stdout.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 stdout.c functions that deal with writing to stdout */
  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 "stdout.h"
  28
  29
  30 /**
  31  * the pre_select function of the stdout task
  32  *
  33  * \param s the scheduler this task was registered to
  34  * \param t the task structure of the stdout task
  35  *
  36  * This function is always successful. If there is data available in the input
  37  * buffer, it adds \a STDOUT_FILENO to the write fd set of \a s.
  38  */
  39 void stdout_pre_select(struct sched *s, struct task *t)
  40 {
  41         struct stdout_task *sot = t->private_data;
  42
  43         t->ret = 1;
  44         sot->check_fd = 0;
  45         if (!*sot->loaded) {
  46                 if (*sot->input_eof) {
  47                         t->ret = -E_STDOUT_EOF;
  48                         s->timeout.tv_sec = 0;
  49                         s->timeout.tv_usec = 1;
  50                 }
  51                 return;
  52         }
  53         sot->check_fd = 1;
  54         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  55 }
  56
  57 /**
  58  * the post select function of the stdout task
  59  *
  60  * \param s the scheduler this task was registered to
  61  * \param t the task structure of the stdout task
  62  *
  63  * This function checks if \a STDOUT_FILENO was included by in the write fd set
  64  * of \a s during the previous pre_select call.  If yes, and STDOUT_FILENO
  65  * appeears to be writable, the data loaded in the input buffer is written to
  66  * stdout.
  67  */
  68 void stdout_post_select(struct sched *s, struct task *t)
  69 {
  70         struct stdout_task *sot = t->private_data;
  71         ssize_t ret;
  72
  73         t->ret = 1;
  74         if (!sot->check_fd) {
  75                 if (*sot->input_eof)
  76                         t->ret = -E_STDOUT_EOF;
  77                 return;
  78         }
  79         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  80                 return;
  81         t->ret = -E_STDOUT_WRITE;
  82         ret = write(STDOUT_FILENO, sot->buf, *sot->loaded);
  83         if (ret <= 0)
  84                 return;
  85         *sot->loaded -= ret;
  86         t->ret = 1;
  87 }
  88
  89 static void stdout_default_event_handler(struct task *t)
  90 {
  91         PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
  92         unregister_task(t);
  93 }
  94
  95 /**
  96  * initialize a stdout task structure with default values
  97  *
  98  * \param sot the stdout task structure
  99  *
 100  * This fills in the pre/post select function poinzters of the task structure
 101  * given by \a sot. It also sets up a default error handler which unregisters
 102  * the task on errors and clears the eof flag of \a sot.
 103  */
 104 void stdout_set_defaults(struct stdout_task *sot)
 105 {
 106         sot->task.private_data = sot;
 107         sot->task.pre_select = stdout_pre_select;
 108         sot->task.post_select = stdout_post_select;
 109         sot->task.event_handler = stdout_default_event_handler;
 110         sot->eof = 0;
 111         sprintf(sot->task.status, "stdout writer");
 112 }