/*-------------------------------------------------------------------------
 *
 * bytea.c
 *	  Functions for the bytea type.
 *
 * Portions Copyright (c) 2025-2026, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *	  src/backend/utils/adt/bytea.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/detoast.h"
#include "common/hashfn.h"
#include "common/int.h"
#include "fmgr.h"
#include "lib/hyperloglog.h"
#include "libpq/pqformat.h"
#include "port/pg_bitutils.h"
#include "port/pg_bswap.h"
#include "utils/builtins.h"
#include "utils/bytea.h"
#include "utils/fmgrprotos.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/sortsupport.h"
#include "utils/uuid.h"
#include "varatt.h"

/* GUC variable */
int			bytea_output = BYTEA_OUTPUT_HEX;

static bytea *bytea_catenate(bytea *t1, bytea *t2);
static bytea *bytea_substring(Datum str, int S, int L,
							  bool length_not_specified);
static bytea *bytea_overlay(bytea *t1, bytea *t2, int sp, int sl);

typedef struct
{
	hyperLogLogState abbr_card; /* Abbreviated key cardinality state */
	hyperLogLogState full_card; /* Full key cardinality state */
	double		prop_card;		/* Required cardinality proportion */
} ByteaSortSupport;

/* Static function declarations for sort support */
static int	byteafastcmp(Datum x, Datum y, SortSupport ssup);
static Datum bytea_abbrev_convert(Datum original, SortSupport ssup);
static bool bytea_abbrev_abort(int memtupcount, SortSupport ssup);

/*
 * bytea_catenate
 *	Guts of byteacat(), broken out so it can be used by other functions
 *
 * Arguments can be in short-header form, but not compressed or out-of-line
 */
static bytea *
bytea_catenate(bytea *t1, bytea *t2)
{
	bytea	   *result;
	int			len1,
				len2,
				len;
	char	   *ptr;

	len1 = VARSIZE_ANY_EXHDR(t1);
	len2 = VARSIZE_ANY_EXHDR(t2);

	/* paranoia ... probably should throw error instead? */
	if (len1 < 0)
		len1 = 0;
	if (len2 < 0)
		len2 = 0;

	len = len1 + len2 + VARHDRSZ;
	result = (bytea *) palloc(len);

	/* Set size of result string... */
	SET_VARSIZE(result, len);

	/* Fill data field of result string... */
	ptr = VARDATA(result);
	if (len1 > 0)
		memcpy(ptr, VARDATA_ANY(t1), len1);
	if (len2 > 0)
		memcpy(ptr + len1, VARDATA_ANY(t2), len2);

	return result;
}

#define PG_STR_GET_BYTEA(str_) \
	DatumGetByteaPP(DirectFunctionCall1(byteain, CStringGetDatum(str_)))

static bytea *
bytea_substring(Datum str,
				int S,
				int L,
				bool length_not_specified)
{
	int32		S1;				/* adjusted start position */
	int32		L1;				/* adjusted substring length */
	int32		E;				/* end position */

	/*
	 * The logic here should generally match text_substring().
	 */
	S1 = Max(S, 1);

	if (length_not_specified)
	{
		/*
		 * Not passed a length - DatumGetByteaPSlice() grabs everything to the
		 * end of the string if we pass it a negative value for length.
		 */
		L1 = -1;
	}
	else if (L < 0)
	{
		/* SQL99 says to throw an error for E < S, i.e., negative length */
		ereport(ERROR,
				(errcode(ERRCODE_SUBSTRING_ERROR),
				 errmsg("negative substring length not allowed")));
		L1 = -1;				/* silence stupider compilers */
	}
	else if (pg_add_s32_overflow(S, L, &E))
	{
		/*
		 * L could be large enough for S + L to overflow, in which case the
		 * substring must run to end of string.
		 */
		L1 = -1;
	}
	else
	{
		/*
		 * A zero or negative value for the end position can happen if the
		 * start was negative or one. SQL99 says to return a zero-length
		 * string.
		 */
		if (E < 1)
			return PG_STR_GET_BYTEA("");

		L1 = E - S1;
	}

	/*
	 * If the start position is past the end of the string, SQL99 says to
	 * return a zero-length string -- DatumGetByteaPSlice() will do that for
	 * us.  We need only convert S1 to zero-based starting position.
	 */
	return DatumGetByteaPSlice(str, S1 - 1, L1);
}

static bytea *
bytea_overlay(bytea *t1, bytea *t2, int sp, int sl)
{
	bytea	   *result;
	bytea	   *s1;
	bytea	   *s2;
	int			sp_pl_sl;

