stdout.c

   1 /*
   2  * Copyright (C) 2006-2011 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 <assert.h>
  10 #include <stdbool.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 #include "buffer_tree.h"
  19
  20 /**
  21  * The pre_select function of the stdout task.
  22  *
  23  * \param s The scheduler this task was registered to.
  24  * \param t The task structure of the stdout task.
  25  *
  26  * This function is always successful. If there is input data available, it
  27  * adds \p STDOUT_FILENO to the write fd set of \a s.
  28  */
  29 static void stdout_pre_select(struct sched *s, struct task *t)
  30 {
  31         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  32         int ret;
  33
  34         t->error = 0;
  35         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  36         if (ret > 0)
  37                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  38         else if (ret < 0)
  39                 sched_min_delay(s);
  40 }
  41
  42 /**
  43  * The post select function of the stdout task.
  44  *
  45  * \param s The scheduler this task was registered to.
  46  * \param t The task structure of the stdout task.
  47  *
  48  * This function writes input data from the buffer tree to stdout if \p
  49  * STDOUT_FILENO is writable.
  50  */
  51 static void stdout_post_select(struct sched *s, struct task *t)
  52 {
  53         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  54         struct btr_node *btrn = sot->btrn;
  55         int ret;
  56         char *buf;
  57         size_t sz;
  58
  59         t->error = 0;
  60         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  61         if (ret < 0)
  62                 goto out;
  63         if (ret == 0)
  64                 return;
  65         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  66                 return;
  67
  68         for (;;) {
  69                 sz = btr_next_buffer(btrn, &buf);
  70                 if (sz == 0)
  71                         break;
  72                 ret = write_nonblock(STDOUT_FILENO, buf, sz);
  73                 if (ret <= 0)
  74                         break;
  75                 btr_consume(btrn, ret);
  76         }
  77 out:
  78         if (ret < 0)
  79                 btr_remove_node(btrn);
  80         t->error = ret;
  81 }
  82 /**
  83  * Initialize a stdout task structure with default values.
  84  *
  85  * \param sot The stdout task structure.
  86  *
  87  * This fills in the pre/post select function pointers of the task structure
  88  * given by \a sot and sets the stdout file descriptor to nonblocking mode.
  89  */
  90 void stdout_set_defaults(struct stdout_task *sot)
  91 {
  92         int ret;
  93
  94         sot->task.pre_select = stdout_pre_select;
  95         sot->task.post_select = stdout_post_select;
  96         sprintf(sot->task.status, "stdout");
  97         ret = mark_fd_nonblocking(STDOUT_FILENO);
  98         if (ret >= 0)
  99                 return;
 100         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 101         exit(EXIT_FAILURE);
 102 }