/******************************************************
Index page routines

(c) 1994-1996 Innobase Oy

Created 2/2/1994 Heikki Tuuri
*******************************************************/

#include "page0page.h"
#ifdef UNIV_NONINL
#include "page0page.ic"
#endif

#include "page0cur.h"
#include "page0zip.h"
#include "lock0lock.h"
#include "fut0lst.h"
#include "btr0sea.h"
#include "buf0buf.h"
#include "srv0srv.h"
#include "btr0btr.h"

/*			THE INDEX PAGE
			==============

The index page consists of a page header which contains the page's
id and other information. On top of it are the the index records
in a heap linked into a one way linear list according to alphabetic order.

Just below page end is an array of pointers which we call page directory,
to about every sixth record in the list. The pointers are placed in
the directory in the alphabetical order of the records pointed to,
enabling us to make binary search using the array. Each slot n:o I
in the directory points to a record, where a 4-bit field contains a count
of those records which are in the linear list between pointer I and
the pointer I - 1 in the directory, including the record
pointed to by pointer I and not including the record pointed to by I - 1.
We say that the record pointed to by slot I, or that slot I, owns
these records. The count is always kept in the range 4 to 8, with
the exception that it is 1 for the first slot, and 1--8 for the second slot.

An essentially binary search can be performed in the list of index
records, like we could do if we had pointer to every record in the
page directory. The data structure is, however, more efficient when
we are doing inserts, because most inserts are just pushed on a heap.
Only every 8th insert requires block move in the directory pointer
table, which itself is quite small. A record is deleted from the page
by just taking it off the linear list and updating the number of owned
records-field of the record which owns it, and updating the page directory,
if necessary. A special case is the one when the record owns itself.
Because the overhead of inserts is so small, we may also increase the
page size from the projected default of 8 kB to 64 kB without too
much loss of efficiency in inserts. Bigger page becomes actual
when the disk transfer rate compared to seek and latency time rises.
On the present system, the page size is set so that the page transfer
time (3 ms) is 20 % of the disk random access time (15 ms).

When the page is split, merged, or becomes full but contains deleted
records, we have to reorganize the page.

Assuming a page size of 8 kB, a typical index page of a secondary
index contains 300 index entries, and the size of the page directory
is 50 x 4 bytes = 200 bytes. */

/*******************************************************************
Looks for the directory slot which owns the given record. */
UNIV_INTERN
ulint
page_dir_find_owner_slot(
/*=====================*/
				/* out: the directory slot number */
	const rec_t*	rec)	/* in: the physical record */
{
	const page_t*			page;
	register uint16			rec_offs_bytes;
	register const page_dir_slot_t*	slot;
	register const page_dir_slot_t*	first_slot;
	register const rec_t*		r = rec;

	ut_ad(page_rec_check(rec));

	page = page_align(rec);
	first_slot = page_dir_get_nth_slot(page, 0);
	slot = page_dir_get_nth_slot(page, page_dir_get_n_slots(page) - 1);

	if (page_is_comp(page)) {
		while (rec_get_n_owned_new(r) == 0) {
			r = rec_get_next_ptr_const(r, TRUE);
			ut_ad(r >= page + PAGE_NEW_SUPREMUM);
			ut_ad(r < page + (UNIV_PAGE_SIZE - PAGE_DIR));
		}
	} else {
		while (rec_get_n_owned_old(r) == 0) {
			r = rec_get_next_ptr_const(r, FALSE);
			ut_ad(r >= page + PAGE_OLD_SUPREMUM);
			ut_ad(r < page + (UNIV_PAGE_SIZE - PAGE_DIR));
		}
	}

	rec_offs_bytes = mach_encode_2(r - page);

	while (UNIV_LIKELY(*(uint16*) slot != rec_offs_bytes)) {

		if (UNIV_UNLIKELY(slot == first_slot)) {
			fprintf(stderr,
				"InnoDB: Probable data corruption on"
				" page %lu\n"
				"InnoDB: Original record ",
				(ulong) page_get_page_no(page));

			if (page_is_comp(page)) {
				fputs("(compact record)", stderr);
			} else {
				rec_print_old(stderr, rec);
			}

			fputs("\n"
			      "InnoDB: on that page.\n"
			      "InnoDB: Cannot find the dir slot for record ",
			      stderr);
			if (page_is_comp(page)) {
				fputs("(compact record)", stderr);
			} else {
				rec_print_old(stderr, page
					      + mach_decode_2(rec_offs_bytes));
			}
			fputs("\n"
			      "InnoDB: on that page!\n", stderr);

			buf_page_print(page, 0);

			ut_error;
		}

		slot += PAGE_DIR_SLOT_SIZE;
	}

	return(((ulint) (first_slot - slot)) / PAGE_DIR_SLOT_SIZE);
}

/******************************************************************
Used to check the consistency of a directory slot. */
static
ibool
page_dir_slot_check(
/*================*/
					/* out: TRUE if succeed */
	page_dir_slot_t*	slot)	/* in: slot */
{
	page_t*	page;
	ulint	n_slots;
	ulint	n_owned;

	ut_a(slot);

	page = page_align(slot);

	n_slots = page_dir_get_n_slots(page);

	ut_a(slot <= page_dir_get_nth_slot(page, 0));
	ut_a(slot >= page_dir_get_nth_slot(page, n_slots - 1));

	ut_a(page_rec_check(page_dir_slot_get_rec(slot)));

	if (page_is_comp(page)) {
		n_owned = rec_get_n_owned_new(page_dir_slot_get_rec(slot));
	} else {
		n_owned = rec_get_n_owned_old(page_dir_slot_get_rec(slot));
	}

	if (slot == page_dir_get_nth_slot(page, 0)) {
		ut_a(n_owned == 1);
	} else if (slot == page_dir_get_nth_slot(page, n_slots - 1)) {
		ut_a(n_owned >= 1);
		ut_a(n_owned <= PAGE_DIR_SLOT_MAX_N_OWNED);
	} else {
		ut_a(n_owned >= PAGE_DIR_SLOT_MIN_N_OWNED);
		ut_a(n_owned <= PAGE_DIR_SLOT_MAX_N_OWNED);
	}

	return(TRUE);
}

/*****************************************************************
Sets the max trx id field value. */
UNIV_INTERN
void
page_set_max_trx_id(
/*================*/
	buf_block_t*	block,	/* in/out: page */
	page_zip_des_t*	page_zip,/* in/out: compressed page, or NULL */
	dulint		trx_id)	/* in: transaction id */
{
	const ibool	is_hashed	= block->is_hashed;
	page_t*		page		= buf_block_get_frame(block);

	if (is_hashed) {
		rw_lock_x_lock(&btr_search_latch);
	}

	/* It is not necessary to write this change to the redo log, as
	during a database recovery we assume that the max trx id of every
	page is the maximum trx id assigned before the crash. */

	mach_write_to_8(page + (PAGE_HEADER + PAGE_MAX_TRX_ID), trx_id);
	if (UNIV_LIKELY_NULL(page_zip)) {
		page_zip_write_header(page_zip,
				      page + (PAGE_HEADER + PAGE_MAX_TRX_ID),
				      8, NULL);
	}

	if (is_hashed) {
		rw_lock_x_unlock(&btr_search_latch);
	}
}

/****************************************************************
Allocates a block of memory from the heap of an index page. */
UNIV_INTERN
byte*
page_mem_alloc_heap(
/*================*/
				/* out: pointer to start of allocated
				buffer, or NULL if allocation fails */
	page_t*		page,	/* in/out: index page */
	page_zip_des_t*	page_zip,/* in/out: compressed page with enough
				space available for inserting the record,
				or NULL */
	ulint		need,	/* in: total number of bytes needed */
	ulint*		heap_no)/* out: this contains the heap number
				of the allocated record
				if allocation succeeds */
{
	byte*	block;
	ulint	avl_space;

	ut_ad(page && heap_no);

	avl_space = page_get_max_insert_size(page, 1);

	if (avl_space >= need) {
		block = page_header_get_ptr(page, PAGE_HEAP_TOP);

		page_header_set_ptr(page, page_zip, PAGE_HEAP_TOP,
				    block + need);
		*heap_no = page_dir_get_n_heap(page);

		page_dir_set_n_heap(page, page_zip, 1 + *heap_no);

		return(block);
	}

	return(NULL);
}

/**************************************************************
Writes a log record of page creation. */
UNIV_INLINE
void
page_create_write_log(
/*==================*/
	buf_frame_t*	frame,	/* in: a buffer frame where the page is
				created */
	mtr_t*		mtr,	/* in: mini-transaction handle */
	ibool		comp)	/* in: TRUE=compact page format */
{
	mlog_write_initial_log_record(frame, comp
				      ? MLOG_COMP_PAGE_CREATE
				      : MLOG_PAGE_CREATE, mtr);
}

/***************************************************************
Parses a redo log record of creating a page. */
UNIV_INTERN
byte*
page_parse_create(
/*==============*/
				/* out: end of log record or NULL */
	byte*		ptr,	/* in: buffer */
	byte*		end_ptr __attribute__((unused)), /* in: buffer end */
	ulint		comp,	/* in: nonzero=compact page format */
	buf_block_t*	block,	/* in: block or NULL */
	mtr_t*		mtr)	/* in: mtr or NULL */
{
	ut_ad(ptr && end_ptr);

	/* The record is empty, except for the record initial part */

	if (block) {
		page_create(block, mtr, comp);
	}

	return(ptr);
}

/**************************************************************
The index page creation function. */
static
page_t*
page_create_low(
/*============*/
					/* out: pointer to the page */
	buf_block_t*	block,		/* in: a buffer block where the
					page is created */
	ulint		comp)		/* in: nonzero=compact page format */
{
	page_dir_slot_t* slot;
	mem_heap_t*	heap;
	dtuple_t*	tuple;
	dfield_t*	field;
	byte*		heap_top;
	rec_t*		infimum_rec;
	rec_t*		supremum_rec;
	page_t*		page;
	dict_index_t*	index;
	ulint*		offsets;

	ut_ad(block);
#if PAGE_BTR_IBUF_FREE_LIST + FLST_BASE_NODE_SIZE > PAGE_DATA
# error "PAGE_BTR_IBUF_FREE_LIST + FLST_BASE_NODE_SIZE > PAGE_DATA"
#endif
#if PAGE_BTR_IBUF_FREE_LIST_NODE + FLST_NODE_SIZE > PAGE_DATA
# error "PAGE_BTR_IBUF_FREE_LIST_NODE + FLST_NODE_SIZE > PAGE_DATA"
#endif

