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 <dirent.h> /* readdir() */
  10 #include <assert.h>
  11
  12
  13 #include "para.h"
  14 #include "string.h"
  15 #include "list.h"
  16 #include "sched.h"
  17 #include "fd.h"
  18 #include "error.h"
  19 #include "stdin.h"
  20
  21 /**
  22  * the pre_select function of the stdin task
  23  *
  24  * \param s the scheduler this task was registered to
  25  * \param t the task structure of the stdin task
  26  *
  27  * This function is always successful. If there is space left in the
  28  * buffer of the stdin task, it adds \p STDIN_FILENO to the read fd set
  29  * of \a s.
  30  */
  31 static void stdin_pre_select(struct sched *s, struct task *t)
  32 {
  33         struct stdin_task *sit = t->private_data;
  34         t->ret = 1;
  35         sit->check_fd = 0;
  36         if (sit->loaded >= sit->bufsize)
  37                 return;
  38         sit->check_fd = 1;
  39         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  40 }
  41
  42 static void stdin_default_event_handler(struct task *t)
  43 {
  44         PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
  45         unregister_task(t);
  46 }
  47
  48 /**
  49  * the post select function of the stdin task
  50  *
  51  * \param s the scheduler this task was registered to
  52  * \param t the task structure of the stdin task
  53  *
  54  * This function checks if \p STDIN_FILENO was included by in the read fd set
  55  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  56  * appeears to be readable, data is read from stdin into the buffer of the
  57  * stdin task.
  58  */
  59 static void stdin_post_select(struct sched *s, struct task *t)
  60 {
  61         struct stdin_task *sit = t->private_data;
  62         ssize_t ret;
  63
  64         t->ret = 1;
  65         if (!sit->check_fd)
  66                 return;
  67         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  68                 return;
  69         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  70         if (ret < 0)
  71                 t->ret = -E_STDIN_READ;
  72         else if (ret > 0) {
  73                 sit->loaded += ret;
  74                 t->ret = ret;
  75         } else
  76                 t->ret = -E_STDIN_EOF;
  77         if (t->ret < 0)
  78                 sit->eof = 1;
  79 }
  80
  81 /**
  82  * Initialize a stdin task structure with default values.
  83  *
  84  * \param sit The stdin task structure.
  85  *
  86  * This fills in the pre/post select function poinzters of the task structure
  87  * given by \a sit. It also sets up a default error handler which unregisters
  88  * the task. Moreover, \a loaded and \a eof are set to zero and \a bufsize is
  89  * initialized to 16 KB (but no buffer is allocated).
  90  */
  91 void stdin_set_defaults(struct stdin_task *sit)
  92 {
  93         sit->bufsize = 16 * 1024,
  94         sit->loaded = 0,
  95         sit->eof = 0,
  96         sit->task.pre_select = stdin_pre_select;
  97         sit->task.post_select = stdin_post_select;
  98         sit->task.event_handler = stdin_default_event_handler;
  99         sit->task.private_data = sit;
 100         mark_fd_nonblock(STDIN_FILENO);
 101         sprintf(sit->task.status, "stdin reader");
 102 }