	/*
	 * Check for possible integer-overflow cases.  For negative sp, throw a
	 * "substring length" error because that's what should be expected
	 * according to the spec's definition of OVERLAY().
	 */
	if (sp <= 0)
		ereport(ERROR,
				(errcode(ERRCODE_SUBSTRING_ERROR),
				 errmsg("negative substring length not allowed")));
	if (pg_add_s32_overflow(sp, sl, &sp_pl_sl))
		ereport(ERROR,
				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				 errmsg("integer out of range")));

	s1 = bytea_substring(PointerGetDatum(t1), 1, sp - 1, false);
	s2 = bytea_substring(PointerGetDatum(t1), sp_pl_sl, -1, true);
	result = bytea_catenate(s1, t2);
	result = bytea_catenate(result, s2);

	return result;
}

/*****************************************************************************
 *	 USER I/O ROUTINES														 *
 *****************************************************************************/

#define VAL(CH)			((CH) - '0')
#define DIG(VAL)		((VAL) + '0')

/*
 *		byteain			- converts from printable representation of byte array
 *
 *		Non-printable characters must be passed as '\nnn' (octal) and are
 *		converted to internal form.  '\' must be passed as '\\'.
 */
Datum
byteain(PG_FUNCTION_ARGS)
{
	char	   *inputText = PG_GETARG_CSTRING(0);
	Node	   *escontext = fcinfo->context;
	size_t		len = strlen(inputText);
	size_t		bc;
	char	   *tp;
	char	   *rp;
	bytea	   *result;

	/* Recognize hex input */
	if (inputText[0] == '\\' && inputText[1] == 'x')
	{
		bc = (len - 2) / 2 + VARHDRSZ;	/* maximum possible length */
		result = palloc(bc);
		bc = hex_decode_safe(inputText + 2, len - 2, VARDATA(result),
							 escontext);
		SET_VARSIZE(result, bc + VARHDRSZ); /* actual length */

		PG_RETURN_BYTEA_P(result);
	}

	/* Else, it's the traditional escaped style */
	result = (bytea *) palloc(len + VARHDRSZ);	/* maximum possible length */

	tp = inputText;
	rp = VARDATA(result);
	while (*tp != '\0')
	{
		if (tp[0] != '\\')
			*rp++ = *tp++;
		else if ((tp[1] >= '0' && tp[1] <= '3') &&
				 (tp[2] >= '0' && tp[2] <= '7') &&
				 (tp[3] >= '0' && tp[3] <= '7'))
		{
			int			v;

			v = VAL(tp[1]);
			v <<= 3;
			v += VAL(tp[2]);
			v <<= 3;
			*rp++ = v + VAL(tp[3]);

			tp += 4;
		}
		else if (tp[1] == '\\')
		{
			*rp++ = '\\';
			tp += 2;
		}
		else
		{
			/*
			 * one backslash, not followed by another or ### valid octal
			 */
			ereturn(escontext, (Datum) 0,
					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
					 errmsg("invalid input syntax for type %s", "bytea")));
		}
	}

	bc = rp - VARDATA(result);	/* actual length */
	SET_VARSIZE(result, bc + VARHDRSZ);

	PG_RETURN_BYTEA_P(result);
}

/*
 *		byteaout		- converts to printable representation of byte array
 *
 *		In the traditional escaped format, non-printable characters are
 *		printed as '\nnn' (octal) and '\' as '\\'.
 */
Datum
byteaout(PG_FUNCTION_ARGS)
{
	bytea	   *vlena = PG_GETARG_BYTEA_PP(0);
	char	   *result;
	char	   *rp;

	if (bytea_output == BYTEA_OUTPUT_HEX)
	{
		/* Print hex format */
		rp = result = palloc(VARSIZE_ANY_EXHDR(vlena) * 2 + 2 + 1);
		*rp++ = '\\';
		*rp++ = 'x';
		rp += hex_encode(VARDATA_ANY(vlena), VARSIZE_ANY_EXHDR(vlena), rp);
	}
	else if (bytea_output == BYTEA_OUTPUT_ESCAPE)
	{
		/* Print traditional escaped format */
		char	   *vp;
		uint64		len;
		int			i;

		len = 1;				/* empty string has 1 char */
		vp = VARDATA_ANY(vlena);
		for (i = VARSIZE_ANY_EXHDR(vlena); i != 0; i--, vp++)
		{
			if (*vp == '\\')
				len += 2;
			else if ((unsigned char) *vp < 0x20 || (unsigned char) *vp > 0x7e)
				len += 4;
			else
				len++;
		}

