From 75aa26d34c4a80142512bd980a416b0fb30044c1 Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@bbn.com>
Date: Tue, 3 Sep 2013 15:50:16 -0400
Subject: [PATCH 1/2] peel_onion(): add support for <rev>^{tag}
Complete the <rev>^{<type>} family of object descriptors by having
<rev>^{tag} dereference <rev> until a tag object is found (or fail if
unable).
At first glance this may not seem very useful, as commits, trees, and
blobs cannot be peeled to a tag, and a tag would just peel to itself.
However, this can be used to ensure that <rev> names a tag object:
$ git rev-parse --verify v1.8.4^{tag}
04f013dc38d7512eadb915eba22efc414f18b869
$ git rev-parse --verify master^{tag}
error: master^{tag}: expected tag type, but the object dereferences to tree type
fatal: Needed a single revision
Users can already ensure that <rev> is a tag object by checking the
output of 'git cat-file -t <rev>', but:
* users may expect <rev>^{tag} to exist given that <rev>^{commit},
<rev>^{tree}, and <rev>^{blob} all exist
* this syntax is more convenient/natural in some circumstances
Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
Documentation/revisions.txt | 3 +++
sha1_name.c | 2 ++
t/t1511-rev-parse-caret.sh | 7 +++++++
3 files changed, 12 insertions(+)
diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index d477b3f6bcb..b3322adf248 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -121,6 +121,9 @@ some output processing may assume ref names in UTF-8.
object that exists, without requiring 'rev' to be a tag, and
without dereferencing 'rev'; because a tag is already an object,
it does not have to be dereferenced even once to get to an object.
++
+'rev{caret}\{tag\}' can be used to ensure that 'rev' identifies an
+existing tag object.
'<rev>{caret}\{\}', e.g. 'v0.99.8{caret}\{\}'::
A suffix '{caret}' followed by an empty brace pair
diff --git a/sha1_name.c b/sha1_name.c
index 65ad066d9bb..6dc496deb00 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -679,6 +679,8 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
sp++; /* beginning of type name, or closing brace for empty */
if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
expected_type = OBJ_COMMIT;
+ else if (!strncmp(tag_type, sp, 3) && sp[3] == '}')
+ expected_type = OBJ_TAG;
else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
expected_type = OBJ_TREE;
else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
diff --git a/t/t1511-rev-parse-caret.sh b/t/t1511-rev-parse-caret.sh
index eaefc777bd9..15973f20945 100755
--- a/t/t1511-rev-parse-caret.sh
+++ b/t/t1511-rev-parse-caret.sh
@@ -54,6 +54,13 @@ test_expect_success 'ref^{tree}' '
test_must_fail git rev-parse blob-tag^{tree}
'
+test_expect_success 'ref^{tag}' '
+ test_must_fail git rev-parse HEAD^{tag} &&
+ git rev-parse commit-tag >expected &&
+ git rev-parse commit-tag^{tag} >actual &&
+ test_cmp expected actual
+'
+
test_expect_success 'ref^{/.}' '
git rev-parse master >expected &&
git rev-parse master^{/.} >actual &&
From c969b6a18d1cde3ffb8a5ca5cd45a57052c2cc95 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Tue, 3 Sep 2013 16:27:30 -0400
Subject: [PATCH 2/2] peel_onion: do not assume length of x_type globals
When we are parsing "rev^{foo}", we check "foo" against the
various global type strings, like "commit_type",
"tree_type", etc. This is nicely abstracted, but then we
destroy the abstraction completely by using magic numbers
that must match the length of the type strings.
We could avoid these magic numbers by using skip_prefix. But
taking a step back, we can realize that using the
"commit_type" global is not really buying us anything. It is
not ever going to change from being "commit" without causing
severe breakage to existing uses. And even if it did change
for some crazy reason, we would want to evaluate its effects
on the "rev^{}" syntax, anyway.
Let's just switch these to using a custom string literal, as
we do for "rev^{object}". The resulting code is more robust
to changes in the type strings, and is more readable.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
sha1_name.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/sha1_name.c b/sha1_name.c
index 6dc496deb00..2f6e5abaafc 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -677,13 +677,13 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
return -1;
sp++; /* beginning of type name, or closing brace for empty */
- if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
+ if (!prefixcmp(sp, "commit}"))
expected_type = OBJ_COMMIT;
- else if (!strncmp(tag_type, sp, 3) && sp[3] == '}')
+ else if (!prefixcmp(sp, "tag}"))
expected_type = OBJ_TAG;
- else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
+ else if (!prefixcmp(sp, "tree}"))
expected_type = OBJ_TREE;
- else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
+ else if (!prefixcmp(sp, "blob}"))
expected_type = OBJ_BLOB;
else if (!prefixcmp(sp, "object}"))
expected_type = OBJ_ANY;