/*

 * blkmap64_ba.c --- Simple bitarray implementation for bitmaps

 *

 * Copyright (C) 2008 Theodore Ts'o.

 *

 * %Begin-Header%

 * This file may be redistributed under the terms of the GNU Public

 * License.

 * %End-Header%

 */

#include "config.h"

#include <stdio.h>

#include <string.h>

#if HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <fcntl.h>

#include <time.h>

#if HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif

#if HAVE_SYS_TYPES_H

#include <sys/types.h>

#endif

#include "ext2_fs.h"

#include "ext2fsP.h"

#include "bmap64.h"

/*

 * Private data for bit array implementation of bitmap ops.

 * Currently, this is just a pointer to our big flat hunk of memory,

 * exactly equivalent to the old-skool char * bitmap member.

 */

struct ext2fs_ba_private_struct {

	char *bitarray;

};

typedef struct ext2fs_ba_private_struct *ext2fs_ba_private;

static errcode_t ba_alloc_private_data (ext2fs_generic_bitmap bitmap)

{

	ext2fs_ba_private bp;

	errcode_t	retval;

	size_t		size;

	/*

	 * Since we only have the one pointer, we could just shove our

	 * private data in the void *private field itself, but then

	 * we'd have to do a fair bit of rewriting if we ever added a

	 * field.  I'm agnostic.

	 */

	retval = ext2fs_get_mem(sizeof (ext2fs_ba_private), &bp);

	if (retval)

		return retval;

	size = (size_t) (((bitmap->real_end - bitmap->start) / 8) + 1);

	retval = ext2fs_get_mem(size, &bp->bitarray);

	if (retval) {

		ext2fs_free_mem(&bp);

		bp = 0;

		return retval;

	}

	bitmap->private = (void *) bp;

	return 0;

}

static errcode_t ba_new_bmap(ext2_filsys fs EXT2FS_ATTR((unused)),

			     ext2fs_generic_bitmap bitmap)

{

	ext2fs_ba_private bp;

	errcode_t	retval;

	size_t		size;

	retval = ba_alloc_private_data (bitmap);

	if (retval)

		return retval;

	bp = (ext2fs_ba_private) bitmap->private;

	size = (size_t) (((bitmap->real_end - bitmap->start) / 8) + 1);

	memset(bp->bitarray, 0, size);

	return 0;

}

static void ba_free_bmap(ext2fs_generic_bitmap bitmap)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	if (!bp)

		return;

	if (bp->bitarray) {

		ext2fs_free_mem (&bp->bitarray);

		bp->bitarray = 0;

	}

	ext2fs_free_mem (&bp);

	bp = 0;

}

static errcode_t ba_copy_bmap(ext2fs_generic_bitmap src,

			      ext2fs_generic_bitmap dest)

{

	ext2fs_ba_private src_bp = (ext2fs_ba_private) src->private;

	ext2fs_ba_private dest_bp;

	errcode_t retval;

	size_t size;

	retval = ba_alloc_private_data (dest);

	if (retval)

		return retval;

	dest_bp = (ext2fs_ba_private) dest->private;

	size = (size_t) (((src->real_end - src->start) / 8) + 1);

	memcpy (dest_bp->bitarray, src_bp->bitarray, size);

	return 0;

}

static errcode_t ba_resize_bmap(ext2fs_generic_bitmap bmap,

				__u64 new_end, __u64 new_real_end)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bmap->private;

	errcode_t	retval;

	size_t		size, new_size;

	__u64		bitno;

	/*

	 * If we're expanding the bitmap, make sure all of the new

	 * parts of the bitmap are zero.

	 */

	if (new_end > bmap->end) {

		bitno = bmap->real_end;

		if (bitno > new_end)

			bitno = new_end;

		for (; bitno > bmap->end; bitno--)

			ext2fs_clear_bit64(bitno - bmap->start, bp->bitarray);

	}

	if (new_real_end == bmap->real_end) {

		bmap->end = new_end;

		return 0;

	}

	size = ((bmap->real_end - bmap->start) / 8) + 1;

	new_size = ((new_real_end - bmap->start) / 8) + 1;

	if (size != new_size) {

		retval = ext2fs_resize_mem(size, new_size, &bp->bitarray);

		if (retval)

			return retval;

	}

	if (new_size > size)

		memset(bp->bitarray + size, 0, new_size - size);

	bmap->end = new_end;

	bmap->real_end = new_real_end;

	return 0;

}

static int ba_mark_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	blk64_t bitno = (blk64_t) arg;

	return ext2fs_set_bit64(bitno - bitmap->start, bp->bitarray);

}

static int ba_unmark_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	blk64_t bitno = (blk64_t) arg;

	return ext2fs_clear_bit64(bitno - bitmap->start, bp->bitarray);

