From de9a4c27fefcc0d104bc9c97f4a93a49a25bf66d Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Wed, 22 Dec 2010 14:23:56 +0100
Subject: [PATCH] Add PQlibVersion() function to libpq
This function is like the PQserverVersion() function except
it returns the version of libpq, making it possible for a client
program or driver to determine which version of libpq is in
use at runtime, and not just at link time.
Suggested by Harald Armin Massa and several others.
---
doc/src/sgml/libpq.sgml | 44 ++++++++++++++++++++++++++++++++
src/interfaces/libpq/exports.txt | 1 +
src/interfaces/libpq/fe-misc.c | 8 ++++++
src/interfaces/libpq/libpq-fe.h | 3 +++
4 files changed, 56 insertions(+)
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index c502439356..7aac6f6829 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -5359,6 +5359,50 @@ void *PQresultAlloc(PGresult *res, size_t nBytes);
</listitem>
</varlistentry>
+ <varlistentry id="libpq-pqlibversion">
+ <term>
+ <function>PQlibVersion</function>
+ <indexterm>
+ <primary>PQlibVersion</primary>
+ <seealso>PQserverVersion</seealso>
+ </indexterm>
+ </term>
+
+ <listitem>
+ <para>
+ Return the version of <productname>libpq</> that is being used.
+<synopsis>
+int PQlibVersion(void);
+</synopsis>
+ </para>
+
+ <para>
+ The result of this function can be used to determine, at
+ runtime, if specific functionality is available in the currently
+ loaded version of libpq. The function can be used, for example,
+ to determine which connection options are available for
+ <function>PQconnectdb</> or if the <literal>hex</> <type>bytea</>
+ output added in PostgreSQL 9.0 is supported.
+ </para>
+
+ <para>
+ The number is formed by converting the major, minor, and revision
+ numbers into two-decimal-digit numbers and appending them together.
+ For example, version 9.1 will be returned as 90100, and version
+ 9.1.2 will be returned as 90102 (leading zeroes are not shown).
+ </para>
+
+ <note>
+ <para>
+ This function appeared in <productname>PostgreSQL</> version 9.1, so
+ it cannot be used to detect required functionality in earlier
+ versions, since linking to it will create a link dependency
+ on version 9.1.
+ </para>
+ </note>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect1>
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
index a6c73af52e..1af8df699e 100644
--- a/src/interfaces/libpq/exports.txt
+++ b/src/interfaces/libpq/exports.txt
@@ -159,3 +159,4 @@ PQconnectdbParams 156
PQconnectStartParams 157
PQping 158
PQpingParams 159
+PQlibVersion 160
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 24ab7cf97a..999f60b0d4 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -66,6 +66,14 @@ static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
time_t end_time);
static int pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
+/*
+ * PQlibVersion: return the libpq version number
+ */
+int
+PQlibVersion(void)
+{
+ return PG_VERSION_NUM;
+}
/*
* fputnbytes: print exactly N bytes to a file
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 271afedb7b..6075ea8151 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -547,6 +547,9 @@ extern int lo_export(PGconn *conn, Oid lobjId, const char *filename);
/* === in fe-misc.c === */
+/* Get the version of the libpq library in use */
+extern int PQlibVersion(void);
+
/* Determine length of multibyte encoded char at *s */
extern int PQmblen(const char *s, int encoding);