mft.c

一个在linux下挂载ntfs文件系统的好工具

 * @vol:	volume on which to extend the mft bitmap attribute
 *
 * Extend the initialized portion of the mft bitmap attribute on the ntfs
 * volume @vol by 8 bytes.
 *
 * Note:  Only changes initialized_size and data_size, i.e. requires that
 * allocated_size is big enough to fit the new initialized_size.
 *
 * Return 0 on success and -1 on error with errno set to the error code.
 */
static int ntfs_mft_bitmap_extend_initialized(ntfs_volume *vol)
{
	s64 old_data_size, old_initialized_size, ll;
	ntfs_attr *mftbmp_na;
	ntfs_attr_search_ctx *ctx;
	ATTR_RECORD *a;
	int err;

	mftbmp_na = vol->mftbmp_na;
	ctx = ntfs_attr_get_search_ctx(mftbmp_na->ni, NULL);
	if (!ctx) {
		ntfs_log_error("Failed to get search context.\n");
		return -1;
	}
	if (ntfs_attr_lookup(mftbmp_na->type, mftbmp_na->name,
			mftbmp_na->name_len, 0, 0, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find first attribute extent of "
				"mft bitmap attribute.\n");
		err = errno;
		goto put_err_out;
	}
	a = ctx->attr;
	old_data_size = mftbmp_na->data_size;
	old_initialized_size = mftbmp_na->initialized_size;
	mftbmp_na->initialized_size += 8;
	a->initialized_size = cpu_to_sle64(mftbmp_na->initialized_size);
	if (mftbmp_na->initialized_size > mftbmp_na->data_size) {
		mftbmp_na->data_size = mftbmp_na->initialized_size;
		a->data_size = cpu_to_sle64(mftbmp_na->data_size);
	}
	/* Ensure the changes make it to disk. */
	ntfs_inode_mark_dirty(ctx->ntfs_ino);
	ntfs_attr_put_search_ctx(ctx);
	/* Initialize the mft bitmap attribute value with zeroes. */
	ll = 0;
	ll = ntfs_attr_pwrite(mftbmp_na, old_initialized_size, 8, &ll);
	if (ll == 8) {
		ntfs_log_debug("Wrote eight initialized bytes to mft bitmap.\n");
		return 0;
	}
	ntfs_log_error("Failed to write to mft bitmap.\n");
	err = errno;
	if (ll >= 0)
		err = EIO;
	/* Try to recover from the error. */
	ctx = ntfs_attr_get_search_ctx(mftbmp_na->ni, NULL);
	if (!ctx) {
		ntfs_log_error("Failed to get search context.%s\n", es);
		goto err_out;
	}
	if (ntfs_attr_lookup(mftbmp_na->type, mftbmp_na->name,
			mftbmp_na->name_len, 0, 0, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find first attribute extent of "
				"mft bitmap attribute.%s\n", es);
put_err_out:
		ntfs_attr_put_search_ctx(ctx);
		goto err_out;
	}
	a = ctx->attr;
	mftbmp_na->initialized_size = old_initialized_size;
	a->initialized_size = cpu_to_sle64(old_initialized_size);
	if (mftbmp_na->data_size != old_data_size) {
		mftbmp_na->data_size = old_data_size;
		a->data_size = cpu_to_sle64(old_data_size);
	}
	ntfs_inode_mark_dirty(ctx->ntfs_ino);
	ntfs_attr_put_search_ctx(ctx);
	ntfs_log_debug("Restored status of mftbmp: allocated_size 0x%llx, "
			"data_size 0x%llx, initialized_size 0x%llx.\n",
			(long long)mftbmp_na->allocated_size,
			(long long)mftbmp_na->data_size,
			(long long)mftbmp_na->initialized_size);
err_out:
	errno = err;
	return -1;
}

/**
 * ntfs_mft_data_extend_allocation - extend mft data attribute
 * @vol:	volume on which to extend the mft data attribute
 *
 * Extend the mft data attribute on the ntfs volume @vol by 16 mft records
 * worth of clusters or if not enough space for this by one mft record worth
 * of clusters.
 *
 * Note:  Only changes allocated_size, i.e. does not touch initialized_size or
 * data_size.
 *
 * Return 0 on success and -1 on error with errno set to the error code.