	/* The infimum and supremum records use a dummy index. */
	if (UNIV_LIKELY(comp)) {
		index = srv_sys->dummy_ind2;
	} else {
		index = srv_sys->dummy_ind1;
	}

	/* 1. INCREMENT MODIFY CLOCK */
	buf_block_modify_clock_inc(block);

	page = buf_block_get_frame(block);

	fil_page_set_type(page, FIL_PAGE_INDEX);

	heap = mem_heap_create(200);

	/* 3. CREATE THE INFIMUM AND SUPREMUM RECORDS */

	/* Create first a data tuple for infimum record */
	tuple = dtuple_create(heap, 1);
	dtuple_set_info_bits(tuple, REC_STATUS_INFIMUM);
	field = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(field, "infimum", 8);
	dtype_set(dfield_get_type(field),
		  DATA_VARCHAR, DATA_ENGLISH | DATA_NOT_NULL, 8);
	/* Set the corresponding physical record to its place in the page
	record heap */

	heap_top = page + PAGE_DATA;

	infimum_rec = rec_convert_dtuple_to_rec(heap_top, index, tuple, 0);

	if (UNIV_LIKELY(comp)) {
		ut_a(infimum_rec == page + PAGE_NEW_INFIMUM);

		rec_set_n_owned_new(infimum_rec, NULL, 1);
		rec_set_heap_no_new(infimum_rec, 0);
	} else {
		ut_a(infimum_rec == page + PAGE_OLD_INFIMUM);

		rec_set_n_owned_old(infimum_rec, 1);
		rec_set_heap_no_old(infimum_rec, 0);
	}

	offsets = rec_get_offsets(infimum_rec, index, NULL,
				  ULINT_UNDEFINED, &heap);

	heap_top = rec_get_end(infimum_rec, offsets);

	/* Create then a tuple for supremum */

	tuple = dtuple_create(heap, 1);
	dtuple_set_info_bits(tuple, REC_STATUS_SUPREMUM);
	field = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(field, "supremum", comp ? 8 : 9);
	dtype_set(dfield_get_type(field),
		  DATA_VARCHAR, DATA_ENGLISH | DATA_NOT_NULL, comp ? 8 : 9);

	supremum_rec = rec_convert_dtuple_to_rec(heap_top, index, tuple, 0);

	if (UNIV_LIKELY(comp)) {
		ut_a(supremum_rec == page + PAGE_NEW_SUPREMUM);

		rec_set_n_owned_new(supremum_rec, NULL, 1);
		rec_set_heap_no_new(supremum_rec, 1);
	} else {
		ut_a(supremum_rec == page + PAGE_OLD_SUPREMUM);

		rec_set_n_owned_old(supremum_rec, 1);
		rec_set_heap_no_old(supremum_rec, 1);
	}

	offsets = rec_get_offsets(supremum_rec, index, offsets,
				  ULINT_UNDEFINED, &heap);
	heap_top = rec_get_end(supremum_rec, offsets);

	ut_ad(heap_top == page
	      + (comp ? PAGE_NEW_SUPREMUM_END : PAGE_OLD_SUPREMUM_END));

	mem_heap_free(heap);

	/* 4. INITIALIZE THE PAGE */

	page_header_set_field(page, NULL, PAGE_N_DIR_SLOTS, 2);
	page_header_set_ptr(page, NULL, PAGE_HEAP_TOP, heap_top);
	page_header_set_field(page, NULL, PAGE_N_HEAP, comp
			      ? 0x8000 | PAGE_HEAP_NO_USER_LOW
			      : PAGE_HEAP_NO_USER_LOW);
	page_header_set_ptr(page, NULL, PAGE_FREE, NULL);
	page_header_set_field(page, NULL, PAGE_GARBAGE, 0);
	page_header_set_ptr(page, NULL, PAGE_LAST_INSERT, NULL);
	page_header_set_field(page, NULL, PAGE_DIRECTION, PAGE_NO_DIRECTION);
	page_header_set_field(page, NULL, PAGE_N_DIRECTION, 0);
	page_header_set_field(page, NULL, PAGE_N_RECS, 0);
	page_set_max_trx_id(block, NULL, ut_dulint_zero);
	memset(heap_top, 0, UNIV_PAGE_SIZE - PAGE_EMPTY_DIR_START
	       - page_offset(heap_top));

	/* 5. SET POINTERS IN RECORDS AND DIR SLOTS */

	/* Set the slots to point to infimum and supremum. */

	slot = page_dir_get_nth_slot(page, 0);
	page_dir_slot_set_rec(slot, infimum_rec);

	slot = page_dir_get_nth_slot(page, 1);
	page_dir_slot_set_rec(slot, supremum_rec);

	/* Set the next pointers in infimum and supremum */

	if (UNIV_LIKELY(comp)) {
		rec_set_next_offs_new(infimum_rec, PAGE_NEW_SUPREMUM);
		rec_set_next_offs_new(supremum_rec, 0);
	} else {
		rec_set_next_offs_old(infimum_rec, PAGE_OLD_SUPREMUM);
		rec_set_next_offs_old(supremum_rec, 0);
	}

	return(page);
}

/**************************************************************
Create an uncompressed B-tree index page. */
UNIV_INTERN
page_t*
page_create(
/*========*/
					/* out: pointer to the page */
	buf_block_t*	block,		/* in: a buffer block where the
					page is created */
	mtr_t*		mtr,		/* in: mini-transaction handle */
	ulint		comp)		/* in: nonzero=compact page format */
{
	page_create_write_log(buf_block_get_frame(block), mtr, comp);
	return(page_create_low(block, comp));
}

/**************************************************************
Create a compressed B-tree index page. */
UNIV_INTERN
page_t*
page_create_zip(
/*============*/
					/* out: pointer to the page */
	buf_block_t*	block,		/* in/out: a buffer frame where the
					page is created */
	dict_index_t*	index,		/* in: the index of the page */
	ulint		level,		/* in: the B-tree level of the page */
	mtr_t*		mtr)		/* in: mini-transaction handle */
{
	page_t*		page;
	page_zip_des_t*	page_zip	= buf_block_get_page_zip(block);

	ut_ad(block);
	ut_ad(page_zip);
	ut_ad(index);
	ut_ad(dict_table_is_comp(index->table));

	page = page_create_low(block, TRUE);
	mach_write_to_2(page + PAGE_HEADER + PAGE_LEVEL, level);

	if (UNIV_UNLIKELY(!page_zip_compress(page_zip, page, index, mtr))) {
		/* The compression of a newly created page
		should always succeed. */
		ut_error;
	}

	return(page);
}

/*****************************************************************
Differs from page_copy_rec_list_end, because this function does not
touch the lock table and max trx id on page or compress the page. */
UNIV_INTERN
void
page_copy_rec_list_end_no_locks(
/*============================*/
	buf_block_t*	new_block,	/* in: index page to copy to */
	buf_block_t*	block,		/* in: index page of rec */
	rec_t*		rec,		/* in: record on page */
	dict_index_t*	index,		/* in: record descriptor */
	mtr_t*		mtr)		/* in: mtr */
{
	page_t*		new_page	= buf_block_get_frame(new_block);
	page_cur_t	cur1;
	rec_t*		cur2;
	mem_heap_t*	heap		= NULL;
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	rec_offs_init(offsets_);

	page_cur_position(rec, block, &cur1);

	if (page_cur_is_before_first(&cur1)) {

		page_cur_move_to_next(&cur1);
	}

	ut_a((ibool)!!page_is_comp(new_page)
	     == dict_table_is_comp(index->table));
	ut_a(page_is_comp(new_page) == page_rec_is_comp(rec));
	ut_a(mach_read_from_2(new_page + UNIV_PAGE_SIZE - 10) == (ulint)
	     (page_is_comp(new_page) ? PAGE_NEW_INFIMUM : PAGE_OLD_INFIMUM));

	cur2 = page_get_infimum_rec(buf_block_get_frame(new_block));

	/* Copy records from the original page to the new page */

	while (!page_cur_is_after_last(&cur1)) {
		rec_t*	cur1_rec = page_cur_get_rec(&cur1);
		rec_t*	ins_rec;
		offsets = rec_get_offsets(cur1_rec, index, offsets,
					  ULINT_UNDEFINED, &heap);
		ins_rec = page_cur_insert_rec_low(cur2, index,
						  cur1_rec, offsets, mtr);
		if (UNIV_UNLIKELY(!ins_rec)) {
			/* Track an assertion failure reported on the mailing
			list on June 18th, 2003 */

			buf_page_print(new_page, 0);
			buf_page_print(page_align(rec), 0);
			ut_print_timestamp(stderr);

			fprintf(stderr,
				"InnoDB: rec offset %lu, cur1 offset %lu,"
				" cur2 offset %lu\n",
				(ulong) page_offset(rec),
				(ulong) page_offset(page_cur_get_rec(&cur1)),
				(ulong) page_offset(cur2));
			ut_error;
		}

		page_cur_move_to_next(&cur1);
		cur2 = ins_rec;
	}

	if (UNIV_LIKELY_NULL(heap)) {
		mem_heap_free(heap);
	}
}

/*****************************************************************
Copies records from page to new_page, from a given record onward,
including that record. Infimum and supremum records are not copied.
The records are copied to the start of the record list on new_page. */
UNIV_INTERN
rec_t*
page_copy_rec_list_end(
/*===================*/
					/* out: pointer to the original
					successor of the infimum record
					on new_page, or NULL on zip overflow
					(new_block will be decompressed) */
	buf_block_t*	new_block,	/* in/out: index page to copy to */
	buf_block_t*	block,		/* in: index page containing rec */
	rec_t*		rec,		/* in: record on page */
	dict_index_t*	index,		/* in: record descriptor */
	mtr_t*		mtr)		/* in: mtr */
{
	page_t*		new_page	= buf_block_get_frame(new_block);
	page_zip_des_t*	new_page_zip	= buf_block_get_page_zip(new_block);
	page_t*		page		= page_align(rec);
	rec_t*		ret		= page_rec_get_next(
		page_get_infimum_rec(new_page));
	ulint		log_mode	= 0; /* remove warning */

