stdin.c

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file stdin.c functions that deal with reading from stdin */
  20
  21 #include "para.h"
  22 #include "string.h"
  23 #include "list.h"
  24 #include "sched.h"
  25 #include "fd.h"
  26 #include "error.h"
  27 #include "stdin.h"
  28
  29 /**
  30  * the pre_select function of the stdin task
  31  *
  32  * \param s the scheduler this task was registered to
  33  * \param t the task structure of the stdin task
  34  *
  35  * This function is always successful. If there is space left in the
  36  * buffer of the stdin task, it adds \a STDIN_FILENO to the read fd set
  37  * of \a s.
  38  */
  39 void stdin_pre_select(struct sched *s, struct task *t)
  40 {
  41         struct stdin_task *sit = t->private_data;
  42         t->ret = 1;
  43         sit->check_fd = 0;
  44         if (sit->loaded >= sit->bufsize)
  45                 return;
  46         sit->check_fd = 1;
  47         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  48 }
  49
  50 static void stdin_default_event_handler(struct task *t)
  51 {
  52         PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
  53         unregister_task(t);
  54 }
  55
  56 /**
  57  * the post select function of the stdin task
  58  *
  59  * \param s the scheduler this task was registered to
  60  * \param t the task structure of the stdin task
  61  *
  62  * This function checks if \a STDIN_FILENO was included by in the read fd set
  63  * of \a s during the previous pre_select call.  If yes, and STDIN_FILENO
  64  * appeears to be readable, data is read from stdin into the buffer of the
  65  * stdin task.
  66  */
  67 void stdin_post_select(struct sched *s, struct task *t)
  68 {
  69         struct stdin_task *sit = t->private_data;
  70         ssize_t ret;
  71
  72         t->ret = 1;
  73         if (!sit->check_fd)
  74                 return;
  75         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  76                 return;
  77         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  78         if (ret < 0)
  79                 t->ret = -E_STDIN_READ;
  80         else if (ret > 0) {
  81                 sit->loaded += ret;
  82                 t->ret = ret;
  83         } else
  84                 t->ret = -E_STDIN_EOF;
  85         if (t->ret < 0)
  86                 sit->eof = 1;
  87 }
  88
  89 /**
  90  * initialize a stdin task structure with default values
  91  *
  92  * \param sit the stdin task structure
  93  *
  94  * This fills in the pre/post select function poinzters of the task structure
  95  * given by \a sot. It also sets up a default error handler which unregisters
  96  * the task. Moreover, \a loaded and \a eof are set to zero and \a bufsize is
  97  * initialized to 16 KB (but no buffer is allocated).
  98  */
  99 void stdin_set_defaults(struct stdin_task *sit)
 100 {
 101         sit->bufsize = 16 * 1024,
 102         sit->loaded = 0,
 103         sit->eof = 0,
 104         sit->task.pre_select = stdin_pre_select;
 105         sit->task.post_select = stdin_post_select;
 106         sit->task.event_handler = stdin_default_event_handler;
 107         sit->task.private_data = sit;
 108         sprintf(sit->task.status, "stdin reader");
 109 }