Lua line numbers when concatenating multiple lua chunks

[Michael Abbott <mabster@...>]

I've been playing around with prefixing the scripts I load with startup 
code.  This I've been doing with lua_load() and chunks.  I've come 
across the problem that if I want to flag a specific error in the code 
that the user wrote I want to be able to tell them in which line number 
in /their/ code this error occurred on.

Is the only way to do this to scan the characters for \r?\n before they 
reach lua_load()?  Also, if this is the case, is there some means of 
solving this when loading a pre-compiled lua chunk?

I've put together a minimal example of this behaviour below (the output 
should indicate an error in line 1, not 3):

Thanks guys,
- Mab

---------->
  ---------->
  C++ code
  <----------
  extern "C" {
      #include "lua.h"
  }
  #include <assert.h>
  #include <stdio.h>
  #include <string.h>

  enum { STATE_PREFIX, STATE_FILE };
  static int state = STATE_PREFIX;
  static const char* prefix = "-- first line\n-- second line\n";

  enum { BUFFER_SIZE = 128 };
  static const char* filename = "test.lua";
  static FILE* file;
  static char fileBuffer[BUFFER_SIZE];

  static const char* ChunkReader(
      lua_State*  L,
      void*       data,
      size_t*     size)
  {
      if (state == STATE_PREFIX) {
          *size = strlen(prefix);
          state = STATE_FILE;
          return prefix;
      } else if (state == STATE_FILE) {
          *size = fread(fileBuffer, 1, BUFFER_SIZE, file);
          return *size ? fileBuffer : 0;
      }

      return 0;
  }

  int main()
  {
      file = fopen(filename, "rt");
      assert(file);

      lua_State* L = lua_open();
      assert(L);
      lua_load(L, ChunkReader, 0, filename);
      assert(lua_gettop(L) == 1);
      assert(lua_type(L, 1) == LUA_TSTRING);
      printf("%s", lua_tostring(L, 1));

      fclose(file);

      return 0;
  }

  ---------->
  test.lua
  <----------
  1 = i	-- obviously an error

  ---------->
  output
  <----------
  [string "test.lua"]:3: unexpected symbol near `1'
<----------