Zero brain studio as a debugger

Now possible to debug pllua untrusted with Zero Brain Studio. At first
mobdebug needs to be installed (luarocks install mobdebug)

To enable extended debug info  we need run  this code:
do $$
    remote_debug_info(true)
$$ language plluau

Then start debugging server in Zero Brain Studio
and then possible to debug line by line code like this:

do $$
local mobdebug = require('mobdebug')
mobdebug.start() -- same as start("localhost", 8172)

print("Start")
local foo = 0
for i = 1, 3 do

  local function bar()
    print("In bar")
  end
  foo = i
  print("Loop")
  bar()
end
print("End")
$$ language plluau

Note: ZBS had a bug in linux when many tabs opened for debugging if ZBS
was in background, but in ZBS github master branch already fixed.

Author: eugwne

Diff for: pllua.c

@@ -78,6 +78,8 @@ Datum pllua_inline_handler(PG_FUNCTION_ARGS) {
 
 void p_lua_mem_cxt(void){}
 void p_lua_master_state(void){}
+void p_remote_debug_info(void){}
+
 
 void push_spi_error(lua_State *L, MemoryContext oldcontext)
 {
@@ -137,6 +139,3 @@ int pg_to_regtype(char *typ_name)
     else
         return -1;
 }
-
-
-

Diff for: pllua.h

@@ -15,6 +15,8 @@ void p_lua_mem_cxt(void);
 
 void p_lua_master_state(void);
 
+void p_remote_debug_info(void);
+
 typedef struct luaP_Buffer {
   int size;
   Datum *value;

Diff for: plluaapi.c

@@ -490,6 +490,26 @@ static int luaP_register_type (lua_State *L) {
   return luaL_error(L, "unknown type %s", reg_name);
 }
 
+static int luaP_remote_debug_info (lua_State *L) {
+    BEGINLUA;
+    if ((lua_gettop(L) != 1)||(!lua_isboolean( L, 1 ))){
+        return luaL_error(L, "wrong arguments lentgh/type");
+    }
+    lua_pushlightuserdata(L, p_remote_debug_info);
+    lua_rawget(L, LUA_REGISTRYINDEX);
+    if (lua_isnil(L,-1)){
+        return luaL_error(L, "trusted lua does not support debugging");
+    }
+    lua_pop(L, 1);
+
+    lua_pushlightuserdata(L, p_remote_debug_info);
+    lua_swap(L);
+    lua_rawset(L, LUA_REGISTRYINDEX);
+
+    ENDLUAV(-1);
+    return -1;
+}
+
 static const luaL_Reg luaP_funcs[] = {
   {"setshared", luaP_setshared},
   {"log", luaP_log},
@@ -501,6 +521,7 @@ static const luaL_Reg luaP_funcs[] = {
   {"register_type", luaP_register_type},
   {"pgfunc", get_pgfunc},
   {"subtransaction", use_subtransaction},
+  {"remote_debug_info", luaP_remote_debug_info},
   {NULL, NULL}
 };
 
@@ -529,6 +550,12 @@ lua_State *luaP_newstate (int trusted) {
   lua_pushlightuserdata(L, p_lua_master_state);
   lua_pushlightuserdata(L, (void *) L);
   lua_rawset(L, LUA_REGISTRYINDEX);
+
+  if(!trusted){
+      lua_pushlightuserdata(L, p_remote_debug_info);
+      lua_pushboolean(L, false);
+      lua_rawset(L, LUA_REGISTRYINDEX);
+  }
   /* core libs */
   if (trusted) {
     const luaL_Reg luaP_trusted_libs[] = {
@@ -697,10 +724,11 @@ static void luaP_newfunction (lua_State *L, int oid, HeapTuple proc,
   Form_pg_proc procst;
   bool isnull;
   Datum prosrc, *argname;
-  const char *s, *fname;
+  const char *source, *fname;
   text *t;
   luaL_Buffer b;
   int init = (*fi == NULL); /* not initialized? */
+  const char *chunk_name = PLLUA_CHUNKNAME;
   /* read proc info */
   procst = (Form_pg_proc) GETSTRUCT(proc);
   prosrc = SysCacheGetAttr(PROCOID, proc, Anum_pg_proc_prosrc, &isnull);
@@ -762,8 +790,18 @@ static void luaP_newfunction (lua_State *L, int oid, HeapTuple proc,
   luaL_addlstring(&b, fname, strlen(fname));
   /* create function */
   luaL_pushresult(&b);
-  s = lua_tostring(L, -1);
-  if (luaL_loadbuffer(L, s, strlen(s), PLLUA_CHUNKNAME))
+  source = lua_tostring(L, -1);
+
+
+  //check if remote debug
+  lua_pushlightuserdata(L, p_remote_debug_info);
+  lua_rawget(L, LUA_REGISTRYINDEX);
+  if  ((!lua_isnil(L,-1))&&lua_toboolean(L, -1)){
+      chunk_name = source;
+  }
+  lua_pop(L, 1);
+
+  if (luaL_loadbuffer(L, source, strlen(source), chunk_name))
     luaP_error(L, "compile");
   lua_remove(L, -2); /* source */
   if (lua_pcall(L, 0, 1, 0)) luaP_error(L, "call");
@@ -1416,7 +1454,17 @@ Datum luaP_inlinehandler (lua_State *L, const char *source) {
   prev = rtds_set_current(funcxt);
   PG_TRY();
   {
-    if (luaL_loadbuffer(L, source, strlen(source), PLLUA_CHUNKNAME))
+      const char *chunk_name = PLLUA_CHUNKNAME;
+
+      lua_pushlightuserdata(L, p_remote_debug_info);
+      lua_rawget(L, LUA_REGISTRYINDEX);
+
+      if  ((!lua_isnil(L,-1))&&lua_toboolean(L, -1)){
+          chunk_name = source;
+      }
+      lua_pop(L, 1);
+
+    if (luaL_loadbuffer(L, source, strlen(source), chunk_name))
       luaP_error(L, "compile");
     if (lua_pcall(L, 0, 0, 0)) {
         funcxt = rtds_unref(funcxt);

Diff for: plluacommon.h

@@ -79,6 +79,8 @@ MemoryContext luaP_getmemctxt (lua_State *L);
 
 lua_State *pllua_getmaster (lua_State *L);
 
+#define lua_swap(L) lua_insert(L, -2)
+
 #define MTOLUA(state) {MemoryContext ___mcxt,___m;\
     ___mcxt = luaP_getmemctxt(state); \
     ___m  = MemoryContextSwitchTo(___mcxt)