Add support for binary I/O of ltree, lquery, and ltxtquery types.

Not much to say here --- does what it says on the tin.  The "binary"
representation in each case is really just the same as the text format,
though we prefix a version-number byte in case anyone ever feels
motivated to change that.  Thus, there's not any expectation of improved
speed or reduced space; the point here is just to allow clients to use
binary format for all columns of a query result or COPY data.

This makes use of the recently added ALTER TYPE support to add binary
I/O functions to an existing data type.  As in commit a808186,
we can piggy-back on there already being a new-for-v13 version of the
ltree extension, so we don't need a new update script file.

Nino Floris, reviewed by Alexander Korotkov and myself

Discussion: https://postgr.es/m/CANmj9Vxx50jOo1L7iSRxd142NyTz6Bdcgg7u9P3Z8o0=HGkYyQ@mail.gmail.com

Author: tglsfdc

contrib/ltree/crc32.c

@@ -20,10 +20,10 @@
 #include "utils/pg_crc.h"
 
 unsigned int
-ltree_crc32_sz(char *buf, int size)
+ltree_crc32_sz(const char *buf, int size)
 {
 	pg_crc32	crc;
-	char	   *p = buf;
+	const char *p = buf;
 
 	INIT_TRADITIONAL_CRC32(crc);
 	while (size > 0)

contrib/ltree/crc32.h

@@ -4,7 +4,7 @@
 /* contrib/ltree/crc32.h */
 
 /* Returns crc32 of data block */
-extern unsigned int ltree_crc32_sz(char *buf, int size);
+extern unsigned int ltree_crc32_sz(const char *buf, int size);
 
 /* Returns crc32 of null-terminated string */
 #define crc32(buf) ltree_crc32_sz((buf),strlen(buf))

contrib/ltree/ltree--1.1--1.2.sql

@@ -3,6 +3,43 @@
 -- complain if script is sourced in psql, rather than via ALTER EXTENSION
 \echo Use "ALTER EXTENSION ltree UPDATE TO '1.2'" to load this file. \quit
 
+CREATE FUNCTION ltree_recv(internal)
+RETURNS ltree
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+CREATE FUNCTION ltree_send(ltree)
+RETURNS bytea
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+ALTER TYPE ltree SET ( RECEIVE = ltree_recv, SEND = ltree_send );
+
+CREATE FUNCTION lquery_recv(internal)
+RETURNS lquery
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+CREATE FUNCTION lquery_send(lquery)
+RETURNS bytea
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+ALTER TYPE lquery SET ( RECEIVE = lquery_recv, SEND = lquery_send );
+
+CREATE FUNCTION ltxtq_recv(internal)
+RETURNS ltxtquery
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+CREATE FUNCTION ltxtq_send(ltxtquery)
+RETURNS bytea
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+ALTER TYPE ltxtquery SET ( RECEIVE = ltxtq_recv, SEND = ltxtq_send );
+
+
 CREATE FUNCTION ltree_gist_options(internal)
 RETURNS void
 AS 'MODULE_PATHNAME', 'ltree_gist_options'

contrib/ltree/ltree_io.c

@@ -8,18 +8,14 @@
 #include <ctype.h>
 
 #include "crc32.h"
+#include "libpq/pqformat.h"
 #include "ltree.h"
 #include "utils/memutils.h"
 
-PG_FUNCTION_INFO_V1(ltree_in);
-PG_FUNCTION_INFO_V1(ltree_out);
-PG_FUNCTION_INFO_V1(lquery_in);
-PG_FUNCTION_INFO_V1(lquery_out);
-
 
 typedef struct
 {
-	char	   *start;
+	const char *start;
 	int			len;			/* length in bytes */
 	int			flag;
 	int			wlen;			/* length in characters */
@@ -28,11 +24,14 @@ typedef struct
 #define LTPRS_WAITNAME	0
 #define LTPRS_WAITDELIM 1
 
-Datum
-ltree_in(PG_FUNCTION_ARGS)
+/*
+ * expects a null terminated string
+ * returns an ltree
+ */
+static ltree *
+parse_ltree(const char *buf)
 {
-	char	   *buf = (char *) PG_GETARG_POINTER(0);
-	char	   *ptr;
+	const char *ptr;
 	nodeitem   *list,
 			   *lptr;
 	int			num = 0,
@@ -141,15 +140,18 @@ ltree_in(PG_FUNCTION_ARGS)
 	}
 
 	pfree(list);
-	PG_RETURN_POINTER(result);
+	return result;
 
 #undef UNCHAR
 }
 
-Datum
-ltree_out(PG_FUNCTION_ARGS)
+/*
+ * expects an ltree
+ * returns a null terminated string
+ */
+static char *
+deparse_ltree(const ltree *in)
 {
-	ltree	   *in = PG_GETARG_LTREE_P(0);
 	char	   *buf,
 			   *ptr;
 	int			i;
@@ -170,11 +172,84 @@ ltree_out(PG_FUNCTION_ARGS)
 	}
 
