Prevent accidental linking of system-supplied copies of libpq.so etc.

tglsfdc · tglsfdc · commit dddfc4cb2edc · 2018-04-03T16:26:05.000-04:00
We were being careless in some places about the order of -L switches in link command lines, such that -L switches referring to external directories could come before those referring to directories within the build tree. This made it possible to accidentally link a system-supplied library, for example /usr/lib/libpq.so, in place of the one built in the build tree. Hilarity ensued, the more so the older the system-supplied library is. To fix, break LDFLAGS into two parts, a sub-variable LDFLAGS_INTERNAL and the main LDFLAGS variable, both of which are "recursively expanded" so that they can be incrementally adjusted by different makefiles. Establish a policy that -L switches for directories in the build tree must always be added to LDFLAGS_INTERNAL, while -L switches for external directories must always be added to LDFLAGS. This is sufficient to ensure a safe search order. For simplicity, we typically also put -l switches for the respective libraries into those same variables. (Traditional make usage would have us put -l switches into LIBS, but cleaning that up is a project for another day, as there's no clear need for it.) This turns out to also require separating SHLIB_LINK into two variables, SHLIB_LINK and SHLIB_LINK_INTERNAL, with a similar rule about which switches go into which variable. And likewise for PG_LIBS. Although this change might appear to affect external users of pgxs.mk, I think it doesn't; they shouldn't have any need to touch the _INTERNAL variables. In passing, tweak src/common/Makefile so that the value of CPPFLAGS recorded in pg_config lacks "-DFRONTEND" and the recorded value of LDFLAGS lacks "-L../../../src/common". Both of those things are mistakes, apparently introduced during prior code rearrangements, as old versions of pg_config don't print them. In general we don't want anything that's specific to the src/common subdirectory to appear in those outputs. This is certainly a bug fix, but in view of the lack of field complaints, I'm unsure whether it's worth the risk of back-patching. In any case it seems wise to see what the buildfarm makes of it first. Discussion: https://postgr.es/m/25214.1522604295@sss.pgh.pa.us
diff --git a/contrib/dblink/Makefile b/contrib/dblink/Makefile
@@ -3,7 +3,7 @@
 MODULE_big = dblink
 OBJS	= dblink.o $(WIN32RES)
 PG_CPPFLAGS = -I$(libpq_srcdir)
-SHLIB_LINK = $(libpq)
+SHLIB_LINK_INTERNAL = $(libpq)
 
 EXTENSION = dblink
 DATA = dblink--1.2.sql dblink--1.1--1.2.sql dblink--1.0--1.1.sql \
diff --git a/contrib/hstore_plperl/Makefile b/contrib/hstore_plperl/Makefile
@@ -28,7 +28,7 @@ ifeq ($(PORTNAME), win32)
 # these settings are the same as for plperl
 override CPPFLAGS += -DPLPERL_HAVE_UID_GID -Wno-comment
 # ... see silliness in plperl Makefile ...
-SHLIB_LINK += $(sort $(wildcard ../../src/pl/plperl/libperl*.a))
+SHLIB_LINK_INTERNAL += $(sort $(wildcard ../../src/pl/plperl/libperl*.a))
 else
 rpathdir = $(perl_archlibexp)/CORE
 SHLIB_LINK += $(perl_embed_ldflags)
diff --git a/contrib/hstore_plpython/Makefile b/contrib/hstore_plpython/Makefile
@@ -26,7 +26,7 @@ endif
 # We must link libpython explicitly
 ifeq ($(PORTNAME), win32)
 # ... see silliness in plpython Makefile ...
-SHLIB_LINK += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
+SHLIB_LINK_INTERNAL += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
 else
 rpathdir = $(python_libdir)
 SHLIB_LINK += $(python_libspec) $(python_additional_libs)
diff --git a/contrib/jsonb_plperl/Makefile b/contrib/jsonb_plperl/Makefile
@@ -27,7 +27,7 @@ ifeq ($(PORTNAME), win32)
 # these settings are the same as for plperl
 override CPPFLAGS += -DPLPERL_HAVE_UID_GID -Wno-comment
 # ... see silliness in plperl Makefile ...
-SHLIB_LINK += $(sort $(wildcard ../../src/pl/plperl/libperl*.a))
+SHLIB_LINK_INTERNAL += $(sort $(wildcard ../../src/pl/plperl/libperl*.a))
 else
 rpathdir = $(perl_archlibexp)/CORE
 SHLIB_LINK += $(perl_embed_ldflags)
diff --git a/contrib/jsonb_plpython/Makefile b/contrib/jsonb_plpython/Makefile
@@ -26,7 +26,7 @@ endif
 # We must link libpython explicitly
 ifeq ($(PORTNAME), win32)
 # ... see silliness in plpython Makefile ...
-SHLIB_LINK += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
+SHLIB_LINK_INTERNAL += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
 else
 rpathdir = $(python_libdir)
 SHLIB_LINK += $(python_libspec) $(python_additional_libs)
diff --git a/contrib/ltree_plpython/Makefile b/contrib/ltree_plpython/Makefile
@@ -26,7 +26,7 @@ endif
 # We must link libpython explicitly
 ifeq ($(PORTNAME), win32)
 # ... see silliness in plpython Makefile ...
-SHLIB_LINK += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
+SHLIB_LINK_INTERNAL += $(sort $(wildcard ../../src/pl/plpython/libpython*.a))
 else
 rpathdir = $(python_libdir)
 SHLIB_LINK += $(python_libspec) $(python_additional_libs)
diff --git a/contrib/oid2name/Makefile b/contrib/oid2name/Makefile
@@ -7,7 +7,7 @@ PROGRAM = oid2name
 OBJS	= oid2name.o $(WIN32RES)
 
