stdout.c

   1 /*
   2  * Copyright (C) 2006-2012 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
  11 #include "para.h"
  12 #include "list.h"
  13 #include "sched.h"
  14 #include "fd.h"
  15 #include "error.h"
  16 #include "stdout.h"
  17 #include "buffer_tree.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 input data available, it
  26  * 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         int ret;
  32
  33         t->error = 0;
  34         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  35         if (ret > 0)
  36                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  37         else if (ret < 0)
  38                 sched_min_delay(s);
  39 }
  40
  41 /**
  42  * The post select function of the stdout task.
  43  *
  44  * \param s The scheduler this task was registered to.
  45  * \param t The task structure of the stdout task.
  46  *
  47  * This function writes input data from the buffer tree to stdout if \p
  48  * STDOUT_FILENO is writable.
  49  */
  50 static void stdout_post_select(struct sched *s, struct task *t)
  51 {
  52         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  53         struct btr_node *btrn = sot->btrn;
  54         int ret;
  55         char *buf;
  56         size_t sz;
  57
  58         t->error = 0;
  59         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  60         if (ret < 0)
  61                 goto out;
  62         if (ret == 0)
  63                 return;
  64         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  65                 return;
  66
  67         for (;;) {
  68                 sz = btr_next_buffer(btrn, &buf);
  69                 if (sz == 0)
  70                         break;
  71                 ret = write_nonblock(STDOUT_FILENO, buf, sz);
  72                 if (ret <= 0)
  73                         break;
  74                 btr_consume(btrn, ret);
  75         }
  76 out:
  77         if (ret < 0)
  78                 btr_remove_node(btrn);
  79         t->error = ret;
  80 }
  81 /**
  82  * Initialize a stdout task structure with default values.
  83  *
  84  * \param sot The stdout task structure.
  85  *
  86  * This fills in the pre/post select function pointers of the task structure
  87  * given by \a sot and sets the stdout file descriptor to nonblocking mode.
  88  */
  89 void stdout_set_defaults(struct stdout_task *sot)
  90 {
  91         int ret;
  92
  93         sot->task.pre_select = stdout_pre_select;
  94         sot->task.post_select = stdout_post_select;
  95         sprintf(sot->task.status, "stdout");
  96         ret = mark_fd_nonblocking(STDOUT_FILENO);
  97         if (ret >= 0)
  98                 return;
  99         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 100         exit(EXIT_FAILURE);
 101 }