stdout.c

   1 /*
   2  * Copyright (C) 2006-2014 Andre Noll <maan@tuebingen.mpg.de>
   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 /* Add STDOUT_FILENO to the write fd set if there is input data available. */
  20 static void stdout_pre_select(struct sched *s, void *context)
  21 {
  22         struct stdout_task *sot = context;
  23         int ret;
  24
  25         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  26         if (ret > 0)
  27                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  28         else if (ret < 0)
  29                 sched_min_delay(s);
  30 }
  31
  32 /*
  33  * This function writes input data from the buffer tree to stdout if
  34  * STDOUT_FILENO is writable.
  35  */
  36 static int stdout_post_select(struct sched *s, void *context)
  37 {
  38         struct stdout_task *sot = context;
  39         struct btr_node *btrn = sot->btrn;
  40         int ret;
  41         char *buf;
  42         size_t sz;
  43
  44         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  45         if (ret < 0)
  46                 goto out;
  47         if (ret == 0)
  48                 return 0;
  49         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  50                 return 0;
  51
  52         if (sot->must_set_nonblock_flag) {
  53                 ret = mark_fd_nonblocking(STDOUT_FILENO);
  54                 if (ret < 0)
  55                         goto out;
  56                 sot->must_set_nonblock_flag = false;
  57         }
  58         for (;;) {
  59                 sz = btr_next_buffer(btrn, &buf);
  60                 if (sz == 0)
  61                         break;
  62                 ret = xwrite(STDOUT_FILENO, buf, sz);
  63                 if (ret <= 0)
  64                         break;
  65                 btr_consume(btrn, ret);
  66         }
  67 out:
  68         if (ret < 0) {
  69                 btr_remove_node(&sot->btrn);
  70                 /* Revert to blocking mode if necessary. */
  71                 fcntl(STDOUT_FILENO, F_SETFL, sot->fd_flags);
  72         }
  73         return ret;
  74 }
  75
  76 /**
  77  * Register a stdout task structure.
  78  *
  79  * \param sot The stdout task structure to register.
  80  * \param s The task will be added to this scheduler's task list.
  81  *
  82  * This sets up \a sot and registers a task with \a sot as context pointer.
  83  */
  84 void stdout_task_register(struct stdout_task *sot, struct sched *s)
  85 {
  86         int ret;
  87         struct task_info ti = {
  88                 .pre_select = stdout_pre_select,
  89                 .post_select = stdout_post_select,
  90                 .context = sot,
  91                 .name = "stdout",
  92         };
  93
  94         /* See stdin.c for details. */
  95         ret = fcntl(STDOUT_FILENO, F_GETFL);
  96         if (ret < 0) {
  97                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
  98                 exit(EXIT_FAILURE);
  99         }
 100         sot->fd_flags = ret;
 101         sot->must_set_nonblock_flag = (sot->fd_flags & O_NONBLOCK) == 0;
 102         sot->task = task_register(&ti, s);
 103 }