errno.c

#include <errno.h>
#include <string.h>
#include <lua.h>
#include <lauxlib.h>
#include <stdlib.h>
#include <sys/xattr.h>
#include "compat.h"

/****************************************************************************/

static void lua_pusherrno(lua_State* L, int err)
{
	int* udata;
	udata = (int*)lua_newuserdata(L, sizeof(int));
	*udata = err;
	luaL_getmetatable(L, "errno");
	lua_setmetatable(L, -2);
}

// Function to check if the object at index on the stack is one of the error userdata of the errno table
// If not it returns 0
// if yes it returns 1 - checks the metatable of the userdata at index and compares it with the metatable of errno
int lua_iserrno(lua_State* L, int index)
{
	int iserrno;
	if (lua_type(L, index)!=LUA_TUSERDATA)
		return 0;
	lua_getmetatable(L, index); // ST = 1
	luaL_getmetatable(L, "errno");  // ST = 2
	iserrno = lua_rawequal(L, -1, -2);
	lua_pop(L, 2);  // ST = 0 -- Balanced
	return iserrno;
}

int lua_toerrno(lua_State* L, int index)
{
	return *(int*)lua_touserdata(L, index);
}

static int luaL_checkerrno(lua_State* L, int index)
{
	return *(int*)luaL_checkudata(L, index, "errno");
}

/****************************************************************************/

static int errno__tostring(lua_State* L)
{
	int err;
	const char* result;

	err = luaL_checkerrno(L, 1);

	result = strerror(err); // strerror returns a pointer to a string that describes the error

	lua_pushstring(L, result);
	return 1;
}

static const luaL_Reg errno_mt[] = {
	{"__tostring", errno__tostring},
	{0, 0},
};

// Function to generate and push the error numbers table on the Lua Stack
void push_errno_table(lua_State* L)
{
	if (luaL_newmetatable(L, "errno"))  // creats a new table to be used as a metatable for userdata
                                        // and sets ["errno"]=new table in the registry
                                        // also sets __name="errno" in the table
                                        // The table will be on top of the stack
                                        // ST += 1
		setfuncs(L, errno_mt, 0);   // registers all the functions in errno_mt into the table on the top of the stack
                                    // i.e. t[funcName] = function
                                    // in this case t.__tostring = errno__tostring
	lua_pop(L, 1);      // remove the metatable from the stack

	lua_newtable(L);    // table errno
	// REGISTER_ERROR does the following:
	// errno[#error] = error where error is a userdata created in lua_pusherrno which basically points to the
	//                  error integer number but has the errno metatable (made above) set to it
	#define REGISTER_ERROR(error) \
		lua_pushstring(L, #error); lua_pusherrno(L, error); lua_settable(L, -3);
	REGISTER_ERROR(EPERM)
	REGISTER_ERROR(ENOENT)
	REGISTER_ERROR(ESRCH)
	REGISTER_ERROR(EINTR)
	REGISTER_ERROR(EIO)
	REGISTER_ERROR(ENXIO)
	REGISTER_ERROR(E2BIG)
	REGISTER_ERROR(ENOEXEC)
	REGISTER_ERROR(EBADF)
	REGISTER_ERROR(ECHILD)
	REGISTER_ERROR(EAGAIN)
	REGISTER_ERROR(ENOMEM)
	REGISTER_ERROR(EACCES)
	REGISTER_ERROR(EFAULT)
	REGISTER_ERROR(ENOTBLK)
	REGISTER_ERROR(EBUSY)
	REGISTER_ERROR(EEXIST)
	REGISTER_ERROR(EXDEV)
	REGISTER_ERROR(ENODEV)
	REGISTER_ERROR(ENOTDIR)
	REGISTER_ERROR(EISDIR)
	REGISTER_ERROR(EINVAL)
	REGISTER_ERROR(ENFILE)
	REGISTER_ERROR(EMFILE)
	REGISTER_ERROR(ENOTTY)
	REGISTER_ERROR(ETXTBSY)
	REGISTER_ERROR(EFBIG)
	REGISTER_ERROR(ENOSPC)
	REGISTER_ERROR(ESPIPE)
	REGISTER_ERROR(EROFS)
	REGISTER_ERROR(EMLINK)
	REGISTER_ERROR(EPIPE)
	REGISTER_ERROR(EDOM)
	REGISTER_ERROR(ERANGE)
	REGISTER_ERROR(ENOSYS)
	REGISTER_ERROR(ENODATA)
	#undef REGISTER_ERROR
	lua_pushstring(L, "ENOATTR"); lua_pusherrno(L, ENODATA); lua_settable(L, -3);
}

/*
Copyright (c) Jérôme Vuarand

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

// vi: ts=4 sts=4 sw=4