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libntfs/source/bootsect.c

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/**
* bootsect.c - Boot sector handling code. Originated from the Linux-NTFS project.
*
* Copyright (c) 2000-2006 Anton Altaparmakov
* Copyright (c) 2003-2008 Szabolcs Szakacsits
* Copyright (c) 2005 Yura Pakhuchiy
*
* This program/include file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program/include file is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (in the main directory of the NTFS-3G
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include "compat.h"
#include "bootsect.h"
#include "debug.h"
#include "logging.h"
/**
* ntfs_boot_sector_is_ntfs - check if buffer contains a valid ntfs boot sector
* @b: buffer containing putative boot sector to analyze
* @silent: if zero, output progress messages to stderr
*
* Check if the buffer @b contains a valid ntfs boot sector. The buffer @b
* must be at least 512 bytes in size.
*
* If @silent is zero, output progress messages to stderr. Otherwise, do not
* output any messages (except when configured with --enable-debug in which
* case warning/debug messages may be displayed).
*
* Return TRUE if @b contains a valid ntfs boot sector and FALSE if not.
*/
BOOL ntfs_boot_sector_is_ntfs(NTFS_BOOT_SECTOR *b)
{
u32 i;
BOOL ret = FALSE;
ntfs_log_debug("Beginning bootsector check.\n");
ntfs_log_debug("Checking OEMid, NTFS signature.\n");
if (b->oem_id != cpu_to_le64(0x202020205346544eULL)) { /* "NTFS " */
ntfs_log_error("NTFS signature is missing.\n");
goto not_ntfs;
}
ntfs_log_debug("Checking bytes per sector.\n");
if (le16_to_cpu(b->bpb.bytes_per_sector) < 256 ||
le16_to_cpu(b->bpb.bytes_per_sector) > 4096) {
ntfs_log_error("Unexpected bytes per sector value (%d).\n",
le16_to_cpu(b->bpb.bytes_per_sector));
goto not_ntfs;
}
ntfs_log_debug("Checking sectors per cluster.\n");
switch (b->bpb.sectors_per_cluster) {
case 1: case 2: case 4: case 8: case 16: case 32: case 64: case 128:
break;
default:
ntfs_log_error("Unexpected sectors per cluster value (%d).\n",
b->bpb.sectors_per_cluster);
goto not_ntfs;
}
ntfs_log_debug("Checking cluster size.\n");
i = (u32)le16_to_cpu(b->bpb.bytes_per_sector) *
b->bpb.sectors_per_cluster;
if (i > 65536) {
ntfs_log_error("Unexpected cluster size (%d).\n", i);
goto not_ntfs;
}
ntfs_log_debug("Checking reserved fields are zero.\n");
if (le16_to_cpu(b->bpb.reserved_sectors) ||
le16_to_cpu(b->bpb.root_entries) ||
le16_to_cpu(b->bpb.sectors) ||
le16_to_cpu(b->bpb.sectors_per_fat) ||
le32_to_cpu(b->bpb.large_sectors) ||
b->bpb.fats) {
ntfs_log_error("Reserved fields aren't zero "
"(%d, %d, %d, %d, %d, %d).\n",
le16_to_cpu(b->bpb.reserved_sectors),
le16_to_cpu(b->bpb.root_entries),
le16_to_cpu(b->bpb.sectors),
le16_to_cpu(b->bpb.sectors_per_fat),
le32_to_cpu(b->bpb.large_sectors),
b->bpb.fats);
goto not_ntfs;
}
ntfs_log_debug("Checking clusters per mft record.\n");
if ((u8)b->clusters_per_mft_record < 0xe1 ||
(u8)b->clusters_per_mft_record > 0xf7) {
switch (b->clusters_per_mft_record) {
case 1: case 2: case 4: case 8: case 0x10: case 0x20: case 0x40:
break;
default:
ntfs_log_error("Unexpected clusters per mft record "
"(%d).\n", b->clusters_per_mft_record);
goto not_ntfs;
}
}
ntfs_log_debug("Checking clusters per index block.\n");
if ((u8)b->clusters_per_index_record < 0xe1 ||
(u8)b->clusters_per_index_record > 0xf7) {
switch (b->clusters_per_index_record) {
case 1: case 2: case 4: case 8: case 0x10: case 0x20: case 0x40:
break;
default:
ntfs_log_error("Unexpected clusters per index record "
"(%d).\n", b->clusters_per_index_record);
goto not_ntfs;
}
}
if (b->end_of_sector_marker != cpu_to_le16(0xaa55))
ntfs_log_debug("Warning: Bootsector has invalid end of sector "
"marker.\n");
ntfs_log_debug("Bootsector check completed successfully.\n");
ret = TRUE;
not_ntfs:
return ret;
}
static const char *last_sector_error =
"HINTS: Either the volume is a RAID/LDM but it wasn't setup yet,\n"
" or it was not setup correctly (e.g. by not using mdadm --build ...),\n"
" or a wrong device is tried to be mounted,\n"
" or the partition table is corrupt (partition is smaller than NTFS),\n"
" or the NTFS boot sector is corrupt (NTFS size is not valid).\n";
/**
* ntfs_boot_sector_parse - setup an ntfs volume from an ntfs boot sector
* @vol: ntfs_volume to setup
* @bs: buffer containing ntfs boot sector to parse
*
* Parse the ntfs bootsector @bs and setup the ntfs volume @vol with the
* obtained values.
