doc: Change email address to maan@tuebingen.mpg.de
[paraslash.git] / stdin.c
1 /*
2 * Copyright (C) 2006-2014 Andre Noll <maan@tuebingen.mpg.de>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file stdin.c Functions that deal with reading from stdin. */
8
9 #include <assert.h>
10 #include <regex.h>
11
12 #include "para.h"
13 #include "list.h"
14 #include "sched.h"
15 #include "fd.h"
16 #include "error.h"
17 #include "stdin.h"
18 #include "buffer_tree.h"
19 #include "string.h"
20
21 /*
22 * If there is space left in the buffer of the stdin task add STDIN_FILENO to
23 * the read fd set of s.
24 */
25 static void stdin_pre_select(struct sched *s, void *context)
26 {
27 struct stdin_task *sit = context;
28 int ret;
29
30 ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
31 if (ret < 0)
32 sched_min_delay(s);
33 if (ret <= 0)
34 return;
35 if (btr_pool_unused(sit->btrp) > 0)
36 return para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
37 sched_request_timeout_ms(100, s);
38 }
39
40 /*
41 * This function checks if STDIN_FILENO was included by in the read fd set of s
42 * during the previous pre_select call. If so, and if STDIN_FILENO is readable,
43 * data is read from stdin and fed into the buffer tree.
44 */
45 static int stdin_post_select(struct sched *s, void *context)
46 {
47 struct stdin_task *sit = context;
48 ssize_t ret;
49 size_t sz, n;
50 char *buf = NULL;
51
52 ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
53 if (ret < 0)
54 goto err;
55 if (ret == 0)
56 return 0;
57 sz = btr_pool_get_buffer(sit->btrp, &buf);
58 if (sz == 0)
59 return 0;
60 if (sit->must_set_nonblock_flag) {
61 ret = mark_fd_nonblocking(STDIN_FILENO);
62 if (ret < 0)
63 goto err;
64 sit->must_set_nonblock_flag = false;
65 }
66 /*
67 * Do not use the maximal size to avoid having only a single buffer
68 * reference for the whole pool. This is bad because if that single
69 * reference can not be freed, we're stuck.
70 */
71 sz = PARA_MIN(sz, btr_pool_size(sit->btrp) / 2);
72 ret = read_nonblock(STDIN_FILENO, buf, sz, &s->rfds, &n);
73 if (n > 0)
74 btr_add_output_pool(sit->btrp, n, sit->btrn);
75 if (ret >= 0)
76 return 0;
77 err:
78 btr_remove_node(&sit->btrn);
79 /* Revert to blocking mode if necessary. */
80 fcntl(STDIN_FILENO, F_SETFL, sit->fd_flags);
81 //btr_pool_free(sit->btrp);
82 return ret;
83 }
84
85 /**
86 * Register a stdin task structure.
87 *
88 * \param sit The stdin task structure to register.
89 * \param s The task will be added to this scheduler's task list.
90 *
91 * This allocates a buffer tree pool for I/O, sets up \a sit and registers a
92 * task with \a sit as context pointer.
93 */
94 void stdin_task_register(struct stdin_task *sit, struct sched *s)
95 {
96 int ret;
97 struct task_info ti = {
98 .name = "stdin",
99 .pre_select = stdin_pre_select,
100 .post_select = stdin_post_select,
101 .context = sit,
102 };
103
104 sit->btrp = btr_pool_new("stdin", 128 * 1024);
105 /*
106 * Both STDIN_FILENO and STDOUT_FILENO may refer to the same open file
107 * description (the terminal), and thus share the same file status
108 * flags. In order to not interfere with the stdout task, we only get
109 * the file status flags for STDIN here and save a copy. The nonblock
110 * flag is set later on the first read.
111 */
112 ret = fcntl(STDIN_FILENO, F_GETFL);
113 if (ret < 0) {
114 PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
115 exit(EXIT_FAILURE);
116 }
117 sit->fd_flags = ret;
118 sit->must_set_nonblock_flag = (sit->fd_flags & O_NONBLOCK) == 0;
119 sit->task = task_register(&ti, s);
120 }