Fix. easy:close removes self from multi handle.

Change. Do not reset Lua state back to NULL.

lakefile

@@ -4,6 +4,7 @@ INITLAKEFILE()
 
 DEFINES = L{DEFINES,
   IF(WINDOWS,  'DLL_EXPORT',  '');
+  IF(DEBUG, 'LCURL_RESET_NULL_LUA', '');
 }
 
 cURL = c.shared{'lcurl',
@@ -30,6 +31,8 @@ target('test', install, function()
   run_test('test_form.lua')
   run_test('test_pause02.c.lua')
   run_test('test_curl.lua')
+  run_test('test_multi_callback.lua')
+  run_test('test_multi_nested_callback.lua')
 
   if not test_summary() then
     quit("test fail")

src/lceasy.c

@@ -40,6 +40,8 @@ static const char *LCURL_EASY = LCURL_EASY_NAME;
  * end)
  * ```
  * So we have to restore previews Lua state in callback contexts.
+ * But if previews Lua state is NULL then we can just do not set it back.
+ * But set it to NULL make esier debug code.
  */
 void lcurl__easy_assign_lua(lua_State *L, lcurl_easy_t *p, lua_State *value, int assign_multi){
   if(p->multi && assign_multi){
@@ -107,6 +109,12 @@ static int lcurl_easy_cleanup(lua_State *L){
   lcurl_easy_t *p = lcurl_geteasy(L);
   int i;
 
+  if(p->multi){
+    CURLMcode code = lcurl__multi_remove_handle(L, p->multi, p);
+
+    //! @todo what I can do if I can not remove it???
+  }
+
   if(p->curl){
     lua_State *curL;
 
@@ -114,6 +122,9 @@ static int lcurl_easy_cleanup(lua_State *L){
     // timerfunction called only for single multi handle.
     curL = p->L; lcurl__easy_assign_lua(L, p, L, 1);
     curl_easy_cleanup(p->curl);
+#ifndef LCURL_RESET_NULL_LUA
+    if(curL != NULL)
+#endif
     lcurl__easy_assign_lua(L, p, curL, 1);
 
     p->curl = NULL;
@@ -163,6 +174,9 @@ static int lcurl_easy_perform(lua_State *L){
   // User should not call `perform` if handle assign to multi
   curL = p->L; lcurl__easy_assign_lua(L, p, L, 0);
   code = curl_easy_perform(p->curl);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__easy_assign_lua(L, p, curL, 0);
 
   if(p->rbuffer.ref != LUA_NOREF){
@@ -1070,6 +1084,9 @@ static int lcurl_easy_pause(lua_State *L){
 
   curL = p->L; lcurl__easy_assign_lua(L, p, L, 1);
   code = curl_easy_pause(p->curl, mask);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__easy_assign_lua(L, p, curL, 1);
 
   if(code != CURLE_OK){

src/lcmulti.c

@@ -28,7 +28,35 @@
 #define LCURL_MULTI_NAME LCURL_PREFIX" Multi"
 static const char *LCURL_MULTI = LCURL_MULTI_NAME;
 
+#if defined(DEBUG) || defined(_DEBUG)
+static void lcurl__multi_validate_sate(lua_State *L, lcurl_multi_t *p){
+  int top = lua_gettop(L);
+
+  lua_rawgeti(L, LCURL_LUA_REGISTRY, p->h_ref);
+  assert(lua_istable(L, -1));
+
+  lua_pushnil(L);
+  while(lua_next(L, -2)){
+    lcurl_easy_t *e = lcurl_geteasy_at(L, -1);
+    void *ptr = lua_touserdata(L, -2);
+
+    assert(e->curl == ptr);
+    assert(e->multi == p);
+    assert(e->L == p->L);
+
+    lua_pop(L, 1);
+  }
+
+  lua_pop(L, 1);
+  assert(lua_gettop(L) == top);
+}
+#else
+#  define lcurl__multi_validate_sate(L, p) (void*)(0)
+#endif
+
 void lcurl__multi_assign_lua(lua_State *L, lcurl_multi_t *p, lua_State *value, int assign_easy){
+  lcurl__multi_validate_sate(L, p);
+
