mft.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

/**
 * mft.c - Mft record handling code. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2000-2004 Anton Altaparmakov
 * Copyright (c)      2005 Yura Pakhuchiy
 * Copyright (c) 2004-2005 Richard Russon
 *
 * 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 Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Modified 01/2007 by Andy McLaughlin for Visopsys port.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <time.h>

#include "compat.h"
#include "types.h"
#include "device.h"
#include "debug.h"
#include "bitmap.h"
#include "attrib.h"
#include "inode.h"
#include "volume.h"
#include "layout.h"
#include "lcnalloc.h"
#include "mft.h"
#include "logging.h"

/**
 * ntfs_mft_records_read - read records from the mft from disk
 * @vol:	volume to read from
 * @mref:	starting mft record number to read
 * @count:	number of mft records to read
 * @b:		output data buffer
 *
 * Read @count mft records starting at @mref from volume @vol into buffer
 * @b. Return 0 on success or -1 on error, with errno set to the error
 * code.
 *
 * If any of the records exceed the initialized size of the $MFT/$DATA
 * attribute, i.e. they cannot possibly be allocated mft records, assume this
 * is a bug and return error code ESPIPE.
 *
 * The read mft records are mst deprotected and are hence ready to use. The
 * caller should check each record with is_baad_record() in case mst
 * deprotection failed.
 *
 * NOTE: @b has to be at least of size @count * vol->mft_record_size.
 */
int ntfs_mft_records_read(const ntfs_volume *vol, const MFT_REF mref,
		const s64 count, MFT_RECORD *b)
{
	s64 br;
	VCN m;

	ntfs_log_trace("Entering for inode 0x%llx.\n", MREF(mref));
	if (!vol || !vol->mft_na || !b || count < 0) {
		errno = EINVAL;
		return -1;
	}
	m = MREF(mref);
	/* Refuse to read non-allocated mft records. */
	if (m + count > vol->mft_na->initialized_size >>
			vol->mft_record_size_bits) {
		errno = ESPIPE;
		return -1;
	}
	br = ntfs_attr_mst_pread(vol->mft_na, m << vol->mft_record_size_bits,
			count, vol->mft_record_size, b);
	if (br != count) {
		if (br != -1)
			errno = EIO;
		if (br >= 0)
			ntfs_log_debug("Error: partition is smaller than it should "
					"be!\n");
		else
			ntfs_log_perror("Error reading $Mft record(s)");
		return -1;
	}
	return 0;
}

/**
 * ntfs_mft_records_write - write mft records to disk
 * @vol:	volume to write to
 * @mref:	starting mft record number to write
 * @count:	number of mft records to write
 * @b:		data buffer containing the mft records to write
 *
 * Write @count mft records starting at @mref from data buffer @b to volume
 * @vol. Return 0 on success or -1 on error, with errno set to the error code.
 *
 * If any of the records exceed the initialized size of the $MFT/$DATA
 * attribute, i.e. they cannot possibly be allocated mft records, assume this
 * is a bug and return error code ESPIPE.
 *
 * Before the mft records are written, they are mst protected. After the write,
 * they are deprotected again, thus resulting in an increase in the update
 * sequence number inside the data buffer @b.
 *
 * If any mft records are written which are also represented in the mft mirror
 * $MFTMirr, we make a copy of the relevant parts of the data buffer @b into a
 * temporary buffer before we do the actual write. Then if at least one mft
 * record was successfully written, we write the appropriate mft records from
 * the copied buffer to the mft mirror, too.
 */
int ntfs_mft_records_write(const ntfs_volume *vol, const MFT_REF mref,
		const s64 count, MFT_RECORD *b)
{
	s64 bw;
	VCN m;
	void *bmirr = NULL;
	int cnt = 0, res = 0;