#ifdef UNIV_ZIP_DEBUG
	if (new_page_zip) {
		page_zip_des_t*	page_zip = buf_block_get_page_zip(block);
		ut_a(page_zip);

		/* Strict page_zip_validate() may fail here.
		Furthermore, btr_compress() may set FIL_PAGE_PREV to
		FIL_NULL on new_page while leaving it intact on
		new_page_zip.  So, we cannot validate new_page_zip. */
		ut_a(page_zip_validate_low(page_zip, page, TRUE));
	}
#endif /* UNIV_ZIP_DEBUG */
	ut_ad(buf_block_get_frame(block) == page);
	ut_ad(page_is_leaf(page) == page_is_leaf(new_page));
	ut_ad(page_is_comp(page) == page_is_comp(new_page));
	/* Here, "ret" may be pointing to a user record or the
	predefined supremum record. */

	if (UNIV_LIKELY_NULL(new_page_zip)) {
		log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);
	}

	if (page_dir_get_n_heap(new_page) == PAGE_HEAP_NO_USER_LOW) {
		page_copy_rec_list_end_to_created_page(new_page, rec,
						       index, mtr);
	} else {
		page_copy_rec_list_end_no_locks(new_block, block, rec,
						index, mtr);
	}

	if (UNIV_LIKELY_NULL(new_page_zip)) {
		mtr_set_log_mode(mtr, log_mode);

		if (UNIV_UNLIKELY
		    (!page_zip_compress(new_page_zip, new_page, index, mtr))) {
			/* Before trying to reorganize the page,
			store the number of preceding records on the page. */
			ulint	ret_pos
				= page_rec_get_n_recs_before(ret);
			/* Before copying, "ret" was the successor of
			the predefined infimum record.  It must still
			have at least one predecessor (the predefined
			infimum record, or a freshly copied record
			that is smaller than "ret"). */
			ut_a(ret_pos > 0);

			if (UNIV_UNLIKELY
			    (!page_zip_reorganize(new_block, index, mtr))) {

				if (UNIV_UNLIKELY
				    (!page_zip_decompress(new_page_zip,
							  new_page))) {
					ut_error;
				}
				ut_ad(page_validate(new_page, index));
				return(NULL);
			} else {
				/* The page was reorganized:
				Seek to ret_pos. */
				ret = new_page + PAGE_NEW_INFIMUM;

				do {
					ret = rec_get_next_ptr(ret, TRUE);
				} while (--ret_pos);
			}
		}
	}

	/* Update the lock table, MAX_TRX_ID, and possible hash index */

	lock_move_rec_list_end(new_block, block, rec);

	page_update_max_trx_id(new_block, new_page_zip,
			       page_get_max_trx_id(page));

	btr_search_move_or_delete_hash_entries(new_block, block, index);

	return(ret);
}

/*****************************************************************
Copies records from page to new_page, up to the given record,
NOT including that record. Infimum and supremum records are not copied.
The records are copied to the end of the record list on new_page. */
UNIV_INTERN
rec_t*
page_copy_rec_list_start(
/*=====================*/
					/* out: pointer to the original
					predecessor of the supremum record
					on new_page, or NULL on zip overflow
					(new_block will be decompressed) */
	buf_block_t*	new_block,	/* in/out: index page to copy to */
	buf_block_t*	block,		/* in: index page containing rec */
	rec_t*		rec,		/* in: record on page */
	dict_index_t*	index,		/* in: record descriptor */
	mtr_t*		mtr)		/* in: mtr */
{
	page_t*		new_page	= buf_block_get_frame(new_block);
	page_zip_des_t*	new_page_zip	= buf_block_get_page_zip(new_block);
	page_cur_t	cur1;
	rec_t*		cur2;
	ulint		log_mode	= 0 /* remove warning */;
	mem_heap_t*	heap		= NULL;
	rec_t*		ret
		= page_rec_get_prev(page_get_supremum_rec(new_page));
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	rec_offs_init(offsets_);

	/* Here, "ret" may be pointing to a user record or the
	predefined infimum record. */

	if (page_rec_is_infimum(rec)) {

		return(ret);
	}

	if (UNIV_LIKELY_NULL(new_page_zip)) {
		log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);
	}

	page_cur_set_before_first(block, &cur1);
	page_cur_move_to_next(&cur1);

	cur2 = ret;

	/* Copy records from the original page to the new page */

	while (page_cur_get_rec(&cur1) != rec) {
		rec_t*	cur1_rec = page_cur_get_rec(&cur1);
		offsets = rec_get_offsets(cur1_rec, index, offsets,
					  ULINT_UNDEFINED, &heap);
		cur2 = page_cur_insert_rec_low(cur2, index,
					       cur1_rec, offsets, mtr);
		ut_a(cur2);

		page_cur_move_to_next(&cur1);
	}

	if (UNIV_LIKELY_NULL(heap)) {
		mem_heap_free(heap);
	}

	if (UNIV_LIKELY_NULL(new_page_zip)) {
		mtr_set_log_mode(mtr, log_mode);

		if (UNIV_UNLIKELY
		    (!page_zip_compress(new_page_zip, new_page, index, mtr))) {
			/* Before trying to reorganize the page,
			store the number of preceding records on the page. */
			ulint	ret_pos
				= page_rec_get_n_recs_before(ret);
			/* Before copying, "ret" was the predecessor
			of the predefined supremum record.  If it was
			the predefined infimum record, then it would
			still be the infimum.  Thus, the assertion
			ut_a(ret_pos > 0) would fail here. */

			if (UNIV_UNLIKELY
			    (!page_zip_reorganize(new_block, index, mtr))) {

				if (UNIV_UNLIKELY
				    (!page_zip_decompress(new_page_zip,
							  new_page))) {
					ut_error;
				}
				ut_ad(page_validate(new_page, index));
				return(NULL);
			} else {
				/* The page was reorganized:
				Seek to ret_pos. */
				ret = new_page + PAGE_NEW_INFIMUM;

				do {
					ret = rec_get_next_ptr(ret, TRUE);
				} while (--ret_pos);
			}
		}
	}

	/* Update MAX_TRX_ID, the lock table, and possible hash index */

	page_update_max_trx_id(new_block, new_page_zip,
			       page_get_max_trx_id(page_align(rec)));

	lock_move_rec_list_start(new_block, block, rec, ret);

	btr_search_move_or_delete_hash_entries(new_block, block, index);

	return(ret);
}

/**************************************************************
Writes a log record of a record list end or start deletion. */
UNIV_INLINE
void
page_delete_rec_list_write_log(
/*===========================*/
	rec_t*		rec,	/* in: record on page */
	dict_index_t*	index,	/* in: record descriptor */
	byte		type,	/* in: operation type:
				MLOG_LIST_END_DELETE, ... */
	mtr_t*		mtr)	/* in: mtr */
{
	byte*	log_ptr;
	ut_ad(type == MLOG_LIST_END_DELETE
	      || type == MLOG_LIST_START_DELETE
	      || type == MLOG_COMP_LIST_END_DELETE
	      || type == MLOG_COMP_LIST_START_DELETE);

	log_ptr = mlog_open_and_write_index(mtr, rec, index, type, 2);
	if (log_ptr) {
		/* Write the parameter as a 2-byte ulint */
		mach_write_to_2(log_ptr, page_offset(rec));
		mlog_close(mtr, log_ptr + 2);
	}
}

/**************************************************************
Parses a log record of a record list end or start deletion. */
UNIV_INTERN
byte*
page_parse_delete_rec_list(
/*=======================*/
				/* out: end of log record or NULL */
	byte		type,	/* in: MLOG_LIST_END_DELETE,
				MLOG_LIST_START_DELETE,
				MLOG_COMP_LIST_END_DELETE or
				MLOG_COMP_LIST_START_DELETE */
	byte*		ptr,	/* in: buffer */
	byte*		end_ptr,/* in: buffer end */
	buf_block_t*	block,	/* in/out: buffer block or NULL */
	dict_index_t*	index,	/* in: record descriptor */
	mtr_t*		mtr)	/* in: mtr or NULL */
{
	page_t*	page;
	ulint	offset;

	ut_ad(type == MLOG_LIST_END_DELETE
	      || type == MLOG_LIST_START_DELETE
	      || type == MLOG_COMP_LIST_END_DELETE
	      || type == MLOG_COMP_LIST_START_DELETE);

	/* Read the record offset as a 2-byte ulint */

	if (end_ptr < ptr + 2) {

		return(NULL);
	}

	offset = mach_read_from_2(ptr);
	ptr += 2;

	if (!block) {

		return(ptr);
	}

	page = buf_block_get_frame(block);

	ut_ad(!!page_is_comp(page) == dict_table_is_comp(index->table));

	if (type == MLOG_LIST_END_DELETE
	    || type == MLOG_COMP_LIST_END_DELETE) {
		page_delete_rec_list_end(page + offset, block, index,
					 ULINT_UNDEFINED, ULINT_UNDEFINED,
					 mtr);
	} else {
		page_delete_rec_list_start(page + offset, block, index, mtr);
	}

	return(ptr);
}

/*****************************************************************
Deletes records from a page from a given record onward, including that record.
The infimum and supremum records are not deleted. */
UNIV_INTERN
void
page_delete_rec_list_end(
/*=====================*/
	rec_t*		rec,	/* in: pointer to record on page */
	buf_block_t*	block,	/* in: buffer block of the page */
	dict_index_t*	index,	/* in: record descriptor */
	ulint		n_recs,	/* in: number of records to delete,
				or ULINT_UNDEFINED if not known */
	ulint		size,	/* in: the sum of the sizes of the
				records in the end of the chain to
				delete, or ULINT_UNDEFINED if not known */
	mtr_t*		mtr)	/* in: mtr */
{
	page_dir_slot_t*slot;
	ulint		slot_index;
	rec_t*		last_rec;
	rec_t*		prev_rec;
	ulint		n_owned;
	page_zip_des_t*	page_zip	= buf_block_get_page_zip(block);
	page_t*		page		= page_align(rec);
	mem_heap_t*	heap		= NULL;
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	rec_offs_init(offsets_);

	ut_ad(size == ULINT_UNDEFINED || size < UNIV_PAGE_SIZE);
	ut_ad(!page_zip || page_rec_is_comp(rec));
#ifdef UNIV_ZIP_DEBUG
	ut_a(!page_zip || page_zip_validate(page_zip, page));
#endif /* UNIV_ZIP_DEBUG */

	if (page_rec_is_infimum(rec)) {
		rec = page_rec_get_next(rec);
	}

	if (page_rec_is_supremum(rec)) {

		return;
	}

	/* Reset the last insert info in the page header and increment
	the modify clock for the frame */

	page_header_set_ptr(page, page_zip, PAGE_LAST_INSERT, NULL);

