stdin.c

   1 /*
   2  * Copyright (C) 2006-2014 Andre Noll <maan@tuebingen.mpg.de>
   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 <regex.h>
  10
  11 #include "para.h"
  12 #include "list.h"
  13 #include "sched.h"
  14 #include "fd.h"
  15 #include "error.h"
  16 #include "stdin.h"
  17 #include "buffer_tree.h"
  18 #include "string.h"
  19
  20 /*
  21  * If there is space left in the buffer of the stdin task add STDIN_FILENO to
  22  * the read fd set of s.
  23  */
  24 static void stdin_pre_select(struct sched *s, void *context)
  25 {
  26         struct stdin_task *sit = context;
  27         int ret;
  28
  29         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  30         if (ret < 0)
  31                 sched_min_delay(s);
  32         if (ret <= 0)
  33                 return;
  34         if (btr_pool_unused(sit->btrp) > 0)
  35                 return para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  36         sched_request_timeout_ms(100, s);
  37 }
  38
  39 /*
  40  * This function checks if STDIN_FILENO was included by in the read fd set of s
  41  * during the previous pre_select call. If so, and if STDIN_FILENO is readable,
  42  * data is read from stdin and fed into the buffer tree.
  43  */
  44 static int stdin_post_select(struct sched *s, void *context)
  45 {
  46         struct stdin_task *sit = context;
  47         ssize_t ret;
  48         size_t sz, n;
  49         char *buf = NULL;
  50
  51         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  52         if (ret < 0)
  53                 goto err;
  54         if (ret == 0)
  55                 return 0;
  56         sz = btr_pool_get_buffer(sit->btrp, &buf);
  57         if (sz == 0)
  58                 return 0;
  59         if (sit->must_set_nonblock_flag) {
  60                 ret = mark_fd_nonblocking(STDIN_FILENO);
  61                 if (ret < 0)
  62                         goto err;
  63                 sit->must_set_nonblock_flag = false;
  64         }
  65         /*
  66          * Do not use the maximal size to avoid having only a single buffer
  67          * reference for the whole pool. This is bad because if that single
  68          * reference can not be freed, we're stuck.
  69          */
  70         sz = PARA_MIN(sz, btr_pool_size(sit->btrp) / 2);
  71         ret = read_nonblock(STDIN_FILENO, buf, sz, &s->rfds, &n);
  72         if (n > 0)
  73                 btr_add_output_pool(sit->btrp, n, sit->btrn);
  74         if (ret >= 0)
  75                 return 0;
  76 err:
  77         btr_remove_node(&sit->btrn);
  78         /* Revert to blocking mode if necessary. */
  79         fcntl(STDIN_FILENO, F_SETFL, sit->fd_flags);
  80         //btr_pool_free(sit->btrp);
  81         return ret;
  82 }
  83
  84 /**
  85  * Register a stdin task structure.
  86  *
  87  * \param sit The stdin task structure to register.
  88  * \param s The task will be added to this scheduler's task list.
  89  *
  90  * This allocates a buffer tree pool for I/O, sets up \a sit and registers a
  91  * task with \a sit as context pointer.
  92  */
  93 void stdin_task_register(struct stdin_task *sit, struct sched *s)
  94 {
  95         int ret;
  96         struct task_info ti = {
  97                 .name = "stdin",
  98                 .pre_select = stdin_pre_select,
  99                 .post_select = stdin_post_select,
 100                 .context = sit,
 101         };
 102
 103         sit->btrp = btr_pool_new("stdin", 128 * 1024);
 104         /*
 105          * Both STDIN_FILENO and STDOUT_FILENO may refer to the same open file
 106          * description (the terminal), and thus share the same file status
 107          * flags. In order to not interfere with the stdout task, we only get
 108          * the file status flags for STDIN here and save a copy. The nonblock
 109          * flag is set later on the first read.
 110          */
 111         ret = fcntl(STDIN_FILENO, F_GETFL);
 112         if (ret < 0) {
 113                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
 114                 exit(EXIT_FAILURE);
 115         }
 116         sit->fd_flags = ret;
 117         sit->must_set_nonblock_flag = (sit->fd_flags & O_NONBLOCK) == 0;
 118         sit->task = task_register(&ti, s);
 119 }