# HG changeset patch
# User jbe
# Date 1407986300 -7200
# Node ID 1a10fef86d97d6d5550bc81e225987df2fd51780
# Parent  035b58aa430a39af02fbde0b439ba2d35b9942e2
Added type checks to C functions of JSON library to avoid crashes due to wrong arguments

diff -r 035b58aa430a -r 1a10fef86d97 libraries/json/json.c
--- a/libraries/json/json.c	Thu Aug 14 01:11:24 2014 +0200
+++ b/libraries/json/json.c	Thu Aug 14 05:18:20 2014 +0200
@@ -818,6 +818,8 @@
 
 // returns the length of a JSON array (or zero for a table without numeric keys):
 static int json_len(lua_State *L) {
+  // require table as first argument:
+  luaL_checktype(L, 1, LUA_TTABLE);
   // stack shall contain one function argument:
   lua_settop(L, 1);
   // push shadow table or nil onto stack:
@@ -831,6 +833,8 @@
 
 // __index metamethod for JSON objects and JSON arrays:
 static int json_index(lua_State *L) {
+  // require table as first argument:
+  luaL_checktype(L, 1, LUA_TTABLE);
   // stack shall contain two function arguments:
   lua_settop(L, 2);
   // replace first argument with its shadow table
@@ -848,6 +852,8 @@
 
 // __newindex metamethod for JSON objects and JSON arrays:
 static int json_newindex(lua_State *L) {
+  // require table as first argument
+  luaL_checktype(L, 1, LUA_TTABLE);
   // stack shall contain three function arguments:
   lua_settop(L, 3);
   // replace first argument with its shadow table
@@ -863,6 +869,8 @@
 
 // function returned as first value by json_pairs function:
 static int json_pairs_iterfunc(lua_State *L) {
+  // require table as first argument
+  luaL_checktype(L, 1, LUA_TTABLE);
   // stack shall contain two function arguments:
   lua_settop(L, 2);
   // get next key value pair from shadow table (argument 1) using previous key (argument 2)
@@ -880,8 +888,8 @@
 // returns a triple such that 'for key, value in pairs(obj) do ... end'
 // iterates through all key value pairs (including JSON null values represented as Lua nil):
 static int json_pairs(lua_State *L) {
-  // require one argument to function
-  luaL_checkany(L, 1);
+  // require table as first argument
+  luaL_checktype(L, 1, LUA_TTABLE);
   // return triple of function json_pairs_iterfunc, shadow table of first argument, and nil:
   lua_pushcfunction(L, json_pairs_iterfunc);
   json_getshadow(L, 1);
@@ -893,6 +901,8 @@
 // function returned as first value by json_ipairs function:
 static int json_ipairs_iterfunc(lua_State *L) {
   lua_Integer idx;
+  // require table as first argument
+  luaL_checktype(L, 1, LUA_TTABLE);
   // stack shall contain two function arguments:
   lua_settop(L, 2);
   // calculate new index by incrementing second argument:
@@ -913,8 +923,8 @@
 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
 // iterates through all values (including JSON null values represented as Lua nil):
 static int json_ipairs(lua_State *L) {
-  // require one argument to function
-  luaL_checkany(L, 1);
+  // require table as first argument
+  luaL_checktype(L, 1, LUA_TTABLE);
   // return triple of function json_ipairs_iterfunc, shadow table of first argument, and zero:
   lua_pushcfunction(L, json_ipairs_iterfunc);
   json_getshadow(L, 1);