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

/**
 * device.c - Low level device io functions. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2004-2006 Anton Altaparmakov
 *
 * 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_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#ifdef HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
#ifdef HAVE_LINUX_FD_H
#include <linux/fd.h>
#endif
#ifdef HAVE_LINUX_HDREG_H
#include <linux/hdreg.h>
#endif

#include "types.h"
#include "mst.h"
#include "debug.h"
#include "device.h"
#include "logging.h"

#if defined(linux) && defined(_IO) && !defined(BLKGETSIZE)
#define BLKGETSIZE	_IO(0x12,96)  /* Get device size in 512-byte blocks. */
#endif
#if defined(linux) && defined(_IOR) && !defined(BLKGETSIZE64)
#define BLKGETSIZE64	_IOR(0x12,114,size_t)	/* Get device size in bytes. */
#endif
#if defined(linux) && !defined(HDIO_GETGEO)
#define HDIO_GETGEO	0x0301	/* Get device geometry. */
#endif
#if defined(linux) && defined(_IO) && !defined(BLKSSZGET)
#	define BLKSSZGET _IO(0x12,104) /* Get device sector size in bytes. */
#endif
#if defined(linux) && defined(_IO) && !defined(BLKBSZSET)
#	define BLKBSZSET _IOW(0x12,113,size_t) /* Set device block size in bytes. */
#endif

/**
 * ntfs_device_alloc - allocate an ntfs device structure and pre-initialize it
 * @name:	name of the device (must be present)
 * @state:	initial device state (usually zero)
 * @dops:	ntfs device operations to use with the device (must be present)
 * @priv_data:	pointer to private data (optional)
 *
 * Allocate an ntfs device structure and pre-initialize it with the user-
 * specified device operations @dops, device state @state, device name @name,
 * and optional private data @priv_data.
 *
 * Note, @name is copied and can hence be freed after this functions returns.
 *
 * On success return a pointer to the allocated ntfs device structure and on
 * error return NULL with errno set to the error code returned by malloc().
 */
struct ntfs_device *ntfs_device_alloc(const char *name, const long state,
		struct ntfs_device_operations *dops, void *priv_data)
{
	struct ntfs_device *dev;

	if (!name) {
		errno = EINVAL;
		return NULL;
	}

	dev = (struct ntfs_device *)malloc(sizeof(struct ntfs_device));
	if (dev) {
		if (!(dev->d_name = strdup(name))) {
			int eo = errno;
			free(dev);
			errno = eo;
			return NULL;
		}
		dev->d_ops = dops;
		dev->d_state = state;
		dev->d_private = priv_data;
	}
	return dev;
}

/**
 * ntfs_device_free - free an ntfs device structure
 * @dev:	ntfs device structure to free
 *
 * Free the ntfs device structure @dev.
 *
 * Return 0 on success or -1 on error with errno set to the error code. The
 * following error codes are defined:
 *	EINVAL		Invalid pointer @dev.
 *	EBUSY		Device is still open. Close it before freeing it!
 */
int ntfs_device_free(struct ntfs_device *dev)
{
	if (!dev) {
		errno = EINVAL;
		return -1;
	}
	if (NDevOpen(dev)) {
		errno = EBUSY;
		return -1;
	}
	free(dev->d_name);
	free(dev);
	return 0;
}

/**
 * ntfs_pread - positioned read from disk
 * @dev:	device to read from
 * @pos:	position in device to read from
 * @count:	number of bytes to read
 * @b:		output data buffer
 *
 * This function will read @count bytes from device @dev at position @pos into
 * the data buffer @b.
 *
 * On success, return the number of successfully read bytes. If this number is
 * lower than @count this means that we have either reached end of file or
 * encountered an error during the read so that the read is partial. 0 means
 * end of file or nothing to read (@count is 0).
 *
 * On error and nothing has been read, return -1 with errno set appropriately
 * to the return code of either seek, read, or set to EINVAL in case of
 * invalid arguments.
 */
s64 ntfs_pread(struct ntfs_device *dev, const s64 pos, s64 count, void *b)
{
	s64 br, total;
	struct ntfs_device_operations *dops;

	ntfs_log_trace("Entering for pos 0x%llx, count 0x%llx.\n", pos, count);
	if (!b || count < 0 || pos < 0) {
		errno = EINVAL;
		return -1;
	}
	if (!count)
		return 0;
	dops = dev->d_ops;
	/* Locate to position. */
	if (dops->seek(dev, pos, SEEK_SET) == (off_t)-1) {
		ntfs_log_perror("ntfs_pread: device seek to 0x%llx returned error",
				pos);
		return -1;
	}
	/* Read the data. */
	for (total = 0; count; count -= br, total += br) {
		br = dops->read(dev, (char*)b + total, count);
		/* If everything ok, continue. */
		if (br > 0)
			continue;
		/* If EOF or error return number of bytes read. */
		if (!br || total)
			return total;
		/* Nothing read and error, return error status. */
		return br;
	}
	/* Finally, return the number of bytes read. */
	return total;
}

