text: /*
  ** $Id: ldblib.c,v 1.151.1.1 2017/04/19 17:20:42 roberto Exp $
  ** Interface from Lua to its debug API
  ** See Copyright Notice in src.h
  */
  
  #define ldblib_c
  #define LUA_LIB
  
  #include "lprefix.h"
  
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "../include/lua.h"
  
  #include "../include/lauxlib.h"
  #include "../include/lualib.h"
  
  
  /*
  ** The hook table at registry[&HOOKKEY] maps threads to their current
  ** hook function. (We only need the unique address of 'HOOKKEY'.)
  */
  static const int HOOKKEY = 0;
  
  
  /*
  ** If L1 != L, L1 can be in any state, and therefore there are no
  ** guarantees about its stack space; any push in L1 must be
  ** checked.
  */
  static void checkstack (lua_State *L, lua_State *L1, int n) {
    if (L != L1 && !lua_checkstack(L1, n))
      luaL_error(L, "stack overflow");
  }
  
  
  static int db_getregistry (lua_State *L) {
    lua_pushvalue(L, LUA_REGISTRYINDEX);
    return 1;
  }
  
  
  static int db_getmetatable (lua_State *L) {
    luaL_checkany(L, 1);
    if (!lua_getmetatable(L, 1)) {
      lua_pushnil(L);  /* no metatable */
    }
    return 1;
  }
  
  
  static int db_setmetatable (lua_State *L) {
    int t = lua_type(L, 2);
    luaL_argcheck(L, t == LUA_TNIL || t == LUA_TTABLE, 2,
                      "nil or table expected");
    lua_settop(L, 2);
    lua_setmetatable(L, 1);
    return 1;  /* return 1st argument */
  }
  
  
  static int db_getuservalue (lua_State *L) {
    if (lua_type(L, 1) != LUA_TUSERDATA)
      lua_pushnil(L);
    else
      lua_getuservalue(L, 1);
    return 1;
  }
  
  
  static int db_setuservalue (lua_State *L) {
    luaL_checktype(L, 1, LUA_TUSERDATA);
    luaL_checkany(L, 2);
    lua_settop(L, 2);
    lua_setuservalue(L, 1);
    return 1;
  }
  
  
  /*
  ** Auxiliary function used by several library functions: check for
  ** an optional thread as function's first argument and set 'arg' with
  ** 1 if this argument is present (so that functions can skip it to
  ** access their other arguments)
  */
  static lua_State *getthread (lua_State *L, int *arg) {
    if (lua_isthread(L, 1)) {
      *arg = 1;
      return lua_tothread(L, 1);
    }
    else {
      *arg = 0;
      return L;  /* function will operate over current thread */
    }
  }
  
  
  /*
  ** Variations of 'lua_settable', used by 'db_getinfo' to put results
  ** from 'lua_getinfo' into result table. Key is always a string;
  ** value can be a string, an int, or a boolean.
  */
  static void settabss (lua_State *L, const char *k, const char *v) {
    lua_pushstring(L, v);
    lua_setfield(L, -2, k);
  }
  
  static void settabsi (lua_State *L, const char *k, int v) {
    lua_pushinteger(L, v);
    lua_setfield(L, -2, k);
  }
  
  static void settabsb (lua_State *L, const char *k, int v) {
    lua_pushboolean(L, v);
    lua_setfield(L, -2, k);
  }
  
  
  /*
  ** In function 'db_getinfo', the call to 'lua_getinfo' may push
  ** results on the stack; later it creates the result table to put
  ** these objects. Function 'treatstackoption' puts the result from
  ** 'lua_getinfo' on top of the result table so that it can call
  ** 'lua_setfield'.
  */
  static void treatstackoption (lua_State *L, lua_State *L1, const char *fname) {
    if (L == L1)
      lua_rotate(L, -2, 1);  /* exchange object and table */
    else
      lua_xmove(L1, L, 1);  /* move object to the "main" stack */
    lua_setfield(L, -2, fname);  /* put object into table */
  }
  
