Import revision 9131ba637f003fb5894e3f6343a27d6322205f18 from FreeBSD.

Change-Id: I8ee418314ea407ca679bcd1bed85bd4cff435c22

1 files changed, 297 insertions, 0 deletions

diff --git a/boot.c b/boot.c
new file mode 100644
index 0000000..56bd57d
--- /dev/null
+++ b/boot.c
@@ -0,0 +1,297 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (C) 1995, 1997 Wolfgang Solfrank
+ * Copyright (c) 1995 Martin Husemann
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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/cdefs.h>
+#ifndef lint
+__RCSID("$NetBSD: boot.c,v 1.11 2006/06/05 16:51:18 christos Exp ");
+static const char rcsid[] =
+  "$FreeBSD$";
+#endif /* not lint */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "ext.h"
+#include "fsutil.h"
+
+int
+readboot(int dosfs, struct bootblock *boot)
+{
+	u_char block[DOSBOOTBLOCKSIZE];
+	u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
+	u_char backup[DOSBOOTBLOCKSIZE];
+	int ret = FSOK;
+	int i;
+
+	if ((size_t)read(dosfs, block, sizeof block) != sizeof block) {
+		perr("could not read boot block");
+		return FSFATAL;
+	}
+
+	if (block[510] != 0x55 || block[511] != 0xaa) {
+		pfatal("Invalid signature in boot block: %02x%02x",
+		    block[511], block[510]);
+		return FSFATAL;
+	}
+
+	memset(boot, 0, sizeof *boot);
+	boot->ValidFat = -1;
+
+	/* decode bios parameter block */
+	boot->bpbBytesPerSec = block[11] + (block[12] << 8);
+	boot->bpbSecPerClust = block[13];
+	boot->bpbResSectors = block[14] + (block[15] << 8);
+	boot->bpbFATs = block[16];
+	boot->bpbRootDirEnts = block[17] + (block[18] << 8);
+	boot->bpbSectors = block[19] + (block[20] << 8);
+	boot->bpbMedia = block[21];
+	boot->bpbFATsmall = block[22] + (block[23] << 8);
+	boot->SecPerTrack = block[24] + (block[25] << 8);
+	boot->bpbHeads = block[26] + (block[27] << 8);
+	boot->bpbHiddenSecs = block[28] + (block[29] << 8) +
+	    (block[30] << 16) + (block[31] << 24);
+	boot->bpbHugeSectors = block[32] + (block[33] << 8) +
+	    (block[34] << 16) + (block[35] << 24);
+
+	boot->FATsecs = boot->bpbFATsmall;
+
+	if (boot->bpbBytesPerSec % DOSBOOTBLOCKSIZE_REAL != 0 ||
+	    boot->bpbBytesPerSec / DOSBOOTBLOCKSIZE_REAL == 0) {
+		pfatal("Invalid sector size: %u", boot->bpbBytesPerSec);
+		return FSFATAL;
+	}
+	if (boot->bpbFATs == 0) {
+		pfatal("Invalid number of FATs: %u", boot->bpbFATs);
+		return FSFATAL;
+	}
+	if (!boot->bpbRootDirEnts)
+		boot->flags |= FAT32;
+	if (boot->flags & FAT32) {
+		boot->FATsecs = block[36] + (block[37] << 8)
+				+ (block[38] << 16) + (block[39] << 24);
+		if (block[40] & 0x80)
+			boot->ValidFat = block[40] & 0x0f;
+
+		/* check version number: */
+		if (block[42] || block[43]) {
+			/* Correct?				XXX */
+			pfatal("Unknown file system version: %x.%x",
+			       block[43], block[42]);
+			return FSFATAL;
+		}
+		boot->bpbRootClust = block[44] + (block[45] << 8)
+			       + (block[46] << 16) + (block[47] << 24);
+		boot->bpbFSInfo = block[48] + (block[49] << 8);
+		boot->bpbBackup = block[50] + (block[51] << 8);
+
+		/* If the OEM Name field is EXFAT, it's not FAT32, so bail */
+		if (!memcmp(&block[3], "EXFAT   ", 8)) {
+			pfatal("exFAT filesystem is not supported.");
+			return FSFATAL;
+		}
+
+		/* check basic parameters */
+		if ((boot->bpbFSInfo == 0) || (boot->bpbSecPerClust == 0)) {
+			/*
+			 * Either the BIOS Parameter Block has been corrupted,
+			 * or this is not a FAT32 filesystem, most likely an
+			 * exFAT filesystem.
+			 */
+			pfatal("Invalid FAT32 Extended BIOS Parameter Block");
+			return FSFATAL;
+		}
+		if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec,
+		    SEEK_SET) != boot->bpbFSInfo * boot->bpbBytesPerSec
+		    || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) {
+			perr("could not read fsinfo block");
+			return FSFATAL;
+		}
+		if (memcmp(fsinfo, "RRaA", 4)
+		    || memcmp(fsinfo + 0x1e4, "rrAa", 4)
+		    || fsinfo[0x1fc]
+		    || fsinfo[0x1fd]
+		    || fsinfo[0x1fe] != 0x55
+		    || fsinfo[0x1ff] != 0xaa
+		    || fsinfo[0x3fc]
+		    || fsinfo[0x3fd]
+		    || fsinfo[0x3fe] != 0x55
+		    || fsinfo[0x3ff] != 0xaa) {
+			pwarn("Invalid signature in fsinfo block\n");
+			if (ask(0, "Fix")) {
+				memcpy(fsinfo, "RRaA", 4);
+				memcpy(fsinfo + 0x1e4, "rrAa", 4);
+				fsinfo[0x1fc] = fsinfo[0x1fd] = 0;
+				fsinfo[0x1fe] = 0x55;
+				fsinfo[0x1ff] = 0xaa;
+				fsinfo[0x3fc] = fsinfo[0x3fd] = 0;
+				fsinfo[0x3fe] = 0x55;
+				fsinfo[0x3ff] = 0xaa;
+				if (lseek(dosfs, boot->bpbFSInfo *
+				    boot->bpbBytesPerSec, SEEK_SET)
+				    != boot->bpbFSInfo * boot->bpbBytesPerSec
