From: "SZEDER Gábor" <szeder.dev@gmail.com> To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com> Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>, Sebastian Staudt <koraktor@gmail.com>, Josh Steadmon <steadmon@google.com>, Johannes Schindelin <Johannes.Schindelin@gmx.de> Subject: Re: [PATCH 2/2] commit-graph tests: fix cryptic unportable "dd" invocation Date: Thu, 21 Feb 2019 21:43:10 +0100 Message-ID: <20190221204310.GS1622@szeder.dev> (raw) In-Reply-To: <20190221192849.6581-3-avarab@gmail.com> On Thu, Feb 21, 2019 at 08:28:49PM +0100, Ævar Arnfjörð Bjarmason wrote: > 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 $zero_pos && This will make Dscho unhappy :) Is there a problem with: dd if=/dev/null of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" ? To my understanding of the specs it's well-defined what it should do, even when $zero_pos is larget than the file size, it's shorter, simpler, and doesn't introduce yet another Perl dependency. > 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 >
next prev parent reply other threads:[~2019-02-21 20:43 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-19 23:29 [ANNOUNCE] Git v2.21.0-rc2 Junio C Hamano 2019-02-20 0:43 ` Randall S. Becker 2019-02-20 19:41 ` Junio C Hamano 2019-02-20 20:46 ` Johannes Schindelin 2019-02-21 13:10 ` Duy Nguyen 2019-02-21 23:55 ` brian m. carlson 2019-02-22 9:13 ` Duy Nguyen 2019-02-21 15:54 ` Randall S. Becker 2019-02-21 20:04 ` Junio C Hamano 2019-02-21 21:06 ` SZEDER Gábor 2019-02-21 21:30 ` Randall S. Becker 2019-02-21 19:59 ` Randall S. Becker 2019-02-21 10:46 ` Git for Windows v2.21.0-rc2, was " Johannes Schindelin 2019-02-21 19:28 ` [PATCH 0/2] BSD portability fixes for 2.21.0-rc2 Ævar Arnfjörð Bjarmason 2019-02-22 0:37 ` Josh Steadmon 2019-02-21 19:28 ` [PATCH 1/2] tests: fix unportable "\?" and "\+" regex syntax Ævar Arnfjörð Bjarmason 2019-02-22 5:00 ` Junio C Hamano 2019-02-21 19:28 ` [PATCH 2/2] commit-graph tests: fix cryptic unportable "dd" invocation Ævar Arnfjörð Bjarmason 2019-02-21 20:43 ` SZEDER Gábor [this message] 2019-02-21 22:26 ` Ævar Arnfjörð Bjarmason 2019-02-22 10:50 ` SZEDER Gábor 2019-02-22 14:34 ` Ævar Arnfjörð Bjarmason 2019-02-22 18:30 ` Junio C Hamano 2019-02-22 18:35 ` Todd Zullinger 2019-02-22 19:23 ` [PATCH v3] commit-graph tests: fix " Junio C Hamano
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