  
  /*
  ** Calls 'lua_getinfo' and collects all results in a new table.
  ** L1 needs stack space for an optional input (function) plus
  ** two optional outputs (function and line table) from function
  ** 'lua_getinfo'.
  */
  static int db_getinfo (lua_State *L) {
    lua_Debug ar;
    int arg;
    lua_State *L1 = getthread(L, &arg);
    const char *options = luaL_optstring(L, arg+2, "flnStu");
    checkstack(L, L1, 3);
    if (lua_isfunction(L, arg + 1)) {  /* info about a function? */
      options = lua_pushfstring(L, ">%s", options);  /* add '>' to 'options' */
      lua_pushvalue(L, arg + 1);  /* move function to 'L1' stack */
      lua_xmove(L, L1, 1);
    }
    else {  /* stack level */
      if (!lua_getstack(L1, (int)luaL_checkinteger(L, arg + 1), &ar)) {
        lua_pushnil(L);  /* level out of range */
        return 1;
      }
    }
    if (!lua_getinfo(L1, options, &ar))
      return luaL_argerror(L, arg+2, "invalid option");
    lua_newtable(L);  /* table to collect results */
    if (strchr(options, 'S')) {
      settabss(L, "source", ar.source);
      settabss(L, "short_src", ar.short_src);
      settabsi(L, "linedefined", ar.linedefined);
      settabsi(L, "lastlinedefined", ar.lastlinedefined);
      settabss(L, "what", ar.what);
    }
    if (strchr(options, 'l'))
      settabsi(L, "currentline", ar.currentline);
    if (strchr(options, 'u')) {
      settabsi(L, "nups", ar.nups);
      settabsi(L, "nparams", ar.nparams);
      settabsb(L, "isvararg", ar.isvararg);
    }
    if (strchr(options, 'n')) {
      settabss(L, "name", ar.name);
      settabss(L, "namewhat", ar.namewhat);
    }
    if (strchr(options, 't'))
      settabsb(L, "istailcall", ar.istailcall);
    if (strchr(options, 'L'))
      treatstackoption(L, L1, "activelines");
    if (strchr(options, 'f'))
      treatstackoption(L, L1, "func");
    return 1;  /* return table */
  }
  
  
  static int db_getlocal (lua_State *L) {
    int arg;
    lua_State *L1 = getthread(L, &arg);
    lua_Debug ar;
    const char *name;
    int nvar = (int)luaL_checkinteger(L, arg + 2);  /* local-variable index */
    if (lua_isfunction(L, arg + 1)) {  /* function argument? */
      lua_pushvalue(L, arg + 1);  /* push function */
      lua_pushstring(L, lua_getlocal(L, NULL, nvar));  /* push local name */
      return 1;  /* return only name (there is no value) */
    }
    else {  /* stack-level argument */
      int level = (int)luaL_checkinteger(L, arg + 1);
      if (!lua_getstack(L1, level, &ar))  /* out of range? */
        return luaL_argerror(L, arg+1, "level out of range");
      checkstack(L, L1, 1);
      name = lua_getlocal(L1, &ar, nvar);
      if (name) {
        lua_xmove(L1, L, 1);  /* move local value */
        lua_pushstring(L, name);  /* push name */
        lua_rotate(L, -2, 1);  /* re-order */
        return 2;
      }
      else {
        lua_pushnil(L);  /* no name (nor value) */
        return 1;
      }
    }
  }
  
  
  static int db_setlocal (lua_State *L) {
    int arg;
    const char *name;
    lua_State *L1 = getthread(L, &arg);
    lua_Debug ar;
    int level = (int)luaL_checkinteger(L, arg + 1);
    int nvar = (int)luaL_checkinteger(L, arg + 2);
    if (!lua_getstack(L1, level, &ar))  /* out of range? */
      return luaL_argerror(L, arg+1, "level out of range");
    luaL_checkany(L, arg+3);
    lua_settop(L, arg+3);
    checkstack(L, L1, 1);
    lua_xmove(L, L1, 1);
    name = lua_setlocal(L1, &ar, nvar);
    if (name == NULL)
      lua_pop(L1, 1);  /* pop value (if not popped by 'lua_setlocal') */
    lua_pushstring(L, name);
    return 1;
  }
  
