/* Copyright 2020 Google LLC
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/


#define lua_c

#include "lprefix.h"


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#include <signal.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME            "lua"
#endif

#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR            "LUA_INIT"
#endif

#define LUA_INITVARVERSION      LUA_INIT_VAR LUA_VERSUFFIX


static lua_State *globalL = NULL;

static const char *progname = LUA_PROGNAME;


/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop (lua_State *L, lua_Debug *ar) {
  (void)ar;  /* unused arg. */
  lua_sethook(L, NULL, 0, 0);  /* reset hook */
  luaL_error(L, "interrupted!");
}


/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction (int i) {
  int flag = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT;
  signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
  lua_sethook(globalL, lstop, flag, 1);
}


/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message (const char *pname, const char *msg) {
  if (pname) lua_writestringerror("%s: ", pname);
  lua_writestringerror("%s\n", msg);
}


/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report (lua_State *L, int status) {
  if (status != LUA_OK) {
    const char *msg = lua_tostring(L, -1);
    l_message(progname, msg);
    lua_pop(L, 1);  /* remove message */
  }
  return status;
}

/*
** Message handler used to run all chunks
*/
static int msghandler (lua_State *L) {
  const char *msg = lua_tostring(L, 1);
  if (msg == NULL) {  /* is error object not a string? */
    if (luaL_callmeta(L, 1, "__tostring") &&  /* does it have a metamethod */
        lua_type(L, -1) == LUA_TSTRING)  /* that produces a string? */
      return 1;  /* that is the message */
    else
      msg = lua_pushfstring(L, "(error object is a %s value)",
                               luaL_typename(L, 1));
  }
  luaL_traceback(L, L, msg, 1);  /* append a standard traceback */
  return 1;  /* return the traceback */
}


/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall (lua_State *L, int narg, int nres) {
  int status;
  int base = lua_gettop(L) - narg;  /* function index */
  lua_pushcfunction(L, msghandler);  /* push message handler */
  lua_insert(L, base);  /* put it under function and args */
  globalL = L;  /* to be available to 'laction' */
  signal(SIGINT, laction);  /* set C-signal handler */
  status = lua_pcall(L, narg, nres, base);
  signal(SIGINT, SIG_DFL); /* reset C-signal handler */
  lua_remove(L, base);  /* remove message handler from the stack */
  return status;
}


static int dochunk (lua_State *L, int status) {
  if (status == LUA_OK) status = docall(L, 0, 0);
  return report(L, status);
}


/* mark in error messages for incomplete statements */
#define EOFMARK         "<eof>"
#define marklen         (sizeof(EOFMARK)/sizeof(char) - 1)

int
LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
    lua_State *L = luaL_newstate();
    if (L == NULL) {
        return 0;
    }
    dochunk(L, luaL_loadbufferx(L, data, size, "test", "t"));

    lua_close(L);
    return 0;
}