/*****************************************************************************

Copyright (c) 1994, 2016, Oracle and/or its affiliates. All Rights Reserved.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is also distributed with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have included with MySQL.

This program 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, version 2.0, for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA

*****************************************************************************/

/********************************************************************//**
@file rem/rem0rec.cc
Record manager

Created 5/30/1994 Heikki Tuuri
*************************************************************************/

#include "rem0rec.h"

#ifdef UNIV_NONINL
#include "rem0rec.ic"
#endif

#include "page0page.h"
#include "mtr0mtr.h"
#include "mtr0log.h"
#include "fts0fts.h"

/*			PHYSICAL RECORD (OLD STYLE)
			===========================

The physical record, which is the data type of all the records
found in index pages of the database, has the following format
(lower addresses and more significant bits inside a byte are below
represented on a higher text line):

| offset of the end of the last field of data, the most significant
  bit is set to 1 if and only if the field is SQL-null,
  if the offset is 2-byte, then the second most significant
  bit is set to 1 if the field is stored on another page:
  mostly this will occur in the case of big BLOB fields |
...
| offset of the end of the first field of data + the SQL-null bit |
| 4 bits used to delete mark a record, and mark a predefined
  minimum record in alphabetical order |
| 4 bits giving the number of records owned by this record
  (this term is explained in page0page.h) |
| 13 bits giving the order number of this record in the
  heap of the index page |
| 10 bits giving the number of fields in this record |
| 1 bit which is set to 1 if the offsets above are given in
  one byte format, 0 if in two byte format |
| two bytes giving an absolute pointer to the next record in the page |
ORIGIN of the record
| first field of data |
...
| last field of data |

The origin of the record is the start address of the first field
of data. The offsets are given relative to the origin.
The offsets of the data fields are stored in an inverted
order because then the offset of the first fields are near the
origin, giving maybe a better processor cache hit rate in searches.

The offsets of the data fields are given as one-byte
(if there are less than 127 bytes of data in the record)
or two-byte unsigned integers. The most significant bit
is not part of the offset, instead it indicates the SQL-null
if the bit is set to 1. */

/*			PHYSICAL RECORD (NEW STYLE)
			===========================

The physical record, which is the data type of all the records
found in index pages of the database, has the following format
(lower addresses and more significant bits inside a byte are below
represented on a higher text line):

| length of the last non-null variable-length field of data:
  if the maximum length is 255, one byte; otherwise,
  0xxxxxxx (one byte, length=0..127), or 1exxxxxxxxxxxxxx (two bytes,
  length=128..16383, extern storage flag) |
...
| length of first variable-length field of data |
| SQL-null flags (1 bit per nullable field), padded to full bytes |
| 4 bits used to delete mark a record, and mark a predefined
  minimum record in alphabetical order |
| 4 bits giving the number of records owned by this record
  (this term is explained in page0page.h) |
| 13 bits giving the order number of this record in the
  heap of the index page |
| 3 bits record type: 000=conventional, 001=node pointer (inside B-tree),
  010=infimum, 011=supremum, 1xx=reserved |
| two bytes giving a relative pointer to the next record in the page |
ORIGIN of the record
| first field of data |
...
| last field of data |

The origin of the record is the start address of the first field
of data. The offsets are given relative to the origin.
The offsets of the data fields are stored in an inverted
order because then the offset of the first fields are near the
origin, giving maybe a better processor cache hit rate in searches.

The offsets of the data fields are given as one-byte
(if there are less than 127 bytes of data in the record)
or two-byte unsigned integers. The most significant bit
is not part of the offset, instead it indicates the SQL-null
if the bit is set to 1. */

/* CANONICAL COORDINATES. A record can be seen as a single
string of 'characters' in the following way: catenate the bytes
in each field, in the order of fields. An SQL-null field
is taken to be an empty sequence of bytes. Then after
the position of each field insert in the string
the 'character' <FIELD-END>, except that after an SQL-null field
insert <NULL-FIELD-END>. Now the ordinal position of each
byte in this canonical string is its canonical coordinate.
So, for the record ("AA", SQL-NULL, "BB", ""), the canonical
string is "AA<FIELD_END><NULL-FIELD-END>BB<FIELD-END><FIELD-END>".
We identify prefixes (= initial segments) of a record
with prefixes of the canonical string. The canonical
length of the prefix is the length of the corresponding
prefix of the canonical string. The canonical length of
a record is the length of its canonical string.

For example, the maximal common prefix of records
("AA", SQL-NULL, "BB", "C") and ("AA", SQL-NULL, "B", "C")
is "AA<FIELD-END><NULL-FIELD-END>B", and its canonical
length is 5.

A complete-field prefix of a record is a prefix which ends at the
end of some field (containing also <FIELD-END>).
A record is a complete-field prefix of another record, if
the corresponding canonical strings have the same property. */

/* this is used to fool compiler in rec_validate */
UNIV_INTERN ulint	rec_dummy;

/***************************************************************//**
Validates the consistency of an old-style physical record.
@return	TRUE if ok */
static
ibool
rec_validate_old(
/*=============*/
	const rec_t*	rec);	/*!< in: physical record */

/******************************************************//**
Determine how many of the first n columns in a compact
physical record are stored externally.
@return	number of externally stored columns */
UNIV_INTERN
ulint
rec_get_n_extern_new(
/*=================*/
	const rec_t*		rec,	/*!< in: compact physical record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint			n)	/*!< in: number of columns to scan */
{
	const byte*	nulls;
	const byte*	lens;
	ulint		null_mask;
	ulint		n_extern;
	ulint		i;

	ut_ad(dict_table_is_comp(index->table));
	ut_ad(rec_get_status(rec) == REC_STATUS_ORDINARY);
	ut_ad(n == ULINT_UNDEFINED || n <= dict_index_get_n_fields(index));

	if (n == ULINT_UNDEFINED) {
		n = dict_index_get_n_fields(index);
	}

	nulls = rec - (REC_N_NEW_EXTRA_BYTES + 1);
	lens = nulls - UT_BITS_IN_BYTES(index->n_nullable);
	null_mask = 1;
	n_extern = 0;
	i = 0;

	/* read the lengths of fields 0..n */
	do {
		const dict_field_t*	field
			= dict_index_get_nth_field(index, i);
		const dict_col_t*	col
			= dict_field_get_col(field);
		ulint			len;

		if (!(col->prtype & DATA_NOT_NULL)) {
			/* nullable field => read the null flag */

			if (UNIV_UNLIKELY(!(byte) null_mask)) {
				nulls--;
				null_mask = 1;
			}

			if (*nulls & null_mask) {
				null_mask <<= 1;
				/* No length is stored for NULL fields. */
				continue;
			}
			null_mask <<= 1;
		}

		if (UNIV_UNLIKELY(!field->fixed_len)) {
			/* Variable-length field: read the length */
			len = *lens--;
			/* If the maximum length of the field is up
			to 255 bytes, the actual length is always
			stored in one byte. If the maximum length is
			more than 255 bytes, the actual length is
			stored in one byte for 0..127.  The length
			will be encoded in two bytes when it is 128 or
			more, or when the field is stored externally. */
			if (UNIV_UNLIKELY(col->len > 255)
			    || UNIV_UNLIKELY(col->mtype == DATA_BLOB)) {
				if (len & 0x80) {
					/* 1exxxxxxx xxxxxxxx */
					if (len & 0x40) {
						n_extern++;
					}
					lens--;
				}
			}
		}
	} while (++i < n);

	return(n_extern);
}

/******************************************************//**
Determine the offset to each field in a leaf-page record
in ROW_FORMAT=COMPACT.  This is a special case of
rec_init_offsets() and rec_get_offsets_func(). */
UNIV_INLINE MY_ATTRIBUTE((nonnull))
void
rec_init_offsets_comp_ordinary(
/*===========================*/
	const rec_t*		rec,	/*!< in: physical record in
					ROW_FORMAT=COMPACT */
	bool			temp,	/*!< in: whether to use the
					format for temporary files in
					index creation */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint*			offsets)/*!< in/out: array of offsets;
					in: n=rec_offs_n_fields(offsets) */
{
	ulint		i		= 0;
	ulint		offs		= 0;
	ulint		any_ext		= 0;
	ulint		n_null		= index->n_nullable;
	const byte*	nulls		= temp
		? rec - 1
		: rec - (1 + REC_N_NEW_EXTRA_BYTES);
	const byte*	lens		= nulls - UT_BITS_IN_BYTES(n_null);
	ulint		null_mask	= 1;