	ntfs_log_trace("Entering for inode 0x%llx.\n", MREF(mref));
	if (!vol || !vol->mft_na || vol->mftmirr_size <= 0 || !b || count < 0) {
		errno = EINVAL;
		return -1;
	}
	m = MREF(mref);
	/* Refuse to write non-allocated mft records. */
	if (m + count > vol->mft_na->initialized_size >>
			vol->mft_record_size_bits) {
		errno = ESPIPE;
		return -1;
	}
	if (m < vol->mftmirr_size) {
		if (!vol->mftmirr_na) {
			errno = EINVAL;
			return -1;
		}
		cnt = vol->mftmirr_size - m;
		if (cnt > count)
			cnt = count;
		bmirr = malloc(cnt * vol->mft_record_size);
		if (!bmirr)
			return -1;
		memcpy(bmirr, b, cnt * vol->mft_record_size);
	}
	bw = ntfs_attr_mst_pwrite(vol->mft_na, m << vol->mft_record_size_bits,
			count, vol->mft_record_size, b);
	if (bw != count) {
		if (bw != -1)
			errno = EIO;
		if (bw >= 0)
			ntfs_log_debug("Error: partial write while writing $Mft "
					"record(s)!\n");
		else
			ntfs_log_perror("Error writing $Mft record(s)");
		res = errno;
	}
	if (bmirr && bw > 0) {
		if (bw < cnt)
			cnt = bw;
		bw = ntfs_attr_mst_pwrite(vol->mftmirr_na,
				m << vol->mft_record_size_bits, cnt,
				vol->mft_record_size, bmirr);
		if (bw != cnt) {
			if (bw != -1)
				errno = EIO;
			ntfs_log_debug("Error: failed to sync $MFTMirr! Run "
					"chkdsk.\n");
			res = errno;
		}
	}
	if (bmirr)
		free(bmirr);
	if (!res)
		return res;
	errno = res;
	return -1;
}

/**
 * ntfs_file_record_read - read a FILE record from the mft from disk
 * @vol:	volume to read from
 * @mref:	mft reference specifying mft record to read
 * @mrec:	address of pointer in which to return the mft record
 * @attr:	address of pointer in which to return the first attribute
 *
 * Read a FILE record from the mft of @vol from the storage medium. @mref
 * specifies the mft record to read, including the sequence number, which can
 * be 0 if no sequence number checking is to be performed.
 *
 * The function allocates a buffer large enough to hold the mft record and
 * reads the record into the buffer (mst deprotecting it in the process).
 * *@mrec is then set to point to the buffer.
 *
 * If @attr is not NULL, *@attr is set to point to the first attribute in the
 * mft record, i.e. *@attr is a pointer into *@mrec.
 *
 * Return 0 on success, or -1 on error, with errno set to the error code.
 *
 * The read mft record is checked for having the magic FILE,
 * and for having a matching sequence number (if MSEQNO(*@mref) != 0).
 * If either of these fails, -1 is returned and errno is set to EIO. If you get
 * this, but you still want to read the mft record (e.g. in order to correct
 * it), use ntfs_mft_record_read() directly.
 *
 * Note: Caller has to free *@mrec when finished.
 *
 * Note: We do not check if the mft record is flagged in use. The caller can
 *	 check if desired.
 */
int ntfs_file_record_read(const ntfs_volume *vol, const MFT_REF mref,
		MFT_RECORD **mrec, ATTR_RECORD **attr)
{
	MFT_RECORD *m;
	ATTR_RECORD *a;
	int err;

	if (!vol || !mrec) {
		errno = EINVAL;
		return -1;
	}
	m = *mrec;
	if (!m) {
		m = (MFT_RECORD*)malloc(vol->mft_record_size);
		if (!m)
			return -1;
	}
	if (ntfs_mft_record_read(vol, mref, m)) {
		err = errno;
		goto read_failed;
	}
	if (!ntfs_is_file_record(m->magic))
		goto file_corrupt;
	if (MSEQNO(mref) && MSEQNO(mref) != le16_to_cpu(m->sequence_number))
		goto file_corrupt;
	a = (ATTR_RECORD*)((char*)m + le16_to_cpu(m->attrs_offset));
	if (p2n(a) < p2n(m) || (char*)a > (char*)m + vol->mft_record_size)
		goto file_corrupt;
	*mrec = m;
	if (attr)
		*attr = a;
	return 0;
file_corrupt:
	ntfs_log_debug("ntfs_file_record_read(): file is corrupt.\n");
	err = EIO;
read_failed:
	if (m != *mrec)
		free(m);
	errno = err;
	return -1;
}

