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                         t->error = -E_ORPHAN;
  58                         btr_del_node(sot->btrn);
  59                         s->timeout.tv_sec = 0;
  60                         s->timeout.tv_usec = 1;
  61                 }
  62                 return;
  63         }
  64         sot->check_fd = 1;
  65         para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  66 }
  67
  68 /**
  69  * The post select function of the stdout task.
  70  *
  71  * \param s The scheduler this task was registered to.
  72  * \param t The task structure of the stdout task.
  73  *
  74  * This function checks if \p STDOUT_FILENO was included by in the write fd set
  75  * of \a s during the previous pre_select call.  If yes, and \p STDOUT_FILENO
  76  * appeears to be writable, the data loaded in the input buffer is written to
  77  * stdout.
  78  */
  79 static void stdout_post_select(struct sched *s, struct task *t)
  80 {
  81         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  82         ssize_t ret;
  83
  84         t->error = 0;
  85         if (!sot->check_fd) {
  86                 if (!*sot->loaded && *sot->input_error < 0)
  87                         t->error = *sot->input_error;
  88                 return;
  89         }
  90         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  91                 return;
  92         ret = write(STDOUT_FILENO, *sot->bufp, *sot->loaded);
  93         if (ret < 0) {
  94                 t->error = -ERRNO_TO_PARA_ERROR(errno);
  95                 return;
  96         }
  97         *sot->loaded -= ret;
  98         if (*sot->loaded)
  99                 memmove(*sot->bufp, *sot->bufp + ret, *sot->loaded);
 100 }
 101
 102 static void stdout_post_select_btr(struct sched *s, struct task *t)
 103 {
 104         struct stdout_task *sot = container_of(t, struct stdout_task, task);
 105         ssize_t ret;
 106         size_t sz = btr_get_input_queue_size(sot->btrn);
 107         bool orphan = btr_no_parent(sot->btrn);
 108         char *buf;
 109
 110         t->error = 0;
 111         if (!sot->check_fd) {
 112                 if (sz == 0 && orphan) {
 113                         t->error = -E_ORPHAN;
 114                         goto err;
 115                 }
 116                 return;
 117         }
 118         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
 119                 return;
 120         sz = btr_next_buffer(sot->btrn, &buf);
 121         if (sz == 0)
 122                 return;
 123         ret = write(STDOUT_FILENO, buf, sz);
 124         if (ret < 0) {
 125                 t->error = -ERRNO_TO_PARA_ERROR(errno);
 126                 goto err;
 127         }
 128         btr_consume(sot->btrn, ret);
 129         return;
 130 err:
 131         btr_del_node(sot->btrn);
 132 }
 133 /**
 134  * Initialize a stdout task structure with default values.
 135  *
 136  * \param sot The stdout task structure.
 137  *
 138  * This fills in the pre/post select function poinzters of the task structure
 139  * given by \a sot.
 140  */
 141 void stdout_set_defaults(struct stdout_task *sot)
 142 {
 143         int ret;
 144
 145         if (sot->btrn) {
 146                 sot->task.pre_select = stdout_pre_select_btr;
 147                 sot->task.post_select = stdout_post_select_btr;
 148         } else {
 149                 sot->task.pre_select = stdout_pre_select;
 150                 sot->task.post_select = stdout_post_select;
 151         }
 152         sprintf(sot->task.status, "stdout writer");
 153         ret = mark_fd_nonblocking(STDOUT_FILENO);
 154         if (ret >= 0)
 155                 return;
 156         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 157         exit(EXIT_FAILURE);
 158 }