#ifdef UNIV_DEBUG
	/* We cannot invoke rec_offs_make_valid() here if temp=true.
	Similarly, rec_offs_validate() will fail in that case, because
	it invokes rec_get_status(). */
	offsets[2] = (ulint) rec;
	offsets[3] = (ulint) index;
#endif /* UNIV_DEBUG */

	ut_ad(temp || dict_table_is_comp(index->table));

	if (temp && dict_table_is_comp(index->table)) {
		/* No need to do adjust fixed_len=0. We only need to
		adjust it for ROW_FORMAT=REDUNDANT. */
		temp = false;
	}

	/* read the lengths of fields 0..n */
	do {
		const dict_field_t*	field
			= dict_index_get_nth_field(index, i);
		const dict_col_t*	col
			= dict_field_get_col(field);
		ulint			len;

		if (!(col->prtype & DATA_NOT_NULL)) {
			/* nullable field => read the null flag */
			ut_ad(n_null--);

			if (UNIV_UNLIKELY(!(byte) null_mask)) {
				nulls--;
				null_mask = 1;
			}

			if (*nulls & null_mask) {
				null_mask <<= 1;
				/* No length is stored for NULL fields.
				We do not advance offs, and we set
				the length to zero and enable the
				SQL NULL flag in offsets[]. */
				len = offs | REC_OFFS_SQL_NULL;
				goto resolved;
			}
			null_mask <<= 1;
		}

		if (!field->fixed_len
		    || (temp && !dict_col_get_fixed_size(col, temp))) {
			/* Variable-length field: read the length */
			len = *lens--;
			/* If the maximum length of the field is up
			to 255 bytes, the actual length is always
			stored in one byte. If the maximum length is
			more than 255 bytes, the actual length is
			stored in one byte for 0..127.  The length
			will be encoded in two bytes when it is 128 or
			more, or when the field is stored externally. */
			if (UNIV_UNLIKELY(col->len > 255)
			    || UNIV_UNLIKELY(col->mtype
					     == DATA_BLOB)) {
				if (len & 0x80) {
					/* 1exxxxxxx xxxxxxxx */
					len <<= 8;
					len |= *lens--;

					offs += len & 0x3fff;
					if (UNIV_UNLIKELY(len
							  & 0x4000)) {
						ut_ad(dict_index_is_clust
						      (index));
						any_ext = REC_OFFS_EXTERNAL;
						len = offs
							| REC_OFFS_EXTERNAL;
					} else {
						len = offs;
					}

					goto resolved;
				}
			}

			len = offs += len;
		} else {
			len = offs += field->fixed_len;
		}
resolved:
		rec_offs_base(offsets)[i + 1] = len;
	} while (++i < rec_offs_n_fields(offsets));

	*rec_offs_base(offsets)
		= (rec - (lens + 1)) | REC_OFFS_COMPACT | any_ext;
}

/******************************************************//**
The following function determines the offsets to each field in the
record.	 The offsets are written to a previously allocated array of
ulint, where rec_offs_n_fields(offsets) has been initialized to the
number of fields in the record.	 The rest of the array will be
initialized by this function.  rec_offs_base(offsets)[0] will be set
to the extra size (if REC_OFFS_COMPACT is set, the record is in the
new format; if REC_OFFS_EXTERNAL is set, the record contains externally
stored columns), and rec_offs_base(offsets)[1..n_fields] will be set to
offsets past the end of fields 0..n_fields, or to the beginning of
fields 1..n_fields+1.  When the high-order bit of the offset at [i+1]
is set (REC_OFFS_SQL_NULL), the field i is NULL.  When the second
high-order bit of the offset at [i+1] is set (REC_OFFS_EXTERNAL), the
field i is being stored externally. */
static
void
rec_init_offsets(
/*=============*/
	const rec_t*		rec,	/*!< in: physical record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint*			offsets)/*!< in/out: array of offsets;
					in: n=rec_offs_n_fields(offsets) */
{
	ulint	i	= 0;
	ulint	offs;

	rec_offs_make_valid(rec, index, offsets);

	if (dict_table_is_comp(index->table)) {
		const byte*	nulls;
		const byte*	lens;
		dict_field_t*	field;
		ulint		null_mask;
		ulint		status = rec_get_status(rec);
		ulint		n_node_ptr_field = ULINT_UNDEFINED;

		switch (UNIV_EXPECT(status, REC_STATUS_ORDINARY)) {
		case REC_STATUS_INFIMUM:
		case REC_STATUS_SUPREMUM:
			/* the field is 8 bytes long */
			rec_offs_base(offsets)[0]
				= REC_N_NEW_EXTRA_BYTES | REC_OFFS_COMPACT;
			rec_offs_base(offsets)[1] = 8;
			return;
		case REC_STATUS_NODE_PTR:
			n_node_ptr_field
				= dict_index_get_n_unique_in_tree(index);
			break;
		case REC_STATUS_ORDINARY:
			rec_init_offsets_comp_ordinary(
				rec, false, index, offsets);
			return;
		}

		nulls = rec - (REC_N_NEW_EXTRA_BYTES + 1);
		lens = nulls - UT_BITS_IN_BYTES(index->n_nullable);
		offs = 0;
		null_mask = 1;

		/* read the lengths of fields 0..n */
		do {
			ulint	len;
			if (UNIV_UNLIKELY(i == n_node_ptr_field)) {
				len = offs += REC_NODE_PTR_SIZE;
				goto resolved;
			}

			field = dict_index_get_nth_field(index, i);
			if (!(dict_field_get_col(field)->prtype
			      & DATA_NOT_NULL)) {
				/* nullable field => read the null flag */

				if (UNIV_UNLIKELY(!(byte) null_mask)) {
					nulls--;
					null_mask = 1;
				}

				if (*nulls & null_mask) {
					null_mask <<= 1;
					/* No length is stored for NULL fields.
					We do not advance offs, and we set
					the length to zero and enable the
					SQL NULL flag in offsets[]. */
					len = offs | REC_OFFS_SQL_NULL;
					goto resolved;
				}
				null_mask <<= 1;
			}

			if (UNIV_UNLIKELY(!field->fixed_len)) {
				/* Variable-length field: read the length */
				const dict_col_t*	col
					= dict_field_get_col(field);
				len = *lens--;
				/* If the maximum length of the field
				is up to 255 bytes, the actual length
				is always stored in one byte. If the
				maximum length is more than 255 bytes,
				the actual length is stored in one
				byte for 0..127.  The length will be
				encoded in two bytes when it is 128 or
				more, or when the field is stored
				externally. */
				if (UNIV_UNLIKELY(col->len > 255)
				    || UNIV_UNLIKELY(col->mtype
						     == DATA_BLOB)) {
					if (len & 0x80) {
						/* 1exxxxxxx xxxxxxxx */

						len <<= 8;
						len |= *lens--;

						/* B-tree node pointers
						must not contain externally
						stored columns.  Thus
						the "e" flag must be 0. */
						ut_a(!(len & 0x4000));
						offs += len & 0x3fff;
						len = offs;

						goto resolved;
					}
				}

				len = offs += len;
			} else {
				len = offs += field->fixed_len;
			}
resolved:
			rec_offs_base(offsets)[i + 1] = len;
		} while (++i < rec_offs_n_fields(offsets));

