Initial configure script

configure.in

@@ -0,0 +1,43 @@
+AC_INIT([repmgr4], [4.0], [pgsql-bugs@postgresql.org], [repmgr4], [https://2ndquadrant.com/en/resources/repmgr/])
+
+AC_COPYRIGHT([Copyright (c) 2010-2017, 2ndQuadrant Ltd.])
+
+AC_ARG_VAR([PG_CONFIG], [Location to find pg_config for target PostgreSQL (default PATH)])
+
+AC_PROG_SED
+
+if test -z "$PG_CONFIG"; then
+  AC_PATH_PROG(PG_CONFIG, pg_config)
+fi
+
+if test -z "$PG_CONFIG"; then
+   AC_MSG_ERROR([could not find pg_config, set PG_CONFIG or PATH])
+fi
+
+pgac_pg_config_version=$($PG_CONFIG --version 2>/dev/null)
+version_num=$(echo "$pgac_pg_config_version"|
+              $SED -e 's/^PostgreSQL \([[0-9]]*\)\.\([[0-9]]*\)\([[a-zA-Z0-9.]]*\)$/\1.\2/')
+
+if test -z "$version_num"; then
+  AC_MSG_ERROR([could not detect the PostgreSQL version, wrong or broken pg_config?])
+fi
+
+version_num_int=$(echo "$version_num"|
+              $SED -e 's/^\([[0-9]]*\)\([[0-9]]*\)$/\1\2/')
+
+if test "$version_num_int" -lt '93'; then
+   AC_MSG_ERROR([repmgr is not compatible with detected PostgreSQL version: $version_num])
+else
+   AC_MSG_NOTICE([building against PostgreSQL $version_num])
+fi
+
+# add includedir to prerequisites, so tests for headers can succeed
+CPPFLAGS="-I$($PG_CONFIG --includedir-server) $CFLAGS"
+
+# check whether we're building inside the source tree.
+if test "$srcdir" -ef '.' ; then
+  vpath_build=no
+else
+  vpath_build=yes
+fi
+AC_SUBST(vpath_build)