}

static int ba_test_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	blk64_t bitno = (blk64_t) arg;

	return ext2fs_test_bit64(bitno - bitmap->start, bp->bitarray);

}

static void ba_mark_bmap_extent(ext2fs_generic_bitmap bitmap, __u64 arg,

				unsigned int num)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	blk64_t bitno = (blk64_t) arg;

	unsigned int i;

	for (i = 0; i < num; i++)

		ext2fs_fast_set_bit64(bitno + i - bitmap->start, bp->bitarray);

}

static void ba_unmark_bmap_extent(ext2fs_generic_bitmap bitmap, __u64 arg,

				  unsigned int num)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	blk64_t bitno = (blk64_t) arg;

	unsigned int i;

	for (i = 0; i < num; i++)

		ext2fs_fast_clear_bit64(bitno + i - bitmap->start, bp->bitarray);

}

static int ba_test_clear_bmap_extent(ext2fs_generic_bitmap bitmap,

				     __u64 start, unsigned int len)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	__u64 start_byte, len_byte = len >> 3;

	unsigned int start_bit, len_bit = len % 8;

	unsigned int first_bit = 0;

	unsigned int last_bit  = 0;

	int mark_count = 0;

	int mark_bit = 0;

	int i;

	const char *ADDR;

	ADDR = bp->bitarray;

	start -= bitmap->start;

	start_byte = start >> 3;

	start_bit = start % 8;

	if (start_bit != 0) {

		/*

		 * The compared start block number or start inode number

		 * is not the first bit in a byte.

		 */

		mark_count = 8 - start_bit;

		if (len < 8 - start_bit) {

			mark_count = (int)len;

			mark_bit = len + start_bit - 1;

		} else

			mark_bit = 7;

		for (i = mark_count; i > 0; i--, mark_bit--)

			first_bit |= 1 << mark_bit;

		/*

		 * Compare blocks or inodes in the first byte.

		 * If there is any marked bit, this function returns 0.

		 */

		if (first_bit & ADDR[start_byte])

			return 0;

		else if (len <= 8 - start_bit)

			return 1;

		start_byte++;

		len_bit = (len - mark_count) % 8;

		len_byte = (len - mark_count) >> 3;

	}

	/*

	 * The compared start block number or start inode number is

	 * the first bit in a byte.

	 */

	if (len_bit != 0) {

		/*

		 * The compared end block number or end inode number is

		 * not the last bit in a byte.

		 */

		for (mark_bit = len_bit - 1; mark_bit >= 0; mark_bit--)

			last_bit |= 1 << mark_bit;

		/*

		 * Compare blocks or inodes in the last byte.

		 * If there is any marked bit, this function returns 0.

		 */

		if (last_bit & ADDR[start_byte + len_byte])

			return 0;

		else if (len_byte == 0)

			return 1;

	}

	/* Check whether all bytes are 0 */

	return ext2fs_mem_is_zero(ADDR + start_byte, len_byte);

}

static errcode_t ba_set_bmap_range(ext2fs_generic_bitmap bitmap,

				     __u64 start, size_t num, void *in)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	memcpy (bp->bitarray + (start >> 3), in, (num + 7) >> 3);

	return 0;

}

static errcode_t ba_get_bmap_range(ext2fs_generic_bitmap bitmap,

				     __u64 start, size_t num, void *out)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	memcpy (out, bp->bitarray + (start >> 3), (num + 7) >> 3);

	return 0;

}

static void ba_clear_bmap(ext2fs_generic_bitmap bitmap)

{

	ext2fs_ba_private bp = (ext2fs_ba_private) bitmap->private;

	memset(bp->bitarray, 0,

	       (size_t) (((bitmap->real_end - bitmap->start) / 8) + 1));

}

#ifdef ENABLE_BMAP_STATS

static void ba_print_stats(ext2fs_generic_bitmap bitmap)

{

	fprintf(stderr, "%16llu Bytes used by bitarray\n",

		((bitmap->real_end - bitmap->start) >> 3) + 1 +

		sizeof(struct ext2fs_ba_private_struct));

}

#else

static void ba_print_stats(ext2fs_generic_bitmap bitmap EXT2FS_ATTR((unused)))

{

}

#endif

/* Find the first zero bit between start and end, inclusive. */

static errcode_t ba_find_first_zero(ext2fs_generic_bitmap bitmap,

				    __u64 start, __u64 end, __u64 *out)

{

	ext2fs_ba_private bp = (ext2fs_ba_private)bitmap->private;

	unsigned long bitpos = start - bitmap->start;

	unsigned long count = end - start + 1;

	int byte_found = 0; /* whether a != 0xff byte has been found */

	const unsigned char *pos;

	unsigned long max_loop_count, i;