	/* The page gets invalid for optimistic searches: increment the
	frame modify clock */

	buf_block_modify_clock_inc(block);

	page_delete_rec_list_write_log(rec, index, page_is_comp(page)
				       ? MLOG_COMP_LIST_END_DELETE
				       : MLOG_LIST_END_DELETE, mtr);

	if (UNIV_LIKELY_NULL(page_zip)) {
		ulint		log_mode;

		ut_a(page_is_comp(page));
		/* Individual deletes are not logged */

		log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);

		do {
			page_cur_t	cur;
			page_cur_position(rec, block, &cur);

			offsets = rec_get_offsets(rec, index, offsets,
						  ULINT_UNDEFINED, &heap);
			rec = rec_get_next_ptr(rec, TRUE);
#ifdef UNIV_ZIP_DEBUG
			ut_a(page_zip_validate(page_zip, page));
#endif /* UNIV_ZIP_DEBUG */
			page_cur_delete_rec(&cur, index, offsets, mtr);
		} while (page_offset(rec) != PAGE_NEW_SUPREMUM);

		if (UNIV_LIKELY_NULL(heap)) {
			mem_heap_free(heap);
		}

		/* Restore log mode */

		mtr_set_log_mode(mtr, log_mode);
		return;
	}

	prev_rec = page_rec_get_prev(rec);

	last_rec = page_rec_get_prev(page_get_supremum_rec(page));

	if ((size == ULINT_UNDEFINED) || (n_recs == ULINT_UNDEFINED)) {
		rec_t*		rec2		= rec;
		/* Calculate the sum of sizes and the number of records */
		size = 0;
		n_recs = 0;

		do {
			ulint	s;
			offsets = rec_get_offsets(rec2, index, offsets,
						  ULINT_UNDEFINED, &heap);
			s = rec_offs_size(offsets);
			ut_ad(rec2 - page + s - rec_offs_extra_size(offsets)
			      < UNIV_PAGE_SIZE);
			ut_ad(size + s < UNIV_PAGE_SIZE);
			size += s;
			n_recs++;

			rec2 = page_rec_get_next(rec2);
		} while (!page_rec_is_supremum(rec2));

		if (UNIV_LIKELY_NULL(heap)) {
			mem_heap_free(heap);
		}
	}

	ut_ad(size < UNIV_PAGE_SIZE);

	/* Update the page directory; there is no need to balance the number
	of the records owned by the supremum record, as it is allowed to be
	less than PAGE_DIR_SLOT_MIN_N_OWNED */

	if (page_is_comp(page)) {
		rec_t*	rec2	= rec;
		ulint	count	= 0;

		while (rec_get_n_owned_new(rec2) == 0) {
			count++;

			rec2 = rec_get_next_ptr(rec2, TRUE);
		}

		ut_ad(rec_get_n_owned_new(rec2) > count);

		n_owned = rec_get_n_owned_new(rec2) - count;
		slot_index = page_dir_find_owner_slot(rec2);
		slot = page_dir_get_nth_slot(page, slot_index);
	} else {
		rec_t*	rec2	= rec;
		ulint	count	= 0;

		while (rec_get_n_owned_old(rec2) == 0) {
			count++;

			rec2 = rec_get_next_ptr(rec2, FALSE);
		}

		ut_ad(rec_get_n_owned_old(rec2) > count);

		n_owned = rec_get_n_owned_old(rec2) - count;
		slot_index = page_dir_find_owner_slot(rec2);
		slot = page_dir_get_nth_slot(page, slot_index);
	}

	page_dir_slot_set_rec(slot, page_get_supremum_rec(page));
	page_dir_slot_set_n_owned(slot, NULL, n_owned);

	page_dir_set_n_slots(page, NULL, slot_index + 1);

	/* Remove the record chain segment from the record chain */
	page_rec_set_next(prev_rec, page_get_supremum_rec(page));

	/* Catenate the deleted chain segment to the page free list */

	page_rec_set_next(last_rec, page_header_get_ptr(page, PAGE_FREE));
	page_header_set_ptr(page, NULL, PAGE_FREE, rec);

	page_header_set_field(page, NULL, PAGE_GARBAGE, size
			      + page_header_get_field(page, PAGE_GARBAGE));

	page_header_set_field(page, NULL, PAGE_N_RECS,
			      (ulint)(page_get_n_recs(page) - n_recs));
}

/*****************************************************************
Deletes records from page, up to the given record, NOT including
that record. Infimum and supremum records are not deleted. */
UNIV_INTERN
void
page_delete_rec_list_start(
/*=======================*/
	rec_t*		rec,	/* in: record on page */
	buf_block_t*	block,	/* in: buffer block of the page */
	dict_index_t*	index,	/* in: record descriptor */
	mtr_t*		mtr)	/* in: mtr */
{
	page_cur_t	cur1;
	ulint		log_mode;
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	mem_heap_t*	heap		= NULL;
	byte		type;

	rec_offs_init(offsets_);

	ut_ad((ibool) !!page_rec_is_comp(rec)
	      == dict_table_is_comp(index->table));
#ifdef UNIV_ZIP_DEBUG
	{
		page_zip_des_t*	page_zip= buf_block_get_page_zip(block);
		page_t*		page	= buf_block_get_frame(block);

		/* page_zip_validate() would detect a min_rec_mark mismatch
		in btr_page_split_and_insert()
		between btr_attach_half_pages() and insert_page = ...
		when btr_page_get_split_rec_to_left() holds
		(direction == FSP_DOWN). */
		ut_a(!page_zip || page_zip_validate_low(page_zip, page, TRUE));
	}
#endif /* UNIV_ZIP_DEBUG */

	if (page_rec_is_infimum(rec)) {

		return;
	}

	if (page_rec_is_comp(rec)) {
		type = MLOG_COMP_LIST_START_DELETE;
	} else {
		type = MLOG_LIST_START_DELETE;
	}

	page_delete_rec_list_write_log(rec, index, type, mtr);

	page_cur_set_before_first(block, &cur1);
	page_cur_move_to_next(&cur1);

	/* Individual deletes are not logged */

	log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);

	while (page_cur_get_rec(&cur1) != rec) {
		offsets = rec_get_offsets(page_cur_get_rec(&cur1), index,
					  offsets, ULINT_UNDEFINED, &heap);
		page_cur_delete_rec(&cur1, index, offsets, mtr);
	}

	if (UNIV_LIKELY_NULL(heap)) {
		mem_heap_free(heap);
	}

	/* Restore log mode */

	mtr_set_log_mode(mtr, log_mode);
}

/*****************************************************************
Moves record list end to another page. Moved records include
split_rec. */
UNIV_INTERN
ibool
page_move_rec_list_end(
/*===================*/
					/* out: TRUE on success; FALSE on
					compression failure
					(new_block will be decompressed) */
	buf_block_t*	new_block,	/* in/out: index page where to move */
	buf_block_t*	block,		/* in: index page from where to move */
	rec_t*		split_rec,	/* in: first record to move */
	dict_index_t*	index,		/* in: record descriptor */
	mtr_t*		mtr)		/* in: mtr */
{
	page_t*		new_page	= buf_block_get_frame(new_block);
	ulint		old_data_size;
	ulint		new_data_size;
	ulint		old_n_recs;
	ulint		new_n_recs;

	old_data_size = page_get_data_size(new_page);
	old_n_recs = page_get_n_recs(new_page);
#ifdef UNIV_ZIP_DEBUG
	{
		page_zip_des_t*	new_page_zip
			= buf_block_get_page_zip(new_block);
		page_zip_des_t*	page_zip
			= buf_block_get_page_zip(block);
		ut_a(!new_page_zip == !page_zip);
		ut_a(!new_page_zip
		     || page_zip_validate(new_page_zip, new_page));
		ut_a(!page_zip
		     || page_zip_validate(page_zip, page_align(split_rec)));
	}
#endif /* UNIV_ZIP_DEBUG */

	if (UNIV_UNLIKELY(!page_copy_rec_list_end(new_block, block,
						  split_rec, index, mtr))) {
		return(FALSE);
	}

	new_data_size = page_get_data_size(new_page);
	new_n_recs = page_get_n_recs(new_page);

	ut_ad(new_data_size >= old_data_size);

	page_delete_rec_list_end(split_rec, block, index,
				 new_n_recs - old_n_recs,
				 new_data_size - old_data_size, mtr);

	return(TRUE);
}

/*****************************************************************
Moves record list start to another page. Moved records do not include
split_rec. */
UNIV_INTERN
ibool
page_move_rec_list_start(
/*=====================*/
					/* out: TRUE on success; FALSE on
					compression failure */
	buf_block_t*	new_block,	/* in/out: index page where to move */
	buf_block_t*	block,		/* in/out: page containing split_rec */
	rec_t*		split_rec,	/* in: first record not to move */
	dict_index_t*	index,		/* in: record descriptor */
	mtr_t*		mtr)		/* in: mtr */
{
	if (UNIV_UNLIKELY(!page_copy_rec_list_start(new_block, block,
						    split_rec, index, mtr))) {
		return(FALSE);
	}

	page_delete_rec_list_start(split_rec, block, index, mtr);

	return(TRUE);
}

/***************************************************************************
This is a low-level operation which is used in a database index creation
to update the page number of a created B-tree to a data dictionary record. */
UNIV_INTERN
void
page_rec_write_index_page_no(
/*=========================*/
	rec_t*	rec,	/* in: record to update */
	ulint	i,	/* in: index of the field to update */
	ulint	page_no,/* in: value to write */
	mtr_t*	mtr)	/* in: mtr */
{
	byte*	data;
	ulint	len;

	data = rec_get_nth_field_old(rec, i, &len);

	ut_ad(len == 4);

	mlog_write_ulint(data, page_no, MLOG_4BYTES, mtr);
}

/******************************************************************
Used to delete n slots from the directory. This function updates
also n_owned fields in the records, so that the first slot after
the deleted ones inherits the records of the deleted slots. */
UNIV_INLINE
void
page_dir_delete_slot(
/*=================*/
	page_t*		page,	/* in/out: the index page */
	page_zip_des_t*	page_zip,/* in/out: compressed page, or NULL */
	ulint		slot_no)/* in: slot to be deleted */
{
	page_dir_slot_t*	slot;
	ulint			n_owned;
	ulint			i;
	ulint			n_slots;

	ut_ad(!page_zip || page_is_comp(page));
	ut_ad(slot_no > 0);
	ut_ad(slot_no + 1 < page_dir_get_n_slots(page));

	n_slots = page_dir_get_n_slots(page);

