Free our message handlers on exit with an atexit function

When setting custom message handlers, we allocate memory and stash
it in a static variable.  For easier valgrind analysis, free that
memory on process exit with an atexit function.

Change-Id: I0a49ebce5a955a7395697e00a53fadafaf1f8293
Reviewed-on: https://gerrit.stanford.edu/1403
Reviewed-by: Russ Allbery <rra@stanford.edu>
Tested-by: Russ Allbery <rra@stanford.edu>

1 files changed, 32 insertions, 0 deletions

diff --git a/util/messages.c b/util/messages.c
index 769166f..c08e222 100644
--- a/util/messages.c
+++ b/util/messages.c
@@ -113,6 +113,9 @@ static message_handler_func *notice_handlers = stdout_handlers;
 static message_handler_func *warn_handlers   = stderr_handlers;
 static message_handler_func *die_handlers    = stderr_handlers;
 
+/* Whether our atexit handler to free the logging functions is registered. */
+static bool free_handlers_registered = false;
+
 /* If non-NULL, called before exit and its return value passed to exit. */
 int (*message_fatal_cleanup)(void) = NULL;
 
@@ -121,6 +124,31 @@ const char *message_program_name = NULL;
 
 
 /*
+ * Free all of the handlers and set them back to the defaults.  Normally, this
+ * is only called on exit.  Doing that isn't necessary, but it frees reachable
+ * memory and allows for comprehensive memory allocation analysis.
+ */
+static void
+message_handlers_free(void)
+{
+    free(debug_handlers);
+    debug_handlers = NULL;
+    if (notice_handlers != stdout_handlers) {
+        free(notice_handlers);
+        notice_handlers = stdout_handlers;
+    }
+    if (warn_handlers != stderr_handlers) {
+        free(warn_handlers);
+        warn_handlers = stderr_handlers;
+    }
+    if (die_handlers != stderr_handlers) {
+        free(die_handlers);
+        die_handlers = stderr_handlers;
+    }
+}
+
+
+/*
  * Set the handlers for a particular message function.  Takes a pointer to the
  * handler list, the count of handlers, and the argument list.
  */
@@ -135,6 +163,10 @@ message_handlers(message_handler_func **list, unsigned int count, va_list args)
     for (i = 0; i < count; i++)
         (*list)[i] = (message_handler_func) va_arg(args, message_handler_func);
     (*list)[count] = NULL;
+    if (!free_handlers_registered) {
+        atexit(message_handlers_free);
+        free_handlers_registered = true;
+    }
 }