Improved systemd socket activation support

Support for multiple unix sockets and activation in forking mode

Signed-off-by: Marius Tomaschewski <mt@suse.de>

2 files changed, 81 insertions, 47 deletions

diff --git a/plugins/imuxsock/imuxsock.c b/plugins/imuxsock/imuxsock.c
index 0eee1122..e456a113 100644
--- a/plugins/imuxsock/imuxsock.c
+++ b/plugins/imuxsock/imuxsock.c
@@ -143,7 +143,7 @@ static int startIndexUxLocalSockets; /* process fd from that index on (used to
 				   * read-only after startup
 				   */
 static int nfd = 1; /* number of Unix sockets open / read-only after startup */
-static int bSysSockFromSystemd = 0;	/* Did we receive the system socket from systemd? */
+static int sd_fds = 0;			/* number of systemd activated sockets */
 
 /* config settings */
 static int bOmitLocalLogging = 0;
@@ -372,41 +372,32 @@ openLogSocket(lstn_t *pLstn)
 	if(pLstn->sockName[0] == '\0')
 		return -1;
 
-       if (ustrcmp(pLstn->sockName, UCHAR_CONSTANT(_PATH_LOG)) == 0) {
-	       bSysSockFromSystemd = 0; /* set default */
-               int r;
-
-               /* System log socket code. Check whether an FD was passed in from systemd. If
-                * so, it's the /dev/log socket, so use it. */
-
-               r = sd_listen_fds(0);
-               if (r < 0) {
-                       errmsg.LogError(-r, NO_ERRCODE, "Failed to acquire systemd socket");
-			ABORT_FINALIZE(RS_RET_ERR_CRE_AFUX);
-               }
-
-               if (r > 1) {
-                       errmsg.LogError(EINVAL, NO_ERRCODE, "Wrong number of systemd sockets passed");
-			ABORT_FINALIZE(RS_RET_ERR_CRE_AFUX);
-               }
-
-               if (r == 1) {
-                       pLstn->fd = SD_LISTEN_FDS_START;
-                       r = sd_is_socket_unix(pLstn->fd, SOCK_DGRAM, -1, _PATH_LOG, 0);
-                       if (r < 0) {
-                               errmsg.LogError(-r, NO_ERRCODE, "Failed to verify systemd socket type");
-				ABORT_FINALIZE(RS_RET_ERR_CRE_AFUX);
-                       }
-
-                       if (!r) {
-                               errmsg.LogError(EINVAL, NO_ERRCODE, "Passed systemd socket of wrong type");
-				ABORT_FINALIZE(RS_RET_ERR_CRE_AFUX);
-                       }
-		       bSysSockFromSystemd = 1; /* indicate we got the socket from systemd */
-		} else {
-			CHKiRet(createLogSocket(pLstn));
+	pLstn->fd = -1;
+
+	if (sd_fds > 0) {
+               /* Check if the current socket is a systemd activated one.
+	        * If so, just use it.
+		*/
+		int fd;
+
+		for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + sd_fds; fd++) {
+			if( sd_is_socket_unix(fd, SOCK_DGRAM, -1, pLstn->sockName, 0) == 1) {
+				/* ok, it matches -- just use as is */
+				pLstn->fd = fd;
+
+				dbgprintf("imuxsock: Acquired UNIX socket '%s' (fd %d) from systemd.\n",
+					pLstn->sockName, pLstn->fd);
+				break;
+			}
+			/*
+			 * otherwise it either didn't matched *this* socket and
+			 * we just continue to check the next one or there were
+			 * an error and we will create a new socket bellow.
+			 */
 		}
-	} else {
+	}
+
+	if (pLstn->fd == -1) {
 		CHKiRet(createLogSocket(pLstn));
 	}
 
@@ -774,12 +765,18 @@ CODESTARTwillRun
 	listeners[0].bUseCreds = (bWritePidSysSock || ratelimitIntervalSysSock) ? 1 : 0;
 	listeners[0].bWritePid = bWritePidSysSock;
 