	/* 1. Reset the n_owned fields of the slots to be
	deleted */
	slot = page_dir_get_nth_slot(page, slot_no);
	n_owned = page_dir_slot_get_n_owned(slot);
	page_dir_slot_set_n_owned(slot, page_zip, 0);

	/* 2. Update the n_owned value of the first non-deleted slot */

	slot = page_dir_get_nth_slot(page, slot_no + 1);
	page_dir_slot_set_n_owned(slot, page_zip,
				  n_owned + page_dir_slot_get_n_owned(slot));

	/* 3. Destroy the slot by copying slots */
	for (i = slot_no + 1; i < n_slots; i++) {
		rec_t*	rec = (rec_t*)
			page_dir_slot_get_rec(page_dir_get_nth_slot(page, i));
		page_dir_slot_set_rec(page_dir_get_nth_slot(page, i - 1), rec);
	}

	/* 4. Zero out the last slot, which will be removed */
	mach_write_to_2(page_dir_get_nth_slot(page, n_slots - 1), 0);

	/* 5. Update the page header */
	page_header_set_field(page, page_zip, PAGE_N_DIR_SLOTS, n_slots - 1);
}

/******************************************************************
Used to add n slots to the directory. Does not set the record pointers
in the added slots or update n_owned values: this is the responsibility
of the caller. */
UNIV_INLINE
void
page_dir_add_slot(
/*==============*/
	page_t*		page,	/* in/out: the index page */
	page_zip_des_t*	page_zip,/* in/out: comprssed page, or NULL */
	ulint		start)	/* in: the slot above which the new slots
				are added */
{
	page_dir_slot_t*	slot;
	ulint			n_slots;

	n_slots = page_dir_get_n_slots(page);

	ut_ad(start < n_slots - 1);

	/* Update the page header */
	page_dir_set_n_slots(page, page_zip, n_slots + 1);

	/* Move slots up */
	slot = page_dir_get_nth_slot(page, n_slots);
	memmove(slot, slot + PAGE_DIR_SLOT_SIZE,
		(n_slots - 1 - start) * PAGE_DIR_SLOT_SIZE);
}

/********************************************************************
Splits a directory slot which owns too many records. */
UNIV_INTERN
void
page_dir_split_slot(
/*================*/
	page_t*		page,	/* in/out: index page */
	page_zip_des_t*	page_zip,/* in/out: compressed page whose
				uncompressed part will be written, or NULL */
	ulint		slot_no)/* in: the directory slot */
{
	rec_t*			rec;
	page_dir_slot_t*	new_slot;
	page_dir_slot_t*	prev_slot;
	page_dir_slot_t*	slot;
	ulint			i;
	ulint			n_owned;

	ut_ad(page);
	ut_ad(!page_zip || page_is_comp(page));
	ut_ad(slot_no > 0);

	slot = page_dir_get_nth_slot(page, slot_no);

	n_owned = page_dir_slot_get_n_owned(slot);
	ut_ad(n_owned == PAGE_DIR_SLOT_MAX_N_OWNED + 1);

	/* 1. We loop to find a record approximately in the middle of the
	records owned by the slot. */

	prev_slot = page_dir_get_nth_slot(page, slot_no - 1);
	rec = (rec_t*) page_dir_slot_get_rec(prev_slot);

	for (i = 0; i < n_owned / 2; i++) {
		rec = page_rec_get_next(rec);
	}

	ut_ad(n_owned / 2 >= PAGE_DIR_SLOT_MIN_N_OWNED);

	/* 2. We add one directory slot immediately below the slot to be
	split. */

	page_dir_add_slot(page, page_zip, slot_no - 1);

	/* The added slot is now number slot_no, and the old slot is
	now number slot_no + 1 */

	new_slot = page_dir_get_nth_slot(page, slot_no);
	slot = page_dir_get_nth_slot(page, slot_no + 1);

	/* 3. We store the appropriate values to the new slot. */

	page_dir_slot_set_rec(new_slot, rec);
	page_dir_slot_set_n_owned(new_slot, page_zip, n_owned / 2);

	/* 4. Finally, we update the number of records field of the
	original slot */

	page_dir_slot_set_n_owned(slot, page_zip, n_owned - (n_owned / 2));
}

/*****************************************************************
Tries to balance the given directory slot with too few records with the upper
neighbor, so that there are at least the minimum number of records owned by
the slot; this may result in the merging of two slots. */
UNIV_INTERN
void
page_dir_balance_slot(
/*==================*/
	page_t*		page,	/* in/out: index page */
	page_zip_des_t*	page_zip,/* in/out: compressed page, or NULL */
	ulint		slot_no)/* in: the directory slot */
{
	page_dir_slot_t*	slot;
	page_dir_slot_t*	up_slot;
	ulint			n_owned;
	ulint			up_n_owned;
	rec_t*			old_rec;
	rec_t*			new_rec;

	ut_ad(page);
	ut_ad(!page_zip || page_is_comp(page));
	ut_ad(slot_no > 0);

	slot = page_dir_get_nth_slot(page, slot_no);

	/* The last directory slot cannot be balanced with the upper
	neighbor, as there is none. */

	if (UNIV_UNLIKELY(slot_no == page_dir_get_n_slots(page) - 1)) {

		return;
	}

	up_slot = page_dir_get_nth_slot(page, slot_no + 1);

	n_owned = page_dir_slot_get_n_owned(slot);
	up_n_owned = page_dir_slot_get_n_owned(up_slot);

	ut_ad(n_owned == PAGE_DIR_SLOT_MIN_N_OWNED - 1);

	/* If the upper slot has the minimum value of n_owned, we will merge
	the two slots, therefore we assert: */
	ut_ad(2 * PAGE_DIR_SLOT_MIN_N_OWNED - 1 <= PAGE_DIR_SLOT_MAX_N_OWNED);

	if (up_n_owned > PAGE_DIR_SLOT_MIN_N_OWNED) {

		/* In this case we can just transfer one record owned
		by the upper slot to the property of the lower slot */
		old_rec = (rec_t*) page_dir_slot_get_rec(slot);

		if (page_is_comp(page)) {
			new_rec = rec_get_next_ptr(old_rec, TRUE);

			rec_set_n_owned_new(old_rec, page_zip, 0);
			rec_set_n_owned_new(new_rec, page_zip, n_owned + 1);
		} else {
			new_rec = rec_get_next_ptr(old_rec, FALSE);

			rec_set_n_owned_old(old_rec, 0);
			rec_set_n_owned_old(new_rec, n_owned + 1);
		}

		page_dir_slot_set_rec(slot, new_rec);

		page_dir_slot_set_n_owned(up_slot, page_zip, up_n_owned -1);
	} else {
		/* In this case we may merge the two slots */
		page_dir_delete_slot(page, page_zip, slot_no);
	}
}

/****************************************************************
Returns the middle record of the record list. If there are an even number
of records in the list, returns the first record of the upper half-list. */
UNIV_INTERN
rec_t*
page_get_middle_rec(
/*================*/
			/* out: middle record */
	page_t*	page)	/* in: page */
{
	page_dir_slot_t*	slot;
	ulint			middle;
	ulint			i;
	ulint			n_owned;
	ulint			count;
	rec_t*			rec;

	/* This many records we must leave behind */
	middle = (page_get_n_recs(page) + PAGE_HEAP_NO_USER_LOW) / 2;

	count = 0;

	for (i = 0;; i++) {

		slot = page_dir_get_nth_slot(page, i);
		n_owned = page_dir_slot_get_n_owned(slot);

		if (count + n_owned > middle) {
			break;
		} else {
			count += n_owned;
		}
	}

	ut_ad(i > 0);
	slot = page_dir_get_nth_slot(page, i - 1);
	rec = (rec_t*) page_dir_slot_get_rec(slot);
	rec = page_rec_get_next(rec);