		/*
		 * In principle len can't overflow uint32 if the input fit in 1GB, but
		 * for safety let's check rather than relying on palloc's internal
		 * check.
		 */
		if (len > MaxAllocSize)
			ereport(ERROR,
					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
					 errmsg_internal("result of bytea output conversion is too large")));
		rp = result = (char *) palloc(len);

		vp = VARDATA_ANY(vlena);
		for (i = VARSIZE_ANY_EXHDR(vlena); i != 0; i--, vp++)
		{
			if (*vp == '\\')
			{
				*rp++ = '\\';
				*rp++ = '\\';
			}
			else if ((unsigned char) *vp < 0x20 || (unsigned char) *vp > 0x7e)
			{
				int			val;	/* holds unprintable chars */

				val = *vp;
				rp[0] = '\\';
				rp[3] = DIG(val & 07);
				val >>= 3;
				rp[2] = DIG(val & 07);
				val >>= 3;
				rp[1] = DIG(val & 03);
				rp += 4;
			}
			else
				*rp++ = *vp;
		}
	}
	else
	{
		elog(ERROR, "unrecognized \"bytea_output\" setting: %d",
			 bytea_output);
		rp = result = NULL;		/* keep compiler quiet */
	}
	*rp = '\0';
	PG_RETURN_CSTRING(result);
}

/*
 *		bytearecv			- converts external binary format to bytea
 */
Datum
bytearecv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
	bytea	   *result;
	int			nbytes;

	nbytes = buf->len - buf->cursor;
	result = (bytea *) palloc(nbytes + VARHDRSZ);
	SET_VARSIZE(result, nbytes + VARHDRSZ);
	pq_copymsgbytes(buf, VARDATA(result), nbytes);
	PG_RETURN_BYTEA_P(result);
}

/*
 *		byteasend			- converts bytea to binary format
 *
 * This is a special case: just copy the input...
 */
Datum
byteasend(PG_FUNCTION_ARGS)
{
	bytea	   *vlena = PG_GETARG_BYTEA_P_COPY(0);

	PG_RETURN_BYTEA_P(vlena);
}

Datum
bytea_string_agg_transfn(PG_FUNCTION_ARGS)
{
	StringInfo	state;

	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);

	/* Append the value unless null, preceding it with the delimiter. */
	if (!PG_ARGISNULL(1))
	{
		bytea	   *value = PG_GETARG_BYTEA_PP(1);
		bool		isfirst = false;

		/*
		 * You might think we can just throw away the first delimiter, however
		 * we must keep it as we may be a parallel worker doing partial
		 * aggregation building a state to send to the main process.  We need
		 * to keep the delimiter of every aggregation so that the combine
		 * function can properly join up the strings of two separately
		 * partially aggregated results.  The first delimiter is only stripped
		 * off in the final function.  To know how much to strip off the front
		 * of the string, we store the length of the first delimiter in the
		 * StringInfo's cursor field, which we don't otherwise need here.
		 */
		if (state == NULL)
		{
			MemoryContext aggcontext;
			MemoryContext oldcontext;

			if (!AggCheckCallContext(fcinfo, &aggcontext))
			{
				/* cannot be called directly because of internal-type argument */
				elog(ERROR, "bytea_string_agg_transfn called in non-aggregate context");
			}

			/*
			 * Create state in aggregate context.  It'll stay there across
			 * subsequent calls.
			 */
			oldcontext = MemoryContextSwitchTo(aggcontext);
			state = makeStringInfo();
			MemoryContextSwitchTo(oldcontext);

			isfirst = true;
		}

		if (!PG_ARGISNULL(2))
		{
			bytea	   *delim = PG_GETARG_BYTEA_PP(2);

			appendBinaryStringInfo(state, VARDATA_ANY(delim),
								   VARSIZE_ANY_EXHDR(delim));
			if (isfirst)
				state->cursor = VARSIZE_ANY_EXHDR(delim);
		}

		appendBinaryStringInfo(state, VARDATA_ANY(value),
							   VARSIZE_ANY_EXHDR(value));
	}

	/*
	 * The transition type for string_agg() is declared to be "internal",
	 * which is a pass-by-value type the same size as a pointer.
	 */
	if (state)
		PG_RETURN_POINTER(state);
	PG_RETURN_NULL();
}

Datum
bytea_string_agg_finalfn(PG_FUNCTION_ARGS)
{
	StringInfo	state;

	/* cannot be called directly because of internal-type argument */
	Assert(AggCheckCallContext(fcinfo, NULL));

	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);

	if (state != NULL)
	{
		/* As per comment in transfn, strip data before the cursor position */
		bytea	   *result;
		int			strippedlen = state->len - state->cursor;

		result = (bytea *) palloc(strippedlen + VARHDRSZ);
		SET_VARSIZE(result, strippedlen + VARHDRSZ);
		memcpy(VARDATA(result), &state->data[state->cursor], strippedlen);
		PG_RETURN_BYTEA_P(result);
	}
	else
		PG_RETURN_NULL();
}

