stdin.c

   1 /*
   2  * Copyright (C) 2006-2009 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 #include "para.h"
  13 #include "list.h"
  14 #include "sched.h"
  15 #include "fd.h"
  16 #include "error.h"
  17 #include "stdin.h"
  18
  19 /**
  20  * The pre_select function of the stdin task.
  21  *
  22  * \param s The scheduler this task was registered to.
  23  * \param t The task structure of the stdin task.
  24  *
  25  * This function is always successful. If there is space left in the
  26  * buffer of the stdin task, it adds \p STDIN_FILENO to the read fd set
  27  * of \a s.
  28  */
  29 static void stdin_pre_select(struct sched *s, struct task *t)
  30 {
  31         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  32
  33         if (sit->output_error && *sit->output_error < 0) {
  34                 t->error = *sit->output_error;
  35                 return;
  36         }
  37         t->error = 0;
  38         sit->check_fd = 0;
  39         if (sit->loaded >= sit->bufsize)
  40                 return;
  41         sit->check_fd = 1;
  42         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  43 }
  44
  45 /**
  46  * The post select function of the stdin task.
  47  *
  48  * \param s The scheduler this task was registered to.
  49  * \param t The task structure of the stdin task.
  50  *
  51  * This function checks if \p STDIN_FILENO was included by in the read fd set
  52  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  53  * appears to be readable, data is read from stdin into the buffer of the
  54  * stdin task.
  55  */
  56 static void stdin_post_select(struct sched *s, struct task *t)
  57 {
  58         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  59         ssize_t ret;
  60
  61         if (sit->output_error && *sit->output_error < 0) {
  62                 t->error = *sit->output_error;
  63                 return;
  64         }
  65         t->error = 0;
  66         if (!sit->check_fd)
  67                 return;
  68         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  69                 return;
  70         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  71         if (ret < 0)
  72                 t->error = ERRNO_TO_PARA_ERROR(errno);
  73         else if (ret > 0)
  74                 sit->loaded += ret;
  75         else
  76                 t->error = -E_STDIN_EOF;
  77 }
  78
  79 /**
  80  * Initialize a stdin task structure with default values.
  81  *
  82  * \param sit The stdin task structure.
  83  *
  84  * This fills in the pre/post select function pointers of the task structure
  85  * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
  86  * mode and \a bufsize is initialized to 16 KB (but no buffer is allocated).
  87  */
  88 void stdin_set_defaults(struct stdin_task *sit)
  89 {
  90         int ret;
  91
  92         sit->bufsize = 32 * 1024,
  93         sit->task.pre_select = stdin_pre_select;
  94         sit->task.post_select = stdin_post_select;
  95         sprintf(sit->task.status, "stdin reader");
  96         ret = mark_fd_nonblocking(STDIN_FILENO);
  97         if (ret >= 0)
  98                 return;
  99         sit->output_error = NULL;
 100         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 101         exit(EXIT_FAILURE);
 102 }