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