  
  /*
  ** get (if 'get' is true) or set an upvalue from a closure
  */
  static int auxupvalue (lua_State *L, int get) {
    const char *name;
    int n = (int)luaL_checkinteger(L, 2);  /* upvalue index */
    luaL_checktype(L, 1, LUA_TFUNCTION);  /* closure */
    name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
    if (name == NULL) return 0;
    lua_pushstring(L, name);
    lua_insert(L, -(get+1));  /* no-op if get is false */
    return get + 1;
  }
  
  
  static int db_getupvalue (lua_State *L) {
    return auxupvalue(L, 1);
  }
  
  
  static int db_setupvalue (lua_State *L) {
    luaL_checkany(L, 3);
    return auxupvalue(L, 0);
  }
  
  
  /*
  ** Check whether a given upvalue from a given closure exists and
  ** returns its index
  */
  static int checkupval (lua_State *L, int argf, int argnup) {
    int nup = (int)luaL_checkinteger(L, argnup);  /* upvalue index */
    luaL_checktype(L, argf, LUA_TFUNCTION);  /* closure */
    luaL_argcheck(L, (lua_getupvalue(L, argf, nup) != NULL), argnup,
                     "invalid upvalue index");
    return nup;
  }
  
  
  static int db_upvalueid (lua_State *L) {
    int n = checkupval(L, 1, 2);
    lua_pushlightuserdata(L, lua_upvalueid(L, 1, n));
    return 1;
  }
  
  
  static int db_upvaluejoin (lua_State *L) {
    int n1 = checkupval(L, 1, 2);
    int n2 = checkupval(L, 3, 4);
    luaL_argcheck(L, !lua_iscfunction(L, 1), 1, "Lua function expected");
    luaL_argcheck(L, !lua_iscfunction(L, 3), 3, "Lua function expected");
    lua_upvaluejoin(L, 1, n1, 3, n2);
    return 0;
  }
  
  
  /*
  ** Call hook function registered at hook table for the current
  ** thread (if there is one)
  */
  static void hookf (lua_State *L, lua_Debug *ar) {
    static const char *const hooknames[] =
      {"call", "return", "line", "count", "tail call"};
    lua_rawgetp(L, LUA_REGISTRYINDEX, &HOOKKEY);
    lua_pushthread(L);
    if (lua_rawget(L, -2) == LUA_TFUNCTION) {  /* is there a hook function? */
      lua_pushstring(L, hooknames[(int)ar->event]);  /* push event name */
      if (ar->currentline >= 0)
        lua_pushinteger(L, ar->currentline);  /* push current line */
      else lua_pushnil(L);
      lua_assert(lua_getinfo(L, "lS", ar));
      lua_call(L, 2, 0);  /* call hook function */
    }
  }
  
  
  /*
  ** Convert a string mask (for 'sethook') into a bit mask
  */
  static int makemask (const char *smask, int count) {
    int mask = 0;
    if (strchr(smask, 'c')) mask |= LUA_MASKCALL;
    if (strchr(smask, 'r')) mask |= LUA_MASKRET;
    if (strchr(smask, 'l')) mask |= LUA_MASKLINE;
    if (count > 0) mask |= LUA_MASKCOUNT;
    return mask;
  }
  
  
  /*
  ** Convert a bit mask (for 'gethook') into a string mask
  */
  static char *unmakemask (int mask, char *smask) {
    int i = 0;
    if (mask & LUA_MASKCALL) smask[i++] = 'c';
    if (mask & LUA_MASKRET) smask[i++] = 'r';
    if (mask & LUA_MASKLINE) smask[i++] = 'l';
    smask[i] = '\0';
    return smask;
  }
  