 PG_CPPFLAGS = -I$(libpq_srcdir)
-PG_LIBS = $(libpq_pgport)
+PG_LIBS_INTERNAL = $(libpq_pgport)
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
diff --git a/contrib/postgres_fdw/Makefile b/contrib/postgres_fdw/Makefile
@@ -5,7 +5,7 @@ OBJS = postgres_fdw.o option.o deparse.o connection.o shippable.o $(WIN32RES)
 PGFILEDESC = "postgres_fdw - foreign data wrapper for PostgreSQL"
 
 PG_CPPFLAGS = -I$(libpq_srcdir)
-SHLIB_LINK = $(libpq)
+SHLIB_LINK_INTERNAL = $(libpq)
 
 EXTENSION = postgres_fdw
 DATA = postgres_fdw--1.0.sql
diff --git a/contrib/spi/Makefile b/contrib/spi/Makefile
@@ -17,8 +17,6 @@ DOCS = $(addsuffix .example, $(MODULES))
 # comment out if you want a quieter refint package for other uses
 PG_CPPFLAGS = -DREFINT_VERBOSE
 
-LDFLAGS_SL += -L$(top_builddir)/src/port -lpgport
-
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)
diff --git a/contrib/vacuumlo/Makefile b/contrib/vacuumlo/Makefile
@@ -7,7 +7,7 @@ PROGRAM = vacuumlo
 OBJS	= vacuumlo.o $(WIN32RES)
 
 PG_CPPFLAGS = -I$(libpq_srcdir)
-PG_LIBS = $(libpq_pgport)
+PG_LIBS_INTERNAL = $(libpq_pgport)
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
@@ -290,17 +290,26 @@ LLVM_LIBS=@LLVM_LIBS@
 LD = @LD@
 with_gnu_ld = @with_gnu_ld@
 
-# We want -L for libpgport.a and libpgcommon.a to be first in LDFLAGS.  We
-# also need LDFLAGS to be a "recursively expanded" variable, else adjustments
-# to rpathdir don't work right.  So we must NOT do LDFLAGS := something,
-# meaning this has to be done first and elsewhere we must only do LDFLAGS +=
-# something.
+# It's critical that within LDFLAGS, all -L switches pointing to build-tree
+# directories come before any -L switches pointing to external directories.
+# Otherwise it's possible for, e.g., a platform-provided copy of libpq.so
+# to get linked in place of the one we've built.  Therefore we adopt the
+# convention that the first component of LDFLAGS is an extra variable
+# LDFLAGS_INTERNAL, and -L and -l switches for PG's own libraries must be
+# put into LDFLAGS_INTERNAL, so they will appear ahead of those for external
+# libraries.
+#
+# We need LDFLAGS and LDFLAGS_INTERNAL to be "recursively expanded" variables,
+# else adjustments to, e.g., rpathdir don't work right.  So we must NOT do
+# "LDFLAGS := something" anywhere, ditto for LDFLAGS_INTERNAL.
+# These initial assignments must be "=" type, and elsewhere we must only do
+# "LDFLAGS += something" or "LDFLAGS_INTERNAL += something".
 ifdef PGXS
-  LDFLAGS = -L$(libdir)
+  LDFLAGS_INTERNAL = -L$(libdir)
 else
-  LDFLAGS = -L$(top_builddir)/src/port -L$(top_builddir)/src/common
+  LDFLAGS_INTERNAL = -L$(top_builddir)/src/port -L$(top_builddir)/src/common
 endif
-LDFLAGS += @LDFLAGS@
+LDFLAGS = $(LDFLAGS_INTERNAL) @LDFLAGS@
 
