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-rw-r--r--demo-json-rpc-server.c55
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);