stdin.c

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file stdin.c functions that deal with reading from stdin */
   8
   9 #include "para.h"
  10 #include "string.h"
  11 #include "list.h"
  12 #include "sched.h"
  13 #include "fd.h"
  14 #include "error.h"
  15 #include "stdin.h"
  16
  17 /**
  18  * the pre_select function of the stdin task
  19  *
  20  * \param s the scheduler this task was registered to
  21  * \param t the task structure of the stdin task
  22  *
  23  * This function is always successful. If there is space left in the
  24  * buffer of the stdin task, it adds \p STDIN_FILENO to the read fd set
  25  * of \a s.
  26  */
  27 void stdin_pre_select(struct sched *s, struct task *t)
  28 {
  29         struct stdin_task *sit = t->private_data;
  30         t->ret = 1;
  31         sit->check_fd = 0;
  32         if (sit->loaded >= sit->bufsize)
  33                 return;
  34         sit->check_fd = 1;
  35         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  36 }
  37
  38 static void stdin_default_event_handler(struct task *t)
  39 {
  40         PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
  41         unregister_task(t);
  42 }
  43
  44 /**
  45  * the post select function of the stdin task
  46  *
  47  * \param s the scheduler this task was registered to
  48  * \param t the task structure of the stdin task
  49  *
  50  * This function checks if \p STDIN_FILENO was included by in the read fd set
  51  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  52  * appeears to be readable, data is read from stdin into the buffer of the
  53  * stdin task.
  54  */
  55 void stdin_post_select(struct sched *s, struct task *t)
  56 {
  57         struct stdin_task *sit = t->private_data;
  58         ssize_t ret;
  59
  60         t->ret = 1;
  61         if (!sit->check_fd)
  62                 return;
  63         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  64                 return;
  65         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  66         if (ret < 0)
  67                 t->ret = -E_STDIN_READ;
  68         else if (ret > 0) {
  69                 sit->loaded += ret;
  70                 t->ret = ret;
  71         } else
  72                 t->ret = -E_STDIN_EOF;
  73         if (t->ret < 0)
  74                 sit->eof = 1;
  75 }
  76
  77 /**
  78  * initialize a stdin task structure with default values
  79  *
  80  * \param sit the stdin task structure
  81  *
  82  * This fills in the pre/post select function poinzters of the task structure
  83  * given by \a sot. It also sets up a default error handler which unregisters
  84  * the task. Moreover, \a loaded and \a eof are set to zero and \a bufsize is
  85  * initialized to 16 KB (but no buffer is allocated).
  86  */
  87 void stdin_set_defaults(struct stdin_task *sit)
  88 {
  89         sit->bufsize = 16 * 1024,
  90         sit->loaded = 0,
  91         sit->eof = 0,
  92         sit->task.pre_select = stdin_pre_select;
  93         sit->task.post_select = stdin_post_select;
  94         sit->task.event_handler = stdin_default_event_handler;
  95         sit->task.private_data = sit;
  96         mark_fd_nonblock(STDIN_FILENO);
  97         sprintf(sit->task.status, "stdin reader");
  98 }