		*rec_offs_base(offsets)
			= (rec - (lens + 1)) | REC_OFFS_COMPACT;
	} else {
		/* Old-style record: determine extra size and end offsets */
		offs = REC_N_OLD_EXTRA_BYTES;
		if (rec_get_1byte_offs_flag(rec)) {
			offs += rec_offs_n_fields(offsets);
			*rec_offs_base(offsets) = offs;
			/* Determine offsets to fields */
			do {
				offs = rec_1_get_field_end_info(rec, i);
				if (offs & REC_1BYTE_SQL_NULL_MASK) {
					offs &= ~REC_1BYTE_SQL_NULL_MASK;
					offs |= REC_OFFS_SQL_NULL;
				}
				rec_offs_base(offsets)[1 + i] = offs;
			} while (++i < rec_offs_n_fields(offsets));
		} else {
			offs += 2 * rec_offs_n_fields(offsets);
			*rec_offs_base(offsets) = offs;
			/* Determine offsets to fields */
			do {
				offs = rec_2_get_field_end_info(rec, i);
				if (offs & REC_2BYTE_SQL_NULL_MASK) {
					offs &= ~REC_2BYTE_SQL_NULL_MASK;
					offs |= REC_OFFS_SQL_NULL;
				}
				if (offs & REC_2BYTE_EXTERN_MASK) {
					offs &= ~REC_2BYTE_EXTERN_MASK;
					offs |= REC_OFFS_EXTERNAL;
					*rec_offs_base(offsets) |= REC_OFFS_EXTERNAL;
				}
				rec_offs_base(offsets)[1 + i] = offs;
			} while (++i < rec_offs_n_fields(offsets));
		}
	}
}

/******************************************************//**
The following function determines the offsets to each field
in the record.	It can reuse a previously returned array.
@return	the new offsets */
UNIV_INTERN
ulint*
rec_get_offsets_func(
/*=================*/
	const rec_t*		rec,	/*!< in: physical record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint*			offsets,/*!< in/out: array consisting of
					offsets[0] allocated elements,
					or an array from rec_get_offsets(),
					or NULL */
	ulint			n_fields,/*!< in: maximum number of
					initialized fields
					 (ULINT_UNDEFINED if all fields) */
#ifdef UNIV_DEBUG
	const char*		file,	/*!< in: file name where called */
	ulint			line,	/*!< in: line number where called */
#endif /* UNIV_DEBUG */
	mem_heap_t**		heap)	/*!< in/out: memory heap */
{
	ulint	n;
	ulint	size;

	ut_ad(rec);
	ut_ad(index);
	ut_ad(heap);

	if (dict_table_is_comp(index->table)) {
		switch (UNIV_EXPECT(rec_get_status(rec),
				    REC_STATUS_ORDINARY)) {
		case REC_STATUS_ORDINARY:
			n = dict_index_get_n_fields(index);
			break;
		case REC_STATUS_NODE_PTR:
			/* Node pointer records consist of the
			uniquely identifying fields of the record
			followed by a child page number field. */
			n = dict_index_get_n_unique_in_tree(index) + 1;
			break;
		case REC_STATUS_INFIMUM:
		case REC_STATUS_SUPREMUM:
			/* infimum or supremum record */
			n = 1;
			break;
		default:
			ut_error;
			return(NULL);
		}
	} else {
		n = rec_get_n_fields_old(rec);
	}

	if (UNIV_UNLIKELY(n_fields < n)) {
		n = n_fields;
	}

	/* The offsets header consists of the allocation size at
	offsets[0] and the REC_OFFS_HEADER_SIZE bytes. */
	size = n + (1 + REC_OFFS_HEADER_SIZE);

	if (UNIV_UNLIKELY(!offsets)
	    || UNIV_UNLIKELY(rec_offs_get_n_alloc(offsets) < size)) {
		if (UNIV_UNLIKELY(!*heap)) {
			*heap = mem_heap_create_at(size * sizeof(ulint),
						   file, line);
		}
		offsets = static_cast<ulint*>(
			mem_heap_alloc(*heap, size * sizeof(ulint)));

		rec_offs_set_n_alloc(offsets, size);
	}

	rec_offs_set_n_fields(offsets, n);
	rec_init_offsets(rec, index, offsets);
	return(offsets);
}

/******************************************************//**
The following function determines the offsets to each field
in the record.  It can reuse a previously allocated array. */
UNIV_INTERN
void
rec_get_offsets_reverse(
/*====================*/
	const byte*		extra,	/*!< in: the extra bytes of a
					compact record in reverse order,
					excluding the fixed-size
					REC_N_NEW_EXTRA_BYTES */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint			node_ptr,/*!< in: nonzero=node pointer,
					0=leaf node */
	ulint*			offsets)/*!< in/out: array consisting of
					offsets[0] allocated elements */
{
	ulint		n;
	ulint		i;
	ulint		offs;
	ulint		any_ext;
	const byte*	nulls;
	const byte*	lens;
	dict_field_t*	field;
	ulint		null_mask;
	ulint		n_node_ptr_field;

	ut_ad(extra);
	ut_ad(index);
	ut_ad(offsets);
	ut_ad(dict_table_is_comp(index->table));

	if (UNIV_UNLIKELY(node_ptr)) {
		n_node_ptr_field = dict_index_get_n_unique_in_tree(index);
		n = n_node_ptr_field + 1;
	} else {
		n_node_ptr_field = ULINT_UNDEFINED;
		n = dict_index_get_n_fields(index);
	}

	ut_a(rec_offs_get_n_alloc(offsets) >= n + (1 + REC_OFFS_HEADER_SIZE));
	rec_offs_set_n_fields(offsets, n);

	nulls = extra;
	lens = nulls + UT_BITS_IN_BYTES(index->n_nullable);
	i = offs = 0;
	null_mask = 1;
	any_ext = 0;

	/* read the lengths of fields 0..n */
	do {
		ulint	len;
		if (UNIV_UNLIKELY(i == n_node_ptr_field)) {
			len = offs += REC_NODE_PTR_SIZE;
			goto resolved;
		}

		field = dict_index_get_nth_field(index, i);
		if (!(dict_field_get_col(field)->prtype & DATA_NOT_NULL)) {
			/* nullable field => read the null flag */

			if (UNIV_UNLIKELY(!(byte) null_mask)) {
				nulls++;
				null_mask = 1;
			}

			if (*nulls & null_mask) {
				null_mask <<= 1;
				/* No length is stored for NULL fields.
				We do not advance offs, and we set
				the length to zero and enable the
				SQL NULL flag in offsets[]. */
				len = offs | REC_OFFS_SQL_NULL;
				goto resolved;
			}
			null_mask <<= 1;
		}

		if (UNIV_UNLIKELY(!field->fixed_len)) {
			/* Variable-length field: read the length */
			const dict_col_t*	col
				= dict_field_get_col(field);
			len = *lens++;
			/* If the maximum length of the field is up
			to 255 bytes, the actual length is always
			stored in one byte. If the maximum length is
			more than 255 bytes, the actual length is
			stored in one byte for 0..127.  The length
			will be encoded in two bytes when it is 128 or
			more, or when the field is stored externally. */
			if (UNIV_UNLIKELY(col->len > 255)
			    || UNIV_UNLIKELY(col->mtype == DATA_BLOB)) {
				if (len & 0x80) {
					/* 1exxxxxxx xxxxxxxx */
					len <<= 8;
					len |= *lens++;

					offs += len & 0x3fff;
					if (UNIV_UNLIKELY(len & 0x4000)) {
						any_ext = REC_OFFS_EXTERNAL;
						len = offs | REC_OFFS_EXTERNAL;
					} else {
						len = offs;
					}

					goto resolved;
				}
			}

			len = offs += len;
		} else {
			len = offs += field->fixed_len;
		}
resolved:
		rec_offs_base(offsets)[i + 1] = len;
	} while (++i < rec_offs_n_fields(offsets));

	ut_ad(lens >= extra);
	*rec_offs_base(offsets) = (lens - extra + REC_N_NEW_EXTRA_BYTES)
		| REC_OFFS_COMPACT | any_ext;
}

