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         int ret;
  52
  53         t->error = 0;
  54         sot->check_fd = 0;
  55         ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
  56         if (ret > 0)
  57                 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
  58         else if (ret < 0) {
  59                 s->timeout.tv_sec = 0;
  60                 s->timeout.tv_usec = 1;
  61         }
  62 }
  63
  64 /**
  65  * The post select function of the stdout task.
  66  *
  67  * \param s The scheduler this task was registered to.
  68  * \param t The task structure of the stdout task.
  69  *
  70  * This function checks if \p STDOUT_FILENO was included by in the write fd set
  71  * of \a s during the previous pre_select call.  If yes, and \p STDOUT_FILENO
  72  * appeears to be writable, the data loaded in the input buffer is written to
  73  * stdout.
  74  */
  75 static void stdout_post_select(struct sched *s, struct task *t)
  76 {
  77         struct stdout_task *sot = container_of(t, struct stdout_task, task);
  78         ssize_t ret;
  79
  80         t->error = 0;
  81         if (!sot->check_fd) {
  82                 if (!*sot->loaded && *sot->input_error < 0)
  83                         t->error = *sot->input_error;
  84                 return;
  85         }
  86         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
  87                 return;
  88         ret = write(STDOUT_FILENO, *sot->bufp, *sot->loaded);
  89         if (ret < 0) {
  90                 t->error = -ERRNO_TO_PARA_ERROR(errno);
  91                 return;
  92         }
  93         *sot->loaded -= ret;
  94         if (*sot->loaded)
  95                 memmove(*sot->bufp, *sot->bufp + ret, *sot->loaded);
  96 }
  97
  98 static void stdout_post_select_btr(struct sched *s, struct task *t)
  99 {
 100         struct stdout_task *sot = container_of(t, struct stdout_task, task);
 101         struct btr_node *btrn = sot->btrn;
 102         int ret;
 103         char *buf;
 104         size_t sz;
 105
 106         t->error = 0;
 107         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
 108         if (ret < 0)
 109                 goto err;
 110         if (ret == 0)
 111                 return;
 112         if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
 113                 return;
 114         sz = btr_next_buffer(btrn, &buf);
 115         assert(sz > 0);
 116         ret = write_nonblock(STDOUT_FILENO, buf, sz, 0);
 117         if (ret < 0)
 118                 goto err;
 119         btr_consume(btrn, ret);
 120         return;
 121 err:
 122         btr_remove_node(btrn);
 123         t->error = ret;
 124 }
 125 /**
 126  * Initialize a stdout task structure with default values.
 127  *
 128  * \param sot The stdout task structure.
 129  *
 130  * This fills in the pre/post select function poinzters of the task structure
 131  * given by \a sot.
 132  */
 133 void stdout_set_defaults(struct stdout_task *sot)
 134 {
 135         int ret;
 136
 137         if (sot->btrn) {
 138                 sot->task.pre_select = stdout_pre_select_btr;
 139                 sot->task.post_select = stdout_post_select_btr;
 140         } else {
 141                 sot->task.pre_select = stdout_pre_select;
 142                 sot->task.post_select = stdout_post_select;
 143         }
 144         sprintf(sot->task.status, "stdout writer");
 145         ret = mark_fd_nonblocking(STDOUT_FILENO);
 146         if (ret >= 0)
 147                 return;
 148         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 149         exit(EXIT_FAILURE);
 150 }