 LDFLAGS_EX = @LDFLAGS_EX@
 # LDFLAGS_SL might have already been assigned by calling makefile
diff --git a/src/Makefile.shlib b/src/Makefile.shlib
@@ -20,12 +20,16 @@
 #
 # NAME                  Name of library to build (no suffix nor "lib" prefix)
 # OBJS                  List of object files to include in library
-# SHLIB_LINK            If shared library relies on other libraries,
-#                       additional stuff to put in its link command
+# SHLIB_LINK            Stuff to append to library's link command
+#                       (typically, -L and -l switches for external libraries)
+# SHLIB_LINK_INTERNAL   -L and -l switches for Postgres-supplied libraries
 # SHLIB_PREREQS         Order-only prerequisites for library build target
 # SHLIB_EXPORTS         (optional) Name of file containing list of symbols to
 #                       export, in the format "function_name  number"
 #
+# Don't use SHLIB_LINK for references to files in the build tree, or the
+# wrong things will happen --- use SHLIB_LINK_INTERNAL for those!
+#
 # When building a shared library, the following version information
 # must also be set.  It should be omitted when building a dynamically
 # loadable module.
@@ -70,6 +74,8 @@
 COMPILER = $(CC) $(CFLAGS)
 LINK.static = $(AR) $(AROPT)
 
+LDFLAGS_INTERNAL += $(SHLIB_LINK_INTERNAL)
+
 
 
 ifdef SO_MAJOR_VERSION
diff --git a/src/backend/replication/libpqwalreceiver/Makefile b/src/backend/replication/libpqwalreceiver/Makefile
@@ -15,7 +15,8 @@ include $(top_builddir)/src/Makefile.global
 override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
 
 OBJS = libpqwalreceiver.o $(WIN32RES)
-SHLIB_LINK = $(libpq) $(filter -lintl, $(LIBS))
+SHLIB_LINK_INTERNAL = $(libpq)
+SHLIB_LINK = $(filter -lintl, $(LIBS))
 SHLIB_PREREQS = submake-libpq
 PGFILEDESC = "libpqwalreceiver - receive WAL during streaming replication"
 NAME = libpqwalreceiver
diff --git a/src/bin/initdb/Makefile b/src/bin/initdb/Makefile
@@ -19,7 +19,7 @@ include $(top_builddir)/src/Makefile.global
 override CPPFLAGS := -DFRONTEND -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(CPPFLAGS)
 
 # note: we need libpq only because fe_utils does
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 # use system timezone data?
 ifneq (,$(with_system_tzdata))
diff --git a/src/bin/pg_basebackup/Makefile b/src/bin/pg_basebackup/Makefile
@@ -19,7 +19,7 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 OBJS=receivelog.o streamutil.o walmethods.o $(WIN32RES)
 
diff --git a/src/bin/pg_ctl/Makefile b/src/bin/pg_ctl/Makefile
@@ -20,7 +20,7 @@ include $(top_builddir)/src/Makefile.global
 # but let's not pull that in on platforms where we don't need it.
 ifeq ($(PORTNAME), win32)
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += $(libpq_pgport)
 SUBMAKE_LIBPQ := submake-libpq
 endif
 
diff --git a/src/bin/pg_dump/Makefile b/src/bin/pg_dump/Makefile
@@ -17,7 +17,7 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 OBJS=	pg_backup_archiver.o pg_backup_db.o pg_backup_custom.o \
 	pg_backup_null.o pg_backup_tar.o pg_backup_directory.o \
diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
@@ -16,7 +16,7 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
-override LDFLAGS := $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
 	fetch.o file_ops.o copy_fetch.o libpq_fetch.o filemap.o logging.o \
diff --git a/src/bin/pg_upgrade/Makefile b/src/bin/pg_upgrade/Makefile
@@ -12,7 +12,7 @@ OBJS = check.o controldata.o dump.o exec.o file.o function.o info.o \
        tablespace.o util.o version.o $(WIN32RES)
 
 override CPPFLAGS := -DDLSUFFIX=\"$(DLSUFFIX)\" -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 
 all: pg_upgrade
diff --git a/src/bin/pgbench/Makefile b/src/bin/pgbench/Makefile
@@ -10,7 +10,7 @@ include $(top_builddir)/src/Makefile.global
 OBJS = pgbench.o exprparse.o $(WIN32RES)
 
