[PATCH 5/8] pretty: after padding, reset padding info

["Martin Ågren" <martin.agren@gmail.com>]

After handling a padding directive ("%<" or "%>"), we leave the `struct
padding_args` in a halfway state. We modify it a bit as we apply the
padding/truncation so that by the time we're done, it can't be in quite
as many states as when we started. Still, we don't fully restore it to
its default, no-action state.

"%<" and "%>" should only affect the next placeholder, but leaving a bit
of state around doesn't make it obvious that we don't spill any of it
into our handling of later placeholders. The previous commit closed off
a way of populating only half the `struct padding_args`, thereby fixing
a bug that *also* relied on then having the other half contain this kind
of lingering data.

After that fix, I haven't figured out a way to provoke a bug using just
this here half of the issue. Still, after handling padding, let's drop
all remnants of the previous "%<" or "%>".

Unlike the bug fixed in the previous commit, this could have some
realistic chance of regressing something for someone if they've actually
been using such state leftovers (knowingly or not). Still, it seems
worthwhile to try to tighten this.

This change to pretty.c would have been sufficient to make the test
added in the previous commit pass. Belt and suspenders.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
 pretty.c                      | 2 ++
 t/t4205-log-pretty-formats.sh | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/pretty.c b/pretty.c
index a4fa052f8b..f53e77ed86 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1893,6 +1893,8 @@ static size_t format_and_pad_commit(struct strbuf *sb, /* in UTF-8 */
 	}
 	strbuf_release(&local_sb);
 	c->pad.flush_type = no_flush;
+	c->pad.truncate = trunc_none;
+	c->pad.padding = 0;
 	return total_consumed;
 }
 
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 26987ecd77..d34a7cec09 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -1124,6 +1124,15 @@ test_expect_success 'log --pretty with space stealing' '
 	test_cmp expect actual
 '
 
+test_expect_success 'only the next placeholder gets truncated' '
+	{
+		git log -1 --pretty="format:%<(4,trunc)%H" &&
+		printf "$(git rev-parse HEAD)"
+	} >expect &&
+	git log -1 --pretty="format:%<(4,trunc)%H%H" >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'log --pretty with invalid padding format' '
 	printf "%s%%<(20" "$(git rev-parse HEAD)" >expect &&
 	git log -1 --pretty="format:%H%<(20" >actual &&
-- 
2.49.0.472.ge94155a9ec