bitmap.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

	ntfs_bmp_rollback(bmp);
	ntfs_attr_close(bmp->attr);

	free(bmp);
}

/**
 * ntfs_bmp_create - Create a representation of a bitmap
 * @inode:
 * @type:
 * @name:
 * @name_len:
 *
 * Description...
 *
 * Returns:
 */
struct ntfs_bmp * ntfs_bmp_create(ntfs_inode *inode, ATTR_TYPES type, ntfschar *name, int name_len)
{
	struct ntfs_bmp *bmp;
	ntfs_attr *attr;

	if (!inode)
		return NULL;

	ntfs_log_trace ("\n");
	attr = ntfs_attr_open(inode, type, name, name_len);
	if (!attr)
		return NULL;

	bmp = calloc(1, sizeof(*bmp));
	if (!bmp) {
		ntfs_attr_close(attr);
		return NULL;
	}

	ntfs_log_critical("bmp = %p, attr = %p, inode = %p, attr->ni->mft_no = %lld\n", bmp, attr, inode, MREF(attr->ni->mft_no));
	bmp->vol       = inode->vol;
	bmp->attr      = attr;
	bmp->data      = NULL;
	bmp->data_vcn  = NULL;
	bmp->count     = 0;

	return bmp;
}

/**
 * ntfs_bmp_add_data - Add a bitmap block to the current cache
 * @bmp:
 * @vcn:
 * @data:
 *
 * Description...
 *
 * Returns:
 */
int ntfs_bmp_add_data(struct ntfs_bmp *bmp, VCN vcn, u8 *data)
{
	int i = 0;
	int old;
	int new;

	if (!bmp || !data)
		return -1;

	ntfs_log_trace ("\n");
	old = ROUND_UP(bmp->count, 16);
	bmp->count++;
	new = ROUND_UP(bmp->count, 16);

	if (old != new) {
		bmp->data     = realloc(bmp->data,      new * sizeof(*bmp->data));
		bmp->data_vcn = realloc(bmp->data_vcn , new * sizeof(*bmp->data_vcn));
	}

	for (i = 0; i < bmp->count-1; i++)
		if (bmp->data_vcn[i] > vcn)
			break;

	if ((bmp->count-i) > 0) {
		memmove(&bmp->data[i+1],     &bmp->data[i],     (bmp->count-i) * sizeof(*bmp->data));
		memmove(&bmp->data_vcn[i+1], &bmp->data_vcn[i], (bmp->count-i) * sizeof(*bmp->data_vcn));
	}

	bmp->data[i]     = data;
	bmp->data_vcn[i] = vcn;

	return bmp->count;
}

/**
 * ntfs_bmp_get_data - Ask for a bitmap block from the cache
 * @bmp:
 * @vcn:
 *
 * Description...
 *
 * Returns:
 */
u8 * ntfs_bmp_get_data(struct ntfs_bmp *bmp, VCN vcn)
{
	u8 *buffer;
	int i;
	int cs;
	int cb;

	if (!bmp)
		return NULL;

	ntfs_log_trace ("\n");
	cs = bmp->vol->cluster_size;
	cb = bmp->vol->cluster_size_bits;

	// XXX range check against vol,attr
	// never compressed, so data = init

	vcn >>= (cb + 3);	// convert to bitmap clusters

	for (i = 0; i < bmp->count; i++) {
		if (vcn == bmp->data_vcn[i]) {
			//ntfs_log_debug("reusing bitmap cluster %lld\n", vcn);
			return bmp->data[i];
		}
	}

	buffer = calloc(1, cs);	// XXX could be smaller if attr size < cluster size
	if (!buffer)
		return NULL;

	//ntfs_log_debug("loading from bitmap cluster %lld\n", vcn);
	//ntfs_log_debug("loading from bitmap byte    %lld\n", vcn<<cb);
	if (ntfs_attr_pread(bmp->attr, vcn<<cb, cs, buffer) < 0) {
		free(buffer);
		return NULL;
	}

	ntfs_bmp_add_data(bmp, vcn, buffer);	// XXX retval
	return buffer;
}

/**
 * ntfs_bmp_set_range - Set a range of bits in the bitmap
 * @bmp:
 * @vcn:
 * @length:
 * @value:
 *
 * Description...
 *
 * Returns:
 */
int ntfs_bmp_set_range(struct ntfs_bmp *bmp, VCN vcn, s64 length, int value)
{
	// shouldn't all the vcns be lcns?
	s64 i;
	u8 *buffer;
	int csib;			// cluster size in bits

	int block_start, block_finish;	// rename to c[sf]  (rename to clust_)
	int vcn_start, vcn_finish;	// rename to v[sf]
	int byte_start, byte_finish;	// rename to b[sf]
	u8 mask_start, mask_finish;	// rename to m[sf]

	s64 a,b;

	if (!bmp)
		return -1;

	ntfs_log_trace ("vcn %lld, length %lld, value %d\n", vcn, length, value);
	if (value)
		value = 0xFF;

	csib = bmp->vol->cluster_size << 3;

	vcn_start  = vcn;
	vcn_finish = vcn + length - 1;

	//ntfs_log_debug("vcn_start = %d, vcn_finish = %d\n", vcn_start, vcn_finish);
	a = ROUND_DOWN(vcn_start,  csib);
	b = ROUND_DOWN(vcn_finish, csib) + 1;

