mft.c

LINUX下读写NTFS分区的工具。 已经集成了通过LIBCONV库支持中文的代码。

 */
int ntfs_mft_record_format(const ntfs_volume *vol, const MFT_REF mref)
{
	MFT_RECORD *m;
	int ret = -1;

	ntfs_log_enter("Entering\n");
	
	m = ntfs_calloc(vol->mft_record_size);
	if (!m)
		goto out;
	
	if (ntfs_mft_record_layout(vol, mref, m))
		goto free_m;
	
	if (ntfs_mft_record_write(vol, mref, m))
		goto free_m;
	
	ret = 0;
free_m:
	free(m);
out:	
	ntfs_log_leave("\n");
	return ret;
}

static const char *es = "  Leaving inconsistent metadata.  Run chkdsk.";

/**
 * 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;
	int ret = -1;

	ntfs_log_enter("Entering\n");
	
	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;
			goto leave;
		}
	}
	pass_start = data_pos;
	buf = ntfs_malloc(PAGE_SIZE);
	if (!buf)
		goto leave;
	
	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);
#ifdef DEBUG
	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_perror("Failed to read $MFT bitmap");
			free(buf);
			goto leave;
		}
		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) {
			size = ll << 3;
			bit = data_pos & 7;
			data_pos &= ~7ull;
			ntfs_log_debug("Before inner for loop: size 0x%x, "
					"data_pos 0x%llx, bit 0x%llx, "
					"*byte 0x%hhx, b %u.\n", size,
					(long long)data_pos, (long long)bit,
					byte ? *byte : -1, b);
			for (; bit < size && data_pos + bit < pass_end;
					bit &= ~7ull, bit += 8) {
				byte = buf + (bit >> 3);
				if (*byte == 0xff)
					continue;
				
				/* Note: ffz() result must be zero based. */
				b = ntfs_ffz((unsigned long)*byte);
				if (b < 8 && b >= (bit & 7)) {
					free(buf);
					ret = data_pos + (bit & ~7ull) + b;
					goto leave;
				}
			}
			ntfs_log_debug("After inner for loop: size 0x%x, "
					"data_pos 0x%llx, bit 0x%llx, "
					"*byte 0x%hhx, b %u.\n", size,
					(long long)data_pos, (long long)bit,
					byte ? *byte : -1, b);
			data_pos += size;
			/*
			 * If the end of the pass has not been reached yet,
			 * continue searching the mft bitmap for a zero bit.
			 */
			if (data_pos < pass_end)
				continue;
		}
		/* Do the next pass. */
		pass++;
		if (pass == 2) {
			/*
			 * Starting the second pass, in which we scan the first
			 * part of the zone which we omitted earlier.
			 */
			pass_end = pass_start;
			data_pos = pass_start = 24;
			ntfs_log_debug("pass %i, pass_start 0x%llx, pass_end "
					"0x%llx.\n", pass, (long long)pass_start,
					(long long)pass_end);
			if (data_pos >= pass_end)
				break;
		}
	}
	/* No free mft records in currently initialized mft bitmap. */
	free(buf);
	errno = ENOSPC;
leave:
	ntfs_log_leave("\n");
	return ret;
}

/**
 * ntfs_mft_bitmap_extend_allocation_i - see ntfs_mft_bitmap_extend_allocation
 */
static int ntfs_mft_bitmap_extend_allocation_i(ntfs_volume *vol)
{
	LCN lcn;
	s64 ll = 0; /* silence compiler warning */
	ntfs_attr *mftbmp_na;
	runlist_element *rl, *rl2 = NULL; /* silence compiler warning */
	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;

	mftbmp_na = vol->mftbmp_na;
	/*
	 * Determine the last lcn of the mft bitmap.  The allocated size of the
	 * mft bitmap cannot be zero so we are ok to do this.
	 */
	rl = ntfs_attr_find_vcn(mftbmp_na, (mftbmp_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 bitmap attribute.\n");
		if (rl)
			errno = EIO;
		return -1;
	}
	lcn = rl->lcn + rl->length;
	