/*-------------------------------------------------------------
 * byteaoctetlen
 *
 * get the number of bytes contained in an instance of type 'bytea'
 *-------------------------------------------------------------
 */
Datum
byteaoctetlen(PG_FUNCTION_ARGS)
{
	Datum		str = PG_GETARG_DATUM(0);

	/* We need not detoast the input at all */
	PG_RETURN_INT32(toast_raw_datum_size(str) - VARHDRSZ);
}

/*
 * byteacat -
 *	  takes two bytea* and returns a bytea* that is the concatenation of
 *	  the two.
 *
 * Cloned from textcat and modified as required.
 */
Datum
byteacat(PG_FUNCTION_ARGS)
{
	bytea	   *t1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *t2 = PG_GETARG_BYTEA_PP(1);

	PG_RETURN_BYTEA_P(bytea_catenate(t1, t2));
}

/*
 * byteaoverlay
 *	Replace specified substring of first string with second
 *
 * The SQL standard defines OVERLAY() in terms of substring and concatenation.
 * This code is a direct implementation of what the standard says.
 */
Datum
byteaoverlay(PG_FUNCTION_ARGS)
{
	bytea	   *t1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *t2 = PG_GETARG_BYTEA_PP(1);
	int			sp = PG_GETARG_INT32(2);	/* substring start position */
	int			sl = PG_GETARG_INT32(3);	/* substring length */

	PG_RETURN_BYTEA_P(bytea_overlay(t1, t2, sp, sl));
}

Datum
byteaoverlay_no_len(PG_FUNCTION_ARGS)
{
	bytea	   *t1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *t2 = PG_GETARG_BYTEA_PP(1);
	int			sp = PG_GETARG_INT32(2);	/* substring start position */
	int			sl;

	sl = VARSIZE_ANY_EXHDR(t2); /* defaults to length(t2) */
	PG_RETURN_BYTEA_P(bytea_overlay(t1, t2, sp, sl));
}

/*
 * bytea_substr()
 * Return a substring starting at the specified position.
 * Cloned from text_substr and modified as required.
 *
 * Input:
 *	- string
 *	- starting position (is one-based)
 *	- string length (optional)
 *
 * If the starting position is zero or less, then return from the start of the string
 * adjusting the length to be consistent with the "negative start" per SQL.
 * If the length is less than zero, an ERROR is thrown. If no third argument
 * (length) is provided, the length to the end of the string is assumed.
 */
Datum
bytea_substr(PG_FUNCTION_ARGS)
{
	PG_RETURN_BYTEA_P(bytea_substring(PG_GETARG_DATUM(0),
									  PG_GETARG_INT32(1),
									  PG_GETARG_INT32(2),
									  false));
}

/*
 * bytea_substr_no_len -
 *	  Wrapper to avoid opr_sanity failure due to
 *	  one function accepting a different number of args.
 */
Datum
bytea_substr_no_len(PG_FUNCTION_ARGS)
{
	PG_RETURN_BYTEA_P(bytea_substring(PG_GETARG_DATUM(0),
									  PG_GETARG_INT32(1),
									  -1,
									  true));
}

/*
 * bit_count
 */
Datum
bytea_bit_count(PG_FUNCTION_ARGS)
{
	bytea	   *t1 = PG_GETARG_BYTEA_PP(0);

	PG_RETURN_INT64(pg_popcount(VARDATA_ANY(t1), VARSIZE_ANY_EXHDR(t1)));
}

/*
 * byteapos -
 *	  Return the position of the specified substring.
 *	  Implements the SQL POSITION() function.
 * Cloned from textpos and modified as required.
 */
Datum
byteapos(PG_FUNCTION_ARGS)
{
	bytea	   *t1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *t2 = PG_GETARG_BYTEA_PP(1);
	int			pos;
	int			px,
				p;
	int			len1,
				len2;
	char	   *p1,
			   *p2;

	len1 = VARSIZE_ANY_EXHDR(t1);
	len2 = VARSIZE_ANY_EXHDR(t2);

	if (len2 <= 0)
		PG_RETURN_INT32(1);		/* result for empty pattern */

	p1 = VARDATA_ANY(t1);
	p2 = VARDATA_ANY(t2);

	pos = 0;
	px = (len1 - len2);
	for (p = 0; p <= px; p++)
	{
		if ((*p2 == *p1) && (memcmp(p1, p2, len2) == 0))
		{
			pos = p + 1;
			break;
		};
		p1++;
	};

