On February 8, 2019 17:35, Jeff King wrote:
> On Fri, Feb 08, 2019 at 05:12:43PM -0500, Randall S. Becker wrote:
> > On February 8, 2019 17:07, brian m. carlson wrote:
> > > On Fri, Feb 08, 2019 at 02:31:57PM -0500, Jeff King wrote:
> > > > > It is available AFAIK on Linux, POSIX, and Windows under Cygwin.
> > > > > That's more than /dev/zero has anyway. I have the patch ready if
> > > > > you want it.
> > > >
> > > > Is it POSIX? Certainly truncate() is, but I didn't think the
> > > > command-line tool was. If it really is available everywhere, then
> > > > yeah, I'd be fine with it.
> > >
> > > It's not. POSIX doesn't specify the command, and macOS lacks it, I
> believe.
> >
> > I'm happy to modify the test (it is in one spot), to make a decision based
> on:
> > a) whether /dev/zero exists
> > b) whether the system is a NonStop
> > c) something else
> >
> > What would you all prefer? It doesn't matter to me one way or another,
> > as long as I can get the dependency to /dev/zero removed so tests will
> > run here.
>
> For the case in t5318, I think we can just put the NULs in a file. Does this
> work on your platform?
Yes, should work just fine.
>
> ---
> diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index
> 16d10ebce8..6d0ccc7eba 100755
> --- a/t/t5318-commit-graph.sh
> +++ b/t/t5318-commit-graph.sh
> @@ -383,7 +383,8 @@ corrupt_graph_and_verify() {
> 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 if=/dev/zero of="$objdir/info/commit-graph" bs=1
> seek="$zero_pos" count=$(($orig_size - $zero_pos)) &&
> + gen_zero_bytes $(($orig_size - $zero_pos)) >zeroes &&
> + dd if=zeroes of="$objdir/info/commit-graph" bs=1 seek="$zero_pos"
> &&
> test_must_fail git commit-graph verify 2>test_err &&
> grep -v "^+" test_err >err &&
> test_i18ngrep "$grepstr" err
> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh index
> 92cf8f812c..4afab14431 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -1302,3 +1302,8 @@ test_set_port () {
> port=$(($port + ${GIT_TEST_STRESS_JOB_NR:-0}))
> eval $var=$port
> }
> +
> +# Generate an output of $1 bytes of all zeroes (NULs, not ASCII zeroes).
> +gen_zero_bytes () {
> + perl -e 'print "\0" x $ARGV[0]' "$@"
> +}
This function does work on platform, so it's good.
> For the others that need infinite zeroes, I think using "yes" makes more
> sense, though we could also teach this function to accept an "infinity"
> parameter.
You could be sneaky about it, I suppose
+# Generate an output of $1 bytes of all zeroes (NULs, not ASCII zeroes).
+ gen_zero_bytes () {
+ if [ $1 -eq -1 ]; then
+ yes | tr 'y' '\0'
+ else
+ perl -e 'print "\0" x $ARGV[0]' "$@"
+ }
Or something alone those lines. It's not even slightly elegant, though. It would be better inside perl, so just
+# Generate an output of $1 bytes of all zeroes (NULs, not ASCII zeroes). If $1 is < 0, output forever.
+ gen_zero_bytes () {
+ perl -e ' if ($ARGV[0] < 0) { while (-1) { print "\0" } } else { print "\0" x $ARGV[0] }' "$@"
+ }
Cheers,
Randall
