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

From: Ivan Khoronzhuk
Date: Fri Sep 20 2019 - 16:48:32 EST


On Fri, Sep 20, 2019 at 10:19:43PM +0300, Ivan Khoronzhuk wrote:
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.

_LBPFLIST := $(subst ;,,$(patsubst LIBBPF_%,%,$(filter LIBBPF_%, \
$(shell cat libbpf.map))))
_LBPF2 := $(foreach v,$(_LBPFLIST), \
$(subst $() $(),,$(foreach n,$(subst ., ,$(v)), \
$(shell printf "%05d" $(n)))))
_LBPF2 := $(foreach v,$(_LBPF2), $(shell printf "%050s" $(v)))
_LBPF_VER := $(word $(words $(sort $(_LBPF2))), $(sort $(_LBPF2)))
LIBBPF_VERSION := $(patsubst %_$(_LBPF_VER),%,$(filter %_$(_LBPF_VER), \
$(join $(addsuffix _, $(_LBPFLIST)),$(_LBPF2))))

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

--
Regards,
Ivan Khoronzhuk