From: Michael R. Crusoe <crusoe@debian.org>
Subject: Add missing references to LDFLAGS and CPPFLAGS
Forwarded: https://sourceforge.net/p/snap7/discussion/bugfix/thread/7934ab5ba4/

Debian sets these to harden the build: https://wiki.debian.org/Hardening
--- snap7.orig/build/unix/common.mk
+++ snap7/build/unix/common.mk
@@ -50,7 +50,7 @@
 	@$(MakeDirCommand) $(@D)
 	@$(MakeDirCommand) $(IntermediateDirectory)
 	@echo $(Objects0)  > $(ObjectsFileList)
-	$(SharedObjectLinkerName) $(OutputSwitch)$(OutputFile) @$(ObjectsFileList) $(LibPath) $(Libs) $(LinkOptions)
+	$(SharedObjectLinkerName) $(LDFLAGS) $(OutputSwitch)$(OutputFile) @$(ObjectsFileList) $(LibPath) $(Libs) $(LinkOptions)
 	$(RM) $(ObjectsFileList)
 
 $(IntermediateDirectory)/.d:
@@ -64,40 +64,40 @@
 ## Objects
 ##
 $(IntermediateDirectory)/sys_snap_msgsock.o: 
-	$(CXX) $(SourceSwitch) "../../src/sys/snap_msgsock.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/sys_snap_msgsock.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/sys/snap_msgsock.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/sys_snap_msgsock.o $(IncludePath)
 
 $(IntermediateDirectory)/sys_snap_sysutils.o:
-	$(CXX) $(SourceSwitch) "../../src/sys/snap_sysutils.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/sys_snap_sysutils.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/sys/snap_sysutils.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/sys_snap_sysutils.o $(IncludePath)
 
 $(IntermediateDirectory)/sys_snap_tcpsrvr.o:
-	$(CXX) $(SourceSwitch) "../../src/sys/snap_tcpsrvr.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/sys_snap_tcpsrvr.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/sys/snap_tcpsrvr.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/sys_snap_tcpsrvr.o $(IncludePath)
 
 $(IntermediateDirectory)/sys_snap_threads.o:
-	$(CXX) $(SourceSwitch) "../../src/sys/snap_threads.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/sys_snap_threads.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/sys/snap_threads.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/sys_snap_threads.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_client.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_client.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_client.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_client.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_client.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_isotcp.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_isotcp.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_isotcp.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_isotcp.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_isotcp.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_partner.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_partner.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_partner.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_partner.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_partner.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_peer.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_peer.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_peer.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_peer.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_peer.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_server.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_server.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_server.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_server.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_server.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_text.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_text.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_text.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_text.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_text.o $(IncludePath)
 
 $(IntermediateDirectory)/core_s7_micro_client.o:
-	$(CXX) $(SourceSwitch) "../../src/core/s7_micro_client.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/core_s7_micro_client.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/core/s7_micro_client.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/core_s7_micro_client.o $(IncludePath)
 
 $(IntermediateDirectory)/lib_snap7_libmain.o:
-	$(CXX) $(SourceSwitch) "../../src/lib/snap7_libmain.cpp" $(CXXFLAGS) -o $(IntermediateDirectory)/lib_snap7_libmain.o $(IncludePath)
+	$(CXX) $(SourceSwitch) "../../src/lib/snap7_libmain.cpp" $(CXXFLAGS) $(CPPFLAGS) -o $(IntermediateDirectory)/lib_snap7_libmain.o $(IncludePath)
 
 ##
 ## Clean / Install
