logging: Notify parent when logging daemon is up

Messages are lost until it is really up because syslogd_is_started is
set too early.  Adding a pipe to do the notification allows the parent
to wait and only set syslogd_is_started when the logging daemon is
actually ready.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Pair-programmed-with: Amitay Isaacs <amitay@gmail.com>

diff --git a/server/ctdb_logging.c b/server/ctdb_logging.c
index 0b6ac12f7f670d5c5bbaa6ce4c0b0369baae926e..44f0da75225fe307ff30549f1f1ace10aeb705f4 100644 (file)
--- a/server/ctdb_logging.c
+++ b/server/ctdb_logging.c
@@ -85,6 +85,8 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
        struct sockaddr_in syslog_sin;
        struct ctdb_syslog_state *state;
        struct tevent_fd *fde;
+       int startup_fd[2];
+       int ret = -1;
 
        state = talloc(ctdb, struct ctdb_syslog_state);
        CTDB_NO_MEMORY(ctdb, state);
@@ -95,23 +97,42 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
                return -1;
        }
        
+       if (pipe(startup_fd) != 0) {
+               printf("Failed to create syslog startup pipe\n");
+               close(state->fd[0]);
+               close(state->fd[1]);
+               talloc_free(state);
+               return -1;
+       }
+       
        ctdb->syslogd_pid = ctdb_fork(ctdb);
        if (ctdb->syslogd_pid == (pid_t)-1) {
                printf("Failed to create syslog child process\n");
                close(state->fd[0]);
                close(state->fd[1]);
+               close(startup_fd[0]);
+               close(startup_fd[1]);
                talloc_free(state);
                return -1;
        }
 
-       syslogd_is_started = 1;
-
        if (ctdb->syslogd_pid != 0) {
+               ssize_t n;
+               int dummy;
+
                DEBUG(DEBUG_ERR,("Starting SYSLOG child process with pid:%d\n", (int)ctdb->syslogd_pid));
 
                close(state->fd[1]);
                set_close_on_exec(state->fd[0]);
 
+               close(startup_fd[1]);
+               n = read(startup_fd[0], &dummy, sizeof(dummy));
+               close(startup_fd[0]);
+               if (n < sizeof(dummy)) {
+                       return -1;
+               }
+
+               syslogd_is_started = 1;
                return 0;
        }
 
@@ -122,7 +143,9 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
        syslog(LOG_ERR, "Starting SYSLOG daemon with pid:%d", (int)getpid());
 
        close(state->fd[0]);
+       close(startup_fd[0]);
        set_close_on_exec(state->fd[1]);
+       set_close_on_exec(startup_fd[1]);
        fde = event_add_fd(ctdb->ev, state, state->fd[1], EVENT_FD_READ,
                     ctdb_syslog_terminate_handler, state);
        tevent_fd_set_auto_close(fde);
@@ -130,7 +153,8 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
        state->syslog_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        if (state->syslog_fd == -1) {
                printf("Failed to create syslog socket\n");
-               return -1;
+               close(startup_fd[1]);
+               return ret;
        }
 
        set_close_on_exec(state->syslog_fd);
@@ -142,11 +166,8 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
        if (bind(state->syslog_fd, (struct sockaddr *)&syslog_sin,
                 sizeof(syslog_sin)) == -1)
        {
-               if (errno == EADDRINUSE) {
-                       /* this is ok, we already have a syslog daemon */
-                       _exit(0);
-               }
                printf("syslog daemon failed to bind to socket. errno:%d(%s)\n", errno, strerror(errno));
+               close(startup_fd[1]);
                _exit(10);
        }
 
@@ -155,6 +176,11 @@ int start_syslog_daemon(struct ctdb_context *ctdb)
                     ctdb_syslog_handler, state);
        tevent_fd_set_auto_close(fde);
 
+       /* Tell parent that we're up */
+       ret = 0;
+       write(startup_fd[1], &ret, sizeof(ret));
+       close(startup_fd[1]);
+
        event_loop_wait(ctdb->ev);
 
        /* this should not happen */