors this way, crippling ourselves + // XXX: we may close our own descriptors this way, crippling ourselves; + // there is no real guarantee that we will start with all three + // descriptors open. In theory we could try to enumerate the descriptors + // at the start of main(). for (int i = 0; i < 3; i++) xclose (i); @@ -2803,6 +2849,7 @@ main (int argc, char *argv[]) LIST_PREPEND (ctx.handlers, &g_request_handler_json_rpc); if (!parse_config (&ctx, &e) + || !lock_pid_file (&ctx, &e) || !setup_listen_fds (&ctx, &e)) { print_error ("%s", e->message); |