Re: [PATCH bpf] libbpf: fix version identification on busybox

[Ivan Khoronzhuk]

On Fri, Sep 20, 2019 at 09:41:54AM -0700, Andrii Nakryiko wrote:
> On Fri, Sep 20, 2019 at 1:22 AM Ivan Khoronzhuk
> <ivan.khoronzhuk@xxxxxxxxxx> wrote:
> > On Thu, Sep 19, 2019 at 01:02:40PM -0700, Andrii Nakryiko wrote:
> > >On Thu, Sep 19, 2019 at 11:22 AM Ivan Khoronzhuk
> > ><ivan.khoronzhuk@xxxxxxxxxx> wrote:
> > >>
> > >> It's very often for embedded to have stripped version of sort in
> > >> busybox, when no -V option present. It breaks build natively on target
> > >> board causing recursive loop.
> > >>
> > >> BusyBox v1.24.1 (2019-04-06 04:09:16 UTC) multi-call binary. \
> > >> Usage: sort [-nrugMcszbdfimSTokt] [-o FILE] [-k \
> > >> start[.offset][opts][,end[.offset][opts]] [-t CHAR] [FILE]...
> > >>
> > >> Lets modify command a little to avoid -V option.
> > >>
> > >> Fixes: dadb81d0afe732 ("libbpf: make libbpf.map source of truth for libbpf version")
> > >>
> > >> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> > >> ---
> > >>
> > >> Based on bpf/master
> > >>
> > >>  tools/lib/bpf/Makefile | 2 +-
> > >>  1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> > >> index c6f94cffe06e..a12490ad6215 100644
> > >> --- a/tools/lib/bpf/Makefile
> > >> +++ b/tools/lib/bpf/Makefile
> > >> @@ -3,7 +3,7 @@
> > >>
> > >>  LIBBPF_VERSION := $(shell \
> > >>         grep -oE '^LIBBPF_([0-9.]+)' libbpf.map | \
> > >> -       sort -rV | head -n1 | cut -d'_' -f2)
> > >> +       cut -d'_' -f2 | sort -r | head -n1)
> > >
> > >You can't just sort alphabetically, because:
> > >
> > >1.2
> > >1.11
> > >
> > >should be in that order. See discussion on mailing thread for original commit.
> >
> > if X1.X2.X3, where X = {0,1,....99999}
> > Then it can be:
> >
> > -LIBBPF_VERSION := $(shell \
> > -       grep -oE '^LIBBPF_([0-9.]+)' libbpf.map | \
> > -       sort -rV | head -n1 | cut -d'_' -f2)
> > +_LBPFLIST := $(patsubst %;,%,$(patsubst LIBBPF_%,%,$(filter LIBBPF_%, \
> > +           $(shell cat libbpf.map))))
> > +_LBPFLIST2 := $(foreach v,$(_LBPFLIST), \
> > +               $(subst $() $(),,$(foreach n,$(subst .,$() $(),$(v)), \
> > +                       $(shell printf "%05d" $(n)))))
> > +_LBPF_VER := $(word $(words $(sort $(_LBPFLIST2))), $(sort $(_LBPFLIST2)))
> > +LIBBPF_VERSION := $(patsubst %_$(_LBPF_VER),%,$(filter %_$(_LBPF_VER), \
> > +        $(join $(addsuffix _, $(_LBPFLIST)),$(_LBPFLIST2))))
> >
> > It's bigger but avoids invocations of grep/sort/cut/head, only cat/printf
> > , thus -V option also.
>
> No way, this is way too ugly (and still unreliable, if we ever have
> X.Y.Z.W or something). I'd rather go with my original approach of
Yes, forgot to add
X1,X2,X3,...XN, where X = {0,1,....99999} and N = const for all versions.
But frankly, 1.0.0 looks too far.

> fetching the last version in libbpf.map file. See
> https://www.spinics.net/lists/netdev/msg592703.html.
>
> > >
> > >>  LIBBPF_MAJOR_VERSION := $(firstword $(subst ., ,$(LIBBPF_VERSION)))
> > >>
> > >>  MAKEFLAGS += --no-print-directory
> > >> --
> > >> 2.17.1
> > >>
> >
> > --
> > Regards,
> > Ivan Khoronzhuk

--
Regards,
Ivan Khoronzhuk