stdout.c

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file stdout.c functions that deal with writing to stdout */
   8
   9 #include "para.h"
  10 #include "string.h"
  11 #include "list.h"
  12 #include "sched.h"
  13 #include "fd.h"
  14 #include "error.h"
  15 #include "stdout.h"
  16
  17 /**
  18  * the pre_select function of the stdout task
  19  *
  20  * \param s the scheduler this task was registered to
  21  * \param t the task structure of the stdout task
  22  *
  23  * This function is always successful. If there is data available in the input
  24  * buffer, it adds \p STDOUT_FILENO to the write fd set of \a s.
  25  */
  26 void stdout_pre_select(struct sched *s, struct task *t)
  27 {
  28         struct stdout_task *sot = t->private_data;
  29
  30         t->ret = 1;
  31         sot->check_fd = 0;
  32         if (!*sot->loaded) {
  33                 if (*sot->input_eof) {
  34                         t->ret = -E_STDOUT_EOF;
  35                         s->timeout.tv_sec = 0;
  36                         s->timeout.tv_usec = 1;
  37                 }
  38                 return;
  39         }
  40         sot->check_fd = 1;
  41         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  42 }
  43
  44 /**
  45  * the post select function of the stdout task
  46  *
  47  * \param s the scheduler this task was registered to
  48  * \param t the task structure of the stdout task
  49  *
  50  * This function checks if \p STDOUT_FILENO was included by in the write fd set
  51  * of \a s during the previous pre_select call.  If yes, and \p STDOUT_FILENO
  52  * appeears to be writable, the data loaded in the input buffer is written to
  53  * stdout.
  54  */
  55 void stdout_post_select(struct sched *s, struct task *t)
  56 {
  57         struct stdout_task *sot = t->private_data;
  58         ssize_t ret;
  59
  60         t->ret = 1;
  61         if (!sot->check_fd) {
  62                 if (*sot->input_eof)
  63                         t->ret = -E_STDOUT_EOF;
  64                 return;
  65         }
  66         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  67                 return;
  68         t->ret = -E_STDOUT_WRITE;
  69         ret = write(STDOUT_FILENO, sot->buf, *sot->loaded);
  70         if (ret <= 0)
  71                 return;
  72         *sot->loaded -= ret;
  73         if (*sot->loaded)
  74                 memmove(sot->buf, sot->buf + ret, *sot->loaded);
  75         t->ret = 1;
  76 }
  77
  78 static void stdout_default_event_handler(struct task *t)
  79 {
  80         PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
  81         unregister_task(t);
  82 }
  83
  84 /**
  85  * initialize a stdout task structure with default values
  86  *
  87  * \param sot the stdout task structure
  88  *
  89  * This fills in the pre/post select function poinzters of the task structure
  90  * given by \a sot. It also sets up a default error handler which unregisters
  91  * the task on errors and clears the eof flag of \a sot.
  92  */
  93 void stdout_set_defaults(struct stdout_task *sot)
  94 {
  95         sot->task.private_data = sot;
  96         sot->task.pre_select = stdout_pre_select;
  97         sot->task.post_select = stdout_post_select;
  98         sot->task.event_handler = stdout_default_event_handler;
  99         sot->eof = 0;
 100         mark_fd_nonblock(STDOUT_FILENO);
 101         sprintf(sot->task.status, "stdout writer");
 102 }