stdout.c

   1 /*
   2  * Copyright (C) 2006-2009 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 <dirent.h> /* readdir() */
  10 #include <assert.h>
  11
  12 #include "para.h"
  13 #include "list.h"
  14 #include "sched.h"
  15 #include "fd.h"
  16 #include "error.h"
  17 #include "stdout.h"
  18
  19 /**
  20  * The pre_select function of the stdout task.
  21  *
  22  * \param s The scheduler this task was registered to.
  23  * \param t The task structure of the stdout task.
  24  *
  25  * This function is always successful. If there is data available in the input
  26  * buffer, it adds \p STDOUT_FILENO to the write fd set of \a s.
  27  */
  28 static void stdout_pre_select(struct sched *s, struct task *t)
  29 {
  30         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  31
  32         t->error = 0;
  33         sot->check_fd = 0;
  34         if (!*sot->loaded) {
  35                 if (*sot->input_error < 0) {
  36                         t->error = *sot->input_error;
  37                         s->timeout.tv_sec = 0;
  38                         s->timeout.tv_usec = 1;
  39                 }
  40                 return;
  41         }
  42         sot->check_fd = 1;
  43         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  44 }
  45
  46 /**
  47  * The post select function of the stdout task.
  48  *
  49  * \param s The scheduler this task was registered to.
  50  * \param t The task structure of the stdout task.
  51  *
  52  * This function checks if \p STDOUT_FILENO was included by in the write fd set
  53  * of \a s during the previous pre_select call.  If yes, and \p STDOUT_FILENO
  54  * appeears to be writable, the data loaded in the input buffer is written to
  55  * stdout.
  56  */
  57 static void stdout_post_select(struct sched *s, struct task *t)
  58 {
  59         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  60         ssize_t ret;
  61
  62         t->error = 0;
  63         if (!sot->check_fd) {
  64                 if (!*sot->loaded && *sot->input_error < 0)
  65                         t->error = *sot->input_error;
  66                 return;
  67         }
  68         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  69                 return;
  70         ret = write(STDOUT_FILENO, *sot->bufp, *sot->loaded);
  71         if (ret < 0) {
  72                 t->error = -ERRNO_TO_PARA_ERROR(errno);
  73                 return;
  74         }
  75         *sot->loaded -= ret;
  76         if (*sot->loaded)
  77                 memmove(*sot->bufp, *sot->bufp + ret, *sot->loaded);
  78 }
  79
  80 /**
  81  * Initialize a stdout task structure with default values.
  82  *
  83  * \param sot The stdout task structure.
  84  *
  85  * This fills in the pre/post select function poinzters of the task structure
  86  * given by \a sot.
  87  */
  88 void stdout_set_defaults(struct stdout_task *sot)
  89 {
  90         int ret;
  91
  92         sot->task.pre_select = stdout_pre_select;
  93         sot->task.post_select = stdout_post_select;
  94         sprintf(sot->task.status, "stdout writer");
  95         ret = mark_fd_nonblocking(STDOUT_FILENO);
  96         if (ret >= 0)
  97                 return;
  98         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
  99         exit(EXIT_FAILURE);
 100 }