/************************************************************//**
The following function is used to get the offset to the nth
data field in an old-style record.
@return	offset to the field */
UNIV_INTERN
ulint
rec_get_nth_field_offs_old(
/*=======================*/
	const rec_t*	rec,	/*!< in: record */
	ulint		n,	/*!< in: index of the field */
	ulint*		len)	/*!< out: length of the field;
				UNIV_SQL_NULL if SQL null */
{
	ulint	os;
	ulint	next_os;

	ut_ad(len);
	ut_a(rec);
	ut_a(n < rec_get_n_fields_old(rec));

	if (rec_get_1byte_offs_flag(rec)) {
		os = rec_1_get_field_start_offs(rec, n);

		next_os = rec_1_get_field_end_info(rec, n);

		if (next_os & REC_1BYTE_SQL_NULL_MASK) {
			*len = UNIV_SQL_NULL;

			return(os);
		}

		next_os = next_os & ~REC_1BYTE_SQL_NULL_MASK;
	} else {
		os = rec_2_get_field_start_offs(rec, n);

		next_os = rec_2_get_field_end_info(rec, n);

		if (next_os & REC_2BYTE_SQL_NULL_MASK) {
			*len = UNIV_SQL_NULL;

			return(os);
		}

		next_os = next_os & ~(REC_2BYTE_SQL_NULL_MASK
				      | REC_2BYTE_EXTERN_MASK);
	}

	*len = next_os - os;

	ut_ad(*len < UNIV_PAGE_SIZE);

	return(os);
}

/**********************************************************//**
Determines the size of a data tuple prefix in ROW_FORMAT=COMPACT.
@return	total size */
UNIV_INLINE MY_ATTRIBUTE((warn_unused_result, nonnull(1,2)))
ulint
rec_get_converted_size_comp_prefix_low(
/*===================================*/
	const dict_index_t*	index,	/*!< in: record descriptor;
					dict_table_is_comp() is
					assumed to hold, even if
					it does not */
	const dfield_t*		fields,	/*!< in: array of data fields */
	ulint			n_fields,/*!< in: number of data fields */
	ulint*			extra,	/*!< out: extra size */
	bool			temp)	/*!< in: whether this is a
					temporary file record */
{
	ulint	extra_size;
	ulint	data_size;
	ulint	i;
	ulint	n_null	= index->n_nullable;
	ut_ad(n_fields > 0);
	ut_ad(n_fields <= dict_index_get_n_fields(index));
	ut_ad(!temp || extra);

	extra_size = temp
		? UT_BITS_IN_BYTES(n_null)
		: REC_N_NEW_EXTRA_BYTES
		+ UT_BITS_IN_BYTES(n_null);
	data_size = 0;

	if (temp && dict_table_is_comp(index->table)) {
		/* No need to do adjust fixed_len=0. We only need to
		adjust it for ROW_FORMAT=REDUNDANT. */
		temp = false;
	}

	/* read the lengths of fields 0..n */
	for (i = 0; i < n_fields; i++) {
		const dict_field_t*	field;
		ulint			len;
		ulint			fixed_len;
		const dict_col_t*	col;

		field = dict_index_get_nth_field(index, i);
		len = dfield_get_len(&fields[i]);
		col = dict_field_get_col(field);

		ut_ad(dict_col_type_assert_equal(col,
						 dfield_get_type(&fields[i])));
		/* All NULLable fields must be included in the n_null count. */
		ut_ad((col->prtype & DATA_NOT_NULL) || n_null--);

		if (dfield_is_null(&fields[i])) {
			/* No length is stored for NULL fields. */
			ut_ad(!(col->prtype & DATA_NOT_NULL));
			continue;
		}

		ut_ad(len <= col->len || col->mtype == DATA_BLOB
		      || (col->len == 0 && col->mtype == DATA_VARCHAR));

		fixed_len = field->fixed_len;
		if (temp && fixed_len
		    && !dict_col_get_fixed_size(col, temp)) {
			fixed_len = 0;
		}
		/* If the maximum length of a variable-length field
		is up to 255 bytes, the actual length is always stored
		in one byte. If the maximum length is more than 255
		bytes, the actual length is stored in one byte for
		0..127.  The length will be encoded in two bytes when
		it is 128 or more, or when the field is stored externally. */

		if (fixed_len) {
#ifdef UNIV_DEBUG
			ulint	mbminlen = DATA_MBMINLEN(col->mbminmaxlen);
			ulint	mbmaxlen = DATA_MBMAXLEN(col->mbminmaxlen);

			ut_ad(len <= fixed_len);

			ut_ad(!mbmaxlen || len >= mbminlen
			      * (fixed_len / mbmaxlen));

			/* dict_index_add_col() should guarantee this */
			ut_ad(!field->prefix_len
			      || fixed_len == field->prefix_len);
#endif /* UNIV_DEBUG */
		} else if (dfield_is_ext(&fields[i])) {
			ut_ad(col->len >= 256 || col->mtype == DATA_BLOB);
			extra_size += 2;
		} else if (len < 128
			   || (col->len < 256 && col->mtype != DATA_BLOB)) {
			extra_size++;
		} else {
			/* For variable-length columns, we look up the
			maximum length from the column itself.  If this
			is a prefix index column shorter than 256 bytes,
			this will waste one byte. */
			extra_size += 2;
		}
		data_size += len;
	}

	if (extra) {
		*extra = extra_size;
	}

	return(extra_size + data_size);
}

/**********************************************************//**
Determines the size of a data tuple prefix in ROW_FORMAT=COMPACT.
@return	total size */
UNIV_INTERN
ulint
rec_get_converted_size_comp_prefix(
/*===============================*/
	const dict_index_t*	index,	/*!< in: record descriptor */
	const dfield_t*		fields,	/*!< in: array of data fields */
	ulint			n_fields,/*!< in: number of data fields */
	ulint*			extra)	/*!< out: extra size */
{
	ut_ad(dict_table_is_comp(index->table));
	return(rec_get_converted_size_comp_prefix_low(
		       index, fields, n_fields, extra, false));
}

/**********************************************************//**
Determines the size of a data tuple in ROW_FORMAT=COMPACT.
@return	total size */
UNIV_INTERN
ulint
rec_get_converted_size_comp(
/*========================*/
	const dict_index_t*	index,	/*!< in: record descriptor;
					dict_table_is_comp() is
					assumed to hold, even if
					it does not */
	ulint			status,	/*!< in: status bits of the record */
	const dfield_t*		fields,	/*!< in: array of data fields */
	ulint			n_fields,/*!< in: number of data fields */
	ulint*			extra)	/*!< out: extra size */
{
	ulint	size;
	ut_ad(n_fields > 0);

	switch (UNIV_EXPECT(status, REC_STATUS_ORDINARY)) {
	case REC_STATUS_ORDINARY:
		ut_ad(n_fields == dict_index_get_n_fields(index));
		size = 0;
		break;
	case REC_STATUS_NODE_PTR:
		n_fields--;
		ut_ad(n_fields == dict_index_get_n_unique_in_tree(index));
		ut_ad(dfield_get_len(&fields[n_fields]) == REC_NODE_PTR_SIZE);
		size = REC_NODE_PTR_SIZE; /* child page number */
		break;
	case REC_STATUS_INFIMUM:
	case REC_STATUS_SUPREMUM:
		/* infimum or supremum record, 8 data bytes */
		if (UNIV_LIKELY_NULL(extra)) {
			*extra = REC_N_NEW_EXTRA_BYTES;
		}
		return(REC_N_NEW_EXTRA_BYTES + 8);
	default:
		ut_error;
		return(ULINT_UNDEFINED);
	}

	return(size + rec_get_converted_size_comp_prefix_low(
		       index, fields, n_fields, extra, false));
}

