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Try to lock a PID file

This commit is contained in:
Přemysl Eric Janouch 2015-03-11 23:56:25 +01:00
parent 012a57b357
commit 4337038819
1 changed files with 51 additions and 4 deletions
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55
demo-json-rpc-server.c
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@ -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);