+				    || write(dosfs, fsinfo, sizeof fsinfo)
+				    != sizeof fsinfo) {
+					perr("Unable to write bpbFSInfo");
+					return FSFATAL;
+				}
+				ret = FSBOOTMOD;
+			} else
+				boot->bpbFSInfo = 0;
+		}
+		if (boot->bpbFSInfo) {
+			boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8)
+				       + (fsinfo[0x1ea] << 16)
+				       + (fsinfo[0x1eb] << 24);
+			boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8)
+				       + (fsinfo[0x1ee] << 16)
+				       + (fsinfo[0x1ef] << 24);
+		}
+
+		if (lseek(dosfs, boot->bpbBackup * boot->bpbBytesPerSec,
+		    SEEK_SET)
+		    != boot->bpbBackup * boot->bpbBytesPerSec
+		    || read(dosfs, backup, sizeof backup) != sizeof  backup) {
+			perr("could not read backup bootblock");
+			return FSFATAL;
+		}
+		backup[65] = block[65];				/* XXX */
+		if (memcmp(block + 11, backup + 11, 79)) {
+			/*
+			 * XXX We require a reference that explains
+			 * that these bytes need to match, or should
+			 * drop the check.  gdt@NetBSD has observed
+			 * filesystems that work fine under Windows XP
+			 * and NetBSD that do not match, so the
+			 * requirement is suspect.  For now, just
+			 * print out useful information and continue.
+			 */
+			pwarn("backup (block %d) mismatch with primary bootblock:\n",
+			        boot->bpbBackup);
+			for (i = 11; i < 11 + 90; i++) {
+				if (block[i] != backup[i])
+					pwarn("\ti=%d\tprimary 0x%02x\tbackup 0x%02x\n",
+					       i, block[i], backup[i]);
+			}
+		}
+		/* Check backup bpbFSInfo?					XXX */
+	}
+
+	if (boot->bpbSecPerClust == 0) {
+		pfatal("Invalid cluster size: %u", boot->bpbSecPerClust);
+		return FSFATAL;
+	}
+	if (boot->bpbSectors) {
+		boot->bpbHugeSectors = 0;
+		boot->NumSectors = boot->bpbSectors;
+	} else
+		boot->NumSectors = boot->bpbHugeSectors;
+	boot->ClusterOffset = (boot->bpbRootDirEnts * 32 +
+	    boot->bpbBytesPerSec - 1) / boot->bpbBytesPerSec +
+	    boot->bpbResSectors + boot->bpbFATs * boot->FATsecs -
+	    CLUST_FIRST * boot->bpbSecPerClust;
+	boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) /
+	    boot->bpbSecPerClust;
+
+	if (boot->flags & FAT32)
+		boot->ClustMask = CLUST32_MASK;
+	else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK))
+		boot->ClustMask = CLUST12_MASK;
+	else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK))
+		boot->ClustMask = CLUST16_MASK;
+	else {
+		pfatal("Filesystem too big (%u clusters) for non-FAT32 partition",
+		       boot->NumClusters);
+		return FSFATAL;
+	}
+
+	switch (boot->ClustMask) {
+	case CLUST32_MASK:
+		boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 4;
+		break;
+	case CLUST16_MASK:
+		boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 2;
+		break;
+	default:
+		boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec * 2) / 3;
+		break;
+	}
+
+	if (boot->NumFatEntries < boot->NumClusters - CLUST_FIRST) {
+		pfatal("FAT size too small, %u entries won't fit into %u sectors\n",
+		       boot->NumClusters, boot->FATsecs);
+		return FSFATAL;
+	}
+	boot->ClusterSize = boot->bpbBytesPerSec * boot->bpbSecPerClust;
+
+	boot->NumFiles = 1;
+	boot->NumFree = 0;
+
+	return ret;
+}
+
+int
+writefsinfo(int dosfs, struct bootblock *boot)
+{
+	u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
+
+	if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET)
+	    != boot->bpbFSInfo * boot->bpbBytesPerSec
+	    || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) {
+		perr("could not read fsinfo block");
+		return FSFATAL;
+	}
+	fsinfo[0x1e8] = (u_char)boot->FSFree;
+	fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8);
+	fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16);
+	fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24);
+	fsinfo[0x1ec] = (u_char)boot->FSNext;
+	fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8);
+	fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16);
+	fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24);
+	if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET)
+	    != boot->bpbFSInfo * boot->bpbBytesPerSec
+	    || write(dosfs, fsinfo, sizeof fsinfo)
+	    != sizeof fsinfo) {
+		perr("Unable to write bpbFSInfo");
+		return FSFATAL;
+	}
+	/*
+	 * Technically, we should return FSBOOTMOD here.
+	 *
+	 * However, since Win95 OSR2 (the first M$ OS that has
+	 * support for FAT32) doesn't maintain the FSINFO block
+	 * correctly, it has to be fixed pretty often.
+	 *
+	 * Therefor, we handle the FSINFO block only informally,
+	 * fixing it if necessary, but otherwise ignoring the
+	 * fact that it was incorrect.
+	 */
+	return 0;
+}