117 lines
3.4 KiB
C
117 lines
3.4 KiB
C
/*
|
|
*
|
|
* Copyright (c) 2003 The Regents of the University of California. All
|
|
* rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* - Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* - Neither the name of the University nor the names of its
|
|
* contributors may be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS''
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
|
|
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
|
|
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
|
|
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
|
|
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
*/
|
|
|
|
|
|
/*
|
|
* FUSD - The Framework for UserSpace Devices - Example program
|
|
*
|
|
* Jeremy Elson <jelson@circlemud.org>
|
|
*
|
|
* drums.c: Example of how to pass data to a callback, inspired by
|
|
* Alessandro Rubini's similar example in his article for Linux
|
|
* Magazine (http://www.linux.it/kerneldocs/devfs/)
|
|
*
|
|
* This example creates a bunch of devices in the /dev/drums
|
|
* directory: /dev/drums/bam, /dev/drums/bum, etc. If you cat one of
|
|
* these devices, it returns a string that's the same as its name.
|
|
*
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
|
|
#include "fusd.h"
|
|
|
|
#define MIN(x, y) ((x) < (y) ? (x) : (y))
|
|
|
|
|
|
/* EXAMPLE START drums.c */
|
|
static char *drums_strings[] = {"bam", "bum", "beat", "boom",
|
|
"bang", "crash", NULL};
|
|
|
|
ssize_t drums_read(struct fusd_file_info *file, char *user_buffer,
|
|
size_t user_length, loff_t *offset)
|
|
{
|
|
int len;
|
|
char sound[128];
|
|
|
|
/* file->device_info is what we passed to fusd_register when we
|
|
* registered the device */
|
|
strcpy(sound, (char *) file->device_info);
|
|
strcat(sound, "\n");
|
|
|
|
/* 1st read returns the sound; 2nd returns EOF */
|
|
if (*offset != 0)
|
|
return 0;
|
|
|
|
/* NEVER return more data than the user asked for */
|
|
len = MIN(user_length, strlen(sound));
|
|
memcpy(user_buffer, sound, len);
|
|
*offset += len;
|
|
return len;
|
|
}
|
|
|
|
/* EXAMPLE STOP drums.c */
|
|
|
|
|
|
int do_open_or_close(struct fusd_file_info *file)
|
|
{
|
|
return 0; /* opens and closes always succeed */
|
|
}
|
|
|
|
|
|
struct fusd_file_operations drums_fops = {
|
|
open: do_open_or_close,
|
|
read: drums_read,
|
|
close: do_open_or_close
|
|
};
|
|
|
|
/* EXAMPLE START drums.c */
|
|
int main(int argc, char *argv[])
|
|
{
|
|
int i;
|
|
char buf[128];
|
|
char devname[128];
|
|
|
|
for (i = 0; drums_strings[i] != NULL; i++) {
|
|
sprintf(buf, "/dev/drums/%s", drums_strings[i]);
|
|
sprintf(devname, "drum%s", drums_strings[i]);
|
|
if (fusd_register(buf, "drums", devname, 0666, drums_strings[i], &drums_fops) < 0)
|
|
fprintf(stderr, "%s register failed: %m\n", drums_strings[i]);
|
|
}
|
|
|
|
fprintf(stderr, "calling fusd_run...\n");
|
|
fusd_run();
|
|
return 0;
|
|
}
|
|
/* EXAMPLE STOP drums.c */
|