complete documentation of stdin.* and stdout.*
[paraslash.git] / stdout.c
1 /*
2 * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file stdout.c functions that deal with writing to stdout */
20
21 #include "para.h"
22 #include "string.h"
23 #include "list.h"
24 #include "sched.h"
25 #include "fd.h"
26 #include "error.h"
27 #include "stdout.h"
28
29
30 /**
31 * the pre_select function of the stdout task
32 *
33 * \param s the scheduler this task was registered to
34 * \param t the task structure of the stdout task
35 *
36 * This function is always successful. If there is data available in the input
37 * buffer, it adds \a STDOUT_FILENO to the write fd set of \a s.
38 */
39 void stdout_pre_select(struct sched *s, struct task *t)
40 {
41 struct stdout_task *sot = t->private_data;
42
43 t->ret = 1;
44 sot->check_fd = 0;
45 if (!*sot->loaded) {
46 if (*sot->input_eof) {
47 t->ret = -E_STDOUT_EOF;
48 s->timeout.tv_sec = 0;
49 s->timeout.tv_usec = 1;
50 }
51 return;
52 }
53 sot->check_fd = 1;
54 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
55 }
56
57 /**
58 * the post select function of the stdout task
59 *
60 * \param s the scheduler this task was registered to
61 * \param t the task structure of the stdout task
62 *
63 * This function checks if \a STDOUT_FILENO was included by in the write fd set
64 * of \a s during the previous pre_select call. If yes, and STDOUT_FILENO
65 * appeears to be writable, the data loaded in the input buffer is written to
66 * stdout.
67 */
68 void stdout_post_select(struct sched *s, struct task *t)
69 {
70 struct stdout_task *sot = t->private_data;
71 ssize_t ret;
72
73 t->ret = 1;
74 if (!sot->check_fd) {
75 if (*sot->input_eof)
76 t->ret = -E_STDOUT_EOF;
77 return;
78 }
79 if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
80 return;
81 t->ret = -E_STDOUT_WRITE;
82 ret = write(STDOUT_FILENO, sot->buf, *sot->loaded);
83 if (ret <= 0)
84 return;
85 *sot->loaded -= ret;
86 t->ret = 1;
87 }
88
89 static void stdout_default_event_handler(struct task *t)
90 {
91 PARA_NOTICE_LOG("%p: %s\n", t, PARA_STRERROR(-t->ret));
92 unregister_task(t);
93 }
94
95 /**
96 * initialize a stdout task structure with default values
97 *
98 * \param sot the stdout task structure
99 *
100 * This fills in the pre/post select function poinzters of the task structure
101 * given by \a sot. It also sets up a default error handler which unregisters
102 * the task on errors and clears the eof flag of \a sot.
103 */
104 void stdout_set_defaults(struct stdout_task *sot)
105 {
106 sot->task.private_data = sot;
107 sot->task.pre_select = stdout_pre_select;
108 sot->task.post_select = stdout_post_select;
109 sot->task.event_handler = stdout_default_event_handler;
110 sot->eof = 0;
111 sprintf(sot->task.status, "stdout writer");
112 }