kernel/lib/sys/select.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2010  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <net/socket.h>
  20 #include <system.h>
  21 #include <select.h>
  22 #include <errno.h>
  23 #include <file.h>
  24 #include <fd.h>
  25
  26 extern unsigned long timer_ticks;
  27
  28 void _fd_clr (int fd, fd_set *set)
  29 {
  30         if (!set || fd < 0)
  31                 return;
  32
  33         unsigned i;
  34
  35         for (i = 0; i < set->count; i ++)
  36                 if (set->fd[i] == fd) {
  37                         set->fd[i] = -1;
  38
  39                         if (set->count == i+1)
  40                                 set->count --;
  41                         break;
  42                 }
  43 }
  44
  45 int _fd_isset (int fd, fd_set *set)
  46 {
  47         if (!set || fd < 0)
  48                 return 0;
  49
  50         unsigned i;
  51
  52         for (i = 0; i < set->count; i ++)
  53                 if (set->fd[i] == fd)
  54                         return 1;
  55
  56         return 0;
  57 }
  58
  59 void _fd_set (int fd, fd_set *set)
  60 {
  61         if (!set || fd < 0)
  62                 return;
  63
  64         unsigned i;
  65         unsigned y = 0;
  66
  67         /* try to find free entry in actual list */
  68         for (i = 0; i < set->count; i ++)
  69                 if (set->fd[i] == -1) {
  70                         set->fd[i] = fd;
  71                         y ++;
  72                         break;
  73                 }
  74
  75         /* add new entry into list */
  76         if (!y) {
  77                 if (set->count < FD_SETSIZE)
  78                         set->fd[set->count ++] = fd;
  79         }
  80 }
  81
  82 void _fd_zero (fd_set *set)
  83 {
  84         if (!set)
  85                 return;
  86
  87         set->count = 0;
  88 }
  89
  90 int select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timeval *timeout)
  91 {
  92         unsigned rfds = 0;
  93         unsigned wfds = 0;
  94         unsigned efds = 0;
  95
  96         if (readfds)
  97                 rfds = (unsigned) readfds->count;
  98         if (writefds)
  99                 wfds = (unsigned) writefds->count;
 100         if (exceptfds)
 101                 efds = (unsigned) exceptfds->count;
 102
 103         /* prevent from memory overwrite */
 104         if (rfds > FD_SETSIZE)
 105                 rfds = FD_SETSIZE;
 106         if (wfds > FD_SETSIZE)
 107                 wfds = FD_SETSIZE;
 108         if (efds > FD_SETSIZE)
 109                 efds = FD_SETSIZE;
 110
 111         unsigned long stime = timer_ticks;
 112         unsigned long ms;
 113
 114         if (timeout)
 115                 ms = timeout->tv_usec / 1000 + timeout->tv_sec * 1000;  // covert to milisecond precise
 116         else
 117                 ms = 50000;
 118
 119         unsigned r;
 120
 121         for (; (stime+ms) >= timer_ticks; ) {
 122                 for (r = 0; r < rfds; r ++) {
 123                         if (readfds->fd[r] == -1)
 124                                 continue;
 125
 126                         fd_t *fd = fd_get (readfds->fd[r]);
 127
 128                         if (!fd) {
 129                                 _fd_clr (readfds->fd[r], readfds);
 130                                 continue;
 131                         }
 132 //printf ("select0: %d\n", readfds->fd[r]);
 133                         /* TODO: stdin, stdout */
 134
 135                         if (fd->flags & FD_SOCK) {      // socket select
 136                                 int ret = sselect (fd->id, 0, 0);
 137
 138                                 if (ret > 0){//printf ("select0: %d - %d\n", readfds->fd[r], ret);
 139                                           goto ready;
 140                                 }
 141                                 continue;
 142                         }
 143
 144                         if (!fd->s) {
 145                                 _fd_clr (fd->id, readfds);
 146                                 continue;
 147                         }
 148
 149 ready:
 150                         _fd_zero (readfds);
 151                         _fd_zero (writefds);
 152                         _fd_zero (exceptfds);
 153
 154                         _fd_set (fd->id, readfds);
 155
 156                         /* TODO: make select to handle more then one event per call */
 157                         return 1;
 158                 }
 159
 160                 schedule ();
 161         }
 162
 163         _fd_zero (readfds);
 164         _fd_zero (writefds);
 165         _fd_zero (exceptfds);
 166
 167         return 0;
 168 }
 169
 170