lua c lib thingy

lnetlib.c

#include <stdlib.h>
#include <sys/utsname.h>
#include <sys/time.h>
#include <string.h>

#define lnetlib_c  /* Define the library */

/* Include the Lua API header files */
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"

/* The 'uname' function.
** It accepts a Lua State (Don't worry about this),
** and doesn't return anything.
*/
static int net_uname (lua_State *L)
{
	const char *option = luaL_checkstring(L, 1); 	/* Reads the string parameter */
	int z;
	struct utsname u_name;	/* Creates an instance of the utsname structure */

	/* Uses the C function 'uname' and stores the
	** results in the structure we just created.
	** You could add some error checking, by testing the value of z -
	** But I cut this out, though you should add it.
	*/
	z = uname(&u_name);

	/* Detects which option was passed to the function,
	** and prints the correspnding uname response.
	** Again, you should add error checking.
	*/
	if ((strcmp(option, "sysname")) == 0)
	{
		printf("sysname  : %s", u_name.sysname);
	}
	else if ((strcmp(option, "nodename")) == 0)
	{
		printf("nodename : %s", u_name.nodename);
	}
	else if ((strcmp(option, "release")) == 0)
	{
		printf("release  : %s", u_name.release);
	}
	else if ((strcmp(option, "version")) == 0)
	{
		printf("version  : %s", u_name.version);
	}
	else if ((strcmp(option, "machine")) == 0)
	{
		printf("machine  : %s", u_name.machine);
	}
	else if ((strcmp(option, "all")) == 0)
	{
		printf("sysname  : %s\n", u_name.sysname);
		printf("nodename : %s\n", u_name.nodename);
		printf("release  : %s\n", u_name.release);
		printf("version  : %s\n", u_name.version);
		printf("machine  : %s\n", u_name.machine);
	}
	return 0;
}

/* Get time of day as unix seconds and microseconds */
static int net_gettimeofday (lua_State *L)
{
	int err;
	struct timeval t_now;
	err = gettimeofday( &t_now, NULL );
	
	if( err == 0 ){
		lua_pushnumber(L, t_now.tv_sec);
		lua_pushnumber(L, t_now.tv_usec);
		return 2;
	} else {
		return 0;
	}
}

/* Get time of day as unix seconds + microseconds float */
static int net_time (lua_State *L)
{
	int err;
	struct timeval t_now;
	err = gettimeofday( &t_now, NULL );
	
	if( err == 0 ){
		lua_pushnumber(L, t_now.tv_sec + t_now.tv_usec * 0.000001);
		return 1;
	} else {
		return 0;
	}
}


/* Now, this defines the functions you have created, into the net library group.
** The right hand name ('net_uname'), is the name of the function in the C code.
** The left hand name, is the name you want it to be called from Lua.
** Take note of the names of variables, they correspond to your 'net' library.
** If you changed the name of the library, you would have to change these
** variables and names.
*/

static const luaL_Reg netlib[] = {
	{"uname", net_uname},
	{"timeofday", net_gettimeofday},
	{"time", net_time},
	{NULL, NULL}
};

/* This defines a function that opens up your library. */
LUALIB_API int luaopen_net (lua_State *L) {
  luaL_openlib(L, LUA_NETLIBNAME, netlib, 0);
  return 1;
}