	//ntfs_log_debug("a = %lld, b = %lld\n", a, b);

	for (i = a; i < b; i += csib) {
		//ntfs_log_debug("ntfs_bmp_get_data %lld\n", i);
		buffer = ntfs_bmp_get_data(bmp, i);
		if (!buffer)
			return -1;

		block_start  = i;
		block_finish = block_start + csib - 1;

		mask_start  = (0xFF << (vcn_start & 7));
		mask_finish = (0xFF >> (7 - (vcn_finish & 7)));

		if ((vcn_start >= block_start) && (vcn_start <= block_finish)) {
			byte_start = (vcn_start - block_start) >> 3;
		} else {
			byte_start = 0;
			mask_start = 0xFF;
		}

		if ((vcn_finish >= block_start) && (vcn_finish <= block_finish)) {
			byte_finish = (vcn_finish - block_start) >> 3;
		} else {
			byte_finish = bmp->vol->cluster_size - 1;
			mask_finish = 0xFF;
		}

		if ((byte_finish - byte_start) > 1) {
			memset(buffer+byte_start+1, value, byte_finish-byte_start-1);
		} else if (byte_finish == byte_start) {
			mask_start &= mask_finish;
			mask_finish = 0x00;
		}

		if (value) {
			buffer[byte_start]  |= mask_start;
			buffer[byte_finish] |= mask_finish;
		} else {
			buffer[byte_start]  &= (~mask_start);
			buffer[byte_finish] &= (~mask_finish);
		}
	}

#if 1
	ntfs_log_debug("Modified: inode %lld, ", bmp->attr->ni->mft_no);
	switch (bmp->attr->type) {
		case AT_BITMAP: ntfs_log_debug("$BITMAP");	break;
		case AT_DATA:   ntfs_log_debug("$DATA");	break;
		default:				break;
	}
	ntfs_log_debug(" vcn %lld-%lld\n", vcn>>12, (vcn+length-1)>>12);
#endif
	return 1;
}

/**
 * ntfs_bmp_find_last_set - Find the last set bit in the bitmap
 * @bmp:
 *
 * Description...
 *
 * Returns:
 */
s64 ntfs_bmp_find_last_set(struct ntfs_bmp *bmp)
{
	s64 clust_count;
	s64 byte_count;
	s64 clust;
	int byte;
	int bit;
	int note;
	u8 *buffer;

	if (!bmp)
		return -2;

	ntfs_log_trace ("\n");
	// find byte size of bmp
	// find cluster size of bmp

	byte_count = bmp->attr->data_size;
	clust_count = ROUND_UP(byte_count, bmp->vol->cluster_size) >> bmp->vol->cluster_size_bits;

	//ntfs_log_debug("bitmap = %lld bytes\n", byte_count);
	//ntfs_log_debug("bitmap = %lld buffers\n", clust_count);

	// for each cluster backwards
	for (clust = clust_count-1; clust >= 0; clust--) {
		//ntfs_log_debug("cluster %lld\n", clust);
		//ntfs_log_debug("get vcn %lld\n", clust << (bmp->vol->cluster_size_bits + 3));
		buffer = ntfs_bmp_get_data(bmp, clust << (bmp->vol->cluster_size_bits + 3));
		//utils_dump_mem(buffer, 0, 8, DM_NO_ASCII);
		if (!buffer)
			return -2;
		if ((clust == (clust_count-1) && ((byte_count % bmp->vol->cluster_size) != 0))) {
			byte = byte_count % bmp->vol->cluster_size;
		} else {
			byte = bmp->vol->cluster_size;
		}
		//ntfs_log_debug("start byte = %d\n", byte);
		// for each byte backward
		for (byte--; byte >= 0; byte--) {
			//ntfs_log_debug("\tbyte %d (%d)\n", byte, buffer[byte]);
			// for each bit shift up
			note = -1;
			for (bit = 7; bit >= 0; bit--) {
				//ntfs_log_debug("\t\tbit %d (%d)\n", (1<<bit), buffer[byte] & (1<<bit));
				if (buffer[byte] & (1<<bit)) {
					// if set, keep note
					note = bit;
					break;
				}
			}
			if (note >= 0) {
				// if note, return value
				//ntfs_log_debug("match %lld (c=%lld,b=%d,n=%d)\n", (((clust << bmp->vol->cluster_size_bits) + byte) << 3) + note, clust, byte, note);
				return ((((clust << bmp->vol->cluster_size_bits) + byte) << 3) + note);
			}
		}
	}

	return -1;
}

/**
 * ntfs_bmp_find_space - Find an unused block of bits in a bitmap
 * @bmp:
 * @start:
 * @size:
 *
 * Description...
 *
 * Returns:
 */
int ntfs_bmp_find_space(struct ntfs_bmp *bmp, LCN start, long size)
{
	if (!bmp)
		return 0;

	ntfs_log_trace ("\n");
	start = 0;
	size = 0;

	/*
	bmp find space - uncached bmp's
		$Bitmap/$DATA	free space on volume
		dir/$BITMAP	free index record
		$MFT/$BITMAP	free record in mft
	*/
	return 0;
}


#endif /* NTFS_RICH */
#endif /* __VISOPSYS__ */