91 lines
2.8 KiB
C
91 lines
2.8 KiB
C
/*
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*
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* Copyright (c) 2003 The Regents of the University of California. All
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* rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Neither the name of the University nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/*
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* FUSD - The Framework for UserSpace Devices - Example program
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*
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* Jeremy Elson <jelson@circlemud.org>
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*
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* hello-world: Simply creates a device called /dev/hello-world, which
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* greets you when you try to get it.
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*
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*/
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/* EXAMPLE START helloworld.c */
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include "fusd.h"
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#define GREETING "Hello, world!\n"
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int do_open_or_close(struct fusd_file_info *file)
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{
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return 0; /* attempts to open and close this file always succeed */
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}
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ssize_t do_read(struct fusd_file_info *file, char *user_buffer,
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size_t user_length, loff_t *offset)
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{
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int retval = 0;
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/* The first read to the device returns a greeting. The second read
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* returns EOF. */
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if (*offset == 0) {
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if (user_length < strlen(GREETING))
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retval = -EINVAL; /* the user must supply a big enough buffer! */
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else {
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memcpy(user_buffer, GREETING, strlen(GREETING)); /* greet user */
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retval = strlen(GREETING); /* retval = number of bytes returned */
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*offset += retval; /* advance user's file pointer */
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}
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}
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return retval;
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}
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int main(int argc, char *argv[])
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{
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struct fusd_file_operations fops = {
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open: do_open_or_close,
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read: do_read,
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close: do_open_or_close };
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if (fusd_register("/dev/hello-world", "test", "hello-world", 0666, NULL, &fops) < 0)
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perror("Unable to register device");
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else {
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printf("/dev/hello-world should now exist - calling fusd_run...\n");
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fusd_run();
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}
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return 0;
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}
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/* EXAMPLE STOP helloworld.c */
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