 */
static int ntfs_mft_data_extend_allocation(ntfs_volume *vol)
{
	LCN lcn;
	VCN old_last_vcn;
	s64 min_nr, nr, ll = 0; /* silence compiler warning */
	ntfs_attr *mft_na;
	runlist_element *rl, *rl2;
	ntfs_attr_search_ctx *ctx;
	MFT_RECORD *m = NULL; /* silence compiler warning */
	ATTR_RECORD *a = NULL; /* silence compiler warning */
	int err, mp_size;
	u32 old_alen = 0; /* silence compiler warning */
	BOOL mp_rebuilt = FALSE;

	ntfs_log_debug("Extending mft data allocation.\n");
	mft_na = vol->mft_na;
	/*
	 * Determine the preferred allocation location, i.e. the last lcn of
	 * the mft data attribute.  The allocated size of the mft data
	 * attribute cannot be zero so we are ok to do this.
	 */
	rl = ntfs_attr_find_vcn(mft_na,
			(mft_na->allocated_size - 1) >> vol->cluster_size_bits);
	if (!rl || !rl->length || rl->lcn < 0) {
		ntfs_log_error("Failed to determine last allocated "
				"cluster of mft data attribute.\n");
		if (rl)
			errno = EIO;
		return -1;
	}
	lcn = rl->lcn + rl->length;
	ntfs_log_debug("Last lcn of mft data attribute is 0x%llx.\n", (long long)lcn);
	/* Minimum allocation is one mft record worth of clusters. */
	min_nr = vol->mft_record_size >> vol->cluster_size_bits;
	if (!min_nr)
		min_nr = 1;
	/* Want to allocate 16 mft records worth of clusters. */
	nr = vol->mft_record_size << 4 >> vol->cluster_size_bits;
	if (!nr)
		nr = min_nr;
	ntfs_log_debug("Trying mft data allocation with default cluster count "
			"%lli.\n", (long long)nr);
	old_last_vcn = rl[1].vcn;
	do {
		rl2 = ntfs_cluster_alloc(vol, old_last_vcn, nr, lcn, MFT_ZONE);
		if (rl2)
			break;
		if (errno != ENOSPC || nr == min_nr) {
			ntfs_log_error("Failed to allocate the minimal "
					"number of clusters (%lli) for the "
					"mft data attribute.\n", (long long)nr);
			return -1;
		}
		/*
		 * There is not enough space to do the allocation, but there
		 * might be enough space to do a minimal allocation so try that
		 * before failing.
		 */
		nr = min_nr;
		ntfs_log_debug("Retrying mft data allocation with minimal cluster "
				"count %lli.\n", (long long)nr);
	} while (1);
	rl = ntfs_runlists_merge(mft_na->rl, rl2);
	if (!rl) {
		err = errno;
		ntfs_log_error("Failed to merge runlists for mft data "
				"attribute.\n");
		if (ntfs_cluster_free_from_rl(vol, rl2))
			ntfs_log_error("Failed to deallocate clusters "
					"from the mft data attribute.%s\n", es);
		free(rl2);
		errno = err;
		return -1;
	}
	mft_na->rl = rl;
	ntfs_log_debug("Allocated %lli clusters.\n", nr);
	/* Find the last run in the new runlist. */
	for (; rl[1].length; rl++)
		;
	/* Update the attribute record as well. */
	ctx = ntfs_attr_get_search_ctx(mft_na->ni, NULL);
	if (!ctx) {
		ntfs_log_error("Failed to get search context.\n");
		goto undo_alloc;
	}
	if (ntfs_attr_lookup(mft_na->type, mft_na->name, mft_na->name_len, 0,
			rl[1].vcn, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find last attribute extent of "
				"mft data attribute.\n");
		goto undo_alloc;
	}
	m = ctx->mrec;
	a = ctx->attr;
	ll = sle64_to_cpu(a->lowest_vcn);
	rl2 = ntfs_attr_find_vcn(mft_na, ll);
	if (!rl2 || !rl2->length) {
		ntfs_log_error("Failed to determine previous last "
				"allocated cluster of mft data attribute.\n");
		if (rl2)
			errno = EIO;
		goto undo_alloc;
	}
	/* Get the size for the new mapping pairs array for this extent. */
	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll);
	if (mp_size <= 0) {
		ntfs_log_error("Get size for mapping pairs failed for "
				"mft data attribute extent.\n");
		goto undo_alloc;
	}
	/* Expand the attribute record if necessary. */
	old_alen = le32_to_cpu(a->length);
	if (ntfs_attr_record_resize(m, a,
			mp_size + le16_to_cpu(a->mapping_pairs_offset))) {
		// TODO: Deal with this by moving this extent to a new mft
		// record or by starting a new extent in a new mft record.