/**
 * ntfs_mft_record_layout - layout an mft record into a memory buffer
 * @vol:	volume to which the mft record will belong
 * @mref:	mft reference specifying the mft record number
 * @mrec:	destination buffer of size >= @vol->mft_record_size bytes
 *
 * Layout an empty, unused mft record with the mft reference @mref into the
 * buffer @m.  The volume @vol is needed because the mft record structure was
 * modified in NTFS 3.1 so we need to know which volume version this mft record
 * will be used on.
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
int ntfs_mft_record_layout(const ntfs_volume *vol, const MFT_REF mref,
		MFT_RECORD *mrec)
{
	ATTR_RECORD *a;

	if (!vol || !mrec) {
		errno = EINVAL;
		return -1;
	}
	/* Aligned to 2-byte boundary. */
	if (vol->major_ver < 3 || (vol->major_ver == 3 && !vol->minor_ver))
		mrec->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD_OLD) + 1) & ~1);
	else {
		/* Abort if mref is > 32 bits. */
		if (MREF(mref) & 0x0000ffff00000000ull) {
			ntfs_log_debug("Mft reference exceeds 32 bits!\n");
			errno = ERANGE;
			return -1;
		}
		mrec->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD) + 1) & ~1);
		/*
		 * Set the NTFS 3.1+ specific fields while we know that the
		 * volume version is 3.1+.
		 */
		mrec->reserved = cpu_to_le16(0);
		mrec->mft_record_number = cpu_to_le32(MREF(mref));
	}
	mrec->magic = magic_FILE;
	if (vol->mft_record_size >= NTFS_BLOCK_SIZE)
		mrec->usa_count = cpu_to_le16(vol->mft_record_size /
				NTFS_BLOCK_SIZE + 1);
	else {
		mrec->usa_count = cpu_to_le16(1);
		ntfs_log_error("Sector size is bigger than MFT record size.  "
				"Setting usa_count to 1.  If Windows chkdsk "
				"reports this as corruption, please email %s "
				"stating that you saw this message and that "
				"the file system created was corrupt.  "
				"Thank you.\n", NTFS_DEV_LIST);
	}
	/* Set the update sequence number to 1. */
	*(u16*)((u8*)mrec + le16_to_cpu(mrec->usa_ofs)) = cpu_to_le16(1);
	mrec->lsn = cpu_to_le64(0ull);
	mrec->sequence_number = cpu_to_le16(1);
	mrec->link_count = cpu_to_le16(0);
	/* Aligned to 8-byte boundary. */
	mrec->attrs_offset = cpu_to_le16((le16_to_cpu(mrec->usa_ofs) +
			(le16_to_cpu(mrec->usa_count) << 1) + 7) & ~7);
	mrec->flags = cpu_to_le16(0);
	/*
	 * Using attrs_offset plus eight bytes (for the termination attribute),
	 * aligned to 8-byte boundary.
	 */
	mrec->bytes_in_use = cpu_to_le32((le16_to_cpu(mrec->attrs_offset) + 8 +
			7) & ~7);
	mrec->bytes_allocated = cpu_to_le32(vol->mft_record_size);
	mrec->base_mft_record = cpu_to_le64((MFT_REF)0);
	mrec->next_attr_instance = cpu_to_le16(0);
	a = (ATTR_RECORD*)((u8*)mrec + le16_to_cpu(mrec->attrs_offset));
	a->type = AT_END;
	a->length = cpu_to_le32(0);
	/* Finally, clear the unused part of the mft record. */
	memset((u8*)a + 8, 0, vol->mft_record_size - ((u8*)a + 8 - (u8*)mrec));
	return 0;
}

