diff --git a/src/interfaces/ecpg/compatlib/.gitignore b/src/interfaces/ecpg/compatlib/.gitignore
index 6eb8a0dc069..ad5ba1354ca 100644
--- a/src/interfaces/ecpg/compatlib/.gitignore
+++ b/src/interfaces/ecpg/compatlib/.gitignore
@@ -2,3 +2,4 @@
 /blibecpg_compatdll.def
 /exports.list
 /snprintf.c
+/strnlen.c
diff --git a/src/interfaces/ecpg/compatlib/Makefile b/src/interfaces/ecpg/compatlib/Makefile
index 04ddcfeab2c..9ea5cf4ac4f 100644
--- a/src/interfaces/ecpg/compatlib/Makefile
+++ b/src/interfaces/ecpg/compatlib/Makefile
@@ -31,7 +31,7 @@ SHLIB_EXPORTS = exports.txt
 # Need to recompile any libpgport object files
 LIBS := $(filter-out -lpgport, $(LIBS))
 
-OBJS= informix.o $(filter snprintf.o, $(LIBOBJS)) $(WIN32RES)
+OBJS= informix.o $(filter snprintf.o strnlen.o, $(LIBOBJS)) $(WIN32RES)
 
 PKG_CONFIG_REQUIRES_PRIVATE = libecpg libpgtypes
 
@@ -48,7 +48,7 @@ submake-pgtypeslib:
 # Shared library stuff
 include $(top_srcdir)/src/Makefile.shlib
 
-snprintf.c: % : $(top_srcdir)/src/port/%
+snprintf.c strnlen.c: % : $(top_srcdir)/src/port/%
 	rm -f $@ && $(LN_S) $< .
 
 install: all installdirs install-lib
@@ -58,6 +58,6 @@ installdirs: installdirs-lib
 uninstall: uninstall-lib
 
 clean distclean: clean-lib
-	rm -f $(OBJS) snprintf.c
+	rm -f $(OBJS) snprintf.c strnlen.c
 
 maintainer-clean: distclean maintainer-clean-lib
diff --git a/src/interfaces/ecpg/ecpglib/.gitignore b/src/interfaces/ecpg/ecpglib/.gitignore
index 8ef6401dd0e..1619e970c29 100644
--- a/src/interfaces/ecpg/ecpglib/.gitignore
+++ b/src/interfaces/ecpg/ecpglib/.gitignore
@@ -5,6 +5,7 @@
 /pgstrcasecmp.c
 /snprintf.c
 /strlcpy.c
+/strnlen.c
 /thread.c
 /win32setlocale.c
 /isinf.c
diff --git a/src/interfaces/ecpg/ecpglib/Makefile b/src/interfaces/ecpg/ecpglib/Makefile
index fbb14073cef..0b0a3e28574 100644
--- a/src/interfaces/ecpg/ecpglib/Makefile
+++ b/src/interfaces/ecpg/ecpglib/Makefile
@@ -27,7 +27,8 @@ LIBS := $(filter-out -lpgport, $(LIBS))
 
 OBJS= execute.o typename.o descriptor.o sqlda.o data.o error.o prepare.o memory.o \
 	connect.o misc.o path.o pgstrcasecmp.o \
-	$(filter snprintf.o strlcpy.o win32setlocale.o isinf.o, $(LIBOBJS)) $(WIN32RES)
+	$(filter snprintf.o strlcpy.o strnlen.o win32setlocale.o isinf.o, $(LIBOBJS)) \
+	$(WIN32RES)
 
 # thread.c is needed only for non-WIN32 implementation of path.c
 ifneq ($(PORTNAME), win32)
@@ -55,7 +56,7 @@ include $(top_srcdir)/src/Makefile.shlib
 # necessarily use the same object files as the backend uses. Instead,
 # symlink the source files in here and build our own object file.
 
-path.c pgstrcasecmp.c snprintf.c strlcpy.c thread.c win32setlocale.c isinf.c: % : $(top_srcdir)/src/port/%
+path.c pgstrcasecmp.c snprintf.c strlcpy.c strnlen.c thread.c win32setlocale.c isinf.c: % : $(top_srcdir)/src/port/%
 	rm -f $@ && $(LN_S) $< .
 