/***********************************************************//**
Sets the value of the ith field SQL null bit of an old-style record. */
UNIV_INTERN
void
rec_set_nth_field_null_bit(
/*=======================*/
	rec_t*	rec,	/*!< in: record */
	ulint	i,	/*!< in: ith field */
	ibool	val)	/*!< in: value to set */
{
	ulint	info;

	if (rec_get_1byte_offs_flag(rec)) {

		info = rec_1_get_field_end_info(rec, i);

		if (val) {
			info = info | REC_1BYTE_SQL_NULL_MASK;
		} else {
			info = info & ~REC_1BYTE_SQL_NULL_MASK;
		}

		rec_1_set_field_end_info(rec, i, info);

		return;
	}

	info = rec_2_get_field_end_info(rec, i);

	if (val) {
		info = info | REC_2BYTE_SQL_NULL_MASK;
	} else {
		info = info & ~REC_2BYTE_SQL_NULL_MASK;
	}

	rec_2_set_field_end_info(rec, i, info);
}

/***********************************************************//**
Sets an old-style record field to SQL null.
The physical size of the field is not changed. */
UNIV_INTERN
void
rec_set_nth_field_sql_null(
/*=======================*/
	rec_t*	rec,	/*!< in: record */
	ulint	n)	/*!< in: index of the field */
{
	ulint	offset;

	offset = rec_get_field_start_offs(rec, n);

	data_write_sql_null(rec + offset, rec_get_nth_field_size(rec, n));

	rec_set_nth_field_null_bit(rec, n, TRUE);
}

/*********************************************************//**
Builds an old-style physical record out of a data tuple and
stores it beginning from the start of the given buffer.
@return	pointer to the origin of physical record */
static
rec_t*
rec_convert_dtuple_to_rec_old(
/*==========================*/
	byte*		buf,	/*!< in: start address of the physical record */
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	ulint		n_ext)	/*!< in: number of externally stored columns */
{
	const dfield_t*	field;
	ulint		n_fields;
	ulint		data_size;
	rec_t*		rec;
	ulint		end_offset;
	ulint		ored_offset;
	ulint		len;
	ulint		i;

	ut_ad(buf && dtuple);
	ut_ad(dtuple_validate(dtuple));
	ut_ad(dtuple_check_typed(dtuple));

	n_fields = dtuple_get_n_fields(dtuple);
	data_size = dtuple_get_data_size(dtuple, 0);

	ut_ad(n_fields > 0);

	/* Calculate the offset of the origin in the physical record */

	rec = buf + rec_get_converted_extra_size(data_size, n_fields, n_ext);
#ifdef UNIV_DEBUG
	/* Suppress Valgrind warnings of ut_ad()
	in mach_write_to_1(), mach_write_to_2() et al. */
	memset(buf, 0xff, rec - buf + data_size);
#endif /* UNIV_DEBUG */
	/* Store the number of fields */
	rec_set_n_fields_old(rec, n_fields);

	/* Set the info bits of the record */
	rec_set_info_bits_old(rec, dtuple_get_info_bits(dtuple)
			      & REC_INFO_BITS_MASK);

	/* Store the data and the offsets */

	end_offset = 0;

	if (!n_ext && data_size <= REC_1BYTE_OFFS_LIMIT) {

		rec_set_1byte_offs_flag(rec, TRUE);

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

			field = dtuple_get_nth_field(dtuple, i);

			if (dfield_is_null(field)) {
				len = dtype_get_sql_null_size(
					dfield_get_type(field), 0);
				data_write_sql_null(rec + end_offset, len);

				end_offset += len;
				ored_offset = end_offset
					| REC_1BYTE_SQL_NULL_MASK;
			} else {
				/* If the data is not SQL null, store it */
				len = dfield_get_len(field);

				memcpy(rec + end_offset,
				       dfield_get_data(field), len);

				end_offset += len;
				ored_offset = end_offset;
			}

			rec_1_set_field_end_info(rec, i, ored_offset);
		}
	} else {
		rec_set_1byte_offs_flag(rec, FALSE);

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

			field = dtuple_get_nth_field(dtuple, i);

			if (dfield_is_null(field)) {
				len = dtype_get_sql_null_size(
					dfield_get_type(field), 0);
				data_write_sql_null(rec + end_offset, len);

				end_offset += len;
				ored_offset = end_offset
					| REC_2BYTE_SQL_NULL_MASK;
			} else {
				/* If the data is not SQL null, store it */
				len = dfield_get_len(field);

				memcpy(rec + end_offset,
				       dfield_get_data(field), len);

				end_offset += len;
				ored_offset = end_offset;

				if (dfield_is_ext(field)) {
					ored_offset |= REC_2BYTE_EXTERN_MASK;
				}
			}

			rec_2_set_field_end_info(rec, i, ored_offset);
		}
	}

	return(rec);
}

/*********************************************************//**
Builds a ROW_FORMAT=COMPACT record out of a data tuple. */
UNIV_INLINE MY_ATTRIBUTE((nonnull))
void
rec_convert_dtuple_to_rec_comp(
/*===========================*/
	rec_t*			rec,	/*!< in: origin of record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	const dfield_t*		fields,	/*!< in: array of data fields */
	ulint			n_fields,/*!< in: number of data fields */
	ulint			status,	/*!< in: status bits of the record */
	bool			temp)	/*!< in: whether to use the
					format for temporary files in
					index creation */
{
	const dfield_t*	field;
	const dtype_t*	type;
	byte*		end;
	byte*		nulls;
	byte*		lens;
	ulint		len;
	ulint		i;
	ulint		n_node_ptr_field;
	ulint		fixed_len;
	ulint		null_mask	= 1;
	ulint		n_null;

	ut_ad(temp || dict_table_is_comp(index->table));
	ut_ad(n_fields > 0);

	if (temp) {
		ut_ad(status == REC_STATUS_ORDINARY);
		ut_ad(n_fields <= dict_index_get_n_fields(index));
		n_node_ptr_field = ULINT_UNDEFINED;
		nulls = rec - 1;
		if (dict_table_is_comp(index->table)) {
			/* No need to do adjust fixed_len=0. We only
			need to adjust it for ROW_FORMAT=REDUNDANT. */
			temp = false;
		}
	} else {
		nulls = rec - (REC_N_NEW_EXTRA_BYTES + 1);

		switch (UNIV_EXPECT(status, REC_STATUS_ORDINARY)) {
		case REC_STATUS_ORDINARY:
			ut_ad(n_fields <= dict_index_get_n_fields(index));
			n_node_ptr_field = ULINT_UNDEFINED;
			break;
		case REC_STATUS_NODE_PTR:
			ut_ad(n_fields
			      == dict_index_get_n_unique_in_tree(index) + 1);
			n_node_ptr_field = n_fields - 1;
			break;
		case REC_STATUS_INFIMUM:
		case REC_STATUS_SUPREMUM:
			ut_ad(n_fields == 1);
			n_node_ptr_field = ULINT_UNDEFINED;
			break;
		default:
			ut_error;
			return;
		}
	}

	end = rec;
	n_null = index->n_nullable;
	lens = nulls - UT_BITS_IN_BYTES(n_null);
	/* clear the SQL-null flags */
	memset(lens + 1, 0, nulls - lens);

