123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147 |
- /*
- *
- * 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>
- *
- * drums2.c: Another 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/)
- *
- * Like the original drums.c, this example creates a bunch of devices
- * in the /dev/drums directory: /dev/drums/bam, /dev/drums/bum, etc.
- * However, it also uses the private_data structure to keep per-file
- * state, and return a string unique to each user of the device.
- *
- * Note, unlike the original drums.c, this driver does not use *offset
- * to remember if this user has read before; cat /dev/drums/X will
- * read infinitely
- *
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <errno.h>
- #include <unistd.h>
- #include "fusd.h"
- #define MIN(x, y) ((x) < (y) ? (x) : (y))
- /* EXAMPLE START drums2.c */
- struct drum_info {
- char *name;
- int num_users;
- } drums[] = {
- { "bam", 0 },
- { "bum", 0 },
- /* ... */
- /* EXAMPLE STOP */
- { "beat", 0 },
- { "boom", 0 },
- { "bang", 0 },
- { "crash", 0 },
- /* EXAMPLE START drums2.c */
- { NULL, 0 }
- };
- int drums_open(struct fusd_file_info *file)
- {
- /* file->device_info is what we passed to fusd_register when we
- * registered the device. It's a pointer into the "drums" struct. */
- struct drum_info *d = (struct drum_info *) file->device_info;
- int *user_num = calloc(1, sizeof(*user_num));
- /* Store this user's unique user number in their private_data */
- *user_num = ++(d->num_users);
- file->private_data = (void *) user_num;
- return 0; /* return success */
- }
- ssize_t drums_read(struct fusd_file_info *file, char *user_buffer,
- size_t user_length, loff_t *offset)
- {
- struct drum_info *d = (struct drum_info *) file->device_info;
- int len;
- char sound[128];
- sprintf(sound, "You are user %d to hear a drum go '%s'!\n",
- *(int *) file->private_data, d->name);
- len = MIN(user_length, strlen(sound));
- memcpy(user_buffer, sound, len);
- *offset += len;
- return len;
- }
- /* EXAMPLE STOP */
- int drums_close(struct fusd_file_info *file)
- {
- return 0; /* closes always succeed */
- }
- struct fusd_file_operations drums_fops = {
- open: drums_open,
- read: drums_read,
- close: drums_close
- };
- /* EXAMPLE START drums2.c */
- int main(int argc, char *argv[])
- {
- struct drum_info *d;
- char buf[128];
- char devname[128];
- for (d = drums; d->name != NULL; d++) {
- sprintf(buf, "/dev/drums/%s", d->name);
- sprintf(devname, "drum%s", d->name);
- if (fusd_register(buf, "drums", devname, 0666, d, &drums_fops) < 0)
- fprintf(stderr, "%s register failed: %m\n", d->name);
- }
- /* ... */
- /* EXAMPLE STOP */
- fprintf(stderr, "calling fusd_run...\n");
- fusd_run();
- return 0;
- }
|