	PG_RETURN_INT32(pos);
}

/*-------------------------------------------------------------
 * byteaGetByte
 *
 * this routine treats "bytea" as an array of bytes.
 * It returns the Nth byte (a number between 0 and 255).
 *-------------------------------------------------------------
 */
Datum
byteaGetByte(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int32		n = PG_GETARG_INT32(1);
	int			len;
	int			byte;

	len = VARSIZE_ANY_EXHDR(v);

	if (n < 0 || n >= len)
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("index %d out of valid range, 0..%d",
						n, len - 1)));

	byte = ((unsigned char *) VARDATA_ANY(v))[n];

	PG_RETURN_INT32(byte);
}

/*-------------------------------------------------------------
 * byteaGetBit
 *
 * This routine treats a "bytea" type like an array of bits.
 * It returns the value of the Nth bit (0 or 1).
 *
 *-------------------------------------------------------------
 */
Datum
byteaGetBit(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int64		n = PG_GETARG_INT64(1);
	int			byteNo,
				bitNo;
	int			len;
	int			byte;

	len = VARSIZE_ANY_EXHDR(v);

	if (n < 0 || n >= (int64) len * 8)
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("index %" PRId64 " out of valid range, 0..%" PRId64,
						n, (int64) len * 8 - 1)));

	/* n/8 is now known < len, so safe to cast to int */
	byteNo = (int) (n / 8);
	bitNo = (int) (n % 8);

	byte = ((unsigned char *) VARDATA_ANY(v))[byteNo];

	if (byte & (1 << bitNo))
		PG_RETURN_INT32(1);
	else
		PG_RETURN_INT32(0);
}

/*-------------------------------------------------------------
 * byteaSetByte
 *
 * Given an instance of type 'bytea' creates a new one with
 * the Nth byte set to the given value.
 *
 *-------------------------------------------------------------
 */
Datum
byteaSetByte(PG_FUNCTION_ARGS)
{
	bytea	   *res = PG_GETARG_BYTEA_P_COPY(0);
	int32		n = PG_GETARG_INT32(1);
	int32		newByte = PG_GETARG_INT32(2);
	int			len;

	len = VARSIZE(res) - VARHDRSZ;

	if (n < 0 || n >= len)
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("index %d out of valid range, 0..%d",
						n, len - 1)));

	/*
	 * Now set the byte.
	 */
	((unsigned char *) VARDATA(res))[n] = newByte;

	PG_RETURN_BYTEA_P(res);
}

/*-------------------------------------------------------------
 * byteaSetBit
 *
 * Given an instance of type 'bytea' creates a new one with
 * the Nth bit set to the given value.
 *
 *-------------------------------------------------------------
 */
Datum
byteaSetBit(PG_FUNCTION_ARGS)
{
	bytea	   *res = PG_GETARG_BYTEA_P_COPY(0);
	int64		n = PG_GETARG_INT64(1);
	int32		newBit = PG_GETARG_INT32(2);
	int			len;
	int			oldByte,
				newByte;
	int			byteNo,
				bitNo;

	len = VARSIZE(res) - VARHDRSZ;

	if (n < 0 || n >= (int64) len * 8)
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("index %" PRId64 " out of valid range, 0..%" PRId64,
						n, (int64) len * 8 - 1)));

	/* n/8 is now known < len, so safe to cast to int */
	byteNo = (int) (n / 8);
	bitNo = (int) (n % 8);

	/*
	 * sanity check!
	 */
	if (newBit != 0 && newBit != 1)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("new bit must be 0 or 1")));

	/*
	 * Update the byte.
	 */
	oldByte = ((unsigned char *) VARDATA(res))[byteNo];

	if (newBit == 0)
		newByte = oldByte & (~(1 << bitNo));
	else
		newByte = oldByte | (1 << bitNo);

	((unsigned char *) VARDATA(res))[byteNo] = newByte;

	PG_RETURN_BYTEA_P(res);
}

/*
 * Return reversed bytea
 */
Datum
bytea_reverse(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	const char *p = VARDATA_ANY(v);
	int			len = VARSIZE_ANY_EXHDR(v);
	const char *endp = p + len;
	bytea	   *result = palloc(len + VARHDRSZ);
	char	   *dst = (char *) VARDATA(result) + len;

	SET_VARSIZE(result, len + VARHDRSZ);

	while (p < endp)
		*(--dst) = *p++;

	PG_RETURN_BYTEA_P(result);
}


/*****************************************************************************
 *	Comparison Functions used for bytea
 *
 * Note: btree indexes need these routines not to leak memory; therefore,
 * be careful to free working copies of toasted datums.  Most places don't
 * need to be so careful.
 *****************************************************************************/

Datum
byteaeq(PG_FUNCTION_ARGS)
{
	Datum		arg1 = PG_GETARG_DATUM(0);
	Datum		arg2 = PG_GETARG_DATUM(1);
	bool		result;
	Size		len1,
				len2;