	/* scan bits until we hit a byte boundary */

	while ((bitpos & 0x7) != 0 && count > 0) {

		if (!ext2fs_test_bit64(bitpos, bp->bitarray)) {

			*out = bitpos + bitmap->start;

			return 0;

		}

		bitpos++;

		count--;

	}

	if (!count)

		return ENOENT;

	pos = ((unsigned char *)bp->bitarray) + (bitpos >> 3);

	/* scan bytes until 8-byte (64-bit) aligned */

	while (count >= 8 && (((uintptr_t)pos) & 0x07)) {

		if (*pos != 0xff) {

			byte_found = 1;

			break;

		}

		pos++;

		count -= 8;

		bitpos += 8;

	}

	if (!byte_found) {

		max_loop_count = count >> 6; /* 8-byte blocks */

		i = max_loop_count;

		while (i) {

			if (*((const __u64 *)pos) != ((__u64)-1))

				break;

			pos += 8;

			i--;

		}

		count -= 64 * (max_loop_count - i);

		bitpos += 64 * (max_loop_count - i);

		max_loop_count = count >> 3;

		i = max_loop_count;

		while (i) {

			if (*pos != 0xff) {

				byte_found = 1;

				break;

			}

			pos++;

			i--;

		}

		count -= 8 * (max_loop_count - i);

		bitpos += 8 * (max_loop_count - i);

	}

	/* Here either count < 8 or byte_found == 1. */

	while (count-- > 0) {

		if (!ext2fs_test_bit64(bitpos, bp->bitarray)) {

			*out = bitpos + bitmap->start;

			return 0;

		}

		bitpos++;

	}

	return ENOENT;

}

/* Find the first one bit between start and end, inclusive. */

static errcode_t ba_find_first_set(ext2fs_generic_bitmap bitmap,

				    __u64 start, __u64 end, __u64 *out)

{

	ext2fs_ba_private bp = (ext2fs_ba_private)bitmap->private;

	unsigned long bitpos = start - bitmap->start;

	unsigned long count = end - start + 1;

	int byte_found = 0; /* whether a != 0xff byte has been found */

	const unsigned char *pos;

	unsigned long max_loop_count, i;

	/* scan bits until we hit a byte boundary */

	while ((bitpos & 0x7) != 0 && count > 0) {

		if (ext2fs_test_bit64(bitpos, bp->bitarray)) {

			*out = bitpos + bitmap->start;

			return 0;

		}

		bitpos++;

		count--;

	}

	if (!count)

		return ENOENT;

	pos = ((unsigned char *)bp->bitarray) + (bitpos >> 3);

	/* scan bytes until 8-byte (64-bit) aligned */

	while (count >= 8 && (((uintptr_t)pos) & 0x07)) {

		if (*pos != 0) {

			byte_found = 1;

			break;

		}

		pos++;

		count -= 8;

		bitpos += 8;

	}

	if (!byte_found) {

		max_loop_count = count >> 6; /* 8-byte blocks */

		i = max_loop_count;

		while (i) {

			if (*((const __u64 *)pos) != 0)

				break;

			pos += 8;

			i--;

		}

		count -= 64 * (max_loop_count - i);

		bitpos += 64 * (max_loop_count - i);

		max_loop_count = count >> 3;

		i = max_loop_count;

		while (i) {

			if (*pos != 0) {

				byte_found = 1;

				break;

			}

			pos++;

			i--;

		}

		count -= 8 * (max_loop_count - i);

		bitpos += 8 * (max_loop_count - i);

	}

	/* Here either count < 8 or byte_found == 1. */

	while (count-- > 0) {

		if (ext2fs_test_bit64(bitpos, bp->bitarray)) {

			*out = bitpos + bitmap->start;

			return 0;

		}

		bitpos++;

	}

	return ENOENT;

}

struct ext2_bitmap_ops ext2fs_blkmap64_bitarray = {

	.type = EXT2FS_BMAP64_BITARRAY,

	.new_bmap = ba_new_bmap,

	.free_bmap = ba_free_bmap,

	.copy_bmap = ba_copy_bmap,

	.resize_bmap = ba_resize_bmap,

	.mark_bmap = ba_mark_bmap,

	.unmark_bmap = ba_unmark_bmap,

	.test_bmap = ba_test_bmap,

	.test_clear_bmap_extent = ba_test_clear_bmap_extent,

	.mark_bmap_extent = ba_mark_bmap_extent,

	.unmark_bmap_extent = ba_unmark_bmap_extent,

	.set_bmap_range = ba_set_bmap_range,

	.get_bmap_range = ba_get_bmap_range,

	.clear_bmap = ba_clear_bmap,

	.print_stats = ba_print_stats,

	.find_first_zero = ba_find_first_zero,

	.find_first_set = ba_find_first_set

};