		// Note: Use the special reserved mft records and ensure that
		// this extent is not required to find the mft record in
		// question.
		errno = EOPNOTSUPP;
		ntfs_log_perror("Not enough space to extended mft data "
				"attribute.\n");
		goto undo_alloc;
	}
	mp_rebuilt = TRUE;
	/*
	 * Generate the mapping pairs array directly into the attribute record.
	 */
	if (ntfs_mapping_pairs_build(vol,
			(u8*)a + le16_to_cpu(a->mapping_pairs_offset), mp_size,
			rl2, ll, NULL)) {
		ntfs_log_error("Failed to build mapping pairs array of "
				"mft data attribute.\n");
		errno = EIO;
		goto undo_alloc;
	}
	/* Update the highest_vcn. */
	a->highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
	/*
	 * We now have extended the mft data allocated_size by nr clusters.
	 * Reflect this in the ntfs_attr structure and the attribute record.
	 * @rl is the last (non-terminator) runlist element of mft data
	 * attribute.
	 */
	if (a->lowest_vcn) {
		/*
		 * We are not in the first attribute extent, switch to it, but
		 * first ensure the changes will make it to disk later.
		 */
		ntfs_inode_mark_dirty(ctx->ntfs_ino);
		ntfs_attr_reinit_search_ctx(ctx);
		if (ntfs_attr_lookup(mft_na->type, mft_na->name,
				mft_na->name_len, 0, 0, NULL, 0, ctx)) {
			ntfs_log_error("Failed to find first attribute "
					"extent of mft data attribute.\n");
			goto restore_undo_alloc;
		}
		a = ctx->attr;
	}
	mft_na->allocated_size += nr << vol->cluster_size_bits;
	a->allocated_size = cpu_to_sle64(mft_na->allocated_size);
	/* Ensure the changes make it to disk. */
	ntfs_inode_mark_dirty(ctx->ntfs_ino);
	ntfs_attr_put_search_ctx(ctx);
	return 0;
restore_undo_alloc:
	err = errno;
	ntfs_attr_reinit_search_ctx(ctx);
	if (ntfs_attr_lookup(mft_na->type, mft_na->name, mft_na->name_len, 0,
			rl[1].vcn, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find last attribute extent of "
				"mft data attribute.%s\n", es);
		ntfs_attr_put_search_ctx(ctx);
		mft_na->allocated_size += nr << vol->cluster_size_bits;
		/*
		 * The only thing that is now wrong is ->allocated_size of the
		 * base attribute extent which chkdsk should be able to fix.
		 */
		errno = err;
		return -1;
	}
	m = ctx->mrec;
	a = ctx->attr;
	a->highest_vcn = cpu_to_sle64(old_last_vcn - 1);
	errno = err;
undo_alloc:
	err = errno;
	if (ntfs_cluster_free(vol, mft_na, old_last_vcn, -1) < 0)
		ntfs_log_error("Failed to free clusters from mft data "
				"attribute.%s\n", es);
	if (ntfs_rl_truncate(&mft_na->rl, old_last_vcn))
		ntfs_log_error("Failed to truncate mft data attribute "
				"runlist.%s\n", es);
	if (mp_rebuilt) {
		if (ntfs_mapping_pairs_build(vol, (u8*)a +
				le16_to_cpu(a->mapping_pairs_offset),
				old_alen - le16_to_cpu(a->mapping_pairs_offset),
				rl2, ll, NULL))
			ntfs_log_error("Failed to restore mapping pairs "
					"array.%s\n", es);
		if (ntfs_attr_record_resize(m, a, old_alen))
			ntfs_log_error("Failed to restore attribute "
					"record.%s\n", es);
		ntfs_inode_mark_dirty(ctx->ntfs_ino);
	}
	if (ctx)
		ntfs_attr_put_search_ctx(ctx);
	errno = err;
	return -1;
}

/**
 * ntfs_mft_record_alloc - allocate an mft record on an ntfs volume
 * @vol:	volume on which to allocate the mft record
 * @base_ni:	open base inode if allocating an extent mft record or NULL
 *
 * Allocate an mft record in $MFT/$DATA of an open ntfs volume @vol.
