[PATCH] util, passt: Close daemon-lifetime fds on exit to avoid Coverity warning

[Jon Maloy <jmaloy@redhat.com>]

conf_open_files() opens four file descriptors (fd_tap_listen,
fd_repair_listen, pidfile_fd, fd_control_listen) that are held for
the entire daemon lifetime.  Because no close() call exists for them
anywhere, Coverity flags each as INCOMPLETE_DEALLOCATOR. This is
clearly a false positive, but we still want to get rid of this
warning.

We now register the execution context so that passt_exit() can use
to close these descriptors before calling _exit().  All exit paths
(signal handler, die(), die_perror()) funnel through passt_exit(),
so this covers all cases.

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 log.h   |  2 ++
 passt.c |  1 +
 util.c  | 22 ++++++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/log.h b/log.h
index 69cfb507..079f429c 100644
--- a/log.h
+++ b/log.h
@@ -63,7 +63,9 @@ extern bool debug_flag;
 /* This would make more sense in util.h, but because we use it in die(), that
  * would cause awkward circular reference problems.
  */
+struct ctx;
 void passt_exit(int status) __attribute__((noreturn));
+void passt_exit_set_ctx(struct ctx *c);
 
 #define LOGFILE_SIZE_DEFAULT		(1024 * 1024UL)
 #define LOGFILE_CUT_RATIO		30	/* When full, cut ~30% size */
diff --git a/passt.c b/passt.c
index b6fc12d4..ec6aa57a 100644
--- a/passt.c
+++ b/passt.c
@@ -392,6 +392,7 @@ int main(int argc, char **argv)
 	sock_probe_features(&c);
 
 	conf(&c, argc, argv);
+	passt_exit_set_ctx(&c);
 	trace_init(c.trace);
 
 	pasta_netns_quit_init(&c);
diff --git a/util.c b/util.c
index b64c29ed..f15b1f9a 100644
--- a/util.c
+++ b/util.c
@@ -1097,6 +1097,17 @@ void abort_with_msg(const char *fmt, ...)
 	abort();
 }
 
+static struct ctx *exit_cleanup_ctx;
+
+/**
+ * passt_exit_set_ctx() - Register context for cleanup on exit
+ * @c:		Execution context
+ */
+void passt_exit_set_ctx(struct ctx *c)
+{
+	exit_cleanup_ctx = c;
+}
+
 /**
  * passt_exit() - Perform vital cleanup and exit
  *
@@ -1108,6 +1119,17 @@ void abort_with_msg(const char *fmt, ...)
  */
 void passt_exit(int status)
 {
+	if (exit_cleanup_ctx) {
+		if (exit_cleanup_ctx->fd_tap_listen >= 0)
+			close(exit_cleanup_ctx->fd_tap_listen);
+		if (exit_cleanup_ctx->fd_repair_listen >= 0)
+			close(exit_cleanup_ctx->fd_repair_listen);
+		if (exit_cleanup_ctx->pidfile_fd >= 0)
+			close(exit_cleanup_ctx->pidfile_fd);
+		if (exit_cleanup_ctx->fd_control_listen >= 0)
+			close(exit_cleanup_ctx->fd_control_listen);
+	}
+
 	/* Make sure we don't leave the pcap file truncated */
 	if (pcap_fd != -1 && fsync(pcap_fd))
 		warn_perror("Failed to flush pcap file, it might be truncated");
-- 
2.52.0