	/* Store the data and the offsets */

	for (i = 0, field = fields; i < n_fields; i++, field++) {
		const dict_field_t*	ifield;

		type = dfield_get_type(field);
		len = dfield_get_len(field);

		if (UNIV_UNLIKELY(i == n_node_ptr_field)) {
			ut_ad(dtype_get_prtype(type) & DATA_NOT_NULL);
			ut_ad(len == REC_NODE_PTR_SIZE);
			memcpy(end, dfield_get_data(field), len);
			end += REC_NODE_PTR_SIZE;
			break;
		}

		if (!(dtype_get_prtype(type) & DATA_NOT_NULL)) {
			/* nullable field */
			ut_ad(n_null--);

			if (UNIV_UNLIKELY(!(byte) null_mask)) {
				nulls--;
				null_mask = 1;
			}

			ut_ad(*nulls < null_mask);

			/* set the null flag if necessary */
			if (dfield_is_null(field)) {
				*nulls |= null_mask;
				null_mask <<= 1;
				continue;
			}

			null_mask <<= 1;
		}
		/* only nullable fields can be null */
		ut_ad(!dfield_is_null(field));

		ifield = dict_index_get_nth_field(index, i);
		fixed_len = ifield->fixed_len;
		if (temp && fixed_len
		    && !dict_col_get_fixed_size(ifield->col, temp)) {
			fixed_len = 0;
		}
		/* If the maximum length of a variable-length field
		is up to 255 bytes, the actual length is always stored
		in one byte. If the maximum length is more than 255
		bytes, the actual length is stored in one byte for
		0..127.  The length will be encoded in two bytes when
		it is 128 or more, or when the field is stored externally. */
		if (fixed_len) {
#ifdef UNIV_DEBUG
			ulint	mbminlen = DATA_MBMINLEN(
				ifield->col->mbminmaxlen);
			ulint	mbmaxlen = DATA_MBMAXLEN(
				ifield->col->mbminmaxlen);

			ut_ad(len <= fixed_len);
			ut_ad(!mbmaxlen || len >= mbminlen
			      * (fixed_len / mbmaxlen));
			ut_ad(!dfield_is_ext(field));
#endif /* UNIV_DEBUG */
		} else if (dfield_is_ext(field)) {
			ut_ad(ifield->col->len >= 256
			      || ifield->col->mtype == DATA_BLOB);
			ut_ad(len <= REC_ANTELOPE_MAX_INDEX_COL_LEN
			      + BTR_EXTERN_FIELD_REF_SIZE);
			*lens-- = (byte) (len >> 8) | 0xc0;
			*lens-- = (byte) len;
		} else {
			ut_ad(len <= dtype_get_len(type)
			      || dtype_get_mtype(type) == DATA_BLOB
			      || !strcmp(index->name,
					 FTS_INDEX_TABLE_IND_NAME));
			if (len < 128
			    || (dtype_get_len(type) < 256
				&& dtype_get_mtype(type) != DATA_BLOB)) {

				*lens-- = (byte) len;
			} else {
				ut_ad(len < 16384);
				*lens-- = (byte) (len >> 8) | 0x80;
				*lens-- = (byte) len;
			}
		}

		memcpy(end, dfield_get_data(field), len);
		end += len;
	}
}

/*********************************************************//**
Builds a new-style physical record out of a data tuple and
stores it beginning from the start of the given buffer.
@return	pointer to the origin of physical record */
static
rec_t*
rec_convert_dtuple_to_rec_new(
/*==========================*/
	byte*			buf,	/*!< in: start address of
					the physical record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	const dtuple_t*		dtuple)	/*!< in: data tuple */
{
	ulint	extra_size;
	ulint	status;
	rec_t*	rec;

	status = dtuple_get_info_bits(dtuple) & REC_NEW_STATUS_MASK;
	rec_get_converted_size_comp(
		index, status, dtuple->fields, dtuple->n_fields, &extra_size);
	rec = buf + extra_size;

	rec_convert_dtuple_to_rec_comp(
		rec, index, dtuple->fields, dtuple->n_fields, status, false);

	/* Set the info bits of the record */
	rec_set_info_and_status_bits(rec, dtuple_get_info_bits(dtuple));

	return(rec);
}

/*********************************************************//**
Builds a physical record out of a data tuple and
stores it beginning from the start of the given buffer.
@return	pointer to the origin of physical record */
UNIV_INTERN
rec_t*
rec_convert_dtuple_to_rec(
/*======================*/
	byte*			buf,	/*!< in: start address of the
					physical record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	const dtuple_t*		dtuple,	/*!< in: data tuple */
	ulint			n_ext)	/*!< in: number of
					externally stored columns */
{
	rec_t*	rec;

	ut_ad(buf != NULL);
	ut_ad(index != NULL);
	ut_ad(dtuple != NULL);
	ut_ad(dtuple_validate(dtuple));
	ut_ad(dtuple_check_typed(dtuple));

	if (dict_table_is_comp(index->table)) {
		rec = rec_convert_dtuple_to_rec_new(buf, index, dtuple);
	} else {
		rec = rec_convert_dtuple_to_rec_old(buf, dtuple, n_ext);
	}

#ifdef UNIV_DEBUG
	{
		mem_heap_t*	heap	= NULL;
		ulint		offsets_[REC_OFFS_NORMAL_SIZE];
		const ulint*	offsets;
		ulint		i;
		rec_offs_init(offsets_);

		offsets = rec_get_offsets(rec, index,
					  offsets_, ULINT_UNDEFINED, &heap);
		ut_ad(rec_validate(rec, offsets));
		ut_ad(dtuple_get_n_fields(dtuple)
		      == rec_offs_n_fields(offsets));

		for (i = 0; i < rec_offs_n_fields(offsets); i++) {
			ut_ad(!dfield_is_ext(dtuple_get_nth_field(dtuple, i))
			      == !rec_offs_nth_extern(offsets, i));
		}

		if (UNIV_LIKELY_NULL(heap)) {
			mem_heap_free(heap);
		}
	}
#endif /* UNIV_DEBUG */
	return(rec);
}

#ifndef UNIV_HOTBACKUP
/**********************************************************//**
Determines the size of a data tuple prefix in ROW_FORMAT=COMPACT.
@return	total size */
UNIV_INTERN
ulint
rec_get_converted_size_temp(
/*========================*/
	const dict_index_t*	index,	/*!< in: record descriptor */
	const dfield_t*		fields,	/*!< in: array of data fields */
	ulint			n_fields,/*!< in: number of data fields */
	ulint*			extra)	/*!< out: extra size */
{
	return(rec_get_converted_size_comp_prefix_low(
		       index, fields, n_fields, extra, true));
}

/******************************************************//**
Determine the offset to each field in temporary file.
@see rec_convert_dtuple_to_temp() */
UNIV_INTERN
void
rec_init_offsets_temp(
/*==================*/
	const rec_t*		rec,	/*!< in: temporary file record */
	const dict_index_t*	index,	/*!< in: record descriptor */
	ulint*			offsets)/*!< in/out: array of offsets;
					in: n=rec_offs_n_fields(offsets) */
{
	rec_init_offsets_comp_ordinary(rec, true, index, offsets);
}

/*********************************************************//**
Builds a temporary file record out of a data tuple.
@see rec_init_offsets_temp() */
UNIV_INTERN
void
rec_convert_dtuple_to_temp(
/*=======================*/
	rec_t*			rec,		/*!< out: record */
	const dict_index_t*	index,		/*!< in: record descriptor */
	const dfield_t*		fields,		/*!< in: array of data fields */
	ulint			n_fields)	/*!< in: number of fields */
{
	rec_convert_dtuple_to_rec_comp(rec, index, fields, n_fields,
				       REC_STATUS_ORDINARY, true);
}

