stdin.c

   1 /*
   2  * Copyright (C) 2006-2009 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 #include <stdbool.h>
  12 #include <regex.h>
  13
  14 #include "para.h"
  15 #include "list.h"
  16 #include "sched.h"
  17 #include "fd.h"
  18 #include "error.h"
  19 #include "stdin.h"
  20 #include "buffer_tree.h"
  21 #include "string.h"
  22
  23 /**
  24  * The pre_select function of the stdin task.
  25  *
  26  * \param s The scheduler this task was registered to.
  27  * \param t The task structure of the stdin task.
  28  *
  29  * This function is always successful. If there is space left in the
  30  * buffer of the stdin task, it adds \p STDIN_FILENO to the read fd set
  31  * of \a s.
  32  */
  33 static void stdin_pre_select(struct sched *s, struct task *t)
  34 {
  35         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  36
  37         if (sit->output_error && *sit->output_error < 0) {
  38                 t->error = *sit->output_error;
  39                 return;
  40         }
  41         t->error = 0;
  42         sit->check_fd = 0;
  43         if (sit->loaded >= sit->bufsize)
  44                 return;
  45         sit->check_fd = 1;
  46         para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  47 }
  48
  49 #define STDIN_MAX_PENDING (100 * 1024)
  50
  51 static void stdin_pre_select_btr(struct sched *s, struct task *t)
  52 {
  53         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  54
  55         if (btr_no_children(sit->btrn)) { /* TODO: defer node deletion to post select */
  56                 t->error = -E_STDIN_NO_CHILD;
  57                 btr_del_node(sit->btrn);
  58                 sit->btrn = NULL;
  59                 return;
  60         }
  61         t->error = 0;
  62         if (btr_bytes_pending(sit->btrn) > STDIN_MAX_PENDING)
  63                 sit->check_fd = 0;
  64         else {
  65                 sit->check_fd = 1;
  66                 para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
  67         }
  68 }
  69
  70 /**
  71  * The post select function of the stdin task.
  72  *
  73  * \param s The scheduler this task was registered to.
  74  * \param t The task structure of the stdin task.
  75  *
  76  * This function checks if \p STDIN_FILENO was included by in the read fd set
  77  * of \a s during the previous pre_select call.  If yes, and \p STDIN_FILENO
  78  * appears to be readable, data is read from stdin into the buffer of the
  79  * stdin task.
  80  */
  81 static void stdin_post_select(struct sched *s, struct task *t)
  82 {
  83         struct stdin_task *sit = container_of(t, struct stdin_task, task);
  84         ssize_t ret;
  85
  86         if (sit->output_error && *sit->output_error < 0) {
  87                 t->error = *sit->output_error;
  88                 return;
  89         }
  90         t->error = 0;
  91         if (!sit->check_fd)
  92                 return;
  93         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
  94                 return;
  95         ret = read(STDIN_FILENO, sit->buf + sit->loaded, sit->bufsize - sit->loaded);
  96         if (ret < 0)
  97                 t->error = ERRNO_TO_PARA_ERROR(errno);
  98         else if (ret > 0)
  99                 sit->loaded += ret;
 100         else
 101                 t->error = -E_STDIN_EOF;
 102 }
 103
 104 #define STDIN_INPUT_BUFFER_SIZE (1024 * 32)
 105 static void stdin_post_select_btr(struct sched *s, struct task *t)
 106 {
 107         struct stdin_task *sit = container_of(t, struct stdin_task, task);
 108         ssize_t ret;
 109         char *buf = NULL;
 110
 111         t->error = -E_STDIN_NO_CHILD;
 112         if (btr_no_children(sit->btrn))
 113                 goto err;
 114
 115         t->error = 0;
 116         if (!sit->check_fd)
 117                 return;
 118         if (!FD_ISSET(STDIN_FILENO, &s->rfds))
 119                 return;
 120
 121         buf = para_malloc(STDIN_INPUT_BUFFER_SIZE);
 122         ret = read(STDIN_FILENO, buf, STDIN_INPUT_BUFFER_SIZE);
 123         //PARA_CRIT_LOG("read ret: %d\n", ret);
 124         if (ret < 0)
 125                 t->error = -ERRNO_TO_PARA_ERROR(errno);
 126         if (ret == 0)
 127                 t->error = -E_STDIN_EOF;
 128         if (t->error < 0)
 129                 goto err;
 130         btr_add_output(buf, ret, sit->btrn);
 131         return;
 132 err:
 133         free(buf);
 134         btr_del_node(sit->btrn);
 135         sit->btrn = NULL;
 136 }
 137
 138 /**
 139  * Initialize a stdin task structure with default values.
 140  *
 141  * \param sit The stdin task structure.
 142  *
 143  * This fills in the pre/post select function pointers of the task structure
 144  * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
 145  * mode and \a bufsize is initialized to 16 KB (but no buffer is allocated).
 146  */
 147 void stdin_set_defaults(struct stdin_task *sit)
 148 {
 149         int ret;
 150
 151         sit->bufsize = 32 * 1024;
 152         if (sit->btrn) {
 153                 sit->task.pre_select = stdin_pre_select_btr;
 154                 sit->task.post_select = stdin_post_select_btr;
 155         } else {
 156                 sit->task.pre_select = stdin_pre_select;
 157                 sit->task.post_select = stdin_post_select;
 158         }
 159         sprintf(sit->task.status, "stdin reader");
 160         ret = mark_fd_nonblocking(STDIN_FILENO);
 161         if (ret >= 0)
 162                 return;
 163         sit->output_error = NULL;
 164         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 165         exit(EXIT_FAILURE);
 166 }