 misc.o: misc.c $(top_builddir)/src/port/pg_config_paths.h
@@ -72,6 +73,6 @@ uninstall: uninstall-lib
 
 clean distclean: clean-lib
 	rm -f $(OBJS)
-	rm -f path.c pgstrcasecmp.c snprintf.c strlcpy.c thread.c win32setlocale.c isinf.c
+	rm -f path.c pgstrcasecmp.c snprintf.c strlcpy.c strnlen.c thread.c win32setlocale.c isinf.c
 
 maintainer-clean: distclean maintainer-clean-lib
diff --git a/src/interfaces/ecpg/pgtypeslib/.gitignore b/src/interfaces/ecpg/pgtypeslib/.gitignore
index fbcd68d7d3e..df46a79972d 100644
--- a/src/interfaces/ecpg/pgtypeslib/.gitignore
+++ b/src/interfaces/ecpg/pgtypeslib/.gitignore
@@ -4,3 +4,4 @@
 /pgstrcasecmp.c
 /rint.c
 /snprintf.c
+/strnlen.c
diff --git a/src/interfaces/ecpg/pgtypeslib/Makefile b/src/interfaces/ecpg/pgtypeslib/Makefile
index 9fc75661b53..960c26ae553 100644
--- a/src/interfaces/ecpg/pgtypeslib/Makefile
+++ b/src/interfaces/ecpg/pgtypeslib/Makefile
@@ -31,7 +31,8 @@ SHLIB_EXPORTS = exports.txt
 
 OBJS= numeric.o datetime.o common.o dt_common.o timestamp.o interval.o \
 	pgstrcasecmp.o \
-	$(filter rint.o snprintf.o, $(LIBOBJS)) $(WIN32RES)
+	$(filter rint.o snprintf.o strnlen.o, $(LIBOBJS)) \
+	$(WIN32RES)
 
 all: all-lib
 
@@ -43,7 +44,7 @@ include $(top_srcdir)/src/Makefile.shlib
 # necessarily use the same object files as the backend uses. Instead,
 # symlink the source files in here and build our own object file.
 
-pgstrcasecmp.c rint.c snprintf.c: % : $(top_srcdir)/src/port/%
+pgstrcasecmp.c rint.c snprintf.c strnlen.c: % : $(top_srcdir)/src/port/%
 	rm -f $@ && $(LN_S) $< .
 
 install: all installdirs install-lib
@@ -53,6 +54,6 @@ installdirs: installdirs-lib
 uninstall: uninstall-lib
 
 clean distclean: clean-lib
-	rm -f $(OBJS) pgstrcasecmp.c rint.c snprintf.c
+	rm -f $(OBJS) pgstrcasecmp.c rint.c snprintf.c strnlen.c
 
 maintainer-clean: distclean maintainer-clean-lib
diff --git a/src/interfaces/libpq/.gitignore b/src/interfaces/libpq/.gitignore
index 6c02dc70551..5c232ae2d11 100644
--- a/src/interfaces/libpq/.gitignore
+++ b/src/interfaces/libpq/.gitignore
@@ -18,6 +18,7 @@
 /snprintf.c
 /strerror.c
 /strlcpy.c
+/strnlen.c
 /thread.c
 /win32error.c
 /win32setlocale.c
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index 87f22d242fb..94eb84be030 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -38,7 +38,7 @@ OBJS=	fe-auth.o fe-auth-scram.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-l
 OBJS += chklocale.o inet_net_ntop.o noblock.o pgstrcasecmp.o pqsignal.o \
 	thread.o
 # libpgport C files that are needed if identified by configure
-OBJS += $(filter crypt.o getaddrinfo.o getpeereid.o inet_aton.o open.o system.o snprintf.o strerror.o strlcpy.o win32error.o win32setlocale.o, $(LIBOBJS))
+OBJS += $(filter crypt.o getaddrinfo.o getpeereid.o inet_aton.o open.o system.o snprintf.o strerror.o strlcpy.o strnlen.o win32error.o win32setlocale.o, $(LIBOBJS))
 
 ifeq ($(enable_strong_random), yes)
 OBJS += pg_strong_random.o
@@ -103,7 +103,7 @@ backend_src = $(top_srcdir)/src/backend
 # the module is needed (see filter hack in OBJS, above).
 # When you add a file here, remember to add it in the "clean" target below.
 
-chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c thread.c win32error.c win32setlocale.c: % : $(top_srcdir)/src/port/%
+chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c strnlen.c thread.c win32error.c win32setlocale.c: % : $(top_srcdir)/src/port/%
 	rm -f $@ && $(LN_S) $< .
 
 ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c: % : $(top_srcdir)/src/common/%
@@ -155,7 +155,7 @@ clean distclean: clean-lib
 # Might be left over from a Win32 client-only build
 	rm -f pg_config_paths.h
 # Remove files we (may have) symlinked in from src/port and other places
-	rm -f chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c thread.c win32error.c win32setlocale.c
+	rm -f chklocale.c crypt.c erand48.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pg_strong_random.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c strnlen.c thread.c win32error.c win32setlocale.c
 	rm -f ip.c md5.c base64.c scram-common.c sha2.c sha2_openssl.c saslprep.c unicode_norm.c
 	rm -f encnames.c wchar.c