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

[Ivan Khoronzhuk]

On Fri, Sep 20, 2019 at 09:34:51PM +0300, Ivan Khoronzhuk wrote:
> 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.

It actually works for any numbs of X1.X2...X100
but not when you have couple kindof:
X1.X2.X3
and
X1.X2.X3.X4

But, no absolutely any problem to extend this solution to handle all cases,
by just adding leading 0 to every "transformed version", say limit it to 10
possible 'dots' (%5*10d) and it will work as clocks. Advantage - mostly make
functions.

Here can be couple more solutions with sed, not sure it can look less maniac.

> > fetching the last version in libbpf.map file. See
> > https://www.spinics.net/lists/netdev/msg592703.html.

Yes it's nice but, no sort, no X1.X2.X3....XN

Main is to solve it for a long time.

> > > > >  LIBBPF_MAJOR_VERSION := $(firstword $(subst ., ,$(LIBBPF_VERSION)))
> > > > >
> > > > >  MAKEFLAGS += --no-print-directory
> > > > > --
> > > > > 2.17.1
> > >
> > > --
> > > Regards,
> > > Ivan Khoronzhuk
>
> --
> Regards,
> Ivan Khoronzhuk

--
Regards,
Ivan Khoronzhuk