stdout: Misc cleanups.
[paraslash.git] / 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 }