stdout.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 stdout.c Functions that deal with writing to stdout. */
   8
   9 #include <dirent.h> /* readdir() */
  10 #include <assert.h>
  11 #include <stdbool.h>
  12
  13 #include "para.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "fd.h"
  17 #include "error.h"
  18 #include "stdout.h"
  19 #include "buffer_tree.h"
  20
  21 /**
  22  * The pre_select function of the stdout task.
  23  *
  24  * \param s The scheduler this task was registered to.
  25  * \param t The task structure of the stdout task.
  26  *
  27  * This function is always successful. If there is data available in the input
  28  * buffer, it adds \p STDOUT_FILENO to the write fd set of \a s.
  29  */
  30 static void stdout_pre_select(struct sched *s, struct task *t)
  31 {
  32         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  33
  34         t->error = 0;
  35         sot->check_fd = 0;
  36         if (!*sot->loaded) {
  37                 if (*sot->input_error < 0) {
  38                         t->error = *sot->input_error;
  39                         s->timeout.tv_sec = 0;
  40                         s->timeout.tv_usec = 1;
  41                 }
  42                 return;
  43         }
  44         sot->check_fd = 1;
  45         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  46 }
  47
  48 static void stdout_pre_select_btr(struct sched *s, struct task *t)
  49 {
  50         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  51         size_t sz = btr_get_input_queue_size(sot->btrn);
  52
  53         t->error = 0;
  54         sot->check_fd = 0;
  55         if (sz == 0) {
  56                 if (btr_no_parent(sot->btrn)) {
  57                         s->timeout.tv_sec = 0;
  58                         s->timeout.tv_usec = 1;
  59                 }
  60                 return;
  61         }
  62         sot->check_fd = 1;
  63         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  64 }
  65
  66 /**
  67  * The post select function of the stdout task.
  68  *
  69  * \param s The scheduler this task was registered to.
  70  * \param t The task structure of the stdout task.
  71  *
  72  * This function checks if \p STDOUT_FILENO was included by in the write fd set
  73  * of \a s during the previous pre_select call.  If yes, and \p STDOUT_FILENO
  74  * appeears to be writable, the data loaded in the input buffer is written to
  75  * stdout.
  76  */
  77 static void stdout_post_select(struct sched *s, struct task *t)
  78 {
  79         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  80         ssize_t ret;
  81
  82         t->error = 0;
  83         if (!sot->check_fd) {
  84                 if (!*sot->loaded && *sot->input_error < 0)
  85                         t->error = *sot->input_error;
  86                 return;
  87         }
  88         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  89                 return;
  90         ret = write(STDOUT_FILENO, *sot->bufp, *sot->loaded);
  91         if (ret < 0) {
  92                 t->error = -ERRNO_TO_PARA_ERROR(errno);
  93                 return;
  94         }
  95         *sot->loaded -= ret;
  96         if (*sot->loaded)
  97                 memmove(*sot->bufp, *sot->bufp + ret, *sot->loaded);
  98 }
  99
 100 static void stdout_post_select_btr(struct sched *s, struct task *t)
 101 {
 102         struct stdout_task *sot = container_of(t, struct stdout_task, task);
 103         ssize_t ret;
 104         size_t sz = btr_get_input_queue_size(sot->btrn);
 105         char *buf;
 106
 107         t->error = 0;
 108         if (!sot->check_fd) {
 109                 if (sz == 0 && btr_no_parent(sot->btrn)) {
 110                         t->error = -E_ORPHAN;
 111                         goto err;
 112                 }
 113                 return;
 114         }
 115         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
 116                 return;
 117         sz = btr_next_buffer(sot->btrn, &buf);
 118         if (sz == 0)
 119                 return;
 120         ret = write_nonblock(STDOUT_FILENO, buf, sz, 0);
 121         if (ret < 0) {
 122                 t->error = -ERRNO_TO_PARA_ERROR(errno);
 123                 goto err;
 124         }
 125         btr_consume(sot->btrn, ret);
 126         return;
 127 err:
 128         btr_del_node(sot->btrn);
 129 }
 130 /**
 131  * Initialize a stdout task structure with default values.
 132  *
 133  * \param sot The stdout task structure.
 134  *
 135  * This fills in the pre/post select function poinzters of the task structure
 136  * given by \a sot.
 137  */
 138 void stdout_set_defaults(struct stdout_task *sot)
 139 {
 140         int ret;
 141
 142         if (sot->btrn) {
 143                 sot->task.pre_select = stdout_pre_select_btr;
 144                 sot->task.post_select = stdout_post_select_btr;
 145         } else {
 146                 sot->task.pre_select = stdout_pre_select;
 147                 sot->task.post_select = stdout_post_select;
 148         }
 149         sprintf(sot->task.status, "stdout writer");
 150         ret = mark_fd_nonblocking(STDOUT_FILENO);
 151         if (ret >= 0)
 152                 return;
 153         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 154         exit(EXIT_FAILURE);
 155 }