/**************************************************************//**
Copies the first n fields of a physical record to a data tuple. The fields
are copied to the memory heap. */
UNIV_INTERN
void
rec_copy_prefix_to_dtuple(
/*======================*/
	dtuple_t*		tuple,		/*!< out: data tuple */
	const rec_t*		rec,		/*!< in: physical record */
	const dict_index_t*	index,		/*!< in: record descriptor */
	ulint			n_fields,	/*!< in: number of fields
						to copy */
	mem_heap_t*		heap)		/*!< in: memory heap */
{
	ulint	i;
	ulint	offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*	offsets	= offsets_;
	rec_offs_init(offsets_);

	offsets = rec_get_offsets(rec, index, offsets, n_fields, &heap);

	ut_ad(rec_validate(rec, offsets));
	ut_ad(dtuple_check_typed(tuple));

	dtuple_set_info_bits(tuple, rec_get_info_bits(
				     rec, dict_table_is_comp(index->table)));

	for (i = 0; i < n_fields; i++) {
		dfield_t*	field;
		const byte*	data;
		ulint		len;

		field = dtuple_get_nth_field(tuple, i);
		data = rec_get_nth_field(rec, offsets, i, &len);

		if (len != UNIV_SQL_NULL) {
			dfield_set_data(field,
					mem_heap_dup(heap, data, len), len);
			ut_ad(!rec_offs_nth_extern(offsets, i));
		} else {
			dfield_set_null(field);
		}
	}
}

/**************************************************************//**
Copies the first n fields of an old-style physical record
to a new physical record in a buffer.
@return	own: copied record */
static
rec_t*
rec_copy_prefix_to_buf_old(
/*=======================*/
	const rec_t*	rec,		/*!< in: physical record */
	ulint		n_fields,	/*!< in: number of fields to copy */
	ulint		area_end,	/*!< in: end of the prefix data */
	byte**		buf,		/*!< in/out: memory buffer for
					the copied prefix, or NULL */
	ulint*		buf_size)	/*!< in/out: buffer size */
{
	rec_t*	copy_rec;
	ulint	area_start;
	ulint	prefix_len;

	if (rec_get_1byte_offs_flag(rec)) {
		area_start = REC_N_OLD_EXTRA_BYTES + n_fields;
	} else {
		area_start = REC_N_OLD_EXTRA_BYTES + 2 * n_fields;
	}

	prefix_len = area_start + area_end;

	if ((*buf == NULL) || (*buf_size < prefix_len)) {
		if (*buf != NULL) {
			mem_free(*buf);
		}

		*buf = static_cast<byte*>(mem_alloc2(prefix_len, buf_size));
	}

	ut_memcpy(*buf, rec - area_start, prefix_len);

	copy_rec = *buf + area_start;

	rec_set_n_fields_old(copy_rec, n_fields);

	return(copy_rec);
}

/**************************************************************//**
Copies the first n fields of a physical record to a new physical record in
a buffer.
@return	own: copied record */
UNIV_INTERN
rec_t*
rec_copy_prefix_to_buf(
/*===================*/
	const rec_t*		rec,		/*!< in: physical record */
	const dict_index_t*	index,		/*!< in: record descriptor */
	ulint			n_fields,	/*!< in: number of fields
						to copy */
	byte**			buf,		/*!< in/out: memory buffer
						for the copied prefix,
						or NULL */
	ulint*			buf_size)	/*!< in/out: buffer size */
{
	const byte*	nulls;
	const byte*	lens;
	ulint		i;
	ulint		prefix_len;
	ulint		null_mask;
	ulint		status;

	UNIV_PREFETCH_RW(*buf);

	if (!dict_table_is_comp(index->table)) {
		ut_ad(rec_validate_old(rec));
		return(rec_copy_prefix_to_buf_old(
			       rec, n_fields,
			       rec_get_field_start_offs(rec, n_fields),
			       buf, buf_size));
	}

	status = rec_get_status(rec);

	switch (status) {
	case REC_STATUS_ORDINARY:
		ut_ad(n_fields <= dict_index_get_n_fields(index));
		break;
	case REC_STATUS_NODE_PTR:
		/* it doesn't make sense to copy the child page number field */
		ut_ad(n_fields <= dict_index_get_n_unique_in_tree(index));
		break;
	case REC_STATUS_INFIMUM:
	case REC_STATUS_SUPREMUM:
		/* infimum or supremum record: no sense to copy anything */
	default:
		ut_error;
		return(NULL);
	}

	nulls = rec - (REC_N_NEW_EXTRA_BYTES + 1);
	lens = nulls - UT_BITS_IN_BYTES(index->n_nullable);
	UNIV_PREFETCH_R(lens);
	prefix_len = 0;
	null_mask = 1;

	/* read the lengths of fields 0..n */
	for (i = 0; i < n_fields; i++) {
		const dict_field_t*	field;
		const dict_col_t*	col;

		field = dict_index_get_nth_field(index, i);
		col = dict_field_get_col(field);

		if (!(col->prtype & DATA_NOT_NULL)) {
			/* nullable field => read the null flag */
			if (UNIV_UNLIKELY(!(byte) null_mask)) {
				nulls--;
				null_mask = 1;
			}

			if (*nulls & null_mask) {
				null_mask <<= 1;
				continue;
			}

			null_mask <<= 1;
		}

		if (field->fixed_len) {
			prefix_len += field->fixed_len;
		} else {
			ulint	len = *lens--;
			/* If the maximum length of the column is up
			to 255 bytes, the actual length is always
			stored in one byte. If the maximum length is
			more than 255 bytes, the actual length is
			stored in one byte for 0..127.  The length
			will be encoded in two bytes when it is 128 or
			more, or when the column is stored externally. */
			if (col->len > 255 || col->mtype == DATA_BLOB) {
				if (len & 0x80) {
					/* 1exxxxxx */
					len &= 0x3f;
					len <<= 8;
					len |= *lens--;
					UNIV_PREFETCH_R(lens);
				}
			}
			prefix_len += len;
		}
	}

	UNIV_PREFETCH_R(rec + prefix_len);

	prefix_len += rec - (lens + 1);

	if ((*buf == NULL) || (*buf_size < prefix_len)) {
		if (*buf != NULL) {
			mem_free(*buf);
		}

		*buf = static_cast<byte*>(mem_alloc2(prefix_len, buf_size));
	}

	memcpy(*buf, lens + 1, prefix_len);

	return(*buf + (rec - (lens + 1)));
}
#endif /* UNIV_HOTBACKUP */

/***************************************************************//**
Validates the consistency of an old-style physical record.
@return	TRUE if ok */
static
ibool
rec_validate_old(
/*=============*/
	const rec_t*	rec)	/*!< in: physical record */
{
	const byte*	data;
	ulint		len;
	ulint		n_fields;
	ulint		len_sum		= 0;
	ulint		sum		= 0;
	ulint		i;

	ut_a(rec);
	n_fields = rec_get_n_fields_old(rec);

	if ((n_fields == 0) || (n_fields > REC_MAX_N_FIELDS)) {
		fprintf(stderr, "InnoDB: Error: record has %lu fields\n",
			(ulong) n_fields);
		return(FALSE);
	}

	for (i = 0; i < n_fields; i++) {
		data = rec_get_nth_field_old(rec, i, &len);

		if (!((len < UNIV_PAGE_SIZE) || (len == UNIV_SQL_NULL))) {
			fprintf(stderr,
				"InnoDB: Error: record field %lu len %lu\n",
				(ulong) i,
				(ulong) len);
			return(FALSE);
		}

		if (len != UNIV_SQL_NULL) {
			len_sum += len;
			sum += *(data + len -1); /* dereference the
						 end of the field to
						 cause a memory trap
						 if possible */
		} else {
			len_sum += rec_get_nth_field_size(rec, i);
		}
	}

	if (len_sum != rec_get_data_size_old(rec)) {
		fprintf(stderr,
			"InnoDB: Error: record len should be %lu, len %lu\n",
			(ulong) len_sum,
			rec_get_data_size_old(rec));
		return(FALSE);
	}

