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

/**
 * bitmap.c - Bitmap handling code. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2002-2006 Anton Altaparmakov
 * Copyright (c) 2004-2005 Richard Russon
 *
 * 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_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#include "types.h"
#include "attrib.h"
#include "bitmap.h"
#include "debug.h"
#include "logging.h"

/**
 * ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value
 * @na:		attribute containing the bitmap
 * @start_bit:	first bit to set
 * @count:	number of bits to set
 * @value:	value to set the bits to (i.e. 0 or 1)
 *
 * Set @count bits starting at bit @start_bit in the bitmap described by the
 * attribute @na to @value, where @value is either 0 or 1.
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
static __inline__ int ntfs_bitmap_set_bits_in_run(ntfs_attr *na, s64 start_bit,
		s64 count, int value)
{
	s64 bufsize, br;
	u8 *buf, *lastbyte_buf;
	int bit, firstbyte, lastbyte, lastbyte_pos, tmp, err;

	if (!na || start_bit < 0 || count < 0) {
		errno = EINVAL;
		return -1;
	}

	bit = start_bit & 7;
	if (bit)
		firstbyte = 1;
	else
		firstbyte = 0;

	/* Calculate the required buffer size in bytes, capping it at 8kiB. */
	bufsize = ((count - (bit ? 8 - bit : 0) + 7) >> 3) + firstbyte;
	if (bufsize > 8192)
		bufsize = 8192;

	/* Allocate memory. */
	buf = (u8*)malloc(bufsize);
	if (!buf)
		return -1;
	/* Depending on @value, zero or set all bits in the allocated buffer. */
	memset(buf, value ? 0xff : 0, bufsize);

	/* If there is a first partial byte... */
	if (bit) {
		/* read it in... */
		br = ntfs_attr_pread(na, start_bit >> 3, 1, buf);
		if (br != 1) {
			free(buf);
			errno = EIO;
			return -1;
		}
		/* and set or clear the appropriate bits in it. */
		while ((bit & 7) && count--) {
			if (value)
				*buf |= 1 << bit++;
			else
				*buf &= ~(1 << bit++);
		}
		/* Update @start_bit to the new position. */
		start_bit = (start_bit + 7) & ~7;
	}

	/* Loop until @count reaches zero. */
	lastbyte = 0;
	lastbyte_buf = NULL;
	bit = count & 7;
	do {
		/* If there is a last partial byte... */
		if (count > 0 && bit) {
			lastbyte_pos = ((count + 7) >> 3) + firstbyte;
			if (!lastbyte_pos) {
				// FIXME: Eeek! BUG!
				ntfs_log_trace("Eeek! lastbyte is zero. Leaving "
						"inconsistent metadata.\n");
				err = EIO;
				goto free_err_out;
			}
			/* and it is in the currently loaded bitmap window... */
			if (lastbyte_pos <= bufsize) {
				lastbyte_buf = buf + lastbyte_pos - 1;

				/* read the byte in... */
				br = ntfs_attr_pread(na, (start_bit + count) >>
						3, 1, lastbyte_buf);
				if (br != 1) {
					// FIXME: Eeek! We need rollback! (AIA)
					ntfs_log_trace("Eeek! Read of last byte "
							"failed. Leaving "
							"inconsistent metadata.\n");
					err = EIO;
					goto free_err_out;
				}
				/* and set/clear the appropriate bits in it. */
				while (bit && count--) {
					if (value)
						*lastbyte_buf |= 1 << --bit;
					else
						*lastbyte_buf &= ~(1 << --bit);
				}
				/* We don't want to come back here... */
				bit = 0;
				/* We have a last byte that we have handled. */
				lastbyte = 1;
			}
		}

		/* Write the prepared buffer to disk. */
		tmp = (start_bit >> 3) - firstbyte;
		br = ntfs_attr_pwrite(na, tmp, bufsize, buf);
		if (br != bufsize) {
			// FIXME: Eeek! We need rollback! (AIA)
			ntfs_log_trace("Eeek! Failed to write buffer to bitmap. "
					"Leaving inconsistent metadata.\n");
			err = EIO;
			goto free_err_out;
		}

		/* Update counters. */
		tmp = (bufsize - firstbyte - lastbyte) << 3;
		if (firstbyte) {
			firstbyte = 0;
			/*
			 * Re-set the partial first byte so a subsequent write
			 * of the buffer does not have stale, incorrect bits.
			 */
			*buf = value ? 0xff : 0;
		}
		start_bit += tmp;
		count -= tmp;
		if (bufsize > (tmp = (count + 7) >> 3))
			bufsize = tmp;

		if (lastbyte && count != 0) {
			// FIXME: Eeek! BUG!
			ntfs_log_trace("Eeek! Last buffer but count is not zero (= "
					"%lli). Leaving inconsistent metadata.\n",
					(long long)count);
			err = EIO;
			goto free_err_out;
		}
	} while (count > 0);