/**
 * ntfs_mft_record_format - format an mft record on an ntfs volume
 * @vol:	volume on which to format the mft record
 * @mref:	mft reference specifying mft record to format
 *
 * Format the mft record with the mft reference @mref in $MFT/$DATA, i.e. lay
 * out an empty, unused mft record in memory and write it to the volume @vol.
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
int ntfs_mft_record_format(const ntfs_volume *vol, const MFT_REF mref)
{
	MFT_RECORD *m;
	int err;

	if (!vol || !vol->mft_na) {
		errno = EINVAL;
		return -1;
	}
	m = malloc(vol->mft_record_size);
	if (!m)
		return -1;
	if (ntfs_mft_record_layout(vol, mref, m)) {
		err = errno;
		free(m);
		errno = err;
		return -1;
	}
	if (ntfs_mft_record_write(vol, mref, m)) {
		err = errno;
		free(m);
		errno = err;
		return -1;
	}
	free(m);
	return 0;
}

#ifndef NTFS_DISABLE_DEBUG_LOGGING
static const char *es = "  Leaving inconsistent metadata.  Run chkdsk.";
#endif

/**
 * ntfs_ffz - Find the first unset (zero) bit in a word
 * @word:
 *
 * Description...
 *
 * Returns:
 */
static inline unsigned int ntfs_ffz(unsigned int word)
{
	return ffs(~word) - 1;
}

#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif

/**
 * ntfs_mft_bitmap_find_free_rec - find a free mft record in the mft bitmap
 * @vol:	volume on which to search for a free mft record
 * @base_ni:	open base inode if allocating an extent mft record or NULL
 *
 * Search for a free mft record in the mft bitmap attribute on the ntfs volume
 * @vol.
 *
 * If @base_ni is NULL start the search at the default allocator position.
 *
 * If @base_ni is not NULL start the search at the mft record after the base
 * mft record @base_ni.
 *
 * Return the free mft record on success and -1 on error with errno set to the
 * error code.  An error code of ENOSPC means that there are no free mft
 * records in the currently initialized mft bitmap.
 */
static int ntfs_mft_bitmap_find_free_rec(ntfs_volume *vol, ntfs_inode *base_ni)
{
	s64 pass_end, ll, data_pos, pass_start, ofs, bit;
	ntfs_attr *mftbmp_na;
	u8 *buf, *byte;
	unsigned int size;
	u8 pass, b;

	mftbmp_na = vol->mftbmp_na;
	/*
	 * Set the end of the pass making sure we do not overflow the mft
	 * bitmap.
	 */
	size = PAGE_SIZE;
	pass_end = vol->mft_na->allocated_size >> vol->mft_record_size_bits;
	ll = mftbmp_na->initialized_size << 3;
	if (pass_end > ll)
		pass_end = ll;
	pass = 1;
	if (!base_ni)
		data_pos = vol->mft_data_pos;
	else
		data_pos = base_ni->mft_no + 1;
	if (data_pos < 24)
		data_pos = 24;
	if (data_pos >= pass_end) {
		data_pos = 24;
		pass = 2;
		/* This happens on a freshly formatted volume. */
		if (data_pos >= pass_end) {
			errno = ENOSPC;
			return -1;
		}
	}
	pass_start = data_pos;
	buf = (u8*)malloc(PAGE_SIZE);
	if (!buf)
		return -1;
	ntfs_log_debug("Starting bitmap search: pass %u, pass_start 0x%llx, "
			"pass_end 0x%llx, data_pos 0x%llx.\n", pass,
			(long long)pass_start, (long long)pass_end,
			(long long)data_pos);
#ifndef NTFS_DISABLE_DEBUG_LOGGING
	byte = NULL;
	b = 0;
#endif
	/* Loop until a free mft record is found. */
	for (; pass <= 2; size = PAGE_SIZE) {
		/* Cap size to pass_end. */
		ofs = data_pos >> 3;
		ll = ((pass_end + 7) >> 3) - ofs;
		if (size > ll)
			size = ll;
		ll = ntfs_attr_pread(mftbmp_na, ofs, size, buf);
		if (ll < 0) {
			ntfs_log_error("Failed to read mft bitmap "
					"attribute, aborting.\n");
			free(buf);
			return -1;
		}
		ntfs_log_debug("Read 0x%llx bytes.\n", (long long)ll);
		/* If we read at least one byte, search @buf for a zero bit. */
		if (ll) {