From e93f19fb66c491f36e9579ccb83517c1e77a9a29 Mon Sep 17 00:00:00 2001
From: Quentin Young <qlyoung@cumulusnetworks.com>
Date: Sun, 11 Aug 2019 19:44:04 +0000
Subject: [PATCH] lib: add Lua stack dumper

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
---
 lib/frrlua.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/frrlua.h |  7 +++++++
 2 files changed, 53 insertions(+)

diff --git a/lib/frrlua.c b/lib/frrlua.c
index 252b667961..15fda79201 100644
--- a/lib/frrlua.c
+++ b/lib/frrlua.c
@@ -25,6 +25,7 @@
 #include "prefix.h"
 #include "frrlua.h"
 #include "log.h"
+#include "buffer.h"
 
 /*
  * FRR convenience functions.
@@ -170,4 +171,49 @@ void frrlua_export_logging(lua_State *L)
 	lua_setfield(L, -2, "log");
 }
 
+/*
+ * Debugging.
+ */
+
+char *frrlua_stackdump(lua_State *L)
+{
+	int top = lua_gettop(L);
+
+	char tmpbuf[64];
+	struct buffer *buf = buffer_new(4098);
+
+	for (int i = 1; i <= top; i++) {
+		int t = lua_type(L, i);
+
+		switch (t) {
+		case LUA_TSTRING: /* strings */
+			snprintf(tmpbuf, sizeof(tmpbuf), "\"%s\"\n",
+				 lua_tostring(L, i));
+			buffer_putstr(buf, tmpbuf);
+			break;
+		case LUA_TBOOLEAN: /* booleans */
+			snprintf(tmpbuf, sizeof(tmpbuf), "%s\n",
+				 lua_toboolean(L, i) ? "true" : "false");
+			buffer_putstr(buf, tmpbuf);
+			break;
+		case LUA_TNUMBER: /* numbers */
+			snprintf(tmpbuf, sizeof(tmpbuf), "%g\n",
+				 lua_tonumber(L, i));
+			buffer_putstr(buf, tmpbuf);
+			break;
+		default: /* other values */
+			snprintf(tmpbuf, sizeof(tmpbuf), "%s\n",
+				 lua_typename(L, t));
+			buffer_putstr(buf, tmpbuf);
+			break;
+		}
+	}
+
+	char *result = XSTRDUP(MTYPE_TMP, buffer_getstr(buf));
+
+	buffer_free(buf);
+
+	return result;
+}
+
 #endif
diff --git a/lib/frrlua.h b/lib/frrlua.h
index f77842b445..bc017b6441 100644
--- a/lib/frrlua.h
+++ b/lib/frrlua.h
@@ -74,6 +74,13 @@ int frrlua_table_get_integer(lua_State *L, const char *key);
  */
 void frrlua_export_logging(lua_State *L);
 
+/*
+ * Dump Lua stack to a string.
+ *
+ * Return value must be freed with XFREE(MTYPE_TMP, ...);
+ */
+char *frrlua_stackdump(lua_State *L);
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.39.5