stdout.c

   1 /* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file stdout.c Functions that deal with writing to stdout. */
   4
   5 #include "para.h"
   6 #include "list.h"
   7 #include "sched.h"
   8 #include "fd.h"
   9 #include "error.h"
  10 #include "stdout.h"
  11 #include "buffer_tree.h"
  12
  13 /* Add STDOUT_FILENO to the write fd set if there is input data available. */
  14 static void stdout_pre_select(struct sched *s, void *context)
  15 {
  16         struct stdout_task *sot = context;
  17         int ret;
  18
  19         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  20         if (ret > 0)
  21                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  22         else if (ret < 0)
  23                 sched_min_delay(s);
  24 }
  25
  26 /*
  27  * This function writes input data from the buffer tree to stdout if
  28  * STDOUT_FILENO is writable.
  29  */
  30 static int stdout_post_select(struct sched *s, void *context)
  31 {
  32         struct stdout_task *sot = context;
  33         struct btr_node *btrn = sot->btrn;
  34         int ret;
  35         char *buf;
  36         size_t sz;
  37
  38         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
  39         if (ret < 0)
  40                 goto out;
  41         if (ret == 0)
  42                 return 0;
  43         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  44                 return 0;
  45
  46         if (sot->must_set_nonblock_flag) {
  47                 ret = mark_fd_nonblocking(STDOUT_FILENO);
  48                 if (ret < 0)
  49                         goto out;
  50                 sot->must_set_nonblock_flag = false;
  51         }
  52         for (;;) {
  53                 sz = btr_next_buffer(btrn, &buf);
  54                 if (sz == 0)
  55                         break;
  56                 ret = xwrite(STDOUT_FILENO, buf, sz);
  57                 if (ret <= 0)
  58                         break;
  59                 btr_consume(btrn, ret);
  60         }
  61 out:
  62         if (ret < 0) {
  63                 btr_remove_node(&sot->btrn);
  64                 /* Revert to blocking mode if necessary. */
  65                 fcntl(STDOUT_FILENO, F_SETFL, sot->fd_flags);
  66         }
  67         return ret;
  68 }
  69
  70 /**
  71  * Register a stdout task structure.
  72  *
  73  * \param sot The stdout task structure to register.
  74  * \param s The task will be added to this scheduler's task list.
  75  *
  76  * This sets up \a sot and registers a task with \a sot as context pointer.
  77  */
  78 void stdout_task_register(struct stdout_task *sot, struct sched *s)
  79 {
  80         int ret;
  81         struct task_info ti = {
  82                 .pre_select = stdout_pre_select,
  83                 .post_select = stdout_post_select,
  84                 .context = sot,
  85                 .name = "stdout",
  86         };
  87
  88         /* See \ref stdin.c for details. */
  89         ret = fcntl(STDOUT_FILENO, F_GETFL);
  90         if (ret < 0) {
  91                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
  92                 exit(EXIT_FAILURE);
  93         }
  94         sot->fd_flags = ret;
  95         sot->must_set_nonblock_flag = (sot->fd_flags & O_NONBLOCK) == 0
  96                 && !isatty(STDOUT_FILENO);
  97         sot->task = task_register(&ti, s);
  98 }