lib: rewrite zlog lock-free & TLS-buffered

This is a full rewrite of the "back end" logging code.  It now uses a
lock-free list to iterate over logging targets, and the targets
themselves are as lock-free as possible.  (syslog() may have a hidden
internal mutex in the C library;  the file/fd targets use a single
write() call which should ensure atomicity kernel-side.)

Note that some functionality is lost in this patch:
- Solaris printstack() backtraces are ditched (unlikely to come back)
- the `log-filter` machinery is gone (re-added in followup commit)
- `terminal monitor` is temporarily stubbed out.  The old code had a
  race condition with VTYs going away.  It'll likely come back rewritten
  and with vtysh support.
- The `zebra_ext_log` hook is gone.  Instead, it's now much easier to
  add a "proper" logging target.

v2: TLS buffer to get some actual performance

Signed-off-by: David Lamparter <equinox@diac24.net>

1 files changed, 15 insertions, 4 deletions

diff --git a/ldpd/ldpd.c b/ldpd/ldpd.c
index 0f9f055d02..818d744207 100644
--- a/ldpd/ldpd.c
+++ b/ldpd/ldpd.c
@@ -308,9 +308,15 @@ main(int argc, char *argv[])
 		exit(1);
 	}
 
-	if (lflag || eflag)
-		openzlog(ldpd_di.progname, "LDP", 0,
-		         LOG_CONS | LOG_NDELAY | LOG_PID, LOG_DAEMON);
+	if (lflag || eflag) {
+		struct zprivs_ids_t ids;
+
+		zprivs_preinit(&ldpd_privs);
+		zprivs_get_ids(&ids);
+
+		zlog_init(ldpd_di.progname, "LDP", 0,
+			  ids.uid_normal, ids.gid_normal);
+	}
 	if (lflag)
 		lde();
 	else if (eflag)
@@ -486,7 +492,7 @@ ldpd_shutdown(void)
 static pid_t
 start_child(enum ldpd_process p, char *argv0, int fd_async, int fd_sync)
 {
-	char	*argv[3];
+	char	*argv[7];
 	int	 argc = 0, nullfd;
 	pid_t	 pid;
 
@@ -529,6 +535,11 @@ start_child(enum ldpd_process p, char *argv0, int fd_async, int fd_sync)
 		argv[argc++] = (char *)"-E";
 		break;
 	}
+
+	argv[argc++] = (char *)"-u";
+	argv[argc++] = (char *)ldpd_privs.user;
+	argv[argc++] = (char *)"-g";
+	argv[argc++] = (char *)ldpd_privs.group;
 	argv[argc++] = NULL;
 
 	execvp(argv0, argv);