abf3d06f17a64249671ffbfb0470aa995a599578
[paraslash.git] / stdout.c
1 /*
2 * Copyright (C) 2006-2013 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 <assert.h>
10
11 #include "para.h"
12 #include "list.h"
13 #include "sched.h"
14 #include "fd.h"
15 #include "error.h"
16 #include "stdout.h"
17 #include "buffer_tree.h"
18
19 /**
20 * The pre_select function of the stdout task.
21 *
22 * \param s The scheduler this task was registered to.
23 * \param t The task structure of the stdout task.
24 *
25 * This function is always successful. If there is input data available, it
26 * adds \p STDOUT_FILENO to the write fd set of \a s.
27 */
28 static void stdout_pre_select(struct sched *s, struct task *t)
29 {
30 struct stdout_task *sot = container_of(t, struct stdout_task, task);
31 int ret;
32
33 ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
34 if (ret > 0)
35 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
36 else if (ret < 0)
37 sched_min_delay(s);
38 }
39
40 /**
41 * The post select function of the stdout task.
42 *
43 * \param s The scheduler this task was registered to.
44 * \param t The task structure of the stdout task.
45 *
46 * This function writes input data from the buffer tree to stdout if \p
47 * STDOUT_FILENO is writable.
48 */
49 static int stdout_post_select(struct sched *s, struct task *t)
50 {
51 struct stdout_task *sot = container_of(t, struct stdout_task, task);
52 struct btr_node *btrn = sot->btrn;
53 int ret;
54 char *buf;
55 size_t sz;
56
57 ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
58 if (ret < 0)
59 goto out;
60 if (ret == 0)
61 return 0;
62 if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
63 return 0;
64
65 for (;;) {
66 sz = btr_next_buffer(btrn, &buf);
67 if (sz == 0)
68 break;
69 ret = xwrite(STDOUT_FILENO, buf, sz);
70 if (ret <= 0)
71 break;
72 btr_consume(btrn, ret);
73 }
74 out:
75 if (ret < 0)
76 btr_remove_node(&sot->btrn);
77 return ret;
78 }
79 /**
80 * Initialize a stdout task structure with default values.
81 *
82 * \param sot The stdout task structure.
83 *
84 * This fills in the pre/post select function pointers of the task structure
85 * given by \a sot and sets the stdout file descriptor to nonblocking mode.
86 */
87 void stdout_set_defaults(struct stdout_task *sot)
88 {
89 int ret;
90
91 sot->task.pre_select = stdout_pre_select;
92 sot->task.post_select = stdout_post_select;
93 sprintf(sot->task.status, "stdout");
94 ret = mark_fd_nonblocking(STDOUT_FILENO);
95 if (ret >= 0)
96 return;
97 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
98 exit(EXIT_FAILURE);
99 }