 override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 ifneq ($(PORTNAME), win32)
 override CFLAGS += $(PTHREAD_CFLAGS)
diff --git a/src/bin/psql/Makefile b/src/bin/psql/Makefile
@@ -19,7 +19,7 @@ include $(top_builddir)/src/Makefile.global
 REFDOCDIR= $(top_srcdir)/doc/src/sgml/ref
 
 override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 OBJS=	command.o common.o copy.o crosstabview.o \
 	describe.o help.o input.o large_obj.o mainloop.o \
diff --git a/src/bin/scripts/Makefile b/src/bin/scripts/Makefile
@@ -19,7 +19,7 @@ include $(top_builddir)/src/Makefile.global
 PROGRAMS = createdb createuser dropdb dropuser clusterdb vacuumdb reindexdb pg_isready
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 all: $(PROGRAMS)
 
diff --git a/src/common/Makefile b/src/common/Makefile
@@ -24,12 +24,9 @@ subdir = src/common
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -DFRONTEND $(CPPFLAGS)
-LIBS += $(PTHREAD_LIBS)
-
 # don't include subdirectory-path-dependent -I and -L switches
 STD_CPPFLAGS := $(filter-out -I$(top_srcdir)/src/include -I$(top_builddir)/src/include,$(CPPFLAGS))
-STD_LDFLAGS := $(filter-out -L$(top_builddir)/src/port,$(LDFLAGS))
+STD_LDFLAGS := $(filter-out -L$(top_builddir)/src/common -L$(top_builddir)/src/port,$(LDFLAGS))
 override CPPFLAGS += -DVAL_CONFIGURE="\"$(configure_args)\""
 override CPPFLAGS += -DVAL_CC="\"$(CC)\""
 override CPPFLAGS += -DVAL_CPPFLAGS="\"$(STD_CPPFLAGS)\""
@@ -40,6 +37,9 @@ override CPPFLAGS += -DVAL_LDFLAGS_EX="\"$(LDFLAGS_EX)\""
 override CPPFLAGS += -DVAL_LDFLAGS_SL="\"$(LDFLAGS_SL)\""
 override CPPFLAGS += -DVAL_LIBS="\"$(LIBS)\""
 
+override CPPFLAGS := -DFRONTEND $(CPPFLAGS)
+LIBS += $(PTHREAD_LIBS)
+
 OBJS_COMMON = base64.o config_info.o controldata_utils.o exec.o ip.o \
 	keywords.o md5.o pg_lzcompress.o pgfnames.o psprintf.o relpath.o \
 	rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
diff --git a/src/interfaces/ecpg/compatlib/Makefile b/src/interfaces/ecpg/compatlib/Makefile
@@ -22,8 +22,8 @@ override CPPFLAGS := -I../include -I$(top_srcdir)/src/interfaces/ecpg/include \
 	-I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 override CFLAGS += $(PTHREAD_CFLAGS)
 
-SHLIB_LINK = -L../ecpglib -lecpg -L../pgtypeslib -lpgtypes $(libpq) \
-	$(filter -lintl -lm, $(LIBS)) $(PTHREAD_LIBS)
+SHLIB_LINK_INTERNAL = -L../ecpglib -lecpg -L../pgtypeslib -lpgtypes $(libpq)
+SHLIB_LINK = $(filter -lintl -lm, $(LIBS)) $(PTHREAD_LIBS)
 SHLIB_PREREQS = submake-ecpglib submake-pgtypeslib
 
 SHLIB_EXPORTS = exports.txt
diff --git a/src/interfaces/ecpg/ecpglib/Makefile b/src/interfaces/ecpg/ecpglib/Makefile
@@ -35,7 +35,8 @@ ifneq ($(PORTNAME), win32)
 OBJS += thread.o
 endif
 
-SHLIB_LINK = -L../pgtypeslib -lpgtypes $(libpq) $(filter -lintl -lm, $(LIBS)) $(PTHREAD_LIBS)
+SHLIB_LINK_INTERNAL = -L../pgtypeslib -lpgtypes $(libpq)
+SHLIB_LINK = $(filter -lintl -lm, $(LIBS)) $(PTHREAD_LIBS)
 SHLIB_PREREQS = submake-libpq submake-pgtypeslib
 
