Re: [PATCH 2/2] commit-graph tests: fix cryptic unportable "dd" invocation
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Feb 22, 2019, 18:30 UTC
- Message-ID
- <xmqqbm33r7zl.fsf@gitster-ct.c.googlers.com>
- In-Reply-To
- <8736of6gej.fsf@evledraar.gmail.com>
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> It was my reading of the seek=* section ("the implementation shall seek
> to the specified offset"). I didn't spot that bit covered in of=*. Yeah,
> I see that's defined & safe after reading that.OK, so...
-- >8 -- From: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Date: Thu, 21 Feb 2019 20:28:49 +0100 Subject: [PATCH] commit-graph tests: fix cryptic unportable "dd" invocation
Change an unportable invocation of "dd" with count=0, that wanted to truncate the commit-graph file. In POSIX it is unspecified what happens when count=0 is provided[1]. The NetBSD "dd" behavior differs from GNU (and seemingly other BSDs), which as left this test broken since d2b86fbaa1 ("commit-graph: fix buffer read-overflow", 2019-01-15).
Copying from /dev/null would seek/truncate to seek=$zero_pos and stop immediately after that (without being able to copy anything), which is the right way to truncate the file.
1. http://pubs.opengroup.org/onlinepubs/9699919799/utilities/dd.html
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Helped-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> --- t/t5318-commit-graph.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index d4bd1522fe..561796f280 100755 --- a/t/t5318-commit-graph.sh +++ b/t/t5318-commit-graph.sh @@ -382,7 +382,7 @@ corrupt_graph_and_verify() { test_when_finished mv commit-graph-backup $objdir/info/commit-graph && cp $objdir/info/commit-graph commit-graph-backup && printf "$data" | dd of="$objdir/info/commit-graph" bs=1 seek="$pos" conv=notrunc && - dd of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" count=0 && + dd of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" if=/dev/null && generate_zero_bytes $(($orig_size - $zero_pos)) >>"$objdir/info/commit-graph" && test_must_fail git commit-graph verify 2>test_err && grep -v "^+" test_err >err &&
-- 2.21.0-rc2