How can I identify my build platform properly?

Question

I want to know a parameter which is an indicator of the current OS. If am supporting Windows and Linux, how can I get a system parameter which differentiates the OS types. This for an OS independent makefile which runs both in Windows and Linux by checking the parameter in an 'if'.

Answer 1

In the past I've checked the value of the environment variable OS. This is set on Windows. For other platforms I've explicitly set it in the environment. This then lets you push platform specific settings into makefiles called ...

makefile.Windows_NT
makefile.Linux
makefile.HPUX

In my main makefile I then just do

SUPPORTED_PLATFORMS=Windows_NT AIX AIX32 Solaris8 Linux HPUX Solaris_64

ifeq (,$(findstring $(OS),$(SUPPORTED_PLATFORMS)))

all %:
        @echo The OS environment variable is set to [$(OS)].
        @echo Please set the OS environment variable to one of the following:
        @echo $(SUPPORTED_PLATFORMS)

else


include makefile.$(OS)


all:
        @$(TCLSH) makefile.tcl
        @$(MAKE) -f makefile.gen


clean:
        @$(TCLSH) makefile.tcl
        @$(MAKE) -f makefile.gen clean
        @$(RM) makefile.gen

etags:
        @$(RM) TAGS
        @etags *.cpp *.h TAGS
        @$(MAKE) -C Core etags
        @$(MAKE) -C Components etags
        @$(MAKE) -C Repository etags

tags: ctags

ctags:
        @ctags *.h
        @$(MAKE) -C Core ctags
        @$(MAKE) -C Components ctags
        @$(MAKE) -C Repository ctags

lint:
        @$(TCLSH) makefile.tcl
        @$(MAKE) -f makefile.gen lint

depends:
        @$(TCLSH) makefile.tcl
        @$(MAKE) -f makefile.gen depends

endif

This all works because I can pull in the platform specific settings via makefile.$(OS)

That's the sum total of my main makefile and it compiles for seven different platforms. You could make the detection cleverer but that would reduce comprehensability.

In each makefile.WHATEVER I provide definitions of things like

#*******************************************************************************
#
#   Platform specific tools
#
CC              = CL
RM              = rm
LINK            = LINK
ETAGS           = c:\emacs\bin\etags
TCLSH           = tclsh83

#*******************************************************************************
#
#   Platform specific CC definitions
#
INCLUDE := $(SYS_INCDIR);$(INCLUDE);$(SOURCE_ROOT_DIR)/SivTech/cpp;$(ORACLE_INCDIR);$(DB2_INCDIR);$(ODBC_INCDIR);$(MYSQL_INCDIR);$(TCL_INCDIR);$(XML_INCDIR);$(XSLT_INCDIR);$(JNI_INCLUDE);$(ACE_INCDIR);$(TAO_INCDIR);$(TAO_SERVICES_INC);$(CPPUNIT_INCDIR);$(ICU_INCDIR);$(SAP_INCDIR);$(QAS_INCDIR);$(INFA_INCDIR);$(MELISSADATA_INCDIR);$(ADDRESSDOCTOR_INCDIR)

CC_DEFS := $(CC_DEFS) -DOS_WIN_95 -D_WIN32_WINNT=0x400 -D_MBCS -DWIN32_LEAN_AND_MEAN -DWIN32 -DWIN32_EXTRA_LEAN $(CC_DEFINES)

CC_FLAGS_CMN    := /c /nologo /G7  /EHsc /W3  $(CC_FLAGS$) $(CC_DEFS) $(MYFLAGS)
CC_FLAGS_DBG    := $(CC_FLAGS_CMN) /Gi /MDd /Od /Zi /RTCu /RTCs /GZ

Obviously this is quite a C/C++ focus makefile but it proves that you can abstract away all of the platform specifics.

Chris

Answer 2

You may be interested in checking out: Pre-defined C/C++ Compiler Macros. It's a goldmine.