 SHLIB_EXPORTS = exports.txt
diff --git a/src/interfaces/ecpg/pgtypeslib/Makefile b/src/interfaces/ecpg/pgtypeslib/Makefile
@@ -25,7 +25,7 @@ override CFLAGS += $(PTHREAD_CFLAGS)
 # Need to recompile any libpgport object files
 LIBS := $(filter-out -lpgport, $(LIBS))
 
-SHLIB_LINK += -lm
+SHLIB_LINK += $(filter -lm, $(LIBS))
 
 SHLIB_EXPORTS = exports.txt
 
diff --git a/src/interfaces/ecpg/test/Makefile.regress b/src/interfaces/ecpg/test/Makefile.regress
@@ -5,8 +5,9 @@ override CPPFLAGS := -I../../include -I$(top_srcdir)/src/interfaces/ecpg/include
 	-I$(libpq_srcdir) $(CPPFLAGS)
 override CFLAGS += $(PTHREAD_CFLAGS)
 
-override LDFLAGS := -L../../ecpglib -L../../pgtypeslib $(filter-out -l%, $(libpq)) $(LDFLAGS)
-override LIBS := -lecpg -lpgtypes $(filter -l%, $(libpq)) $(LIBS) $(PTHREAD_LIBS)
+LDFLAGS_INTERNAL += -L../../ecpglib -lecpg -L../../pgtypeslib -lpgtypes $(libpq)
+
+override LIBS += $(PTHREAD_LIBS)
 
 # Standard way to invoke the ecpg preprocessor
 ECPG = ../../preproc/ecpg --regression -I$(srcdir)/../../include -I$(srcdir)
diff --git a/src/interfaces/ecpg/test/compat_informix/Makefile b/src/interfaces/ecpg/test/compat_informix/Makefile
@@ -6,8 +6,7 @@ include $(top_srcdir)/$(subdir)/../Makefile.regress
 # Use special informix compatibility switch for all tests in this directory
 ECPG += -C INFORMIX
 
-override LDFLAGS := -L../../compatlib $(LDFLAGS)
-override LIBS := -lecpg_compat $(LIBS)
+LDFLAGS_INTERNAL += -L../../compatlib -lecpg_compat
 
 TESTS = test_informix test_informix.c \
         test_informix2 test_informix2.c \
diff --git a/src/interfaces/libpq/test/Makefile b/src/interfaces/libpq/test/Makefile
@@ -3,11 +3,11 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 ifeq ($(PORTNAME), win32)
-LDLIBS += -lws2_32
+LDFLAGS += -lws2_32
 endif
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDLIBS := $(libpq_pgport) $(LDLIBS)
+LDFLAGS_INTERNAL += $(libpq_pgport)
 
 PROGS = uri-regress
 
diff --git a/src/makefiles/pgxs.mk b/src/makefiles/pgxs.mk
@@ -45,7 +45,9 @@
 #   EXTRA_CLEAN -- extra files to remove in 'make clean'
 #   PG_CPPFLAGS -- will be added to CPPFLAGS
 #   PG_LIBS -- will be added to PROGRAM link line
+#   PG_LIBS_INTERNAL -- same, for references to libraries within build tree
 #   SHLIB_LINK -- will be added to MODULE_big link line
+#   SHLIB_LINK_INTERNAL -- same, for references to libraries within build tree
 #   PG_CONFIG -- path to pg_config program for the PostgreSQL installation
 #     to build against (typically just "pg_config" to use the first one in
 #     your PATH)
@@ -315,5 +317,5 @@ endif
 
 ifdef PROGRAM
 $(PROGRAM): $(OBJS)
-	$(CC) $(CFLAGS) $(OBJS) $(PG_LIBS) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
+	$(CC) $(CFLAGS) $(OBJS) $(PG_LIBS_INTERNAL) $(LDFLAGS) $(LDFLAGS_EX) $(PG_LIBS) $(LIBS) -o $@$(X)
 endif
diff --git a/src/test/examples/Makefile b/src/test/examples/Makefile
@@ -7,11 +7,11 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 ifeq ($(PORTNAME), win32)
-LDLIBS += -lws2_32
+LDFLAGS += -lws2_32
 endif
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDLIBS := $(libpq_pgport) $(LDLIBS)
+LDFLAGS_INTERNAL += $(libpq_pgport)
 
 
 PROGS = testlibpq testlibpq2 testlibpq3 testlibpq4 testlo testlo64
diff --git a/src/tools/findoidjoins/Makefile b/src/tools/findoidjoins/Makefile
@@ -13,7 +13,7 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
-override LDFLAGS := $(libpq_pgport) $(LDFLAGS)
+LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS= findoidjoins.o
 
