stdin.c

   1 /*
   2  * Copyright (C) 2006-2012 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 <assert.h>
  10 #include <regex.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 #include "buffer_tree.h"
  19 #include "string.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         int ret;
  35
  36         t->error = 0;
  37         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  38         if (ret < 0)
  39                 sched_min_delay(s);
  40         if (ret <= 0)
  41                 return;
  42         if (btr_pool_unused(sit->btrp) > 0)
  43                 return para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  44         sched_request_timeout_ms(100, s);
  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 and fed into the buffer
  56  * tree.
  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         size_t sz, n;
  63         char *buf = NULL;
  64
  65         t->error = 0;
  66         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  67         if (ret < 0)
  68                 goto err;
  69         if (ret == 0)
  70                 return;
  71         sz = btr_pool_get_buffer(sit->btrp, &buf);
  72         if (sz == 0)
  73                 return;
  74         /*
  75          * Do not use the maximal size to avoid having only a single buffer
  76          * reference for the whole pool. This is bad because if that single
  77          * reference can not be freed, we're stuck.
  78          */
  79         sz = PARA_MIN(sz, btr_pool_size(sit->btrp) / 2);
  80         ret = read_nonblock(STDIN_FILENO, buf, sz, &s->rfds, &n);
  81         if (n > 0)
  82                 btr_add_output_pool(sit->btrp, n, sit->btrn);
  83         if (ret >= 0)
  84                 return;
  85 err:
  86         btr_remove_node(sit->btrn);
  87         //btr_pool_free(sit->btrp);
  88         t->error = ret;
  89 }
  90
  91 /**
  92  * Initialize a stdin task structure with default values.
  93  *
  94  * \param sit The stdin task structure.
  95  *
  96  * This fills in the pre/post select function pointers of the task structure
  97  * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
  98  * mode, and a buffer tree is created.
  99  */
 100 void stdin_set_defaults(struct stdin_task *sit)
 101 {
 102         int ret;
 103
 104         sit->task.pre_select = stdin_pre_select;
 105         sit->task.post_select = stdin_post_select;
 106         sit->btrp = btr_pool_new("stdin", 128 * 1024);
 107         sprintf(sit->task.status, "stdin reader");
 108         ret = mark_fd_nonblocking(STDIN_FILENO);
 109         if (ret >= 0)
 110                 return;
 111         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 112         exit(EXIT_FAILURE);
 113 }