[syslog-ng] [PATCH 2/2] afsocket: Support a smooth upgrade path to recent systemd

[Gergely Nagy]

When the journal was introduced in systemd, it started to pass
/run/systemd/journal/syslog to syslogds (it was passing down /dev/log
before). Since we verify that the FD to open matches the expected
filename, we didn't pick up the fd due to the filename mismatch.

This can be fixed on the system() source level, where it can decide
which to generate into the config. However, for setups that do not use
system() for one reason or the other, this does not work.

For them, the best solution is to try and check the passed FDs with
/run/systemd/journal/syslog as the filename, so if all else fails, we
pick that up. This patch does just that.

Signed-off-by: Gergely Nagy <algernon at balabit.hu>
---
 modules/afsocket/afunix.c |   51 ++++++++++++++++++++++++++++++--------------
 1 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/modules/afsocket/afunix.c b/modules/afsocket/afunix.c
index 8145f1a..dff1efe 100644
--- a/modules/afsocket/afunix.c
+++ b/modules/afsocket/afunix.c
@@ -71,8 +71,9 @@ afunix_sd_set_perm(LogDriver *s, gint perm)
 }
 
 #if ENABLE_SYSTEMD
-static gboolean
-afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
+static gint
+afunix_sd_acquire_socket_with_fn(AFSocketSourceDriver *s, gint *result_fd,
+                                 const gchar *filename)
 {
   AFUnixSourceDriver *self = (AFUnixSourceDriver *) s;
   gint fd, fds;
@@ -82,7 +83,7 @@ afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
   fds = sd_listen_fds(0);
 
   if (fds == 0)
-    return TRUE;
+    return 1;
 
   msg_debug("Systemd socket activation",
 	    evt_tag_int("systemd-sockets", fds),
@@ -94,19 +95,19 @@ afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
     {
       msg_error("Failed to acquire systemd sockets, incorrectly set LISTEN_FDS environment variable?",
 		NULL);
-      return FALSE;
+      return -1;
     }
   else if (fds > 0)
     {
       for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + fds; fd++)
 	{
 	  /* check if any type is available */
-	  if (sd_is_socket_unix(fd, 0, -1, self->filename, 0))
+	  if (sd_is_socket_unix(fd, 0, -1, filename, 0))
 	    {
               int type = (self->super.flags & AFSOCKET_STREAM) ? SOCK_STREAM : SOCK_DGRAM;
 
 	      /* check if it matches our idea of the socket type */
-              if (sd_is_socket_unix(fd, type, -1, self->filename, 0))
+              if (sd_is_socket_unix(fd, type, -1, filename, 0))
                 {
                   *result_fd = fd;
                   break;
@@ -114,11 +115,11 @@ afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
               else
                 {
                   msg_error("The systemd supplied UNIX domain socket is of a different type, check the configured driver and the matching systemd unit file",
-		            evt_tag_str("filename", self->filename),
+		            evt_tag_str("filename", filename),
 		            evt_tag_int("systemd-sock-fd", fd),
                             evt_tag_str("expecting", type == SOCK_STREAM ? "unix-stream()" : "unix-dgram()"),
                             NULL);
-                  return FALSE;
+                  return -1;
                 }
             }
           else
@@ -130,31 +131,49 @@ afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
                */
 
               msg_debug("Ignoring systemd supplied fd as it is not a UNIX domain socket",
-		        evt_tag_str("filename", self->filename),
+		        evt_tag_str("filename", filename),
 		        evt_tag_int("systemd-sock-fd", fd),
 		        NULL);
             }
 	}
     }
   else
-    return TRUE;
+    return 1;
 
   if (*result_fd != -1)
     {
       g_fd_set_nonblock(*result_fd, TRUE);
       g_fd_set_cloexec(*result_fd, TRUE);
       msg_verbose("Acquired systemd socket",
-		  evt_tag_str("filename", self->filename),
+		  evt_tag_str("filename", filename),
 		  evt_tag_int("systemd-sock-fd", *result_fd),
 		  NULL);
+      return 1;
     }
-  else
+  msg_debug("Failed to acquire systemd socket, trying to open ourselves",
+	    evt_tag_str("filename", filename),
+            NULL);
+  return 0;
+}
+
+static gboolean
+afunix_sd_acquire_socket(AFSocketSourceDriver *s, gint *result_fd)
+{
+  AFUnixSourceDriver *self = (AFUnixSourceDriver *) s;
+  int status;
+
+  status = afunix_sd_acquire_socket_with_fn(s, result_fd, self->filename);
+  if (status == 0)
     {
-      msg_debug("Failed to acquire systemd socket, trying to open ourselves",
-		evt_tag_str("filename", self->filename),
-		NULL);
+      status = afunix_sd_acquire_socket_with_fn(s, result_fd, "/run/systemd/journal/syslog");
+      if (status == 1)
+        {
+          g_free(self->filename);
+          self->filename = g_strdup("/run/systemd/journal/syslog");
+          return TRUE;
+        }
     }
-  return TRUE;
+  return !!(status == 1);
 }
 
 #else
-- 
1.7.9.1