 *
 * If @base_ni is NULL make the mft record a base mft record and allocate it at
 * the default allocator position.
 *
 * If @base_ni is not NULL make the allocated mft record an extent record,
 * allocate it starting at the mft record after the base mft record and attach
 * the allocated and opened ntfs inode to the base inode @base_ni.
 *
 * On success return the now opened ntfs (extent) inode of the mft record.
 *
 * On error return NULL with errno set to the error code.
 *
 * To find a free mft record, we scan the mft bitmap for a zero bit.  To
 * optimize this we start scanning at the place specified by @base_ni or if
 * @base_ni is NULL we start where we last stopped and we perform wrap around
 * when we reach the end.  Note, we do not try to allocate mft records below
 * number 24 because numbers 0 to 15 are the defined system files anyway and 16
 * to 24 are special in that they are used for storing extension mft records
 * for the $DATA attribute of $MFT.  This is required to avoid the possibility
 * of creating a run list with a circular dependence which once written to disk
 * can never be read in again.  Windows will only use records 16 to 24 for
 * normal files if the volume is completely out of space.  We never use them
 * which means that when the volume is really out of space we cannot create any
 * more files while Windows can still create up to 8 small files.  We can start
 * doing this at some later time, it does not matter much for now.
 *
 * When scanning the mft bitmap, we only search up to the last allocated mft
 * record.  If there are no free records left in the range 24 to number of
 * allocated mft records, then we extend the $MFT/$DATA attribute in order to
 * create free mft records.  We extend the allocated size of $MFT/$DATA by 16
 * records at a time or one cluster, if cluster size is above 16kiB.  If there
 * is not sufficient space to do this, we try to extend by a single mft record
 * or one cluster, if cluster size is above the mft record size, but we only do
 * this if there is enough free space, which we know from the values returned
 * by the failed cluster allocation function when we tried to do the first
 * allocation.
 *
 * No matter how many mft records we allocate, we initialize only the first
 * allocated mft record, incrementing mft data size and initialized size
 * accordingly, open an ntfs_inode for it and return it to the caller, unless
 * there are less than 24 mft records, in which case we allocate and initialize
 * mft records until we reach record 24 which we consider as the first free mft
 * record for use by normal files.
 *
 * If during any stage we overflow the initialized data in the mft bitmap, we
 * extend the initialized size (and data size) by 8 bytes, allocating another
 * cluster if required.  The bitmap data size has to be at least equal to the
 * number of mft records in the mft, but it can be bigger, in which case the
 * superfluous bits are padded with zeroes.
 *
 * Thus, when we return successfully (return value non-zero), we will have:
 *	- initialized / extended the mft bitmap if necessary,
 *	- initialized / extended the mft data if necessary,
 *	- set the bit corresponding to the mft record being allocated in the
 *	  mft bitmap,
 *	- open an ntfs_inode for the allocated mft record, and we will
 *	- return the ntfs_inode.
 *
 * On error (return value zero), nothing will have changed.  If we had changed
 * anything before the error occurred, we will have reverted back to the
 * starting state before returning to the caller.  Thus, except for bugs, we
 * should always leave the volume in a consistent state when returning from
 * this function.
 *
 * Note, this function cannot make use of most of the normal functions, like
 * for example for attribute resizing, etc, because when the run list overflows
 * the base mft record and an attribute list is used, it is very important that
 * the extension mft records used to store the $DATA attribute of $MFT can be
 * reached without having to read the information contained inside them, as
 * this would make it impossible to find them in the first place after the
 * volume is dismounted.  $MFT/$BITMAP probably does not need to follow this
 * rule because the bitmap is not essential for finding the mft records, but on
 * the other hand, handling the bitmap in this special way would make life
 * easier because otherwise there might be circular invocations of functions
 * when reading the bitmap but if we are careful, we should be able to avoid
 * all problems.
 */
ntfs_inode *ntfs_mft_record_alloc(ntfs_volume *vol, ntfs_inode *base_ni)
{