Fix mysql_get_client_version() function

MariaDB Connector/C 3.1.10 changed API of mysql_get_client_version()
function. Before that release it returned client version. With that release
it started returning Connector/C package version.

So when compiling with MariaDB Connector/C client library, redefine
mysql_get_client_version() to always returns client version via function
mariadb_get_infov(MARIADB_CLIENT_VERSION_ID) call.

Driver code expects for a long time that mysql_get_client_version() call
returns client version and not something different.

Function mariadb_get_infov() is supported since MariaDB Connector/C 3.0+.

Fixes: perl5-dbi/DBD-mysql#333

Author: pali

Makefile.PL

@@ -757,7 +757,13 @@ sub Configure {
                     # libmysqld.a from MySQL 8.x is broken too
                     $function .= "\n#if !defined(MARIADB_BASE_VERSION) && !defined(MARIADB_PACKAGE_VERSION)\nif (mysql_get_client_version() >= 80000) return 1;\n#endif\n";
                 }
-                $function .= 'return (mysql_get_client_version() == MYSQL_VERSION_ID) ? 0 : 1;';
+                # MariaDB Connector/C 3.1.10+ has broken mysql_get_client_version() function, so use mariadb_get_infov(MARIADB_CLIENT_VERSION_ID) instead
+                $function .= "size_t version;\n";
+                $function .= "#if defined(MARIADB_PACKAGE_VERSION) && defined(MARIADB_PACKAGE_VERSION_ID) && MARIADB_PACKAGE_VERSION_ID >= 30000\n";
+                $function .= "if (mariadb_get_infov((void *)0, MARIADB_CLIENT_VERSION_ID, &version) != 0)\n";
+                $function .= "#endif\n";
+                $function .= "version = mysql_get_client_version();\n";
+                $function .= 'return (version == MYSQL_VERSION_ID) ? 0 : 1;';
                 # libmysqld is built using g++ rather than gcc and sometimes
                 # we have to use libstdc++ to resolve linking problems
                 foreach my $add_ldflags (undef, '-lstdc++') {

dbdimp.h

@@ -322,6 +322,32 @@ PERL_STATIC_INLINE UV SvUV_nomg(pTHX_ SV *sv)
 #define my_bool bool
 #endif
 
+/*
+ * MariaDB Connector/C 3.1.10 changed API of mysql_get_client_version()
+ * function. Before that release it returned client version. With that release
+ * it started returning Connector/C package version.
+ *
+ * So when compiling with MariaDB Connector/C client library, redefine
+ * mysql_get_client_version() to always returns client version via function
+ * mariadb_get_infov(MARIADB_CLIENT_VERSION_ID) call.
+ *
+ * Driver code expects for a long time that mysql_get_client_version() call
+ * returns client version and not something different.
+ *
+ * Function mariadb_get_infov() is supported since MariaDB Connector/C 3.0+.
+ */
+#if defined(MARIADB_PACKAGE_VERSION) && defined(MARIADB_PACKAGE_VERSION_ID) && MARIADB_PACKAGE_VERSION_ID >= 30000
+PERL_STATIC_INLINE unsigned long mariadb_get_client_version(void)
+{
+  /* MARIADB_CLIENT_VERSION_ID really expects size_t type, documentation is wrong and says unsigned int. */
+  size_t version;
+  if (mariadb_get_infov(NULL, MARIADB_CLIENT_VERSION_ID, &version) != 0)
+    version = mysql_get_client_version(); /* On error fallback to mysql_get_client_version() */
+  return version;
+}
+#define mysql_get_client_version() mariadb_get_client_version()
+#endif
+
 /* MYSQL_SECURE_AUTH became a no-op from MySQL 5.7.5 and is removed from MySQL 8.0.3 */
 #if defined(MARIADB_BASE_VERSION) || MYSQL_VERSION_ID <= 50704
 #define HAVE_SECURE_AUTH