With GNU Make, we can implement a fairly effective version check mechanism.
# *-*-* vim settings *-*-*# :set list ts=3# inspired from:# a) J. Cumming
make book# b ) O'Reilly Mecklenburg make book.# c ) Paul Smith GNU Make
author.
SHELL := /bin/sh
NULL := ONE := 1
SPC := $(NULL) $(NULL)TAB := $(NULL) $(NULL)DOT := .
TRUE := $(ONE)FALSE := $(NULL)
VALID_FALSE_VALUES := 0 -0 0. $(NULL) 0.0
[0-9] := 0 1 2 3 4 5 6 7 8 9
X16 := X X X XX16 += $(X16)X16 += $(X16)
define MAX_INT$(strip \ $(foreach i,$(X16), \
$(foreach j,$(X16), \ $(foreach
k,$(X16),$(X16)))))endef
# $(call encode,$1) converts a number to that many number of Xsencode =
$(wordlist 1,$1,$(MAX_INT))
# $(call boolify,$1) converts string to booleandefine boolify$(strip \ $(if
$1, \ $(if $(filter
$1,$(VALID_FALSE_VALUES)),\ $(FALSE),
\ $(TRUE)), \
$(FALSE)))endef
# $(call not,$1) invert the sense of a booleandefine not$(strip \ $(if
$(call boolify,$1),\ $(FALSE), \
$(TRUE)))endef
# $(call bool2num,$1) converts boolean to numberbool2num = $(words $(call
boolify,$1))
# $(call streq,$1,$2) string comparestreq = $(call not,$(subst
x$1,$(NULL),x$2)$(subst x$2,$(NULL),x$1))
# $(call max,$1,$2) maximum of two numbersdefine max$(strip \ $(words
\ $(subst XX,X, \ $(join
\ $(call encode,$1),\
$(call encode,$2)))))endef
# $(call gt,$1,$2) greater of two numbersgt = $(call boolify,$(filter-out
$2,$(call max,$1,$2)))
define strip_leading_0s$(strip \ $(if $(call streq,$(patsubst
00%,0%,$1),$1), \ $(if $(patsubst 0%,%,$1),
\ $(patsubst 0%,%,$1), \
0), \ $(call
strip_leading_0s,$(patsubst 00%,0%,$1))))endef
# $(call eq,$1,$2) compares equality of two numbersdefine eq$(strip \ $(if
$(filter $(call strip_leading_0s,$1),$(call strip_leading_0s,$2)),\
$(TRUE),\ $(FALSE)))endef
# $(call cmp,$1,$2) compare two numbersdefine cmp$(strip \ $(if $(call
eq,$1,$2), \ 0, \ $(if $(call
gt,$1,$2),\ 1, \ -1)))endef
# $(call v2w,$1) splits version string into its componentsv2w = $(subst
$(DOT),$(SPC),$1)
# $(call msd_ver,version_string)msd_ver = $(word 1,$(call v2w,$1))
# $(call remd_ver,version_string)remd_ver = $(wordlist 2,$(words $(call
v2w,$1)),$(call v2w,$1))
pack = $(subst $(SPC),$(NULL),$1)
# $(call _unpack,$1,$2)define _unpack$(strip \ $(if $(word 2,$1),
\ $(call _unpack,
\ $(wordlist 2,$(words $1),$1), \
$(subst $(word 1,$1),$(word 1,$1)$(SPC),$2)),\ $(subst $1,$1
,$2)))endef
# $(call unpack,$1)unpack = $(call _unpack,$([0-9]),$1)
strlen = $(words $(call unpack,$1))
msd3 = $(call pack,$(wordlist 1,3,$(call unpack,$1)))
rest = $(call pack,$(wordlist 4,$(words $(call unpack,$1)),$(call unpack,$1)))
define _norm_minor$(strip \ $(if $(call gt,$(call strlen,$1),3),$(call
strip_leading_0s,$(call msd3,$1))$(DOT)$(call _norm_minor,$(call rest,$1)),\
$(if $(call eq,$(call strlen,$1),1),$(call strip_leading_0s,$(1)00),\
$(if $(call eq,$(call strlen,$1),2),$(call
strip_leading_0s,$(1)0),\ $(call
strip_leading_0s,$1)))))endef
# $(call norm_minor,$1) normalize the minor version number incase of
major.minor onlydefine norm_minor$(strip \ $(if $(call gt,$(words $(call
v2w,$(call _norm_minor,$1))),1),\ $(call _norm_minor,$1),
\ $(call _norm_minor,$1).0))endef
define _normalize_ver$(strip \$(if $(word 2,$(call v2w,$1)),\ $(call
