usbloadergx/source/libntfs/bitmap.c
2009-12-19 14:06:57 +00:00

301 lines
7.9 KiB
C

/**
* bitmap.c - Bitmap handling code. Originated from the Linux-NTFS project.
*
* Copyright (c) 2002-2006 Anton Altaparmakov
* Copyright (c) 2004-2005 Richard Russon
* Copyright (c) 2004-2008 Szabolcs Szakacsits
*
* 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 NTFS-3G
* 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 "types.h"
#include "attrib.h"
#include "bitmap.h"
#include "debug.h"
#include "logging.h"
#include "misc.h"
/**
* ntfs_bit_set - set a bit in a field of bits
* @bitmap: field of bits
* @bit: bit to set
* @new_value: value to set bit to (0 or 1)
*
* Set the bit @bit in the @bitmap to @new_value. Ignore all errors.
*/
void ntfs_bit_set(u8 *bitmap, const u64 bit, const u8 new_value)
{
if (!bitmap || new_value > 1)
return;
if (!new_value)
bitmap[bit >> 3] &= ~(1 << (bit & 7));
else
bitmap[bit >> 3] |= (1 << (bit & 7));
}
/**
* ntfs_bit_get - get value of a bit in a field of bits
* @bitmap: field of bits
* @bit: bit to get
*
* Get and return the value of the bit @bit in @bitmap (0 or 1).
* Return -1 on error.
*/
char ntfs_bit_get(const u8 *bitmap, const u64 bit)
{
if (!bitmap)
return -1;
return (bitmap[bit >> 3] >> (bit & 7)) & 1;
}
/**
* ntfs_bit_get_and_set - get value of a bit in a field of bits and set it
* @bitmap: field of bits
* @bit: bit to get/set
* @new_value: value to set bit to (0 or 1)
*
* Return the value of the bit @bit and set it to @new_value (0 or 1).
* Return -1 on error.
*/
char ntfs_bit_get_and_set(u8 *bitmap, const u64 bit, const u8 new_value)
{
register u8 old_bit, shift;
if (!bitmap || new_value > 1)
return -1;
shift = bit & 7;
old_bit = (bitmap[bit >> 3] >> shift) & 1;
if (new_value != old_bit)
bitmap[bit >> 3] ^= 1 << shift;
return old_bit;
}
/**
* 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)
{
s64 bufsize, br;
u8 *buf, *lastbyte_buf;
int bit, firstbyte, lastbyte, lastbyte_pos, tmp, ret = -1;
if (!na || start_bit < 0 || count < 0) {
errno = EINVAL;
ntfs_log_perror("%s: Invalid argument (%p, %lld, %lld)",
__FUNCTION__, na, (long long)start_bit, (long long)count);
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 = 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) {
if (br >= 0)
errno = EIO;
goto free_err_out;
}
/* 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_error("Lastbyte is zero. Leaving "
"inconsistent metadata.\n");
errno = 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)
if (br >= 0)
errno = EIO;
ntfs_log_perror("Reading of last byte "
"failed (%lld). Leaving inconsistent "
"metadata", (long long)br);
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)
if (br >= 0)
errno = EIO;
ntfs_log_perror("Failed to write buffer to bitmap "
"(%lld != %lld). Leaving inconsistent metadata",
(long long)br, (long long)bufsize);
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_error("Last buffer but count is not zero "
"(%lld). Leaving inconsistent metadata.\n",
(long long)count);
errno = EIO;
goto free_err_out;
}
} while (count > 0);
ret = 0;
free_err_out:
free(buf);
return ret;
}
/**
* 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)
{
int ret;
ntfs_log_enter("Set from bit %lld, count %lld\n",
(long long)start_bit, (long long)count);
ret = ntfs_bitmap_set_bits_in_run(na, start_bit, count, 1);
ntfs_log_leave("\n");
return ret;
}
/**
* 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)
{
int ret;
ntfs_log_enter("Clear from bit %lld, count %lld\n",
(long long)start_bit, (long long)count);
ret = ntfs_bitmap_set_bits_in_run(na, start_bit, count, 0);
ntfs_log_leave("\n");
return ret;
}