/* $NetBSD: riscospart.c,v 1.6 2020/09/29 02:58:52 msaitoh Exp $ */ /*- * Copyright (c) 2006 Ben Harris * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ /* * Copyright (c) 1995 Mark Brinicombe * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. */ #include <sys/types.h> #include <sys/param.h> #include <sys/disklabel.h> #include <sys/disklabel_acorn.h> #include <lib/libsa/stand.h> #include "riscospart.h" /* * This function should be shared between here, * sys/arch/arm/arm/disksubr_acorn.c, and * sys/fs/filecorefs/filecore_utils.c, rather than being copied. */ /* * static int filecore_checksum(u_char *bootblock) * * Calculates the filecore boot block checksum. This is used to validate * a filecore boot block on the disk. If a boot block is validated then * it is used to locate the partition table. If the boot block is not * validated, it is assumed that the whole disk is NetBSD. * * The basic algorithm is: * * for (each byte in block, excluding checksum) { * sum += byte; * if (sum > 255) * sum -= 255; * } * * That's equivalent to summing all of the bytes in the block * (excluding the checksum byte, of course), then calculating the * checksum as "cksum = sum - ((sum - 1) / 255) * 255)". That * expression may or may not yield a faster checksum function, * but it's easier to reason about. * * Note that if you have a block filled with bytes of a single * value "X" (regardless of that value!) and calculate the cksum * of the block (excluding the checksum byte), you will _always_ * end up with a checksum of X. (Do the math; that can be derived * from the checksum calculation function!) That means that * blocks which contain bytes which all have the same value will * always checksum properly. That's a _very_ unlikely occurrence * (probably impossible, actually) for a valid filecore boot block, * so we treat such blocks as invalid. */ static int filecore_checksum(u_char *bootblock) { u_char byte0, accum_diff; u_int sum; int i; sum = 0; accum_diff = 0; byte0 = bootblock[0]; /* * Sum the contents of the block, keeping track of whether * or not all bytes are the same. If 'accum_diff' ends up * being zero, all of the bytes are, in fact, the same. */ for (i = 0; i < 511; ++i) { sum += bootblock[i]; accum_diff |= bootblock[i] ^ byte0; } /* * Check to see if the checksum byte is the same as the * rest of the bytes, too. (Note that if all of the bytes * are the same except the checksum, a checksum compare * won't succeed, but that's not our problem.) */ accum_diff |= bootblock[i] ^ byte0; /* All bytes in block are the same; call it invalid. */ if (accum_diff == 0) return (-1); return (sum - ((sum - 1) / 255) * 255); } int getdisklabel_acorn(struct open_file *f, struct disklabel *lp) { size_t rsize; int err; char *buf; struct filecore_bootblock *bb; daddr_t labelsect; char *msg; buf = alloc(DEV_BSIZE); err = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ, FILECORE_BOOT_SECTOR, DEV_BSIZE, buf, &rsize); if (err != 0) goto out; bb = (struct filecore_bootblock *) buf; if (bb->checksum == filecore_checksum((u_char *)bb)) { if (bb->partition_type == PARTITION_FORMAT_RISCBSD) labelsect = ((bb->partition_cyl_high << 8) + bb->partition_cyl_low) * bb->heads * bb->secspertrack + LABELSECTOR; else { err = EUNLAB; goto out; } } else labelsect = LABELSECTOR; err = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ, labelsect, DEV_BSIZE, buf, &rsize); if (err != 0) goto out; msg = getdisklabel(buf, lp); if (msg) { printf("%s\n", msg); err = ERDLAB; } out: dealloc(buf, DEV_BSIZE); return err; }
