[PATCH v2] t8002: fix ambiguous printf conversion specifications

[PATCH v2] t8002: fix ambiguous printf conversion specifications

[Jan Palus]

In e7fb2ca945 (builtin/blame: fix out-of-bounds write with blank
boundary commits, 2025-01-10), we have introduced two new tests that
expect a certain amount of padding. This padding is generated via
printf using the "%0.s" conversion specification. That directive is
ambiguous because it might be interpreted as field width (most shells)
or 0-padding flag for numeric fields (coreutils).

Fix this issue by using "%${N}s" instead, which is already being
used in other tests (i.e. t5300, t0450) and is unambiguous.

Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Jan Palus <jpalus@fastmail.com>
---
 t/t8002-blame.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/t/t8002-blame.sh b/t/t8002-blame.sh
index 1ad039e123..e98993276a 100755
--- a/t/t8002-blame.sh
+++ b/t/t8002-blame.sh
@@ -138,7 +138,7 @@ test_expect_success 'blame --abbrev -b truncates the blank boundary' '
 	# Note that `--abbrev=` always gets incremented by 1, which is why we
 	# expect 11 leading spaces and not 10.
 	cat >expect <<-EOF &&
-	$(printf "%0.s " $(test_seq 11)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
+	$(printf "%11s" "") (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
 	EOF
 	git blame -b --abbrev=10 ^HEAD -- abbrev.t >actual &&
 	test_cmp expect actual
@@ -146,7 +146,7 @@ test_expect_success 'blame --abbrev -b truncates the blank boundary' '
 
 test_expect_success 'blame with excessive --abbrev and -b culls to hash length' '
 	cat >expect <<-EOF &&
-	$(printf "%0.s " $(test_seq $hexsz)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
+	$(printf "%${hexsz}s" "") (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
 	EOF
 	git blame -b --abbrev=9000 ^HEAD -- abbrev.t >actual &&
 	test_cmp expect actual
-- 
2.48.1

Re: [PATCH v2] t8002: fix ambiguous printf conversion specifications

[Junio C Hamano]

Jan Palus <jpalus@fastmail.com> writes:

> -	$(printf "%0.s " $(test_seq 11)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
> +	$(printf "%11s" "") (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev

This obviously is much clearer than the obscure original that
concatenates " " 11 times (for 11 arguments that printf receives).

Nice.

> @@ -146,7 +146,7 @@ test_expect_success 'blame --abbrev -b truncates the blank boundary' '
>  
>  test_expect_success 'blame with excessive --abbrev and -b culls to hash length' '
>  	cat >expect <<-EOF &&
> -	$(printf "%0.s " $(test_seq $hexsz)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
> +	$(printf "%${hexsz}s" "") (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev

The fact that $hexsz was not quoted in the original made me look at
how it is defined (as an unquoted variable reference is often a way
to lose unwanted leading whitespaces, e.g. bytes=$(wc -c <foo) &&
show $bytes), but it seems that hexsz would not get any leading (or
trailing) whitespaces so this rewrite perfectly fine.

Thanks.  Will queue.