Fix a memory leak caused by repeatedly allocating the libbacktrace state at every printed backtrace

Signed-off-by: Haru <haru@dotalux.com>

3 files changed, 32 insertions, 11 deletions

diff --git a/src/common/core.c b/src/common/core.c
index 54358b85c..5be90a411 100644
--- a/src/common/core.c
+++ b/src/common/core.c
@@ -489,6 +489,7 @@ int main(int argc, char **argv)
 
 	iMalloc->init();// needed for Show* in display_title() [FlavioJS]
 	showmsg->init();
+	nullpo->init();
 
 	cmdline->init();
 
@@ -552,6 +553,7 @@ int main(int argc, char **argv)
 	cmdline->final();
 	//sysinfo->final(); Called by iMalloc->final()
 
+	nullpo->final();
 	iMalloc->final();
 	showmsg->final(); // Should be after iMalloc->final()
 
diff --git a/src/common/nullpo.c b/src/common/nullpo.c
index e43b91bb8..d28d7ee4b 100644
--- a/src/common/nullpo.c
+++ b/src/common/nullpo.c
@@ -74,12 +74,6 @@ static void nullpo_backtrace_print(struct backtrace_state *state)
  */
 static void assert_report(const char *file, int line, const char *func, const char *targetname, const char *title)
 {
-#if !defined(HAVE_LIBBACKTRACE) && defined(HAVE_EXECINFO)
-	void *array[10];
-	int size;
-	char **strings;
-	int i;
-#endif // !defined(HAVE_LIBBACKTRACE) && defined(HAVE_EXECINFO)
 	if (file == NULL)
 		file = "??";
 
@@ -89,17 +83,31 @@ static void assert_report(const char *file, int line, const char *func, const ch
 	ShowError("--- %s --------------------------------------------\n", title);
 	ShowError("%s:%d: '%s' in function `%s'\n", file, line, targetname, func);
 #ifdef HAVE_LIBBACKTRACE
-	struct backtrace_state *state = backtrace_create_state("hercules", BACKTRACE_SUPPORTS_THREADS, nullpo_error_callback, NULL);
-	nullpo_backtrace_print(state);
+	if (nullpo->backtrace_state != NULL)
+		nullpo_backtrace_print(nullpo->backtrace_state);
 #elif defined(HAVE_EXECINFO)
-	size = (int)backtrace(array, 10);
-	strings = backtrace_symbols(array, size);
-	for (i = 0; i < size; i++)
+	void *array[10];
+	int size = (int)backtrace(array, 10);
+	char **strings = backtrace_symbols(array, size);
+	for (int i = 0; i < size; i++)
 		ShowError("%s\n", strings[i]);
 	free(strings);
 #endif // HAVE_LIBBACKTRACE
 	ShowError("--- end %s ----------------------------------------\n", title);
+}
 
+static void nullpo_init(void)
+{
+#ifdef HAVE_LIBBACKTRACE
+	nullpo->backtrace_state = backtrace_create_state("hercules", BACKTRACE_SUPPORTS_THREADS, nullpo_error_callback, NULL);
+#endif
+}
+
+static void nullpo_final(void)
+{
+	// FIXME: libbacktrace doesn't provide a backtrace_free_state, and it's unsafe to pass the state to
+	// backtrace_free (the function itself uses the state internally). For the time being, we'll leave the state
+	// allocated until program termination as shown in their examples.
 }
 
 /**
@@ -108,5 +116,9 @@ static void assert_report(const char *file, int line, const char *func, const ch
 void nullpo_defaults(void)
 {
 	nullpo = &nullpo_s;
+	nullpo->init = nullpo_init;
+	nullpo->final = nullpo_final;
 	nullpo->assert_report = assert_report;
+
+	nullpo->backtrace_state = NULL;
 }
diff --git a/src/common/nullpo.h b/src/common/nullpo.h
index fc5386243..3eb002834 100644
--- a/src/common/nullpo.h
+++ b/src/common/nullpo.h
@@ -28,6 +28,8 @@
 // if need disable asserts checks this line can be commented
 #define ASSERT_CHECK
 
+struct backtrace_state;
+
 /** Assert */
 
 #if defined(ASSERT_CHECK)
@@ -148,7 +150,12 @@
 
 
 struct nullpo_interface {
+	void (*init) (void);
+	void (*final) (void);
+
 	void (*assert_report) (const char *file, int line, const char *func, const char *targetname, const char *title);
+
+	struct backtrace_state *backtrace_state;
 };
 
 #ifdef HERCULES_CORE