stdout.c

   1 /*
   2  * Copyright (C) 2006-2013 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         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  34         if (ret > 0)
  35                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  36         else if (ret < 0)
  37                 sched_min_delay(s);
  38 }
  39
  40 /**
  41  * The post select function of the stdout task.
  42  *
  43  * \param s The scheduler this task was registered to.
  44  * \param t The task structure of the stdout task.
  45  *
  46  * This function writes input data from the buffer tree to stdout if \p
  47  * STDOUT_FILENO is writable.
  48  */
  49 static int stdout_post_select(struct sched *s, struct task *t)
  50 {
  51         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  52         struct btr_node *btrn = sot->btrn;
  53         int ret;
  54         char *buf;
  55         size_t sz;
  56
  57         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  58         if (ret < 0)
  59                 goto out;
  60         if (ret == 0)
  61                 return 0;
  62         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  63                 return 0;
  64
  65         if (sot->must_set_nonblock_flag) {
  66                 ret = mark_fd_nonblocking(STDOUT_FILENO);
  67                 if (ret < 0)
  68                         goto out;
  69                 sot->must_set_nonblock_flag = false;
  70         }
  71         for (;;) {
  72                 sz = btr_next_buffer(btrn, &buf);
  73                 if (sz == 0)
  74                         break;
  75                 ret = xwrite(STDOUT_FILENO, buf, sz);
  76                 if (ret <= 0)
  77                         break;
  78                 btr_consume(btrn, ret);
  79         }
  80 out:
  81         if (ret < 0) {
  82                 btr_remove_node(&sot->btrn);
  83                 /* Revert to blocking mode if necessary. */
  84                 fcntl(STDOUT_FILENO, F_SETFL, sot->fd_flags);
  85         }
  86         return ret;
  87 }
  88 /**
  89  * Initialize a stdout task structure with default values.
  90  *
  91  * \param sot The stdout task structure.
  92  *
  93  * This fills in the pre/post select function pointers of the task structure
  94  * given by \a sot.
  95  */
  96 void stdout_set_defaults(struct stdout_task *sot)
  97 {
  98         int ret;
  99
 100         sot->task.pre_select = stdout_pre_select;
 101         sot->task.post_select = stdout_post_select;
 102         sprintf(sot->task.status, "stdout");
 103
 104         /* See stdin.c for details. */
 105         ret = fcntl(STDOUT_FILENO, F_GETFL);
 106         if (ret < 0) {
 107                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
 108                 exit(EXIT_FAILURE);
 109         }
 110         sot->fd_flags = ret;
 111         sot->must_set_nonblock_flag = (sot->fd_flags & O_NONBLOCK) == 0;
 112 }