stdin.c

   1 /* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file stdin.c Functions that deal with reading from stdin. */
   4
   5 #include <regex.h>
   6
   7 #include "para.h"
   8 #include "list.h"
   9 #include "sched.h"
  10 #include "fd.h"
  11 #include "error.h"
  12 #include "stdin.h"
  13 #include "buffer_tree.h"
  14 #include "string.h"
  15
  16 /*
  17  * If there is space left in the buffer of the stdin task add STDIN_FILENO to
  18  * the read fd set of s.
  19  */
  20 static void stdin_pre_select(struct sched *s, void *context)
  21 {
  22         struct stdin_task *sit = context;
  23         int ret;
  24
  25         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  26         if (ret < 0)
  27                 sched_min_delay(s);
  28         if (ret <= 0)
  29                 return;
  30         if (btr_pool_unused(sit->btrp) > 0)
  31                 return para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  32         sched_request_timeout_ms(100, s);
  33 }
  34
  35 /*
  36  * This function checks if STDIN_FILENO was included by in the read fd set of s
  37  * during the previous pre_select call. If so, and if STDIN_FILENO is readable,
  38  * data is read from stdin and fed into the buffer tree.
  39  */
  40 static int stdin_post_select(struct sched *s, void *context)
  41 {
  42         struct stdin_task *sit = context;
  43         ssize_t ret;
  44         size_t sz, n;
  45         char *buf = NULL;
  46
  47         ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
  48         if (ret < 0)
  49                 goto err;
  50         if (ret == 0)
  51                 return 0;
  52         sz = btr_pool_get_buffer(sit->btrp, &buf);
  53         if (sz == 0)
  54                 return 0;
  55         if (sit->must_set_nonblock_flag) {
  56                 ret = mark_fd_nonblocking(STDIN_FILENO);
  57                 if (ret < 0)
  58                         goto err;
  59                 sit->must_set_nonblock_flag = false;
  60         }
  61         /*
  62          * Do not use the maximal size to avoid having only a single buffer
  63          * reference for the whole pool. This is bad because if that single
  64          * reference can not be freed, we're stuck.
  65          */
  66         sz = PARA_MIN(sz, btr_pool_size(sit->btrp) / 2);
  67         ret = read_nonblock(STDIN_FILENO, buf, sz, &s->rfds, &n);
  68         if (n > 0)
  69                 btr_add_output_pool(sit->btrp, n, sit->btrn);
  70         if (ret >= 0)
  71                 return 0;
  72 err:
  73         btr_remove_node(&sit->btrn);
  74         /* Revert to blocking mode if necessary. */
  75         fcntl(STDIN_FILENO, F_SETFL, sit->fd_flags);
  76         //btr_pool_free(sit->btrp);
  77         return ret;
  78 }
  79
  80 /**
  81  * Register a stdin task structure.
  82  *
  83  * \param sit The stdin task structure to register.
  84  * \param s The task will be added to this scheduler's task list.
  85  *
  86  * This allocates a buffer tree pool for I/O, sets up \a sit and registers a
  87  * task with \a sit as context pointer.
  88  */
  89 void stdin_task_register(struct stdin_task *sit, struct sched *s)
  90 {
  91         int ret;
  92         struct task_info ti = {
  93                 .name = "stdin",
  94                 .pre_select = stdin_pre_select,
  95                 .post_select = stdin_post_select,
  96                 .context = sit,
  97         };
  98
  99         sit->btrp = btr_pool_new("stdin", 128 * 1024);
 100         /*
 101          * Both STDIN_FILENO and STDOUT_FILENO may refer to the same open file
 102          * description (the terminal), and thus share the same file status
 103          * flags. In order to not interfere with the stdout task, we only get
 104          * the file status flags for STDIN here and save a copy. The nonblock
 105          * flag is set later on the first read.
 106          */
 107         ret = fcntl(STDIN_FILENO, F_GETFL);
 108         if (ret < 0) {
 109                 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
 110                 exit(EXIT_FAILURE);
 111         }
 112         sit->fd_flags = ret;
 113         sit->must_set_nonblock_flag = (sit->fd_flags & O_NONBLOCK) == 0
 114                 && !isatty(STDIN_FILENO);
 115         sit->task = task_register(&ti, s);
 116 }