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         t->error = 0;
  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 /**
  43  * The post select function of the stdin task.
  44  *
  45  * \param s The scheduler this task was registered to.
  46  * \param t The task structure of the stdin task.
  47  *
  48  * This function checks if \p STDIN_FILENO was included by in the read fd set
  49  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  50  * appears to be readable, data is read from stdin into the buffer of the
  51  * stdin task.
  52  */
  53 static void stdin_post_select(struct sched *s, struct task *t)
  54 {
  55         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  56         ssize_t ret;
  57
  58         t->error = 0;
  59         if (!sit->check_fd)
  60                 return;
  61         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  62                 return;
  63         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  64         if (ret < 0)
  65                 t->error = ERRNO_TO_PARA_ERROR(errno);
  66         else if (ret > 0)
  67                 sit->loaded += ret;
  68         else
  69                 t->error = -E_STDIN_EOF;
  70 }
  71
  72 /**
  73  * Initialize a stdin task structure with default values.
  74  *
  75  * \param sit The stdin task structure.
  76  *
  77  * This fills in the pre/post select function pointers of the task structure
  78  * given by \a sit. It also sets up a default error handler which unregisters
  79  * the task. Moreover, \a loaded and \a eof are set to zero and \a bufsize is
  80  * initialized to 16 KB (but no buffer is allocated).
  81  */
  82 void stdin_set_defaults(struct stdin_task *sit)
  83 {
  84         int ret;
  85
  86         sit->bufsize = 16 * 1024,
  87         sit->loaded = 0,
  88         sit->task.pre_select = stdin_pre_select;
  89         sit->task.post_select = stdin_post_select;
  90         sprintf(sit->task.status, "stdin reader");
  91         ret = mark_fd_nonblocking(STDIN_FILENO);
  92         if (ret >= 0)
  93                 return;
  94         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
  95         exit(EXIT_FAILURE);
  96 }