	/* There are now count records behind rec */

	for (i = 0; i < middle - count; i++) {
		rec = page_rec_get_next(rec);
	}

	return(rec);
}

/*******************************************************************
Returns the number of records before the given record in chain.
The number includes infimum and supremum records. */
UNIV_INTERN
ulint
page_rec_get_n_recs_before(
/*=======================*/
				/* out: number of records */
	const rec_t*	rec)	/* in: the physical record */
{
	const page_dir_slot_t*	slot;
	const rec_t*		slot_rec;
	const page_t*		page;
	ulint			i;
	lint			n	= 0;

	ut_ad(page_rec_check(rec));

	page = page_align(rec);
	if (page_is_comp(page)) {
		while (rec_get_n_owned_new(rec) == 0) {

			rec = rec_get_next_ptr_const(rec, TRUE);
			n--;
		}

		for (i = 0; ; i++) {
			slot = page_dir_get_nth_slot(page, i);
			slot_rec = page_dir_slot_get_rec(slot);

			n += rec_get_n_owned_new(slot_rec);

			if (rec == slot_rec) {

				break;
			}
		}
	} else {
		while (rec_get_n_owned_old(rec) == 0) {

			rec = rec_get_next_ptr_const(rec, FALSE);
			n--;
		}

		for (i = 0; ; i++) {
			slot = page_dir_get_nth_slot(page, i);
			slot_rec = page_dir_slot_get_rec(slot);

			n += rec_get_n_owned_old(slot_rec);

			if (rec == slot_rec) {

				break;
			}
		}
	}

	n--;

	ut_ad(n >= 0);

	return((ulint) n);
}

/****************************************************************
Prints record contents including the data relevant only in
the index page context. */
UNIV_INTERN
void
page_rec_print(
/*===========*/
	const rec_t*	rec,	/* in: physical record */
	const ulint*	offsets)/* in: record descriptor */
{
	ut_a(!page_rec_is_comp(rec) == !rec_offs_comp(offsets));
	rec_print_new(stderr, rec, offsets);
	if (page_rec_is_comp(rec)) {
		fprintf(stderr,
			" n_owned: %lu; heap_no: %lu; next rec: %lu\n",
			(ulong) rec_get_n_owned_new(rec),
			(ulong) rec_get_heap_no_new(rec),
			(ulong) rec_get_next_offs(rec, TRUE));
	} else {
		fprintf(stderr,
			" n_owned: %lu; heap_no: %lu; next rec: %lu\n",
			(ulong) rec_get_n_owned_old(rec),
			(ulong) rec_get_heap_no_old(rec),
			(ulong) rec_get_next_offs(rec, TRUE));
	}

	page_rec_check(rec);
	rec_validate(rec, offsets);
}

/*******************************************************************
This is used to print the contents of the directory for
debugging purposes. */
UNIV_INTERN
void
page_dir_print(
/*===========*/
	page_t*	page,	/* in: index page */
	ulint	pr_n)	/* in: print n first and n last entries */
{
	ulint			n;
	ulint			i;
	page_dir_slot_t*	slot;

	n = page_dir_get_n_slots(page);

	fprintf(stderr, "--------------------------------\n"
		"PAGE DIRECTORY\n"
		"Page address %p\n"
		"Directory stack top at offs: %lu; number of slots: %lu\n",
		page, (ulong) page_offset(page_dir_get_nth_slot(page, n - 1)),
		(ulong) n);
	for (i = 0; i < n; i++) {
		slot = page_dir_get_nth_slot(page, i);
		if ((i == pr_n) && (i < n - pr_n)) {
			fputs("    ...   \n", stderr);
		}
		if ((i < pr_n) || (i >= n - pr_n)) {
			fprintf(stderr,
				"Contents of slot: %lu: n_owned: %lu,"
				" rec offs: %lu\n",
				(ulong) i,
				(ulong) page_dir_slot_get_n_owned(slot),
				(ulong)
				page_offset(page_dir_slot_get_rec(slot)));
		}
	}
	fprintf(stderr, "Total of %lu records\n"
		"--------------------------------\n",
		(ulong) (PAGE_HEAP_NO_USER_LOW + page_get_n_recs(page)));
}

/*******************************************************************
This is used to print the contents of the page record list for
debugging purposes. */
UNIV_INTERN
void
page_print_list(
/*============*/
	buf_block_t*	block,	/* in: index page */
	dict_index_t*	index,	/* in: dictionary index of the page */
	ulint		pr_n)	/* in: print n first and n last entries */
{
	page_t*		page		= block->frame;
	page_cur_t	cur;
	ulint		count;
	ulint		n_recs;
	mem_heap_t*	heap		= NULL;
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	rec_offs_init(offsets_);

	ut_a((ibool)!!page_is_comp(page) == dict_table_is_comp(index->table));

	fprintf(stderr,
		"--------------------------------\n"
		"PAGE RECORD LIST\n"
		"Page address %p\n", page);

	n_recs = page_get_n_recs(page);

	page_cur_set_before_first(block, &cur);
	count = 0;
	for (;;) {
		offsets = rec_get_offsets(cur.rec, index, offsets,
					  ULINT_UNDEFINED, &heap);
		page_rec_print(cur.rec, offsets);

		if (count == pr_n) {
			break;
		}
		if (page_cur_is_after_last(&cur)) {
			break;
		}
		page_cur_move_to_next(&cur);
		count++;
	}

	if (n_recs > 2 * pr_n) {
		fputs(" ... \n", stderr);
	}

	while (!page_cur_is_after_last(&cur)) {
		page_cur_move_to_next(&cur);

		if (count + pr_n >= n_recs) {
			offsets = rec_get_offsets(cur.rec, index, offsets,
						  ULINT_UNDEFINED, &heap);
			page_rec_print(cur.rec, offsets);
		}
		count++;
	}

	fprintf(stderr,
		"Total of %lu records \n"
		"--------------------------------\n",
		(ulong) (count + 1));

	if (UNIV_LIKELY_NULL(heap)) {
		mem_heap_free(heap);
	}
}

/*******************************************************************
Prints the info in a page header. */
UNIV_INTERN
void
page_header_print(
/*==============*/
	const page_t*	page)
{
	fprintf(stderr,
		"--------------------------------\n"
		"PAGE HEADER INFO\n"
		"Page address %p, n records %lu (%s)\n"
		"n dir slots %lu, heap top %lu\n"
		"Page n heap %lu, free %lu, garbage %lu\n"
		"Page last insert %lu, direction %lu, n direction %lu\n",
		page, (ulong) page_header_get_field(page, PAGE_N_RECS),
		page_is_comp(page) ? "compact format" : "original format",
		(ulong) page_header_get_field(page, PAGE_N_DIR_SLOTS),
		(ulong) page_header_get_field(page, PAGE_HEAP_TOP),
		(ulong) page_dir_get_n_heap(page),
		(ulong) page_header_get_field(page, PAGE_FREE),
		(ulong) page_header_get_field(page, PAGE_GARBAGE),
		(ulong) page_header_get_field(page, PAGE_LAST_INSERT),
		(ulong) page_header_get_field(page, PAGE_DIRECTION),
		(ulong) page_header_get_field(page, PAGE_N_DIRECTION));
}

/*******************************************************************
This is used to print the contents of the page for
debugging purposes. */
UNIV_INTERN
void
page_print(
/*=======*/
	buf_block_t*	block,	/* in: index page */
	dict_index_t*	index,	/* in: dictionary index of the page */
	ulint		dn,	/* in: print dn first and last entries
				in directory */
	ulint		rn)	/* in: print rn first and last records
				in directory */
{
	page_t*	page = block->frame;

	page_header_print(page);
	page_dir_print(page, dn);
	page_print_list(block, index, rn);
}

/*******************************************************************
The following is used to validate a record on a page. This function
differs from rec_validate as it can also check the n_owned field and
the heap_no field. */
UNIV_INTERN
ibool
page_rec_validate(
/*==============*/
				/* out: TRUE if ok */
	rec_t*		rec,	/* in: physical record */
	const ulint*	offsets)/* in: array returned by rec_get_offsets() */
{
	ulint	n_owned;
	ulint	heap_no;
	page_t*	page;

	page = page_align(rec);
	ut_a(!page_is_comp(page) == !rec_offs_comp(offsets));

	page_rec_check(rec);
	rec_validate(rec, offsets);

	if (page_rec_is_comp(rec)) {
		n_owned = rec_get_n_owned_new(rec);
		heap_no = rec_get_heap_no_new(rec);
	} else {
		n_owned = rec_get_n_owned_old(rec);
		heap_no = rec_get_heap_no_old(rec);
	}

	if (UNIV_UNLIKELY(!(n_owned <= PAGE_DIR_SLOT_MAX_N_OWNED))) {
		fprintf(stderr,
			"InnoDB: Dir slot of rec %lu, n owned too big %lu\n",
			(ulong) page_offset(rec), (ulong) n_owned);
		return(FALSE);
	}

	if (UNIV_UNLIKELY(!(heap_no < page_dir_get_n_heap(page)))) {
		fprintf(stderr,
			"InnoDB: Heap no of rec %lu too big %lu %lu\n",
			(ulong) page_offset(rec), (ulong) heap_no,
			(ulong) page_dir_get_n_heap(page));
		return(FALSE);
	}

	return(TRUE);
}

/*******************************************************************
Checks that the first directory slot points to the infimum record and
the last to the supremum. This function is intended to track if the
bug fixed in 4.0.14 has caused corruption to users' databases. */
UNIV_INTERN
void
page_check_dir(
/*===========*/
	const page_t*	page)	/* in: index page */
{
	ulint	n_slots;
	ulint	infimum_offs;
	ulint	supremum_offs;

	n_slots = page_dir_get_n_slots(page);
	infimum_offs = mach_read_from_2(page_dir_get_nth_slot(page, 0));
	supremum_offs = mach_read_from_2(page_dir_get_nth_slot(page,
							       n_slots - 1));

	if (UNIV_UNLIKELY(!page_rec_is_infimum_low(infimum_offs))) {

		fprintf(stderr,
			"InnoDB: Page directory corruption:"
			" infimum not pointed to\n");
		buf_page_print(page, 0);
	}

	if (UNIV_UNLIKELY(!page_rec_is_supremum_low(supremum_offs))) {

		fprintf(stderr,
			"InnoDB: Page directory corruption:"
			" supremum not pointed to\n");
		buf_page_print(page, 0);
	}
}

/*******************************************************************
This function checks the consistency of an index page when we do not
know the index. This is also resilient so that this should never crash
even if the page is total garbage. */
UNIV_INTERN
ibool
page_simple_validate_old(
/*=====================*/
			/* out: TRUE if ok */
	page_t*	page)	/* in: old-style index page */
{
	page_dir_slot_t* slot;
	ulint		slot_no;
	ulint		n_slots;
	rec_t*		rec;
	byte*		rec_heap_top;
	ulint		count;
	ulint		own_count;
	ibool		ret	= FALSE;

	ut_a(!page_is_comp(page));