 	*ptr = '\0';
-	PG_FREE_IF_COPY(in, 0);
+	return buf;
+}
+
+/*
+ * Basic ltree I/O functions
+ */
+PG_FUNCTION_INFO_V1(ltree_in);
+Datum
+ltree_in(PG_FUNCTION_ARGS)
+{
+	char	   *buf = (char *) PG_GETARG_POINTER(0);
+
+	PG_RETURN_POINTER(parse_ltree(buf));
+}
+
+PG_FUNCTION_INFO_V1(ltree_out);
+Datum
+ltree_out(PG_FUNCTION_ARGS)
+{
+	ltree	   *in = PG_GETARG_LTREE_P(0);
+
+	PG_RETURN_POINTER(deparse_ltree(in));
+}
+
+/*
+ * ltree type send function
+ *
+ * The type is sent as text in binary mode, so this is almost the same
+ * as the output function, but it's prefixed with a version number so we
+ * can change the binary format sent in future if necessary. For now,
+ * only version 1 is supported.
+ */
+PG_FUNCTION_INFO_V1(ltree_send);
+Datum
+ltree_send(PG_FUNCTION_ARGS)
+{
+	ltree	   *in = PG_GETARG_LTREE_P(0);
+	StringInfoData buf;
+	int			version = 1;
+	char	   *res = deparse_ltree(in);
+
+	pq_begintypsend(&buf);
+	pq_sendint8(&buf, version);
+	pq_sendtext(&buf, res, strlen(res));
+	pfree(res);
+
+	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
+}
+
+/*
+ * ltree type recv function
+ *
+ * The type is sent as text in binary mode, so this is almost the same
+ * as the input function, but it's prefixed with a version number so we
+ * can change the binary format sent in future if necessary. For now,
+ * only version 1 is supported.
+ */
+PG_FUNCTION_INFO_V1(ltree_recv);
+Datum
+ltree_recv(PG_FUNCTION_ARGS)
+{
+	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
+	int			version = pq_getmsgint(buf, 1);
+	char	   *str;
+	int			nbytes;
+	ltree	   *res;
 
-	PG_RETURN_POINTER(buf);
+	if (version != 1)
+		elog(ERROR, "unsupported ltree version number %d", version);
+
+	str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
+	res = parse_ltree(str);
+	pfree(str);
+
+	PG_RETURN_POINTER(res);
 }
 
+
 #define LQPRS_WAITLEVEL 0
 #define LQPRS_WAITDELIM 1
 #define LQPRS_WAITOPEN	2
@@ -190,11 +265,14 @@ ltree_out(PG_FUNCTION_ARGS)
 #define ITEMSIZE	MAXALIGN(LQL_HDRSIZE+sizeof(nodeitem*))
 #define NEXTLEV(x) ( (lquery_level*)( ((char*)(x)) + ITEMSIZE) )
 
-Datum
-lquery_in(PG_FUNCTION_ARGS)
+/*
+ * expects a null terminated string
+ * returns an lquery
+ */
+static lquery *
+parse_lquery(const char *buf)
 {
-	char	   *buf = (char *) PG_GETARG_POINTER(0);
-	char	   *ptr;
+	const char *ptr;
 	int			num = 0,
 				totallen = 0,
 				numOR = 0;
@@ -563,15 +641,18 @@ lquery_in(PG_FUNCTION_ARGS)
 	}
 
 	pfree(tmpql);
-	PG_RETURN_POINTER(result);
+	return result;
 
 #undef UNCHAR
 }
 
-Datum
-lquery_out(PG_FUNCTION_ARGS)
+/*
+ * expects an lquery
+ * returns a null terminated string
+ */
+static char *
+deparse_lquery(const lquery *in)
 {
-	lquery	   *in = PG_GETARG_LQUERY_P(0);
 	char	   *buf,
 			   *ptr;
 	int			i,
@@ -679,7 +760,79 @@ lquery_out(PG_FUNCTION_ARGS)
 	}
 
 	*ptr = '\0';
-	PG_FREE_IF_COPY(in, 0);
+	return buf;
+}
+
+/*
+ * Basic lquery I/O functions
+ */
+PG_FUNCTION_INFO_V1(lquery_in);
+Datum
+lquery_in(PG_FUNCTION_ARGS)
+{
+	char	   *buf = (char *) PG_GETARG_POINTER(0);
+
+	PG_RETURN_POINTER(parse_lquery(buf));
+}
+
+PG_FUNCTION_INFO_V1(lquery_out);
+Datum
+lquery_out(PG_FUNCTION_ARGS)
+{
+	lquery	   *in = PG_GETARG_LQUERY_P(0);
+
+	PG_RETURN_POINTER(deparse_lquery(in));
+}
+
+/*
+ * lquery type send function
+ *
+ * The type is sent as text in binary mode, so this is almost the same
+ * as the output function, but it's prefixed with a version number so we
+ * can change the binary format sent in future if necessary. For now,
+ * only version 1 is supported.
+ */
+PG_FUNCTION_INFO_V1(lquery_send);
+Datum
+lquery_send(PG_FUNCTION_ARGS)
+{
+	lquery	   *in = PG_GETARG_LQUERY_P(0);
+	StringInfoData buf;
+	int			version = 1;
+	char	   *res = deparse_lquery(in);
+
+	pq_begintypsend(&buf);
+	pq_sendint8(&buf, version);
+	pq_sendtext(&buf, res, strlen(res));
+	pfree(res);
+
+	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
+}
+
+/*
+ * lquery type recv function
+ *
+ * The type is sent as text in binary mode, so this is almost the same
+ * as the input function, but it's prefixed with a version number so we
+ * can change the binary format sent in future if necessary. For now,
+ * only version 1 is supported.
+ */
+PG_FUNCTION_INFO_V1(lquery_recv);
+Datum
+lquery_recv(PG_FUNCTION_ARGS)
+{
+	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
+	int			version = pq_getmsgint(buf, 1);
+	char	   *str;
+	int			nbytes;
+	lquery	   *res;
+
+	if (version != 1)
+		elog(ERROR, "unsupported lquery version number %d", version);
+
+	str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
+	res = parse_lquery(str);
+	pfree(str);
 
-	PG_RETURN_POINTER(buf);
+	PG_RETURN_POINTER(res);
 }