	/*
	 * We can use a fast path for unequal lengths, which might save us from
	 * having to detoast one or both values.
	 */
	len1 = toast_raw_datum_size(arg1);
	len2 = toast_raw_datum_size(arg2);
	if (len1 != len2)
		result = false;
	else
	{
		bytea	   *barg1 = DatumGetByteaPP(arg1);
		bytea	   *barg2 = DatumGetByteaPP(arg2);

		result = (memcmp(VARDATA_ANY(barg1), VARDATA_ANY(barg2),
						 len1 - VARHDRSZ) == 0);

		PG_FREE_IF_COPY(barg1, 0);
		PG_FREE_IF_COPY(barg2, 1);
	}

	PG_RETURN_BOOL(result);
}

Datum
byteane(PG_FUNCTION_ARGS)
{
	Datum		arg1 = PG_GETARG_DATUM(0);
	Datum		arg2 = PG_GETARG_DATUM(1);
	bool		result;
	Size		len1,
				len2;

	/*
	 * We can use a fast path for unequal lengths, which might save us from
	 * having to detoast one or both values.
	 */
	len1 = toast_raw_datum_size(arg1);
	len2 = toast_raw_datum_size(arg2);
	if (len1 != len2)
		result = true;
	else
	{
		bytea	   *barg1 = DatumGetByteaPP(arg1);
		bytea	   *barg2 = DatumGetByteaPP(arg2);

		result = (memcmp(VARDATA_ANY(barg1), VARDATA_ANY(barg2),
						 len1 - VARHDRSZ) != 0);

		PG_FREE_IF_COPY(barg1, 0);
		PG_FREE_IF_COPY(barg2, 1);
	}

	PG_RETURN_BOOL(result);
}

Datum
bytealt(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL((cmp < 0) || ((cmp == 0) && (len1 < len2)));
}

Datum
byteale(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL((cmp < 0) || ((cmp == 0) && (len1 <= len2)));
}

Datum
byteagt(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL((cmp > 0) || ((cmp == 0) && (len1 > len2)));
}

Datum
byteage(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL((cmp > 0) || ((cmp == 0) && (len1 >= len2)));
}

Datum
byteacmp(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));
	if ((cmp == 0) && (len1 != len2))
		cmp = (len1 < len2) ? -1 : 1;

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_INT32(cmp);
}

Datum
bytea_larger(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	bytea	   *result;
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));
	result = ((cmp > 0) || ((cmp == 0) && (len1 > len2)) ? arg1 : arg2);

	PG_RETURN_BYTEA_P(result);
}

Datum
bytea_smaller(PG_FUNCTION_ARGS)
{
	bytea	   *arg1 = PG_GETARG_BYTEA_PP(0);
	bytea	   *arg2 = PG_GETARG_BYTEA_PP(1);
	bytea	   *result;
	int			len1,
				len2;
	int			cmp;

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	cmp = memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), Min(len1, len2));
	result = ((cmp < 0) || ((cmp == 0) && (len1 < len2)) ? arg1 : arg2);

	PG_RETURN_BYTEA_P(result);
}

/*
 * sortsupport comparison func
 */
static int
byteafastcmp(Datum x, Datum y, SortSupport ssup)
{
	bytea	   *arg1 = DatumGetByteaPP(x);
	bytea	   *arg2 = DatumGetByteaPP(y);
	char	   *a1p,
			   *a2p;
	int			len1,
				len2,
				result;

	a1p = VARDATA_ANY(arg1);
	a2p = VARDATA_ANY(arg2);

	len1 = VARSIZE_ANY_EXHDR(arg1);
	len2 = VARSIZE_ANY_EXHDR(arg2);

	result = memcmp(a1p, a2p, Min(len1, len2));
	if ((result == 0) && (len1 != len2))
		result = (len1 < len2) ? -1 : 1;

	/* We can't afford to leak memory here. */
	if (PointerGetDatum(arg1) != x)
		pfree(arg1);
	if (PointerGetDatum(arg2) != y)
		pfree(arg2);

	return result;
}

/*
 * Conversion routine for sortsupport.  Converts original to abbreviated key
 * representation.  Our encoding strategy is simple -- pack the first 8 bytes
 * of the bytea data into a Datum (on little-endian machines, the bytes are
 * stored in reverse order), and treat it as an unsigned integer.
 */
static Datum
bytea_abbrev_convert(Datum original, SortSupport ssup)
{
	const size_t max_prefix_bytes = sizeof(Datum);
	ByteaSortSupport *bss = (ByteaSortSupport *) ssup->ssup_extra;
	bytea	   *authoritative = DatumGetByteaPP(original);
	char	   *authoritative_data = VARDATA_ANY(authoritative);
	Datum		res;
	char	   *pres;
	int			len;
	uint32		hash;

	pres = (char *) &res;