	rec_dummy = sum; /* This is here only to fool the compiler */

	return(TRUE);
}

/***************************************************************//**
Validates the consistency of a physical record.
@return	TRUE if ok */
UNIV_INTERN
ibool
rec_validate(
/*=========*/
	const rec_t*	rec,	/*!< in: physical record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	const byte*	data;
	ulint		len;
	ulint		n_fields;
	ulint		len_sum		= 0;
	ulint		sum		= 0;
	ulint		i;

	ut_a(rec);
	n_fields = rec_offs_n_fields(offsets);

	if ((n_fields == 0) || (n_fields > REC_MAX_N_FIELDS)) {
		fprintf(stderr, "InnoDB: Error: record has %lu fields\n",
			(ulong) n_fields);
		return(FALSE);
	}

	ut_a(rec_offs_comp(offsets) || n_fields <= rec_get_n_fields_old(rec));

	for (i = 0; i < n_fields; i++) {
		data = rec_get_nth_field(rec, offsets, i, &len);

		if (!((len < UNIV_PAGE_SIZE) || (len == UNIV_SQL_NULL))) {
			fprintf(stderr,
				"InnoDB: Error: record field %lu len %lu\n",
				(ulong) i,
				(ulong) len);
			return(FALSE);
		}

		if (len != UNIV_SQL_NULL) {
			len_sum += len;
			sum += *(data + len -1); /* dereference the
						 end of the field to
						 cause a memory trap
						 if possible */
		} else if (!rec_offs_comp(offsets)) {
			len_sum += rec_get_nth_field_size(rec, i);
		}
	}

	if (len_sum != rec_offs_data_size(offsets)) {
		fprintf(stderr,
			"InnoDB: Error: record len should be %lu, len %lu\n",
			(ulong) len_sum,
			(ulong) rec_offs_data_size(offsets));
		return(FALSE);
	}

	rec_dummy = sum; /* This is here only to fool the compiler */

	if (!rec_offs_comp(offsets)) {
		ut_a(rec_validate_old(rec));
	}

	return(TRUE);
}

/***************************************************************//**
Prints an old-style physical record. */
UNIV_INTERN
void
rec_print_old(
/*==========*/
	FILE*		file,	/*!< in: file where to print */
	const rec_t*	rec)	/*!< in: physical record */
{
	const byte*	data;
	ulint		len;
	ulint		n;
	ulint		i;

	ut_ad(rec);

	n = rec_get_n_fields_old(rec);

	fprintf(file, "PHYSICAL RECORD: n_fields %lu;"
		" %u-byte offsets; info bits %lu\n",
		(ulong) n,
		rec_get_1byte_offs_flag(rec) ? 1 : 2,
		(ulong) rec_get_info_bits(rec, FALSE));

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

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

		fprintf(file, " %lu:", (ulong) i);

		if (len != UNIV_SQL_NULL) {
			if (len <= 30) {

				ut_print_buf(file, data, len);
			} else {
				ut_print_buf(file, data, 30);

				fprintf(file, " (total %lu bytes)",
					(ulong) len);
			}
		} else {
			fprintf(file, " SQL NULL, size %lu ",
				rec_get_nth_field_size(rec, i));
		}

		putc(';', file);
		putc('\n', file);
	}

	rec_validate_old(rec);
}

#ifndef UNIV_HOTBACKUP
/***************************************************************//**
Prints a physical record in ROW_FORMAT=COMPACT.  Ignores the
record header. */
UNIV_INTERN
void
rec_print_comp(
/*===========*/
	FILE*		file,	/*!< in: file where to print */
	const rec_t*	rec,	/*!< in: physical record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	ulint	i;

	for (i = 0; i < rec_offs_n_fields(offsets); i++) {
		const byte*	data;
		ulint		len;

		data = rec_get_nth_field(rec, offsets, i, &len);

		fprintf(file, " %lu:", (ulong) i);

		if (len != UNIV_SQL_NULL) {
			if (len <= 30) {

				ut_print_buf(file, data, len);
			} else if (rec_offs_nth_extern(offsets, i)) {
				ut_print_buf(file, data, 30);
				fprintf(file, " (total %lu bytes, external)",
					(ulong) len);
				ut_print_buf(file, data + len
					     - BTR_EXTERN_FIELD_REF_SIZE,
					     BTR_EXTERN_FIELD_REF_SIZE);
			} else {
				ut_print_buf(file, data, 30);

				fprintf(file, " (total %lu bytes)",
					(ulong) len);
			}
		} else {
			fputs(" SQL NULL", file);
		}
		putc(';', file);
		putc('\n', file);
	}
}

/***************************************************************//**
Prints a physical record. */
UNIV_INTERN
void
rec_print_new(
/*==========*/
	FILE*		file,	/*!< in: file where to print */
	const rec_t*	rec,	/*!< in: physical record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	ut_ad(rec);
	ut_ad(offsets);
	ut_ad(rec_offs_validate(rec, NULL, offsets));

	if (!rec_offs_comp(offsets)) {
		rec_print_old(file, rec);
		return;
	}

	fprintf(file, "PHYSICAL RECORD: n_fields %lu;"
		" compact format; info bits %lu\n",
		(ulong) rec_offs_n_fields(offsets),
		(ulong) rec_get_info_bits(rec, TRUE));

	rec_print_comp(file, rec, offsets);
	rec_validate(rec, offsets);
}

/***************************************************************//**
Prints a physical record. */
UNIV_INTERN
void
rec_print(
/*======*/
	FILE*			file,	/*!< in: file where to print */
	const rec_t*		rec,	/*!< in: physical record */
	const dict_index_t*	index)	/*!< in: record descriptor */
{
	ut_ad(index);

	if (!dict_table_is_comp(index->table)) {
		rec_print_old(file, rec);
		return;
	} else {
		mem_heap_t*	heap	= NULL;
		ulint		offsets_[REC_OFFS_NORMAL_SIZE];
		rec_offs_init(offsets_);

		rec_print_new(file, rec,
			      rec_get_offsets(rec, index, offsets_,
					      ULINT_UNDEFINED, &heap));
		if (UNIV_LIKELY_NULL(heap)) {
			mem_heap_free(heap);
		}
	}
}

# ifdef UNIV_DEBUG
/************************************************************//**
Reads the DB_TRX_ID of a clustered index record.
@return	the value of DB_TRX_ID */
UNIV_INTERN
trx_id_t
rec_get_trx_id(
/*===========*/
	const rec_t*		rec,	/*!< in: record */
	const dict_index_t*	index)	/*!< in: clustered index */
{
	const page_t*	page
		= page_align(rec);
	ulint		trx_id_col
		= dict_index_get_sys_col_pos(index, DATA_TRX_ID);
	const byte*	trx_id;
	ulint		len;
	mem_heap_t*	heap		= NULL;
	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
	ulint*		offsets		= offsets_;
	rec_offs_init(offsets_);

	ut_ad(fil_page_get_type(page) == FIL_PAGE_INDEX);
	ut_ad(mach_read_from_8(page + PAGE_HEADER + PAGE_INDEX_ID)
	      == index->id);
	ut_ad(dict_index_is_clust(index));
	ut_ad(trx_id_col > 0);
	ut_ad(trx_id_col != ULINT_UNDEFINED);

	offsets = rec_get_offsets(rec, index, offsets, trx_id_col + 1, &heap);

	trx_id = rec_get_nth_field(rec, offsets, trx_id_col, &len);

	ut_ad(len == DATA_TRX_ID_LEN);

	if (heap) {
		mem_heap_free(heap);
	}

	return(trx_read_trx_id(trx_id));
}
# endif /* UNIV_DEBUG */
#endif /* !UNIV_HOTBACKUP */