	rl2 = ntfs_cluster_alloc(vol, rl[1].vcn, 1, lcn, DATA_ZONE);
	if (!rl2) {
		ntfs_log_error("Failed to allocate a cluster for "
				"the mft bitmap.\n");
		return -1;
	}
	rl = ntfs_runlists_merge(mftbmp_na->rl, rl2);
	if (!rl) {
		err = errno;
		ntfs_log_error("Failed to merge runlists for mft "
				"bitmap.\n");
		if (ntfs_cluster_free_from_rl(vol, rl2))
			ntfs_log_error("Failed to deallocate "
					"cluster.%s\n", es);
		free(rl2);
		errno = err;
		return -1;
	}
	mftbmp_na->rl = rl;
	ntfs_log_debug("Adding one run to mft bitmap.\n");
	/* Find the last run in the new runlist. */
	for (; rl[1].length; rl++)
		;
	/*
	 * Update the attribute record as well.  Note: @rl is the last
	 * (non-terminator) runlist element of mft bitmap.
	 */
	ctx = ntfs_attr_get_search_ctx(mftbmp_na->ni, NULL);
	if (!ctx)
		goto undo_alloc;

	if (ntfs_attr_lookup(mftbmp_na->type, mftbmp_na->name,
			mftbmp_na->name_len, 0, rl[1].vcn, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find last attribute extent of "
				"mft bitmap attribute.\n");
		goto undo_alloc;
	}
	m = ctx->mrec;
	a = ctx->attr;
	ll = sle64_to_cpu(a->lowest_vcn);
	rl2 = ntfs_attr_find_vcn(mftbmp_na, ll);
	if (!rl2 || !rl2->length) {
		ntfs_log_error("Failed to determine previous last "
				"allocated cluster of mft bitmap 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 bitmap 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.
		ntfs_log_error("Not enough space in this mft record to "
				"accommodate extended mft bitmap attribute "
				"extent.  Cannot handle this yet.\n");
		errno = EOPNOTSUPP;
		goto undo_alloc;
	}
	mp_rebuilt = TRUE;
	/* Generate the mapping pairs array directly into the attr 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 for "
				"mft bitmap 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 bitmap allocated_size by one cluster.
	 * Reflect this in the ntfs_attr structure and the attribute record.
	 */
	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(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");
			goto restore_undo_alloc;
		}
		a = ctx->attr;
	}
	mftbmp_na->allocated_size += vol->cluster_size;
	a->allocated_size = cpu_to_sle64(mftbmp_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(mftbmp_na->type, mftbmp_na->name,
			mftbmp_na->name_len, 0, rl[1].vcn, NULL, 0, ctx)) {
		ntfs_log_error("Failed to find last attribute extent of "
				"mft bitmap attribute.%s\n", es);
		ntfs_attr_put_search_ctx(ctx);
		mftbmp_na->allocated_size += vol->cluster_size;
		/*
		 * 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(rl[1].vcn - 2);
	errno = err;
undo_alloc:
	err = errno;

	/* Remove the last run from the runlist. */
	lcn = rl->lcn;
	rl->lcn = rl[1].lcn;
	rl->length = 0;
	
	/* FIXME: use an ntfs_cluster_free_* function */
	if (ntfs_bitmap_clear_bit(vol->lcnbmp_na, lcn))
		ntfs_log_error("Failed to free cluster.%s\n", es);
	else
		vol->free_clusters++;
	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_bitmap_extend_allocation - extend mft bitmap attribute by a cluster
 * @vol:	volume on which to extend the mft bitmap attribute
 *
 * Extend the mft bitmap attribute on the ntfs volume @vol by one cluster.
 *
 * 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_bitmap_extend_allocation(ntfs_volume *vol)
{
	int ret;
	
	ntfs_log_enter("Entering\n");
	ret = ntfs_mft_bitmap_extend_allocation_i(vol);
	ntfs_log_leave("\n");
	return ret;
}
/**
 * ntfs_mft_bitmap_extend_initialized - extend mft bitmap initialized data
 * @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.