From 799c2881e1206d99f789e5466bfca48762471561 Mon Sep 17 00:00:00 2001
From: Paul Kulchenko <paul@kulchenko.com>
Date: Wed, 27 Apr 2022 20:37:55 -0700
Subject: [PATCH] Fix reporting of Lua stack items from various hook calls

Some hooks can be called after OnHttpRequest, which may leave an
anchored item on stack, so this have to be taken into account to
avoid spurious reports.
---
 tool/net/luacheck.h | 16 +++++++++-------
 tool/net/redbean.c  | 11 ++++++-----
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/tool/net/luacheck.h b/tool/net/luacheck.h
index c5506387a..b800e48f8 100644
--- a/tool/net/luacheck.h
+++ b/tool/net/luacheck.h
@@ -7,13 +7,15 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-#define AssertLuaStackIsEmpty(L)                  \
-  do {                                            \
-    if (lua_gettop(L)) {                          \
-      char *s = LuaFormatStack(L);                \
-      WARNF("lua stack should be empty!\n%s", s); \
-      free(s);                                    \
-    }                                             \
+#define AssertLuaStackIsAt(L, level)       \
+  do {                                     \
+    if (lua_gettop(L) > level) {           \
+      char *s = LuaFormatStack(L);         \
+      WARNF("lua stack should be at %d;"   \
+            " extra values ignored:\n%s",  \
+            level, s);                     \
+      free(s);                             \
+    }                                      \
   } while (0)
 
 COSMOPOLITAN_C_END_
diff --git a/tool/net/redbean.c b/tool/net/redbean.c
index 6af6e3eef..43b851a20 100644
--- a/tool/net/redbean.c
+++ b/tool/net/redbean.c
@@ -1071,7 +1071,7 @@ static bool LuaEvalCode(const char *code) {
     lua_pop(L, 1);  // pop error
     return false;
   }
-  AssertLuaStackIsEmpty(L);
+  AssertLuaStackIsAt(L, 0);
   return true;
 }
 
@@ -1099,7 +1099,7 @@ static bool LuaOnClientConnection(void) {
     dropit = false;
   }
   lua_pop(L, 1);  // pop result or error
-  AssertLuaStackIsEmpty(L);
+  AssertLuaStackIsAt(L, 0);
   return dropit;
 #else
   return false;
@@ -1123,7 +1123,7 @@ static void LuaOnProcessCreate(int pid) {
     LogLuaError("OnProcessCreate", lua_tostring(L, -1));
     lua_pop(L, 1);  // pop error
   }
-  AssertLuaStackIsEmpty(L);
+  AssertLuaStackIsAt(L, 0);
 #endif
 }
 
@@ -1136,7 +1136,7 @@ static void LuaOnProcessDestroy(int pid) {
     LogLuaError("OnProcessDestroy", lua_tostring(L, -1));
     lua_pop(L, 1);  // pop error
   }
-  AssertLuaStackIsEmpty(L);
+  AssertLuaStackIsAt(L, 0);
 #endif
 }
 
@@ -1154,12 +1154,13 @@ static inline bool IsHookDefined(const char *s) {
 static void CallSimpleHook(const char *s) {
 #ifndef STATIC
   lua_State *L = GL;
+  int n = lua_gettop(L);
   lua_getglobal(L, s);
   if (LuaCallWithTrace(L, 0, 0, NULL) != LUA_OK) {
     LogLuaError(s, lua_tostring(L, -1));
     lua_pop(L, 1);  // pop error
   }
-  AssertLuaStackIsEmpty(L);
+  AssertLuaStackIsAt(L, n);
 #endif
 }