	/* Done! */
	free(buf);
	return 0;

free_err_out:
	free(buf);
	errno = err;
	return -1;
}

/**
 * ntfs_bitmap_set_run - set a run of bits in a bitmap
 * @na:		attribute containing the bitmap
 * @start_bit:	first bit to set
 * @count:	number of bits to set
 *
 * Set @count bits starting at bit @start_bit in the bitmap described by the
 * attribute @na.
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
int ntfs_bitmap_set_run(ntfs_attr *na, s64 start_bit, s64 count)
{
	return ntfs_bitmap_set_bits_in_run(na, start_bit, count, 1);
}

/**
 * ntfs_bitmap_clear_run - clear a run of bits in a bitmap
 * @na:		attribute containing the bitmap
 * @start_bit:	first bit to clear
 * @count:	number of bits to clear
 *
 * Clear @count bits starting at bit @start_bit in the bitmap described by the
 * attribute @na.
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
int ntfs_bitmap_clear_run(ntfs_attr *na, s64 start_bit, s64 count)
{
	ntfs_log_trace("Dealloc from bit 0x%llx, count 0x%llx.\n",
		       (long long)start_bit, (long long)count);

	return ntfs_bitmap_set_bits_in_run(na, start_bit, count, 0);
}


#ifndef __VISOPSYS__
#ifdef NTFS_RICH

#include "layout.h"
#include "volume.h"
#include "rich.h"

/**
 * ntfs_bmp_rollback - Discard the in-memory bitmap changes
 * @bmp:
 *
 * Description...
 *
 * Returns:
 */
int ntfs_bmp_rollback(struct ntfs_bmp *bmp)
{
	int i;

	if ((!bmp) || (bmp->count == 0))
		return 0;

	ntfs_log_trace ("bmp %p, records %d, attr %lld/%02X\n", bmp, bmp->count, MREF(bmp->attr->ni->mft_no), bmp->attr->type);

	for (i = 0; i < bmp->count; i++)
		free(bmp->data[i]);

	free(bmp->data);
	free(bmp->data_vcn);
	bmp->data = NULL;
	bmp->data_vcn = NULL;
	bmp->count = 0;

	return 0;
}

/**
 * ntfs_bmp_commit - Write the cached bitmap data to disk
 * @bmp:
 *
 * Description...
 *
 * Returns:
 */
int ntfs_bmp_commit(struct ntfs_bmp *bmp)
{
	int i;
	u32 cs;
	u32 ws; // write size

	if (!bmp)
		return 0;
	if (bmp->count == 0)
		return 0;

	ntfs_log_trace ("bmp %p, records %d, attr %lld/%02X\n", bmp, bmp->count, MREF(bmp->attr->ni->mft_no), bmp->attr->type);
#if 0
	ntfs_log_debug("attr = 0x%02X\n", bmp->attr->type);
	ntfs_log_debug("resident = %d\n", !NAttrNonResident(bmp->attr));
	ntfs_log_debug("\ta size = %lld\n", bmp->attr->allocated_size);
	ntfs_log_debug("\td size = %lld\n", bmp->attr->data_size);
	ntfs_log_debug("\ti size = %lld\n", bmp->attr->initialized_size);
#endif

	ntfs_log_debug("commit bmp inode %lld, 0x%02X (%sresident)\n", bmp->attr->ni->mft_no, bmp->attr->type, NAttrNonResident(bmp->attr) ? "non-" : "");

	if (NAttrNonResident(bmp->attr)) {
		cs = bmp->vol->cluster_size;

		// non-resident
		for (i = 0; i < bmp->count; i++) {
			if (((bmp->data_vcn[i]+1) * cs) < bmp->attr->data_size)
				ws = cs;
			else
				ws = bmp->attr->data_size & (cs - 1);
			//ntfs_log_debug("writing %d bytes\n", ws);
			ntfs_attr_pwrite(bmp->attr, bmp->data_vcn[i] * cs, ws, bmp->data[i]); // XXX retval
			ntfs_log_warning("\tntfs_attr_pwrite(vcn %lld)\n", bmp->data_vcn[i]);
		}
	} else {
		// resident
		ntfs_attr_pwrite(bmp->attr, bmp->data_vcn[0], bmp->attr->data_size, bmp->data[0]); // XXX retval
		ntfs_log_warning("\tntfs_attr_pwrite resident (%lld)\n", bmp->attr->data_size);
	}

	ntfs_bmp_rollback(bmp);

	return 0;
}

/**
 * ntfs_bmp_free - Destroy a bitmap object
 * @bmp:
 *
 * Description...
 *
 * Returns:
 */
void ntfs_bmp_free(struct ntfs_bmp *bmp)
{
	if (!bmp)
		return;

	ntfs_log_trace ("bmp %p, records %d, attr %lld/%02X\n", bmp, bmp->count, MREF(bmp->attr->ni->mft_no), bmp->attr->type);