device.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

	}
	if (!count)
		return 0;
	/* Prepare data for writing. */
	for (i = 0; i < count; ++i) {
		int err;

		err = ntfs_mst_pre_write_fixup((NTFS_RECORD*)
				((u8*)b + i * bksize), bksize);
		if (err < 0) {
			/* Abort write at this position. */
			if (!i)
				return err;
			count = i;
			break;
		}
	}
	/* Write the prepared data. */
	written = ntfs_pwrite(dev, pos, count * bksize, b);
	/* Quickly deprotect the data again. */
	for (i = 0; i < count; ++i)
		ntfs_mst_post_write_fixup((NTFS_RECORD*)((u8*)b + i * bksize));
	if (written <= 0)
		return written;
	/* Finally, return the number of complete blocks written. */
	return written / bksize;
}

/**
 * ntfs_cluster_read - read ntfs clusters
 * @vol:	volume to read from
 * @lcn:	starting logical cluster number
 * @count:	number of clusters to read
 * @b:		output data buffer
 *
 * Read @count ntfs clusters starting at logical cluster number @lcn from
 * volume @vol into buffer @b. Return number of clusters read or -1 on error,
 * with errno set to the error code.
 */
s64 ntfs_cluster_read(const ntfs_volume *vol, const s64 lcn, const s64 count,
		void *b)
{
	s64 br;

	if (!vol || lcn < 0 || count < 0) {
		errno = EINVAL;
		return -1;
	}
	if (vol->nr_clusters < lcn + count) {
		errno = ESPIPE;
		return -1;
	}
	br = ntfs_pread(vol->dev, lcn << vol->cluster_size_bits,
			count << vol->cluster_size_bits, b);
	if (br < 0) {
		ntfs_log_perror("Error reading cluster(s)");
		return br;
	}
	return br >> vol->cluster_size_bits;
}

/**
 * ntfs_cluster_write - write ntfs clusters
 * @vol:	volume to write to
 * @lcn:	starting logical cluster number
 * @count:	number of clusters to write
 * @b:		data buffer to write to disk
 *
 * Write @count ntfs clusters starting at logical cluster number @lcn from
 * buffer @b to volume @vol. Return the number of clusters written or -1 on
 * error, with errno set to the error code.
 */
s64 ntfs_cluster_write(const ntfs_volume *vol, const s64 lcn,
		const s64 count, const void *b)
{
	s64 bw;

	if (!vol || lcn < 0 || count < 0) {
		errno = EINVAL;
		return -1;
	}
	if (vol->nr_clusters < lcn + count) {
		errno = ESPIPE;
		return -1;
	}
	if (!NVolReadOnly(vol))
		bw = ntfs_pwrite(vol->dev, lcn << vol->cluster_size_bits,
				count << vol->cluster_size_bits, b);
	else
		bw = count << vol->cluster_size_bits;
	if (bw < 0) {
		ntfs_log_perror("Error writing cluster(s)");
		return bw;
	}
	return bw >> vol->cluster_size_bits;
}
#endif /* __VISOPSYS__ */

/**
 * ntfs_device_offset_valid - test if a device offset is valid
 * @dev:	open device
 * @ofs:	offset to test for validity
 *
 * Test if the offset @ofs is an existing location on the device described
 * by the open device structure @dev.
 *
 * Return 0 if it is valid and -1 if it is not valid.
 */
static inline int ntfs_device_offset_valid(struct ntfs_device *dev, s64 ofs)
{
	char ch;

	if (dev->d_ops->seek(dev, ofs, SEEK_SET) >= 0 &&
			dev->d_ops->read(dev, &ch, 1) == 1)
		return 0;
	return -1;
}

/**
 * ntfs_device_size_get - return the size of a device in blocks
 * @dev:	open device
 * @block_size:	block size in bytes in which to return the result
 *
 * Return the number of @block_size sized blocks in the device described by the
 * open device @dev.
 *
 * Adapted from e2fsutils-1.19, Copyright (C) 1995 Theodore Ts'o.
 *
 * On error return -1 with errno set to the error code.
 */
s64 ntfs_device_size_get(struct ntfs_device *dev, int block_size)
{
	s64 high, low;

	if (!dev || block_size <= 0 || (block_size - 1) & block_size) {
		errno = EINVAL;
		return -1;
	}
#ifdef BLKGETSIZE64
	{	u64 size;

		if (dev->d_ops->ioctl(dev, BLKGETSIZE64, &size) >= 0) {
			ntfs_log_debug("BLKGETSIZE64 nr bytes = %llu (0x%llx)\n",
					(unsigned long long)size,
					(unsigned long long)size);
			return (s64)size / block_size;
		}
	}
#endif
#ifdef BLKGETSIZE
	{	unsigned long size;

		if (dev->d_ops->ioctl(dev, BLKGETSIZE, &size) >= 0) {
			ntfs_log_debug("BLKGETSIZE nr 512 byte blocks = %lu (0x%lx)\n",
					size, size);
			return (s64)size * 512 / block_size;
		}
	}
#endif
#ifdef FDGETPRM
	{       struct floppy_struct this_floppy;

		if (dev->d_ops->ioctl(dev, FDGETPRM, &this_floppy) >= 0) {
			ntfs_log_debug("FDGETPRM nr 512 byte blocks = %lu (0x%lx)\n",
					(unsigned long)this_floppy.size,
					(unsigned long)this_floppy.size);
			return (s64)this_floppy.size * 512 / block_size;
		}
	}
#endif
	/*
	 * We couldn't figure it out by using a specialized ioctl,
	 * so do binary search to find the size of the device.
	 */
	low = 0LL;
	for (high = 1024LL; !ntfs_device_offset_valid(dev, high); high <<= 1)
		low = high;
	while (low < high - 1LL) {
		const s64 mid = (low + high) / 2;

		if (!ntfs_device_offset_valid(dev, mid))
			low = mid;
		else
			high = mid;
	}
	dev->d_ops->seek(dev, 0LL, SEEK_SET);
	return (low + 1LL) / block_size;
}