	/* Check first that the record heap and the directory do not
	overlap. */

	n_slots = page_dir_get_n_slots(page);

	if (UNIV_UNLIKELY(n_slots > UNIV_PAGE_SIZE / 4)) {
		fprintf(stderr,
			"InnoDB: Nonsensical number %lu of page dir slots\n",
			(ulong) n_slots);

		goto func_exit;
	}

	rec_heap_top = page_header_get_ptr(page, PAGE_HEAP_TOP);

	if (UNIV_UNLIKELY(rec_heap_top
			  > page_dir_get_nth_slot(page, n_slots - 1))) {

		fprintf(stderr,
			"InnoDB: Record heap and dir overlap on a page,"
			" heap top %lu, dir %lu\n",
			(ulong) page_header_get_field(page, PAGE_HEAP_TOP),
			(ulong)
			page_offset(page_dir_get_nth_slot(page, n_slots - 1)));

		goto func_exit;
	}

	/* Validate the record list in a loop checking also that it is
	consistent with the page record directory. */

	count = 0;
	own_count = 1;
	slot_no = 0;
	slot = page_dir_get_nth_slot(page, slot_no);

	rec = page_get_infimum_rec(page);

	for (;;) {
		if (UNIV_UNLIKELY(rec > rec_heap_top)) {
			fprintf(stderr,
				"InnoDB: Record %lu is above"
				" rec heap top %lu\n",
				(ulong)(rec - page),
				(ulong)(rec_heap_top - page));

			goto func_exit;
		}

		if (UNIV_UNLIKELY(rec_get_n_owned_old(rec))) {
			/* This is a record pointed to by a dir slot */
			if (UNIV_UNLIKELY(rec_get_n_owned_old(rec)
					  != own_count)) {

				fprintf(stderr,
					"InnoDB: Wrong owned count %lu, %lu,"
					" rec %lu\n",
					(ulong) rec_get_n_owned_old(rec),
					(ulong) own_count,
					(ulong)(rec - page));

				goto func_exit;
			}

			if (UNIV_UNLIKELY
			    (page_dir_slot_get_rec(slot) != rec)) {
				fprintf(stderr,
					"InnoDB: Dir slot does not point"
					" to right rec %lu\n",
					(ulong)(rec - page));

				goto func_exit;
			}

			own_count = 0;

			if (!page_rec_is_supremum(rec)) {
				slot_no++;
				slot = page_dir_get_nth_slot(page, slot_no);
			}
		}

		if (page_rec_is_supremum(rec)) {

			break;
		}

		if (UNIV_UNLIKELY
		    (rec_get_next_offs(rec, FALSE) < FIL_PAGE_DATA
		     || rec_get_next_offs(rec, FALSE) >= UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Next record offset"
				" nonsensical %lu for rec %lu\n",
				(ulong) rec_get_next_offs(rec, FALSE),
				(ulong) (rec - page));

			goto func_exit;
		}

		count++;

		if (UNIV_UNLIKELY(count > UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Page record list appears"
				" to be circular %lu\n",
				(ulong) count);
			goto func_exit;
		}

		rec = page_rec_get_next(rec);
		own_count++;
	}

	if (UNIV_UNLIKELY(rec_get_n_owned_old(rec) == 0)) {
		fprintf(stderr, "InnoDB: n owned is zero in a supremum rec\n");

		goto func_exit;
	}

	if (UNIV_UNLIKELY(slot_no != n_slots - 1)) {
		fprintf(stderr, "InnoDB: n slots wrong %lu, %lu\n",
			(ulong) slot_no, (ulong) (n_slots - 1));
		goto func_exit;
	}

	if (UNIV_UNLIKELY(page_header_get_field(page, PAGE_N_RECS)
			  + PAGE_HEAP_NO_USER_LOW
			  != count + 1)) {
		fprintf(stderr, "InnoDB: n recs wrong %lu %lu\n",
			(ulong) page_header_get_field(page, PAGE_N_RECS)
			+ PAGE_HEAP_NO_USER_LOW,
			(ulong) (count + 1));

		goto func_exit;
	}

	/* Check then the free list */
	rec = page_header_get_ptr(page, PAGE_FREE);

	while (rec != NULL) {
		if (UNIV_UNLIKELY(rec < page + FIL_PAGE_DATA
				  || rec >= page + UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Free list record has"
				" a nonsensical offset %lu\n",
				(ulong) (rec - page));

			goto func_exit;
		}

		if (UNIV_UNLIKELY(rec > rec_heap_top)) {
			fprintf(stderr,
				"InnoDB: Free list record %lu"
				" is above rec heap top %lu\n",
				(ulong) (rec - page),
				(ulong) (rec_heap_top - page));

			goto func_exit;
		}

		count++;

		if (UNIV_UNLIKELY(count > UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Page free list appears"
				" to be circular %lu\n",
				(ulong) count);
			goto func_exit;
		}

		rec = page_rec_get_next(rec);
	}

	if (UNIV_UNLIKELY(page_dir_get_n_heap(page) != count + 1)) {

		fprintf(stderr, "InnoDB: N heap is wrong %lu, %lu\n",
			(ulong) page_dir_get_n_heap(page),
			(ulong) (count + 1));

		goto func_exit;
	}

	ret = TRUE;

func_exit:
	return(ret);
}

/*******************************************************************
This function checks the consistency of an index page when we do not
know the index. This is also resilient so that this should never crash
even if the page is total garbage. */
UNIV_INTERN
ibool
page_simple_validate_new(
/*=====================*/
			/* out: TRUE if ok */
	page_t*	page)	/* in: new-style index page */
{
	page_dir_slot_t* slot;
	ulint		slot_no;
	ulint		n_slots;
	rec_t*		rec;
	byte*		rec_heap_top;
	ulint		count;
	ulint		own_count;
	ibool		ret	= FALSE;

	ut_a(page_is_comp(page));

	/* Check first that the record heap and the directory do not
	overlap. */

	n_slots = page_dir_get_n_slots(page);

	if (UNIV_UNLIKELY(n_slots > UNIV_PAGE_SIZE / 4)) {
		fprintf(stderr,
			"InnoDB: Nonsensical number %lu"
			" of page dir slots\n", (ulong) n_slots);

		goto func_exit;
	}

	rec_heap_top = page_header_get_ptr(page, PAGE_HEAP_TOP);

	if (UNIV_UNLIKELY(rec_heap_top
			  > page_dir_get_nth_slot(page, n_slots - 1))) {

		fprintf(stderr,
			"InnoDB: Record heap and dir overlap on a page,"
			" heap top %lu, dir %lu\n",
			(ulong) page_header_get_field(page, PAGE_HEAP_TOP),
			(ulong)
			page_offset(page_dir_get_nth_slot(page, n_slots - 1)));

		goto func_exit;
	}

	/* Validate the record list in a loop checking also that it is
	consistent with the page record directory. */

	count = 0;
	own_count = 1;
	slot_no = 0;
	slot = page_dir_get_nth_slot(page, slot_no);

	rec = page_get_infimum_rec(page);

	for (;;) {
		if (UNIV_UNLIKELY(rec > rec_heap_top)) {
			fprintf(stderr,
				"InnoDB: Record %lu is above rec"
				" heap top %lu\n",
				(ulong) page_offset(rec),
				(ulong) page_offset(rec_heap_top));

			goto func_exit;
		}

		if (UNIV_UNLIKELY(rec_get_n_owned_new(rec))) {
			/* This is a record pointed to by a dir slot */
			if (UNIV_UNLIKELY(rec_get_n_owned_new(rec)
					  != own_count)) {

				fprintf(stderr,
					"InnoDB: Wrong owned count %lu, %lu,"
					" rec %lu\n",
					(ulong) rec_get_n_owned_new(rec),
					(ulong) own_count,
					(ulong) page_offset(rec));

				goto func_exit;
			}

			if (UNIV_UNLIKELY
			    (page_dir_slot_get_rec(slot) != rec)) {
				fprintf(stderr,
					"InnoDB: Dir slot does not point"
					" to right rec %lu\n",
					(ulong) page_offset(rec));

				goto func_exit;
			}

			own_count = 0;

			if (!page_rec_is_supremum(rec)) {
				slot_no++;
				slot = page_dir_get_nth_slot(page, slot_no);
			}
		}

		if (page_rec_is_supremum(rec)) {

			break;
		}

		if (UNIV_UNLIKELY
		    (rec_get_next_offs(rec, TRUE) < FIL_PAGE_DATA
		     || rec_get_next_offs(rec, TRUE) >= UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Next record offset nonsensical %lu"
				" for rec %lu\n",
				(ulong) rec_get_next_offs(rec, TRUE),
				(ulong) page_offset(rec));

			goto func_exit;
		}

		count++;

		if (UNIV_UNLIKELY(count > UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Page record list appears"
				" to be circular %lu\n",
				(ulong) count);
			goto func_exit;
		}

		rec = page_rec_get_next(rec);
		own_count++;
	}

	if (UNIV_UNLIKELY(rec_get_n_owned_new(rec) == 0)) {
		fprintf(stderr, "InnoDB: n owned is zero"
			" in a supremum rec\n");

		goto func_exit;
	}

	if (UNIV_UNLIKELY(slot_no != n_slots - 1)) {
		fprintf(stderr, "InnoDB: n slots wrong %lu, %lu\n",
			(ulong) slot_no, (ulong) (n_slots - 1));
		goto func_exit;
	}

	if (UNIV_UNLIKELY(page_header_get_field(page, PAGE_N_RECS)
			  + PAGE_HEAP_NO_USER_LOW
			  != count + 1)) {
		fprintf(stderr, "InnoDB: n recs wrong %lu %lu\n",
			(ulong) page_header_get_field(page, PAGE_N_RECS)
			+ PAGE_HEAP_NO_USER_LOW,
			(ulong) (count + 1));

		goto func_exit;
	}

	/* Check then the free list */
	rec = page_header_get_ptr(page, PAGE_FREE);

	while (rec != NULL) {
		if (UNIV_UNLIKELY(rec < page + FIL_PAGE_DATA
				  || rec >= page + UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Free list record has"
				" a nonsensical offset %lu\n",
				(ulong) page_offset(rec));

			goto func_exit;
		}

		if (UNIV_UNLIKELY(rec > rec_heap_top)) {
			fprintf(stderr,
				"InnoDB: Free list record %lu"
				" is above rec heap top %lu\n",
				(ulong) page_offset(rec),
				(ulong) page_offset(rec_heap_top));

			goto func_exit;
		}

		count++;