  
  static int db_sethook (lua_State *L) {
    int arg, mask, count;
    lua_Hook func;
    lua_State *L1 = getthread(L, &arg);
    if (lua_isnoneornil(L, arg+1)) {  /* no hook? */
      lua_settop(L, arg+1);
      func = NULL; mask = 0; count = 0;  /* turn off hooks */
    }
    else {
      const char *smask = luaL_checkstring(L, arg+2);
      luaL_checktype(L, arg+1, LUA_TFUNCTION);
      count = (int)luaL_optinteger(L, arg + 3, 0);
      func = hookf; mask = makemask(smask, count);
    }
    if (lua_rawgetp(L, LUA_REGISTRYINDEX, &HOOKKEY) == LUA_TNIL) {
      lua_createtable(L, 0, 2);  /* create a hook table */
      lua_pushvalue(L, -1);
      lua_rawsetp(L, LUA_REGISTRYINDEX, &HOOKKEY);  /* set it in position */
      lua_pushstring(L, "k");
      lua_setfield(L, -2, "__mode");  /** hooktable.__mode = "k" */
      lua_pushvalue(L, -1);
      lua_setmetatable(L, -2);  /* setmetatable(hooktable) = hooktable */
    }
    checkstack(L, L1, 1);
    lua_pushthread(L1); lua_xmove(L1, L, 1);  /* key (thread) */
    lua_pushvalue(L, arg + 1);  /* value (hook function) */
    lua_rawset(L, -3);  /* hooktable[L1] = new Lua hook */
    lua_sethook(L1, func, mask, count);
    return 0;
  }
  
  
  static int db_gethook (lua_State *L) {
    int arg;
    lua_State *L1 = getthread(L, &arg);
    char buff[5];
    int mask = lua_gethookmask(L1);
    lua_Hook hook = lua_gethook(L1);
    if (hook == NULL)  /* no hook? */
      lua_pushnil(L);
    else if (hook != hookf)  /* external hook? */
      lua_pushliteral(L, "external hook");
    else {  /* hook table must exist */
      lua_rawgetp(L, LUA_REGISTRYINDEX, &HOOKKEY);
      checkstack(L, L1, 1);
      lua_pushthread(L1); lua_xmove(L1, L, 1);
      lua_rawget(L, -2);   /* 1st result = hooktable[L1] */
      lua_remove(L, -2);  /* remove hook table */
    }
    lua_pushstring(L, unmakemask(mask, buff));  /* 2nd result = mask */
    lua_pushinteger(L, lua_gethookcount(L1));  /* 3rd result = count */
    return 3;
  }
  
  
  static int db_debug (lua_State *L) {
    for (;;) {
      char buffer[250];
      lua_writestringerror("%s", "lua_debug> ");
      if (fgets(buffer, sizeof(buffer), stdin) == 0 ||
          strcmp(buffer, "cont\n") == 0)
        return 0;
      if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") ||
          lua_pcall(L, 0, 0, 0))
        lua_writestringerror("%s\n", lua_tostring(L, -1));
      lua_settop(L, 0);  /* remove eventual returns */
    }
  }
  
  
  static int db_traceback (lua_State *L) {
    int arg;
    lua_State *L1 = getthread(L, &arg);
    const char *msg = lua_tostring(L, arg + 1);
    if (msg == NULL && !lua_isnoneornil(L, arg + 1))  /* non-string 'msg'? */
      lua_pushvalue(L, arg + 1);  /* return it untouched */
    else {
      int level = (int)luaL_optinteger(L, arg + 2, (L == L1) ? 1 : 0);
      luaL_traceback(L, L1, msg, level);
    }
    return 1;
  }
  
  
  static const luaL_Reg dblib[] = {
    {"debug", db_debug},
    {"getuservalue", db_getuservalue},
    {"gethook", db_gethook},
    {"getinfo", db_getinfo},
    {"getlocal", db_getlocal},
    {"getregistry", db_getregistry},
    {"getmetatable", db_getmetatable},
    {"getupvalue", db_getupvalue},
    {"upvaluejoin", db_upvaluejoin},
    {"upvalueid", db_upvalueid},
    {"setuservalue", db_setuservalue},
    {"sethook", db_sethook},
    {"setlocal", db_setlocal},
    {"setmetatable", db_setmetatable},
    {"setupvalue", db_setupvalue},
    {"traceback", db_traceback},
    {NULL, NULL}
  };
  
  
  LUAMOD_API int luaopen_debug (lua_State *L) {
    luaL_newlib(L, dblib);
    return 1;
  }
  
  