243da80fc6
an initial release. Primary remaining problem: udev-style kernels don't allow registration of a preexisting class right now. This will need to be fixed semi-immediately. git-svn-id: http://svn.xiph.org/trunk/fusd@12316 0101bb08-14d6-0310-b084-bc0e0c8e3800
114 lines
3.3 KiB
C
114 lines
3.3 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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* uid-filter. This program shows how you can use some of the
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* meta-data provided in the fusd_file_info structure to affect your
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* driver's behavior.
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*
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* In particular, this driver creates a device, /dev/my-pid, that can
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* not be read by anyone other than the driver owner (not even root!).
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* When you read from the device, it returns your PID to you.
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*
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* $Id$
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*/
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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 <unistd.h>
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#include "fusd.h"
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int do_close(struct fusd_file_info *file)
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{
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return 0; /* attempts to close the file always succeed */
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}
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/* EXAMPLE START uid-filter.c */
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int do_open(struct fusd_file_info *file)
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{
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/* If the UID of the process trying to do the read doesn't match the
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* UID of the owner of the driver, return -EPERM. If you run this
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* driver as a normal user, even root won't be able to read from the
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* device file created! */
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if (file->uid != getuid())
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return -EPERM;
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return 0;
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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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char buf[128];
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int len;
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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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return 0;
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/* len gets set to the number of characters written to buf */
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len = sprintf(buf, "Your PID is %d. Have a nice day.\n", file->pid);
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/* NEVER return more data than the user asked for */
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if (user_length < len)
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len = user_length;
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memcpy(user_buffer, buf, len);
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*offset += len;
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return len;
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}
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/* EXAMPLE STOP uid-filter.c */
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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,
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read: do_read,
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close: do_close };
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if (fusd_register("/dev/my-pid", "misc", "my-pid", 0666, NULL, &fops) < 0)
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perror("Unable to register device");
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else {
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printf("/dev/my-pid 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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