		if (UNIV_UNLIKELY(count > UNIV_PAGE_SIZE)) {
			fprintf(stderr,
				"InnoDB: Page free list appears"
				" to be circular %lu\n",
				(ulong) count);
			goto func_exit;
		}

		rec = page_rec_get_next(rec);
	}

	if (UNIV_UNLIKELY(page_dir_get_n_heap(page) != count + 1)) {

		fprintf(stderr, "InnoDB: N heap is wrong %lu, %lu\n",
			(ulong) page_dir_get_n_heap(page),
			(ulong) (count + 1));

		goto func_exit;
	}

	ret = TRUE;

func_exit:
	return(ret);
}

/*******************************************************************
This function checks the consistency of an index page. */
UNIV_INTERN
ibool
page_validate(
/*==========*/
				/* out: TRUE if ok */
	page_t*		page,	/* in: index page */
	dict_index_t*	index)	/* in: data dictionary index containing
				the page record type definition */
{
	page_dir_slot_t*slot;
	mem_heap_t*	heap;
	byte*		buf;
	ulint		count;
	ulint		own_count;
	ulint		rec_own_count;
	ulint		slot_no;
	ulint		data_size;
	rec_t*		rec;
	rec_t*		old_rec		= NULL;
	ulint		offs;
	ulint		n_slots;
	ibool		ret		= FALSE;
	ulint		i;
	ulint*		offsets		= NULL;
	ulint*		old_offsets	= NULL;

	if (UNIV_UNLIKELY((ibool) !!page_is_comp(page)
			  != dict_table_is_comp(index->table))) {
		fputs("InnoDB: 'compact format' flag mismatch\n", stderr);
		goto func_exit2;
	}
	if (page_is_comp(page)) {
		if (UNIV_UNLIKELY(!page_simple_validate_new(page))) {
			goto func_exit2;
		}
	} else {
		if (UNIV_UNLIKELY(!page_simple_validate_old(page))) {
			goto func_exit2;
		}
	}

	heap = mem_heap_create(UNIV_PAGE_SIZE + 200);

	/* The following buffer is used to check that the
	records in the page record heap do not overlap */

	buf = mem_heap_zalloc(heap, UNIV_PAGE_SIZE);

	/* Check first that the record heap and the directory do not
	overlap. */

	n_slots = page_dir_get_n_slots(page);

	if (UNIV_UNLIKELY(!(page_header_get_ptr(page, PAGE_HEAP_TOP)
			    <= page_dir_get_nth_slot(page, n_slots - 1)))) {

		fputs("InnoDB: Record heap and dir overlap on a page ",
		      stderr);
		dict_index_name_print(stderr, NULL, index);
		fprintf(stderr, ", %p, %p\n",
			page_header_get_ptr(page, PAGE_HEAP_TOP),
			page_dir_get_nth_slot(page, n_slots - 1));

		goto func_exit;
	}

	/* Validate the record list in a loop checking also that
	it is consistent with the directory. */
	count = 0;
	data_size = 0;
	own_count = 1;
	slot_no = 0;
	slot = page_dir_get_nth_slot(page, slot_no);

	rec = page_get_infimum_rec(page);

	for (;;) {
		offsets = rec_get_offsets(rec, index, offsets,
					  ULINT_UNDEFINED, &heap);

		if (page_is_comp(page) && page_rec_is_user_rec(rec)
		    && UNIV_UNLIKELY(rec_get_node_ptr_flag(rec)
				     == page_is_leaf(page))) {
			fputs("InnoDB: node_ptr flag mismatch\n", stderr);
			goto func_exit;
		}

		if (UNIV_UNLIKELY(!page_rec_validate(rec, offsets))) {
			goto func_exit;
		}

		/* Check that the records are in the ascending order */
		if (UNIV_LIKELY(count >= PAGE_HEAP_NO_USER_LOW)
		    && !page_rec_is_supremum(rec)) {
			if (UNIV_UNLIKELY
			    (1 != cmp_rec_rec(rec, old_rec,
					      offsets, old_offsets, index))) {
				fprintf(stderr,
					"InnoDB: Records in wrong order"
					" on page %lu ",
					(ulong) page_get_page_no(page));
				dict_index_name_print(stderr, NULL, index);
				fputs("\nInnoDB: previous record ", stderr);
				rec_print_new(stderr, old_rec, old_offsets);
				fputs("\nInnoDB: record ", stderr);
				rec_print_new(stderr, rec, offsets);
				putc('\n', stderr);

				goto func_exit;
			}
		}

		if (page_rec_is_user_rec(rec)) {

			data_size += rec_offs_size(offsets);
		}

		offs = page_offset(rec_get_start(rec, offsets));

		for (i = rec_offs_size(offsets); i--; ) {
			if (UNIV_UNLIKELY(buf[offs + i])) {
				/* No other record may overlap this */

				fputs("InnoDB: Record overlaps another\n",
				      stderr);
				goto func_exit;
			}

			buf[offs + i] = 1;
		}

		if (page_is_comp(page)) {
			rec_own_count = rec_get_n_owned_new(rec);
		} else {
			rec_own_count = rec_get_n_owned_old(rec);
		}

		if (UNIV_UNLIKELY(rec_own_count)) {
			/* This is a record pointed to by a dir slot */
			if (UNIV_UNLIKELY(rec_own_count != own_count)) {
				fprintf(stderr,
					"InnoDB: Wrong owned count %lu, %lu\n",
					(ulong) rec_own_count,
					(ulong) own_count);
				goto func_exit;
			}

			if (page_dir_slot_get_rec(slot) != rec) {
				fputs("InnoDB: Dir slot does not"
				      " point to right rec\n",
				      stderr);
				goto func_exit;
			}

			page_dir_slot_check(slot);

			own_count = 0;
			if (!page_rec_is_supremum(rec)) {
				slot_no++;
				slot = page_dir_get_nth_slot(page, slot_no);
			}
		}

		if (page_rec_is_supremum(rec)) {
			break;
		}

		count++;
		own_count++;
		old_rec = rec;
		rec = page_rec_get_next(rec);

		/* set old_offsets to offsets; recycle offsets */
		{
			ulint* offs = old_offsets;
			old_offsets = offsets;
			offsets = offs;
		}
	}

	if (page_is_comp(page)) {
		if (UNIV_UNLIKELY(rec_get_n_owned_new(rec) == 0)) {

			goto n_owned_zero;
		}
	} else if (UNIV_UNLIKELY(rec_get_n_owned_old(rec) == 0)) {
n_owned_zero:
		fputs("InnoDB: n owned is zero\n", stderr);
		goto func_exit;
	}

	if (UNIV_UNLIKELY(slot_no != n_slots - 1)) {
		fprintf(stderr, "InnoDB: n slots wrong %lu %lu\n",
			(ulong) slot_no, (ulong) (n_slots - 1));
		goto func_exit;
	}

	if (UNIV_UNLIKELY(page_header_get_field(page, PAGE_N_RECS)
			  + PAGE_HEAP_NO_USER_LOW
			  != count + 1)) {
		fprintf(stderr, "InnoDB: n recs wrong %lu %lu\n",
			(ulong) page_header_get_field(page, PAGE_N_RECS)
			+ PAGE_HEAP_NO_USER_LOW,
			(ulong) (count + 1));
		goto func_exit;
	}

	if (UNIV_UNLIKELY(data_size != page_get_data_size(page))) {
		fprintf(stderr,
			"InnoDB: Summed data size %lu, returned by func %lu\n",
			(ulong) data_size, (ulong) page_get_data_size(page));
		goto func_exit;
	}

	/* Check then the free list */
	rec = page_header_get_ptr(page, PAGE_FREE);

	while (rec != NULL) {
		offsets = rec_get_offsets(rec, index, offsets,
					  ULINT_UNDEFINED, &heap);
		if (UNIV_UNLIKELY(!page_rec_validate(rec, offsets))) {

			goto func_exit;
		}

		count++;
		offs = page_offset(rec_get_start(rec, offsets));

		for (i = rec_offs_size(offsets); i--; ) {

			if (UNIV_UNLIKELY(buf[offs + i])) {
				fputs("InnoDB: Record overlaps another"
				      " in free list\n", stderr);
				goto func_exit;
			}

			buf[offs + i] = 1;
		}

		rec = page_rec_get_next(rec);
	}

	if (UNIV_UNLIKELY(page_dir_get_n_heap(page) != count + 1)) {
		fprintf(stderr, "InnoDB: N heap is wrong %lu %lu\n",
			(ulong) page_dir_get_n_heap(page),
			(ulong) count + 1);
		goto func_exit;
	}

	ret = TRUE;

func_exit:
	mem_heap_free(heap);

	if (UNIV_UNLIKELY(ret == FALSE)) {
func_exit2:
		fprintf(stderr, "InnoDB: Apparent corruption in page %lu in ",
			(ulong) page_get_page_no(page));
		dict_index_name_print(stderr, NULL, index);
		putc('\n', stderr);
		buf_page_print(page, 0);
	}

	return(ret);
}

/*******************************************************************
Looks in the page record list for a record with the given heap number. */
UNIV_INTERN
const rec_t*
page_find_rec_with_heap_no(
/*=======================*/
				/* out: record, NULL if not found */
	const page_t*	page,	/* in: index page */
	ulint		heap_no)/* in: heap number */
{
	const rec_t*	rec;

	if (page_is_comp(page)) {
		rec = page + PAGE_NEW_INFIMUM;

		for(;;) {
			ulint	rec_heap_no = rec_get_heap_no_new(rec);

			if (rec_heap_no == heap_no) {

				return(rec);
			} else if (rec_heap_no == PAGE_HEAP_NO_SUPREMUM) {

				return(NULL);
			}

			rec = page + rec_get_next_offs(rec, TRUE);
		}
	} else {
		rec = page + PAGE_OLD_INFIMUM;

		for (;;) {
			ulint	rec_heap_no = rec_get_heap_no_old(rec);

			if (rec_heap_no == heap_no) {

				return(rec);
			} else if (rec_heap_no == PAGE_HEAP_NO_SUPREMUM) {

				return(NULL);
			}

			rec = page + rec_get_next_offs(rec, FALSE);
		}
	}
}