	/* memset(), so any non-overwritten bytes are NUL */
	memset(pres, 0, max_prefix_bytes);
	len = VARSIZE_ANY_EXHDR(authoritative);

	/*
	 * Short byteas will have terminating NUL bytes in the abbreviated datum.
	 * Abbreviated comparison need not make a distinction between these NUL
	 * bytes, and NUL bytes representing actual NULs in the authoritative
	 * representation.
	 *
	 * Hopefully a comparison at or past one abbreviated key's terminating NUL
	 * byte will resolve the comparison without consulting the authoritative
	 * representation; specifically, some later non-NUL byte in the longer
	 * bytea can resolve the comparison against a subsequent terminating NUL
	 * in the shorter bytea.  There will usually be what is effectively a
	 * "length-wise" resolution there and then.
	 *
	 * If that doesn't work out -- if all bytes in the longer bytea positioned
	 * at or past the offset of the smaller bytea (first) terminating NUL are
	 * actually representative of NUL bytes in the authoritative binary bytea
	 * (perhaps with some *terminating* NUL bytes towards the end of the
	 * longer bytea iff it happens to still be small) -- then an authoritative
	 * tie-breaker will happen, and do the right thing: explicitly consider
	 * bytea length.
	 */
	memcpy(pres, authoritative_data, Min(len, max_prefix_bytes));

	/*
	 * Maintain approximate cardinality of both abbreviated keys and original,
	 * authoritative keys using HyperLogLog.  Used as cheap insurance against
	 * the worst case, where we do many string abbreviations for no saving in
	 * full memcmp()-based comparisons.  These statistics are used by
	 * bytea_abbrev_abort().
	 *
	 * First, Hash key proper, or a significant fraction of it.  Mix in length
	 * in order to compensate for cases where differences are past
	 * PG_CACHE_LINE_SIZE bytes, so as to limit the overhead of hashing.
	 */
	hash = DatumGetUInt32(hash_any((unsigned char *) authoritative_data,
								   Min(len, PG_CACHE_LINE_SIZE)));

	if (len > PG_CACHE_LINE_SIZE)
		hash ^= DatumGetUInt32(hash_uint32((uint32) len));

	addHyperLogLog(&bss->full_card, hash);

	/* Hash abbreviated key */
	{
		uint32		tmp;

		tmp = DatumGetUInt32(res) ^ (uint32) (DatumGetUInt64(res) >> 32);
		hash = DatumGetUInt32(hash_uint32(tmp));
	}

	addHyperLogLog(&bss->abbr_card, hash);

	/*
	 * Byteswap on little-endian machines.
	 *
	 * This is needed so that ssup_datum_unsigned_cmp() works correctly on all
	 * platforms.
	 */
	res = DatumBigEndianToNative(res);

	/* Don't leak memory here */
	if (PointerGetDatum(authoritative) != original)
		pfree(authoritative);

	return res;
}

/*
 * Callback for estimating effectiveness of abbreviated key optimization, using
 * heuristic rules.  Returns value indicating if the abbreviation optimization
 * should be aborted, based on its projected effectiveness.
 *
 * This is based on varstr_abbrev_abort(), but some comments have been elided
 * for brevity. See there for more details.
 */
static bool
bytea_abbrev_abort(int memtupcount, SortSupport ssup)
{
	ByteaSortSupport *bss = (ByteaSortSupport *) ssup->ssup_extra;
	double		abbrev_distinct,
				key_distinct;

	Assert(ssup->abbreviate);

	/* Have a little patience */
	if (memtupcount < 100)
		return false;

	abbrev_distinct = estimateHyperLogLog(&bss->abbr_card);
	key_distinct = estimateHyperLogLog(&bss->full_card);

	/*
	 * Clamp cardinality estimates to at least one distinct value.  While
	 * NULLs are generally disregarded, if only NULL values were seen so far,
	 * that might misrepresent costs if we failed to clamp.
	 */
	if (abbrev_distinct < 1.0)
		abbrev_distinct = 1.0;

	if (key_distinct < 1.0)
		key_distinct = 1.0;

	if (trace_sort)
	{
		double		norm_abbrev_card = abbrev_distinct / (double) memtupcount;

		elog(LOG, "bytea_abbrev: abbrev_distinct after %d: %f "
			 "(key_distinct: %f, norm_abbrev_card: %f, prop_card: %f)",
			 memtupcount, abbrev_distinct, key_distinct, norm_abbrev_card,
			 bss->prop_card);
	}

