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 "para.h"
  10 #include "list.h"
  11 #include "sched.h"
  12 #include "fd.h"
  13 #include "error.h"
  14 #include "stdout.h"
  15 #include "buffer_tree.h"
  16
  17 /* Add STDOUT_FILENO to the write fd set if there is input data available. */
  18 static void stdout_pre_select(struct sched *s, void *context)
  19 {
  20         struct stdout_task *sot = context;
  21         int ret;
  22
  23         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  24         if (ret > 0)
  25                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  26         else if (ret < 0)
  27                 sched_min_delay(s);
  28 }
  29
  30 /*
  31  * This function writes input data from the buffer tree to stdout if
  32  * STDOUT_FILENO is writable.
  33  */
  34 static int stdout_post_select(struct sched *s, void *context)
  35 {
  36         struct stdout_task *sot = context;
  37         struct btr_node *btrn = sot->btrn;
  38         int ret;
  39         char *buf;
  40         size_t sz;
  41
  42         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  43         if (ret < 0)
  44                 goto out;
  45         if (ret == 0)
  46                 return 0;
  47         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  48                 return 0;
  49
  50         if (sot->must_set_nonblock_flag) {
  51                 ret = mark_fd_nonblocking(STDOUT_FILENO);
  52                 if (ret < 0)
  53                         goto out;
  54                 sot->must_set_nonblock_flag = false;
  55         }
  56         for (;;) {
  57                 sz = btr_next_buffer(btrn, &buf);
  58                 if (sz == 0)
  59                         break;
  60                 ret = xwrite(STDOUT_FILENO, buf, sz);
  61                 if (ret <= 0)
  62                         break;
  63                 btr_consume(btrn, ret);
  64         }
  65 out:
  66         if (ret < 0) {
  67                 btr_remove_node(&sot->btrn);
  68                 /* Revert to blocking mode if necessary. */
  69                 fcntl(STDOUT_FILENO, F_SETFL, sot->fd_flags);
  70         }
  71         return ret;
  72 }
  73
  74 /**
  75  * Register a stdout task structure.
  76  *
  77  * \param sot The stdout task structure to register.
  78  * \param s The task will be added to this scheduler's task list.
  79  *
  80  * This sets up \a sot and registers a task with \a sot as context pointer.
  81  */
  82 void stdout_task_register(struct stdout_task *sot, struct sched *s)
  83 {
  84         int ret;
  85         struct task_info ti = {
  86                 .pre_select = stdout_pre_select,
  87                 .post_select = stdout_post_select,
  88                 .context = sot,
  89                 .name = "stdout",
  90         };
  91
  92         /* See stdin.c for details. */
  93         ret = fcntl(STDOUT_FILENO, F_GETFL);
  94         if (ret < 0) {
  95                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
  96                 exit(EXIT_FAILURE);
  97         }
  98         sot->fd_flags = ret;
  99         sot->must_set_nonblock_flag = (sot->fd_flags & O_NONBLOCK) == 0;
 100         sot->task = task_register(&ti, s);
 101 }