[PATCH 2/2] commit-graph tests: fix cryptic unportable "dd" invocation
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Feb 21, 2019, 19:28 UTC
- Message-ID
- <20190221192849.6581-3-avarab@gmail.com>
- In-Reply-To
- <xmqq8sybz7b2.fsf@gitster-ct.c.googlers.com>
Change an unportable invocation of "dd" that truncated the commit-graph to call Perl's truncate() function instead.
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).
In POSIX the truncate(2) and ftruncate(2) functions are portable. We've used the latter since 271421cd34 ("Update partial HTTP transfers.", 2005-09-30), but the truncate(1) command-line tool is GNU-specific. Thus let's use Perl's version of it. We could also just introduce a "test-tool truncate" in the future if we wanted to avoid shelling out to perl.
On Linux and NetBSD we don't need the "if -s $ARGV[0] > $ARGV[1]" condition I'm adding. We never have a $zero_pos longer than the file being truncated. But let's have that condition to future-proof the code, and because "the behavior is undefined if LENGTH is greater than the length of the file" (perldoc -f truncate).
1. http://pubs.opengroup.org/onlinepubs/9699919799/utilities/dd.html
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- t/t5318-commit-graph.sh | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index d4bd1522fe..d99bea6cce 100755 --- a/t/t5318-commit-graph.sh +++ b/t/t5318-commit-graph.sh @@ -382,7 +382,8 @@ 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 && + perl -we 'truncate $ARGV[0], $ARGV[1] if -s $ARGV[0] > $ARGV[1]' \ + $objdir/info/commit-graph $zero_pos && 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.rc0.258.g878e2cd30e