   if((assign_easy)&&(p->L != value)){
     lua_rawgeti(L, LCURL_LUA_REGISTRY, p->h_ref);
     lua_pushnil(L);
@@ -145,10 +173,16 @@ static int lcurl_multi_add_handle(lua_State *L){
   lua_rawsetp(L, -2, e->curl);
   lua_settop(L, 1);
 
+  // all `esay` handles have to have same L
+  lcurl__easy_assign_lua(L, e, p->L, 0);
+
   e->multi = p;
 
   curL = p->L; lcurl__multi_assign_lua(L, p, L, 1);
   code = curl_multi_add_handle(p->curl, e->curl);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__multi_assign_lua(L, p, curL, 1);
 
   if(code != CURLM_OK){
@@ -166,30 +200,42 @@ static int lcurl_multi_add_handle(lua_State *L){
 static int lcurl_multi_remove_handle(lua_State *L){
   lcurl_multi_t *p = lcurl_getmulti(L);
   lcurl_easy_t  *e = lcurl_geteasy_at(L, 2);
+  CURLMcode code = lcurl__multi_remove_handle(L, p, e);
+
+  if(code != CURLM_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_MULTI, code);
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+CURLMcode lcurl__multi_remove_handle(lua_State *L, lcurl_multi_t *p, lcurl_easy_t *e){
   CURLMcode code;
   lua_State *curL;
 
   if(e->multi != p){
     // cURL returns CURLM_OK for such call so we do the same.
     // tested on 7.37.1
-    lua_settop(L, 1);
+    return CURLM_OK;
-    return 1;
   }
 
   curL = p->L; lcurl__multi_assign_lua(L, p, L, 1);
   code = curl_multi_remove_handle(p->curl, e->curl);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__multi_assign_lua(L, p, curL, 1);
 
-  if(code != CURLM_OK){
+  if(code == CURLM_OK){
-    lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_MULTI, code);
-  }
-
     e->multi = NULL;
     lua_rawgeti(L, LCURL_LUA_REGISTRY, p->h_ref);
     lua_pushnil(L);
     lua_rawsetp(L, -2, e->curl);
-  lua_settop(L, 1);
+    lua_pop(L, 1);
-  return 1;
+  }
+ 
+  return code;
 }
 
 static int lcurl_multi_perform(lua_State *L){
@@ -200,6 +246,9 @@ static int lcurl_multi_perform(lua_State *L){
 
   curL = p->L; lcurl__multi_assign_lua(L, p, L, 1);
   while((code = curl_multi_perform(p->curl, &running_handles)) == CURLM_CALL_MULTI_PERFORM);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__multi_assign_lua(L, p, curL, 1);
 
   if(code != CURLM_OK){
@@ -232,6 +281,9 @@ static int lcurl_multi_info_read(lua_State *L){
 
       curL = p->L; lcurl__multi_assign_lua(L, p, L, 1);
       code = curl_multi_remove_handle(p->curl, e->curl);
+#ifndef LCURL_RESET_NULL_LUA
+      if(curL != NULL)
+#endif
       lcurl__multi_assign_lua(L, p, curL, 1);
 
       if(CURLM_OK == code){
@@ -337,6 +389,9 @@ static int lcurl_multi_socket_action(lua_State *L){
 
   curL = p->L; lcurl__multi_assign_lua(L, p, L, 1);
   code = curl_multi_socket_action(p->curl, s, mask, &n);
+#ifndef LCURL_RESET_NULL_LUA
+  if(curL != NULL)
+#endif
   lcurl__multi_assign_lua(L, p, curL, 1);
 
   if(code != CURLM_OK){

src/lcmulti.h

@@ -33,4 +33,6 @@ void lcurl_multi_initlib(lua_State *L, int nup);
 
 void lcurl__multi_assign_lua(lua_State *L, lcurl_multi_t *p, lua_State *value, int assign_easy);
 
+CURLMcode lcurl__multi_remove_handle(lua_State *L, lcurl_multi_t *p, lcurl_easy_t *e);
+
 #endif