+	sd_fds = sd_listen_fds(0);
+	if (sd_fds < 0) {
+		errmsg.LogError(-r, NO_ERRCODE, "imuxsock: Failed to acquire systemd socket");
+		ABORT_FINALIZE(RS_RET_ERR_CRE_AFUX);
+	}
+
 	/* initialize and return if will run or not */
 	actSocks = 0;
 	for (i = startIndexUxLocalSockets ; i < nfd ; i++) {
 		if(openLogSocket(&(listeners[i])) == RS_RET_OK) {
 			++actSocks;
-			dbgprintf("Opened UNIX socket '%s' (fd %d).\n", listeners[i].sockName, listeners[i].fd);
+			dbgprintf("imuxsock: Opened UNIX socket '%s' (fd %d).\n", listeners[i].sockName, listeners[i].fd);
 		}
 	}
 
@@ -806,15 +803,19 @@ CODESTARTafterRun
 		if (listeners[i].fd != -1)
 			close(listeners[i].fd);
 
-       /* Clean-up files. If systemd passed us a socket it is
-        * systemd's job to clean it up.*/
-       if(bSysSockFromSystemd) {
-	       DBGPRINTF("imuxsock: got system socket from systemd, not unlinking it\n");
-               i = 1;
-       } else
-               i = startIndexUxLocalSockets;
-       for(; i < nfd; i++)
+       /* Clean-up files. */
+       for(i = startIndexUxLocalSockets; i < nfd; i++)
 		if (listeners[i].sockName && listeners[i].fd != -1) {
+
+			/* If systemd passed us a socket it is systemd's job to clean it up.
+			 * Do not unlink it -- we will get same socket (node) from systemd
+			 * e.g. on restart again.
+			 */
+			if (sd_fds > 0 &&
+			    listeners[i].fd >= SD_LISTEN_FDS_START &&
+			    listeners[i].fd <  SD_LISTEN_FDS_START + sd_fds)
+				continue;
+
 			DBGPRINTF("imuxsock: unlinking unix socket file[%d] %s\n", i, listeners[i].sockName);
 			unlink((char*) listeners[i].sockName);
 		}
diff --git a/tools/syslogd.c b/tools/syslogd.c
index 19a5900c..52c0be5f 100644
--- a/tools/syslogd.c
+++ b/tools/syslogd.c
@@ -2429,13 +2429,46 @@ doGlblProcessInit(void)
 				 */
 				exit(1); /* "good" exit - after forking, not diasabling anything */
 			}
+
 			num_fds = getdtablesize();
 			close(0);
 			/* we keep stdout and stderr open in case we have to emit something */
+			i = 3;
+
+			/* if (sd_booted()) */ {
+				const char *e;
+				char buf[24] = { '\0' };
+				char *p = NULL;
+				unsigned long l;
+				int fds;
+
+				/* fork & systemd socket activation:
+				 * fetch listen pid and update to ours,
+				 * when it is set to pid of our parent.
+				 */
+				if ( (e = getenv("LISTEN_PID"))) {
+					errno = 0;
+					l = strtoul(e, &p, 10);
+					if (errno ==  0 && l > 0 && (!p || !*p)) {
+						if (getppid() == (pid_t)l) {
+							snprintf(buf, sizeof(buf), "%d",
+								 getpid());
+							setenv("LISTEN_PID", buf, 1);
+						}
+					}
+				}
+
+				/*
+				 * close only all further fds, except
+				 * of the fds provided by systemd.
+				 */
+				sd_fds = sd_listen_fds(0);
+				if (sd_fds > 0)
+					i = SD_LISTEN_FDS_START + sd_fds;
+			}
+			for ( ; i < num_fds; i++)
+				(void) close(i);
 
-                       if (sd_listen_fds(0) <= 0)
-                               for (i = 3; i < num_fds; i++)
-                                       (void) close(i);
 			untty();
 		} else {
 			fputs(" Already running. If you want to run multiple instances, you need "