OpenSolaris_b135/lib/libntfs/common/libntfs/bitmap.c
/**
* 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
*/
#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 "compat.h"
#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 int ntfs_bitmap_set_bits_in_run(ntfs_attr *na, s64 start_bit,
s64 count, int value)
{
ntfs_volume *vol = na->ni->vol;
s64 bufsize, br, left = count;
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;
buf = (u8*)ntfs_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) && left--) {
if (value)
*buf |= 1 << bit++;
else
*buf &= ~(1 << bit++);
}
/* Update @start_bit to the new position. */
start_bit = (start_bit + 7) & ~7;
}
/* Loop until @left reaches zero. */
lastbyte = 0;
lastbyte_buf = NULL;
bit = left & 7;
do {
/* If there is a last partial byte... */
if (left > 0 && bit) {
lastbyte_pos = ((left + 7) >> 3) + firstbyte;
if (!lastbyte_pos) {
// FIXME: Eeek! BUG!
ntfs_log_trace("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 + left) >>
3, 1, lastbyte_buf);
if (br != 1) {
// FIXME: Eeek! We need rollback! (AIA)
ntfs_log_trace("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 && left--) {
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("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;
left -= tmp;
if (bufsize > (tmp = (left + 7) >> 3))
bufsize = tmp;
if (lastbyte && left != 0) {
// FIXME: Eeek! BUG!
ntfs_log_trace("Last buffer but count is not zero (= "
"%lli). Leaving inconsistent metadata."
"\n", (long long)left);
err = EIO;
goto free_err_out;
}
} while (left > 0);
/* Update free clusters and MFT records. */
if (na == vol->mftbmp_na) {
if (value)
vol->nr_free_mft_records -= count;
else
vol->nr_free_mft_records += count;
}
if (na == vol->lcnbmp_na) {
if (value)
vol->nr_free_clusters -= count;
else
vol->nr_free_clusters += count;
}
/* 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);
}