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 <dirent.h> /* readdir() */
  10 #include <assert.h>
  11 #include <stdbool.h>
  12
  13 #include "para.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "fd.h"
  17 #include "error.h"
  18 #include "stdout.h"
  19 #include "buffer_tree.h"
  20
  21 /**
  22  * The pre_select function of the stdout task.
  23  *
  24  * \param s The scheduler this task was registered to.
  25  * \param t The task structure of the stdout task.
  26  *
  27  * This function is always successful. If there is input data available, it
  28  * adds \p STDOUT_FILENO to the write fd set of \a s.
  29  */
  30 static void stdout_pre_select(struct sched *s, struct task *t)
  31 {
  32         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  33         int ret;
  34
  35         t->error = 0;
  36         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  37         if (ret > 0)
  38                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  39         else if (ret < 0)
  40                 sched_min_delay(s);
  41 }
  42
  43 /**
  44  * The post select function of the stdout task.
  45  *
  46  * \param s The scheduler this task was registered to.
  47  * \param t The task structure of the stdout task.
  48  *
  49  * This function writes input data from the buffer tree to stdout if \p
  50  * STDOUT_FILENO is writable.
  51  */
  52 static void stdout_post_select(struct sched *s, struct task *t)
  53 {
  54         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  55         struct btr_node *btrn = sot->btrn;
  56         int ret;
  57         char *buf;
  58         size_t sz;
  59
  60         t->error = 0;
  61         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  62         if (ret < 0)
  63                 goto out;
  64         if (ret == 0)
  65                 return;
  66         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  67                 return;
  68
  69         for (;;) {
  70                 sz = btr_next_buffer(btrn, &buf);
  71                 if (sz == 0)
  72                         break;
  73                 ret = write_nonblock(STDOUT_FILENO, buf, sz);
  74                 if (ret <= 0)
  75                         break;
  76                 btr_consume(btrn, ret);
  77         }
  78 out:
  79         if (ret < 0)
  80                 btr_remove_node(btrn);
  81         t->error = ret;
  82 }
  83 /**
  84  * Initialize a stdout task structure with default values.
  85  *
  86  * \param sot The stdout task structure.
  87  *
  88  * This fills in the pre/post select function pointers of the task structure
  89  * given by \a sot and sets the stdout file descriptor to nonblocking mode.
  90  */
  91 void stdout_set_defaults(struct stdout_task *sot)
  92 {
  93         int ret;
  94
  95         sot->task.pre_select = stdout_pre_select;
  96         sot->task.post_select = stdout_post_select;
  97         sprintf(sot->task.status, "stdout");
  98         ret = mark_fd_nonblocking(STDOUT_FILENO);
  99         if (ret >= 0)
 100                 return;
 101         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 102         exit(EXIT_FAILURE);
 103 }