stdin.c

   1 /*
   2  * Copyright (C) 2006-2011 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 <stdbool.h>
  11 #include <regex.h>
  12
  13 #include "para.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "fd.h"
  17 #include "error.h"
  18 #include "stdin.h"
  19 #include "buffer_tree.h"
  20 #include "string.h"
  21
  22 /**
  23  * The pre_select function of the stdin task.
  24  *
  25  * \param s The scheduler this task was registered to.
  26  * \param t The task structure of the stdin task.
  27  *
  28  * This function is always successful. If there is space left in the
  29  * buffer of the stdin task, it adds \p STDIN_FILENO to the read fd set
  30  * of \a s.
  31  */
  32 static void stdin_pre_select(struct sched *s, struct task *t)
  33 {
  34         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  35         int ret;
  36
  37         t->error = 0;
  38         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  39         if (ret < 0)
  40                 sched_min_delay(s);
  41         if (ret <= 0)
  42                 return;
  43         if (btr_pool_unused(sit->btrp) > 0)
  44                 return para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  45         sched_request_timeout_ms(100, s);
  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  * appears to be readable, data is read from stdin and fed into the buffer
  57  * tree.
  58  */
  59 static void stdin_post_select(struct sched *s, struct task *t)
  60 {
  61         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  62         ssize_t ret;
  63         size_t sz, n;
  64         char *buf = NULL;
  65
  66         t->error = 0;
  67         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  68         if (ret < 0)
  69                 goto err;
  70         if (ret == 0)
  71                 return;
  72         sz = btr_pool_get_buffer(sit->btrp, &buf);
  73         if (sz == 0)
  74                 return;
  75         /*
  76          * Do not use the maximal size to avoid having only a single buffer
  77          * reference for the whole pool. This is bad because if that single
  78          * reference can not be freed, we're stuck.
  79          */
  80         sz = PARA_MIN(sz, btr_pool_size(sit->btrp) / 2);
  81         ret = read_nonblock(STDIN_FILENO, buf, sz, &s->rfds, &n);
  82         if (n > 0)
  83                 btr_add_output_pool(sit->btrp, n, sit->btrn);
  84         if (ret >= 0)
  85                 return;
  86 err:
  87         btr_remove_node(sit->btrn);
  88         //btr_pool_free(sit->btrp);
  89         t->error = ret;
  90 }
  91
  92 /**
  93  * Initialize a stdin task structure with default values.
  94  *
  95  * \param sit The stdin task structure.
  96  *
  97  * This fills in the pre/post select function pointers of the task structure
  98  * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
  99  * mode, and a buffer tree is created.
 100  */
 101 void stdin_set_defaults(struct stdin_task *sit)
 102 {
 103         int ret;
 104
 105         sit->task.pre_select = stdin_pre_select;
 106         sit->task.post_select = stdin_post_select;
 107         sit->btrp = btr_pool_new("stdin", 64 * 1024);
 108         sprintf(sit->task.status, "stdin reader");
 109         ret = mark_fd_nonblocking(STDIN_FILENO);
 110         if (ret >= 0)
 111                 return;
 112         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 113         exit(EXIT_FAILURE);
 114 }