#ifndef __VISOPSYS__
/**
 * ntfs_device_partition_start_sector_get - get starting sector of a partition
 * @dev:	open device
 *
 * On success, return the starting sector of the partition @dev in the parent
 * block device of @dev.  On error return -1 with errno set to the error code.
 *
 * The following error codes are defined:
 *	EINVAL		Input parameter error
 *	EOPNOTSUPP	System does not support HDIO_GETGEO ioctl
 *	ENOTTY		@dev is a file or a device not supporting HDIO_GETGEO
 */
s64 ntfs_device_partition_start_sector_get(struct ntfs_device *dev)
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
#ifdef HDIO_GETGEO
	{	struct hd_geometry geo;

		if (!dev->d_ops->ioctl(dev, HDIO_GETGEO, &geo)) {
			ntfs_log_debug("HDIO_GETGEO start_sect = %lu (0x%lx)\n",
					geo.start, geo.start);
			return geo.start;
		}
	}
#else
	errno = EOPNOTSUPP;
#endif
	return -1;
}

/**
 * ntfs_device_heads_get - get number of heads of device
 * @dev:		open device
 *
 * On success, return the number of heads on the device @dev.  On error return
 * -1 with errno set to the error code.
 *
 * The following error codes are defined:
 *	EINVAL		Input parameter error
 *	EOPNOTSUPP	System does not support HDIO_GETGEO ioctl
 *	ENOTTY		@dev is a file or a device not supporting HDIO_GETGEO
 */
int ntfs_device_heads_get(struct ntfs_device *dev)
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
#ifdef HDIO_GETGEO
	{	struct hd_geometry geo;

		if (!dev->d_ops->ioctl(dev, HDIO_GETGEO, &geo)) {
			ntfs_log_debug("HDIO_GETGEO heads = %u (0x%x)\n",
					(unsigned)geo.heads,
					(unsigned)geo.heads);
			return geo.heads;
		}
	}
#else
	errno = EOPNOTSUPP;
#endif
	return -1;
}

/**
 * ntfs_device_sectors_per_track_get - get number of sectors per track of device
 * @dev:		open device
 *
 * On success, return the number of sectors per track on the device @dev.  On
 * error return -1 with errno set to the error code.
 *
 * The following error codes are defined:
 *	EINVAL		Input parameter error
 *	EOPNOTSUPP	System does not support HDIO_GETGEO ioctl
 *	ENOTTY		@dev is a file or a device not supporting HDIO_GETGEO
 */
int ntfs_device_sectors_per_track_get(struct ntfs_device *dev)
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
#ifdef HDIO_GETGEO
	{	struct hd_geometry geo;

		if (!dev->d_ops->ioctl(dev, HDIO_GETGEO, &geo)) {
			ntfs_log_debug("HDIO_GETGEO sectors_per_track = %u (0x%x)\n",
					(unsigned)geo.sectors,
					(unsigned)geo.sectors);
			return geo.sectors;
		}
	}
#else
	errno = EOPNOTSUPP;
#endif
	return -1;
}

/**
 * ntfs_device_sector_size_get - get sector size of a device
 * @dev:	open device
 *
 * On success, return the sector size in bytes of the device @dev.
 * On error return -1 with errno set to the error code.
 *
 * The following error codes are defined:
 *	EINVAL		Input parameter error
 *	EOPNOTSUPP	System does not support BLKSSZGET ioctl
 *	ENOTTY		@dev is a file or a device not supporting BLKSSZGET
 */
int ntfs_device_sector_size_get(struct ntfs_device *dev)
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
#ifdef BLKSSZGET
	{
		int sect_size = 0;

		if (!dev->d_ops->ioctl(dev, BLKSSZGET, &sect_size)) {
			ntfs_log_debug("BLKSSZGET sector size = %d bytes\n",
					sect_size);
			return sect_size;
		}
	}
#else
	errno = EOPNOTSUPP;
#endif
	return -1;
}
#endif /* __VISOPSYS__ */

/**
 * ntfs_device_block_size_set - set block size of a device
 * @dev:	open device
 * @block_size: block size to set @dev to
 *
 * On success, return 0.
 * On error return -1 with errno set to the error code.
 *
 * The following error codes are defined:
 *	EINVAL		Input parameter error
 *	EOPNOTSUPP	System does not support BLKBSZSET ioctl
 *	ENOTTY		@dev is a file or a device not supporting BLKBSZSET
 */
int ntfs_device_block_size_set(struct ntfs_device *dev,
		int block_size __attribute__((unused)))
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
#ifdef BLKBSZSET
	{
		size_t s_block_size = block_size;
		if (!dev->d_ops->ioctl(dev, BLKBSZSET, &s_block_size)) {
			ntfs_log_debug("Used BLKBSZSET to set block size to "
					"%d bytes.\n", block_size);
			return 0;
		}
		/* If not a block device, pretend it was successful. */
		if (!NDevBlock(dev))
			return 0;
	}
#else
	/* If not a block device, pretend it was successful. */
	if (!NDevBlock(dev))
		return 0;
	errno = EOPNOTSUPP;
#endif
	return -1;
}