threads / patch / 45234

patchinterpret_branch_name(): handle auto-namelen for @{-1}

Subject: [PATCH] interpret_branch_name(): handle auto-namelen for @{-1}

## tl;dr

3 messages between Feb 27, 2017 and Feb 27, 2017. Diffs are folded; open one to read it.

replies: 2people: 2as markdown or json

Jeff King· Feb 27, 2017, 09:25 UTC · lore

The interpret_branch_name() function takes a ptr/len pair for the name, but you can pass "0" for "namelen", which will cause it to check the length with strlen().

However, before we do that auto-namelen magic, we call interpret_nth_prior_checkout(), which gets fed the bogus "0". This was broken by 8cd4249c4 (interpret_branch_name: always respect "namelen" parameter, 2014-01-15). Though to be fair to that commit, it was broken in the _opposite_ direction before, where we would always treat "name" as a string even if a length was passed.

You can see the bug with "git log -g @{-1}". That code path always passes "0", and without this patch it cannot figure out which branch's reflog to show.

We can fix it by a small reordering of the code.
Signed-off-by: Jeff King <peff@peff.net>
---
Noticed while digging on the nearby thread:
  http://public-inbox.org/git/20170227090233.uk7dfruggytgmuw2@sigill.intra.peff.net/
 sha1_name.c         | 3 ++-
 t/t0100-previous.sh | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
Show changes to 2 files +10 −1

sha1_name.c, t/t0100-previous.sh

diff --git a/sha1_name.c b/sha1_name.c
index 73a915ff1..9b5d14b4b 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1263,11 +1263,12 @@ int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
 {
 	char *at;
 	const char *start;
-	int len = interpret_nth_prior_checkout(name, namelen, buf);
+	int len;
 
 	if (!namelen)
 		namelen = strlen(name);
 
+	len = interpret_nth_prior_checkout(name, namelen, buf);
 	if (!len) {
 		return len; /* syntax Ok, not enough switches */
 	} else if (len > 0) {
diff --git a/t/t0100-previous.sh b/t/t0100-previous.sh
index e0a694023..58c0b7e9b 100755
--- a/t/t0100-previous.sh
+++ b/t/t0100-previous.sh
@@ -56,5 +56,13 @@ test_expect_success 'merge @{-100} before checking out that many branches yet' '
 	test_must_fail git merge @{-100}
 '
 
+test_expect_success 'log -g @{-1}' '
+	git checkout -b last_branch &&
+	git checkout -b new_branch &&
+	echo "last_branch@{0}" >expect &&
+	git log -g --format=%gd @{-1} >actual &&
+	test_cmp expect actual
+'
+
 test_done
 

-- 
2.12.0.624.gbb1b07a2c
Jeff King· Feb 27, 2017, 09:31 UTC · re: Jeff King · lore

Re: [PATCH] interpret_branch_name(): handle auto-namelen for @{-1}

On Mon, Feb 27, 2017 at 04:25:40AM -0500, Jeff King wrote:
Show 7 quoted lines
> However, before we do that auto-namelen magic, we call
> interpret_nth_prior_checkout(), which gets fed the bogus
> "0". This was broken by 8cd4249c4 (interpret_branch_name:
> always respect "namelen" parameter, 2014-01-15).  Though to
> be fair to that commit, it was broken in the _opposite_
> direction before, where we would always treat "name" as a
> string even if a length was passed.

That commit is mine, by the way. More embarrassing than introducing the bug is that I _noticed_ the problem at the time and wrote a paragraph in the commit message rationalizing why it was OK, rather than just doing this trivial fix.

-Peff
Junio C Hamano· Feb 27, 2017, 19:27 UTC · re: Jeff King · lore

Re: [PATCH] interpret_branch_name(): handle auto-namelen for @{-1}

Jeff King <peff@peff.net> writes:
Show 14 quoted lines
> On Mon, Feb 27, 2017 at 04:25:40AM -0500, Jeff King wrote:
>
>> However, before we do that auto-namelen magic, we call
>> interpret_nth_prior_checkout(), which gets fed the bogus
>> "0". This was broken by 8cd4249c4 (interpret_branch_name:
>> always respect "namelen" parameter, 2014-01-15).  Though to
>> be fair to that commit, it was broken in the _opposite_
>> direction before, where we would always treat "name" as a
>> string even if a length was passed.
>
> That commit is mine, by the way. More embarrassing than introducing the
> bug is that I _noticed_ the problem at the time and wrote a paragraph in
> the commit message rationalizing why it was OK, rather than just doing
> this trivial fix.

Thanks, I should also be embarrased since I didn't even notice the issue when we queued it ;-)

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