1 /*
2 *
3 * Copyright (c) 2003 The Regents of the University of California. All
4 * rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * - Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * - Neither the name of the University nor the names of its
14 * contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS''
18 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
19 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
20 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
21 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
22 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
23 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
24 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
25 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 */
30
31
32 /*
33 * FUSD - The Framework for UserSpace Devices - Example program
34 *
35 * Jeremy Elson <jelson@circlemud.org>
36 *
37 * console-read: This example demonstrates the easiest possible way to
38 * block a client system call: by blocking the driver itself. Not
39 * recommended for anything but the most trivial drivers -- if you
40 * need a template from which to start on a real driver, use pager.c
41 * instead.
42 *
43 * $Id: console-read.c,v 1.6 2007-12-08 04:05:01 girod Exp $
44 */
45
46 #include <stdio.h>
47 #include <string.h>
48 #include <errno.h>
49
50 #include <fusd/cygwin_compat.h>
51
52 #include "fusd.h"
53
54 #define MIN(x, y) ((x) < (y) ? (x) : (y))
55
56 int do_open_or_close(struct fusd_file_info *file)
57 {
58 return 0; /* attempts to open and close this file always succeed */
59 }
60
61 /* EXAMPLE START console-read.c */
62 ssize_t do_read(struct fusd_file_info *file, char *user_buffer,
63 size_t user_length, loff_t *offset)
64 {
65 char buf[128];
66
67 if (*offset > 0)
68 return 0;
69
70 /* print a prompt */
71 printf("Got a read from pid %d. What do we say?\n> ", file->pid);
72 fflush(stdout);
73
74 /* get a response from the console */
75 if (fgets(buf, sizeof(buf) - 1, stdin) == NULL)
76 return 0;
77
78 /* compute length of the response, and return */
79 user_length = MIN(user_length, strlen(buf));
80 memcpy(user_buffer, buf, user_length);
81 *offset += user_length;
82 return user_length;
83 }
84 /* EXAMPLE STOP */
85
86 int main(int argc, char *argv[])
87 {
88 struct fusd_file_operations fops = {
89 open: do_open_or_close,
90 read: do_read,
91 close: do_open_or_close };
92
93 if (fusd_register("/dev/console-read", 0666, NULL, &fops) < 0)
94 perror("Unable to register device");
95 else {
96 printf("/dev/console-read should now exist - calling fusd_run...\n");
97 fusd_run();
98 }
99 return 0;
100 }
101
102
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