strip_leading_0s,$(call msd_ver,$1))$(DOT)$(call _normalize_ver,$(call
remd_ver,$1)),\ $(call strip_leading_0s,$1)))endef
define normalize_ver$(strip \$(if $(word 3,$(call v2w,$1)),\ $(call
_normalize_ver,$1),\ $(if $(word 2,$(call v2w,$1)),\ $(call
strip_leading_0s,$(word 1,$(call v2w,$1))).$(call norm_minor,$(word 2,$(call
v2w,$1))),\ $(call strip_leading_0s,$1).0.0)))endef
# $(call _cmpver,verstringA,verstringB)define _cmpver$(strip \ $(if $(call
msd_ver,$1), \ $(if $(call
msd_ver,$2), \
$(if $(call eq,$(call msd_ver,$1),$(call msd_ver,$2)), \
$(if $(call remd_ver,$1)$(call remd_ver,$2), \
$(call _cmpver,$(call remd_ver,$1),$(call
remd_ver,$2)),\ 0),
\ $(call cmp,$(call
msd_ver,$1),$(call msd_ver,$2))), \ $(if $(call
eq,$(call msd_ver,$1),0), \
$(if $(call remd_ver,$1), \
$(call _cmpver,$(call remd_ver,$1),), \
0),
\ 1)),
\ $(if $(call msd_ver,$2),
\ $(if $(call eq,$(call msd_ver,$2),0),
\ $(if $(call remd_ver,$2)
, \ $(call
_cmpver,,$(call remd_ver,$2)), \
0), \
-1))))endef
# $(call cmpver,verstringA,verstringB)cmpver = $(call _cmpver,$(call
normalize_ver,$1),$(call normalize_ver,$2))
# $(call version_ge,verstringA,verstringB)version_ge = $(if $(call eq,$(call
cmpver,$2,$1),1),$(FALSE),$(TRUE))
#i := 002 2 2.3 2.3.0 2.03 2.03.2 2.03.0 04.3 004.03 04.3.2 04.3.0 5.2.300#i :=
5.2.3000123#i := 0.2 0.02 0.00002 0.00002.1 0.00002.0 0.00002#i :=
0.0002.1.002423.42343242.0000000#i := 2.3#i := 43#i := 2 02 002 20 200 0 00 000
0000 000000000000#########################
> From: david.aldr...@emea.nec.com
> To: help-make@gnu.org
> Subject: How to switch behaviour according to glibc version?
> Date: Tue, 5 Apr 2016 08:54:01 +0000
>
> Hi
>
> I am running gnu make 4.1 on Ubuntu. Make builds my C++ application that
> requires glibc 2.22 or higher. Ubuntu 14.04 has only glibc 2.19 so my
> makefile checks the host o/s and, if it's Ubuntu, it links to my private copy
> of glibc 2.22:
>
> GLIBC_FLAGS=
> ifeq ($(DISTRO),debian)
> echo "Warning: detected Ubuntu o/s so using different glibc to that
> installed on this system"
> GLIBC=$(MY_OPEN_SOURCE_LIBS)/glibc/v2_22/
> GLIBC_FLAGS=
> -Wl,-rpath=${GLIBC}:${GLIBC}/math:${GLIBC}/elf:${GLIBC}/dlfcn:${GLIBC}/nss:${GLIBC}/nis:${GLIBC}/rt:${GLIBC}/resolv:${GLIBC}/crypt:${GLIBC}/nptl\
> -Wl,--dynamic-linker=${GLIBC}/elf/ld.so
> endif
>
> Now, Ubuntu 16.04 has glibc 2.23, so there I can use the standard glibc
> packaged for the o/s. So I want to change the makefile code to only use my
> private copy of glibc if glibc is <2.22.
>
> I'm not sure whether it's best to detect the o/s version or the glibc
> version. I can do the latter with:
>
> ~$ ldd --version
> ldd (Ubuntu GLIBC 2.23-0ubuntu2) 2.23
> Copyright (C) 2016 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> Written by Roland McGrath and Ulrich Drepper.
>
> My question is, how can I extract the glibc version number from that ldd
> response and use it in my makefile to only set GLIBC and GLIBC_FLAGS if the
> glibc version is <2.22?
>
> Best regards
>
> David
>
> _______________________________________________
> Help-make mailing list
> Help-make@gnu.org
> https://lists.gnu.org/mailman/listinfo/help-make
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