*
* Return 0 on success or -1 on error with errno set to the error code EINVAL.
*/
int ntfs_boot_sector_parse(ntfs_volume *vol, const NTFS_BOOT_SECTOR *bs)
{
s64 sectors;
u8 sectors_per_cluster;
s8 c;
/* We return -1 with errno = EINVAL on error. */
errno = EINVAL;
vol->sector_size = le16_to_cpu(bs->bpb.bytes_per_sector);
vol->sector_size_bits = ffs(vol->sector_size) - 1;
ntfs_log_debug("SectorSize = 0x%x\n", vol->sector_size);
ntfs_log_debug("SectorSizeBits = %u\n", vol->sector_size_bits);
/*
* The bounds checks on mft_lcn and mft_mirr_lcn (i.e. them being
* below or equal the number_of_clusters) really belong in the
* ntfs_boot_sector_is_ntfs but in this way we can just do this once.
*/
sectors_per_cluster = bs->bpb.sectors_per_cluster;
ntfs_log_debug("SectorsPerCluster = 0x%x\n", sectors_per_cluster);
if (sectors_per_cluster & (sectors_per_cluster - 1)) {
ntfs_log_error("sectors_per_cluster (%d) is not a power of 2."
"\n", sectors_per_cluster);
return -1;
}
sectors = sle64_to_cpu(bs->number_of_sectors);
ntfs_log_debug("NumberOfSectors = %lld\n", (long long)sectors);
if (!sectors) {
ntfs_log_error("Volume size is set to zero.\n");
return -1;
}
if (vol->dev->d_ops->seek(vol->dev,
(sectors - 1) << vol->sector_size_bits,
SEEK_SET) == -1) {
ntfs_log_perror("Failed to read last sector (%lld)",
(long long)sectors);
ntfs_log_error("%s", last_sector_error);
return -1;
}
vol->nr_clusters = sectors >> (ffs(sectors_per_cluster) - 1);
vol->mft_lcn = sle64_to_cpu(bs->mft_lcn);
vol->mftmirr_lcn = sle64_to_cpu(bs->mftmirr_lcn);
ntfs_log_debug("MFT LCN = %lld\n", (long long)vol->mft_lcn);
ntfs_log_debug("MFTMirr LCN = %lld\n", (long long)vol->mftmirr_lcn);
if (vol->mft_lcn > vol->nr_clusters ||
vol->mftmirr_lcn > vol->nr_clusters) {
ntfs_log_error("$MFT LCN (%lld) or $MFTMirr LCN (%lld) is "
"greater than the number of clusters (%lld).\n",
(long long)vol->mft_lcn, (long long)vol->mftmirr_lcn,
(long long)vol->nr_clusters);
return -1;
}
vol->cluster_size = sectors_per_cluster * vol->sector_size;
if (vol->cluster_size & (vol->cluster_size - 1)) {
ntfs_log_error("cluster_size (%d) is not a power of 2.\n",
vol->cluster_size);
return -1;
}
vol->cluster_size_bits = ffs(vol->cluster_size) - 1;
/*
* Need to get the clusters per mft record and handle it if it is
* negative. Then calculate the mft_record_size. A value of 0x80 is
* illegal, thus signed char is actually ok!
*/
c = bs->clusters_per_mft_record;
ntfs_log_debug("ClusterSize = 0x%x\n", (unsigned)vol->cluster_size);
ntfs_log_debug("ClusterSizeBits = %u\n", vol->cluster_size_bits);
ntfs_log_debug("ClustersPerMftRecord = 0x%x\n", c);
/*
* When clusters_per_mft_record is negative, it means that it is to
* be taken to be the negative base 2 logarithm of the mft_record_size
* min bytes. Then:
* mft_record_size = 2^(-clusters_per_mft_record) bytes.
*/
if (c < 0)
vol->mft_record_size = 1 << -c;
else
vol->mft_record_size = c << vol->cluster_size_bits;
if (vol->mft_record_size & (vol->mft_record_size - 1)) {
ntfs_log_error("mft_record_size (%d) is not a power of 2.\n",
vol->mft_record_size);
return -1;
}
vol->mft_record_size_bits = ffs(vol->mft_record_size) - 1;
ntfs_log_debug("MftRecordSize = 0x%x\n", (unsigned)vol->mft_record_size);
ntfs_log_debug("MftRecordSizeBits = %u\n", vol->mft_record_size_bits);
/* Same as above for INDX record. */
c = bs->clusters_per_index_record;
ntfs_log_debug("ClustersPerINDXRecord = 0x%x\n", c);
if (c < 0)
vol->indx_record_size = 1 << -c;
else
vol->indx_record_size = c << vol->cluster_size_bits;
vol->indx_record_size_bits = ffs(vol->indx_record_size) - 1;
ntfs_log_debug("INDXRecordSize = 0x%x\n", (unsigned)vol->indx_record_size);
ntfs_log_debug("INDXRecordSizeBits = %u\n", vol->indx_record_size_bits);
/*
* Work out the size of the MFT mirror in number of mft records. If the
* cluster size is less than or equal to the size taken by four mft
* records, the mft mirror stores the first four mft records. If the
* cluster size is bigger than the size taken by four mft records, the
* mft mirror contains as many mft records as will fit into one
* cluster.
*/
if (vol->cluster_size <= 4 * vol->mft_record_size)
vol->mftmirr_size = 4;
else
vol->mftmirr_size = vol->cluster_size / vol->mft_record_size;
return 0;
}
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