	/*
	 * If the number of distinct abbreviated keys approximately matches the
	 * number of distinct original keys, continue with abbreviation.
	 */
	if (abbrev_distinct > key_distinct * bss->prop_card)
	{
		/*
		 * Decay required cardinality aggressively after 10,000 tuples.
		 */
		if (memtupcount > 10000)
			bss->prop_card *= 0.65;

		return false;
	}

	/*
	 * Abort abbreviation strategy.
	 */
	if (trace_sort)
		elog(LOG, "bytea_abbrev: aborted abbreviation at %d "
			 "(abbrev_distinct: %f, key_distinct: %f, prop_card: %f)",
			 memtupcount, abbrev_distinct, key_distinct, bss->prop_card);

	return true;
}

Datum
bytea_sortsupport(PG_FUNCTION_ARGS)
{
	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
	MemoryContext oldcontext;

	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);

	ssup->comparator = byteafastcmp;

	/*
	 * Set up abbreviation support if requested.
	 */
	if (ssup->abbreviate)
	{
		ByteaSortSupport *bss;

		bss = palloc_object(ByteaSortSupport);
		bss->prop_card = 0.20;
		initHyperLogLog(&bss->abbr_card, 10);
		initHyperLogLog(&bss->full_card, 10);

		ssup->ssup_extra = bss;
		ssup->abbrev_full_comparator = ssup->comparator;
		ssup->comparator = ssup_datum_unsigned_cmp;
		ssup->abbrev_converter = bytea_abbrev_convert;
		ssup->abbrev_abort = bytea_abbrev_abort;
	}

	MemoryContextSwitchTo(oldcontext);

	PG_RETURN_VOID();
}

/* Cast bytea -> int2 */
Datum
bytea_int2(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int			len = VARSIZE_ANY_EXHDR(v);
	uint16		result;

	/* Check that the byte array is not too long */
	if (len > sizeof(result))
		ereturn(fcinfo->context, (Datum) 0,
				errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				errmsg("smallint out of range"));

	/* Convert it to an integer; most significant bytes come first */
	result = 0;
	for (int i = 0; i < len; i++)
	{
		result <<= BITS_PER_BYTE;
		result |= ((unsigned char *) VARDATA_ANY(v))[i];
	}

	PG_RETURN_INT16(result);
}

/* Cast bytea -> int4 */
Datum
bytea_int4(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int			len = VARSIZE_ANY_EXHDR(v);
	uint32		result;

	/* Check that the byte array is not too long */
	if (len > sizeof(result))
		ereturn(fcinfo->context, (Datum) 0,
				errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				errmsg("integer out of range"));

	/* Convert it to an integer; most significant bytes come first */
	result = 0;
	for (int i = 0; i < len; i++)
	{
		result <<= BITS_PER_BYTE;
		result |= ((unsigned char *) VARDATA_ANY(v))[i];
	}

	PG_RETURN_INT32(result);
}

/* Cast bytea -> int8 */
Datum
bytea_int8(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int			len = VARSIZE_ANY_EXHDR(v);
	uint64		result;

	/* Check that the byte array is not too long */
	if (len > sizeof(result))
		ereturn(fcinfo->context, (Datum) 0,
				errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
				errmsg("bigint out of range"));

	/* Convert it to an integer; most significant bytes come first */
	result = 0;
	for (int i = 0; i < len; i++)
	{
		result <<= BITS_PER_BYTE;
		result |= ((unsigned char *) VARDATA_ANY(v))[i];
	}

	PG_RETURN_INT64(result);
}

/* Cast int2 -> bytea; can just use int2send() */
Datum
int2_bytea(PG_FUNCTION_ARGS)
{
	return int2send(fcinfo);
}

/* Cast int4 -> bytea; can just use int4send() */
Datum
int4_bytea(PG_FUNCTION_ARGS)
{
	return int4send(fcinfo);
}

/* Cast int8 -> bytea; can just use int8send() */
Datum
int8_bytea(PG_FUNCTION_ARGS)
{
	return int8send(fcinfo);
}

/* Cast bytea -> uuid */
Datum
bytea_uuid(PG_FUNCTION_ARGS)
{
	bytea	   *v = PG_GETARG_BYTEA_PP(0);
	int			len = VARSIZE_ANY_EXHDR(v);
	pg_uuid_t  *uuid;

	if (len != UUID_LEN)
		ereturn(fcinfo->context, (Datum) 0,
				(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
				 errmsg("invalid input length for type %s", "uuid"),
				 errdetail("Expected %d bytes, got %d.", UUID_LEN, len)));

	uuid = palloc_object(pg_uuid_t);
	memcpy(uuid->data, VARDATA_ANY(v), UUID_LEN);
	PG_RETURN_UUID_P(uuid);
}

/* Cast uuid -> bytea; can just use uuid_send() */
Datum
uuid_bytea(PG_FUNCTION_ARGS)
{
	return uuid_send(fcinfo);
}
