stdin.c

   1 /*
   2  * Copyright (C) 2006-2008 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 = container_of(t, struct stdin_task, task);
  34
  35         if (sit->output_error && *sit->output_error < 0) {
  36                 t->error = *sit->output_error;
  37                 return;
  38         }
  39         t->error = 0;
  40         sit->check_fd = 0;
  41         if (sit->loaded >= sit->bufsize)
  42                 return;
  43         sit->check_fd = 1;
  44         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  45 }
  46
  47 /**
  48  * The post select function of the stdin task.
  49  *
  50  * \param s The scheduler this task was registered to.
  51  * \param t The task structure of the stdin task.
  52  *
  53  * This function checks if \p STDIN_FILENO was included by in the read fd set
  54  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  55  * appears to be readable, data is read from stdin into the buffer of the
  56  * stdin task.
  57  */
  58 static void stdin_post_select(struct sched *s, struct task *t)
  59 {
  60         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  61         ssize_t ret;
  62
  63         if (sit->output_error && *sit->output_error < 0) {
  64                 t->error = *sit->output_error;
  65                 return;
  66         }
  67         t->error = 0;
  68         if (!sit->check_fd)
  69                 return;
  70         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  71                 return;
  72         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  73         if (ret < 0)
  74                 t->error = ERRNO_TO_PARA_ERROR(errno);
  75         else if (ret > 0)
  76                 sit->loaded += ret;
  77         else
  78                 t->error = -E_STDIN_EOF;
  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 pointers of the task structure
  87  * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
  88  * mode and \a bufsize is initialized to 16 KB (but no buffer is allocated).
  89  */
  90 void stdin_set_defaults(struct stdin_task *sit)
  91 {
  92         int ret;
  93
  94         sit->bufsize = 16 * 1024,
  95         sit->task.pre_select = stdin_pre_select;
  96         sit->task.post_select = stdin_post_select;
  97         sprintf(sit->task.status, "stdin reader");
  98         ret = mark_fd_nonblocking(STDIN_FILENO);
  99         if (ret >= 0)
 100                 return;
 101         sit->output_error = NULL;
 102         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 103         exit(EXIT_FAILURE);
 104 }