libs/nixio/src/select.c

   1 /*
   2  * nixio - Linux I/O library for lua
   3  *
   4  *   Copyright (C) 2009 Steven Barth <steven@midlink.org>
   5  *
   6  *  Licensed under the Apache License, Version 2.0 (the "License");
   7  *  you may not use this file except in compliance with the License.
   8  *  You may obtain a copy of the License at
   9  *
  10  *      http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  *  Unless required by applicable law or agreed to in writing, software
  13  *  distributed under the License is distributed on an "AS IS" BASIS,
  14  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  *  See the License for the specific language governing permissions and
  16  *  limitations under the License.
  17  */
  18
  19 #include <lua.h>
  20 #include <lualib.h>
  21 #include <lauxlib.h>
  22 #include <sys/select.h>
  23 #include "nixio.h"
  24
  25 static int nixio_select(lua_State *L) {
  26         int nfds = 0, tmpfd = -1, i = 0, j = 0, o = 0, k, tlen;
  27         fd_set rfds, wfds, xfds;
  28         fd_set *fdsets[3] = {&rfds, &wfds, &xfds};
  29         FD_ZERO(fdsets[0]);
  30         FD_ZERO(fdsets[1]);
  31         FD_ZERO(fdsets[2]);
  32
  33         struct timeval timeout;
  34         timeout.tv_sec = luaL_optinteger(L, 4, 0);
  35         timeout.tv_usec = luaL_optinteger(L, 5, 0);
  36
  37         /* create fdsets */
  38         for (i=0; i<3; i++) {
  39                 o = i + 1;
  40                 if (lua_isnoneornil(L, o)) {
  41                         fdsets[i] = NULL;
  42                         continue;
  43                 }
  44
  45                 luaL_checktype(L, o, LUA_TTABLE);
  46                 tlen = lua_objlen(L, o);
  47                 luaL_argcheck(L, tlen <= FD_SETSIZE, o, "too many fds");
  48
  49                 for (j=1; j<=tlen; j++) {
  50                         lua_rawgeti(L, o, j);
  51                         tmpfd = nixio__checkfd(L, -1);
  52                         FD_SET(tmpfd, fdsets[i]);
  53                         if (tmpfd >= nfds) {
  54                                 nfds = tmpfd + 1;
  55                         }
  56                         lua_pop(L, 1);
  57                 }
  58         }
  59
  60         int stat = select(nfds, fdsets[0], fdsets[1], fdsets[2], &timeout);
  61
  62         if (stat < 0) {
  63                 return nixio__perror(L);
  64         } else if (stat == 0) {
  65                 lua_pushinteger(L, stat);
  66                 for (i=1; i<=3; i++) {
  67                         if (lua_isnoneornil(L, i)) {
  68                                 lua_pushnil(L);
  69                         } else {
  70                                 lua_newtable(L);
  71                         }
  72                 }
  73         } else {
  74                 lua_pushinteger(L, stat);
  75
  76                 /* create return tables */
  77                 for (i=0; i<3; i++) {
  78                         o = i + 1;
  79                         if (lua_isnoneornil(L, o)) {
  80                                 lua_pushnil(L);
  81                                 continue;
  82                         }
  83
  84                         lua_newtable(L);
  85                         tlen = lua_objlen(L, o);
  86                         k = 1;
  87
  88                         for (j=1; j<=tlen; j++) {
  89                                 lua_rawgeti(L, o, j);
  90                                 tmpfd = nixio__tofd(L, -1);
  91                                 if (FD_ISSET(tmpfd, fdsets[i])) {
  92                                         lua_rawseti(L, -2, k++);
  93                                 } else {
  94                                         lua_pop(L, 1);
  95                                 }
  96                         }
  97                 }
  98         }
  99         return 4;
 100 }
 101
 102 /* module table */
 103 static const luaL_reg R[] = {
 104         {"select",      nixio_select},
 105         {NULL,                  NULL}
 106 };
 107
 108 void nixio_open_select(lua_State *L) {
 109         luaL_register(L, NULL, R);
 110 }