/* * * 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 * * console-read: This example demonstrates the easiest possible way to * block a client system call: by blocking the driver itself. Not * recommended for anything but the most trivial drivers -- if you * need a template from which to start on a real driver, use pager.c * instead. * */ #include #include #include #include "fusd.h" #define MIN(x, y) ((x) < (y) ? (x) : (y)) int do_open_or_close(struct fusd_file_info *file) { return 0; /* attempts to open and close this file always succeed */ } /* EXAMPLE START console-read.c */ ssize_t do_read(struct fusd_file_info *file, char *user_buffer, size_t user_length, loff_t *offset) { char buf[128]; if (*offset > 0) return 0; /* print a prompt */ printf("Got a read from pid %d. What do we say?\n> ", file->pid); fflush(stdout); /* get a response from the console */ if (fgets(buf, sizeof(buf) - 1, stdin) == NULL) return 0; /* compute length of the response, and return */ user_length = MIN(user_length, strlen(buf)); memcpy(user_buffer, buf, user_length); *offset += user_length; return user_length; } /* EXAMPLE STOP */ int main(int argc, char *argv[]) { struct fusd_file_operations fops = { open: do_open_or_close, read: do_read, close: do_open_or_close }; if (fusd_register("/dev/console-read", "test", "console-read", 0666, NULL, &fops) < 0) perror("Unable to register device"); else { printf("/dev/console-read should now exist - calling fusd_run...\n"); fusd_run(); } return 0; }