/**
 * ntfs_pwrite - positioned write to disk
 * @dev:	device to write to
 * @pos:	position in file descriptor to write to
 * @count:	number of bytes to write
 * @b:		data buffer to write to disk
 *
 * This function will write @count bytes from data buffer @b to the device @dev
 * at position @pos.
 *
 * On success, return the number of successfully written bytes. If this number
 * is lower than @count this means that the write has been interrupted in
 * flight or that an error was encountered during the write so that the write
 * is partial. 0 means nothing was written (also return 0 when @count is 0).
 *
 * On error and nothing has been written, return -1 with errno set
 * appropriately to the return code of either seek, write, or set
 * to EINVAL in case of invalid arguments.
 */
s64 ntfs_pwrite(struct ntfs_device *dev, const s64 pos, s64 count,
		const void *b)
{
	s64 written, total;
	struct ntfs_device_operations *dops;

	ntfs_log_trace("Entering for pos 0x%llx, count 0x%llx.\n", pos, count);
	if (!b || count < 0 || pos < 0) {
		errno = EINVAL;
		return -1;
	}
	if (!count)
		return 0;
	if (NDevReadOnly(dev)) {
		errno = EROFS;
		return -1;
	}
	dops = dev->d_ops;
	/* Locate to position. */
	if (dops->seek(dev, pos, SEEK_SET) == (off_t)-1) {
		ntfs_log_perror("ntfs_pwrite: seek to 0x%llx returned error",
				pos);
		return -1;
	}
	NDevSetDirty(dev);
	/* Write the data. */
	for (total = 0; count; count -= written, total += written) {
		written = dops->write(dev, (const char*)b + total, count);
		/* If everything ok, continue. */
		if (written > 0)
			continue;
		/*
		 * If nothing written or error return number of bytes written.
		 */
		if (!written || total)
			break;
		/* Nothing written and error, return error status. */
		return written;
	}
	/* Finally, return the number of bytes written. */
	return total;
}

/**
 * ntfs_mst_pread - multi sector transfer (mst) positioned read
 * @dev:	device to read from
 * @pos:	position in file descriptor to read from
 * @count:	number of blocks to read
 * @bksize:	size of each block that needs mst deprotecting
 * @b:		output data buffer
 *
 * Multi sector transfer (mst) positioned read. This function will read @count
 * blocks of size @bksize bytes each from device @dev at position @pos into the
 * the data buffer @b.
 *
 * On success, return the number of successfully read blocks. If this number is
 * lower than @count this means that we have reached end of file, that the read
 * was interrupted, or that an error was encountered during the read so that
 * the read is partial. 0 means end of file or nothing was read (also return 0
 * when @count or @bksize are 0).
 *
 * On error and nothing was read, return -1 with errno set appropriately to the
 * return code of either seek, read, or set to EINVAL in case of invalid
 * arguments.
 *
 * NOTE: If an incomplete multi sector transfer has been detected the magic
 * will have been changed to magic_BAAD but no error will be returned. Thus it
 * is possible that we return count blocks as being read but that any number
 * (between zero and count!) of these blocks is actually subject to a multi
 * sector transfer error. This should be detected by the caller by checking for
 * the magic being "BAAD".
 */
s64 ntfs_mst_pread(struct ntfs_device *dev, const s64 pos, s64 count,
		const u32 bksize, void *b)
{
	s64 br, i;

	if (bksize & (bksize - 1) || bksize % NTFS_BLOCK_SIZE) {
		errno = EINVAL;
		return -1;
	}
	/* Do the read. */
	br = ntfs_pread(dev, pos, count * bksize, b);
	if (br < 0)
		return br;
	/*
	 * Apply fixups to successfully read data, disregarding any errors
	 * returned from the MST fixup function. This is because we want to
	 * fixup everything possible and we rely on the fact that the "BAAD"
	 * magic will be detected later on.
	 */
	count = br / bksize;
	for (i = 0; i < count; ++i)
		ntfs_mst_post_read_fixup((NTFS_RECORD*)
				((u8*)b + i * bksize), bksize);
	/* Finally, return the number of complete blocks read. */
	return count;
}

#ifndef __VISOPSYS__
/**
 * ntfs_mst_pwrite - multi sector transfer (mst) positioned write
 * @dev:	device to write to
 * @pos:	position in file descriptor to write to
 * @count:	number of blocks to write
 * @bksize:	size of each block that needs mst protecting
 * @b:		data buffer to write to disk
 *
 * Multi sector transfer (mst) positioned write. This function will write
 * @count blocks of size @bksize bytes each from data buffer @b to the device
 * @dev at position @pos.
 *
 * On success, return the number of successfully written blocks. If this number
 * is lower than @count this means that the write has been interrupted or that
 * an error was encountered during the write so that the write is partial. 0
 * means nothing was written (also return 0 when @count or @bksize are 0).
 *
 * On error and nothing has been written, return -1 with errno set
 * appropriately to the return code of either seek, write, or set
 * to EINVAL in case of invalid arguments.
 *
 * NOTE: We mst protect the data, write it, then mst deprotect it using a quick
 * deprotect algorithm (no checking). This saves us from making a copy before
 * the write and at the same time causes the usn to be incremented in the
 * buffer. This conceptually fits in better with the idea that cached data is
 * always deprotected and protection is performed when the data is actually
 * going to hit the disk and the cache is immediately deprotected again
 * simulating an mst read on the written data. This way cache coherency is
 * achieved.
 */
s64 ntfs_mst_pwrite(struct ntfs_device *dev, const s64 pos, s64 count,
		const u32 bksize, void *b)
{
	s64 written, i;

	if (count < 0 || bksize % NTFS_BLOCK_SIZE) {
		errno = EINVAL;
		return -1;