Re: [PATCH v2] sha1-name.c: Fix handling of revisions that contain paths with brackets

[Duy Nguyen <pclouds@gmail.com>]

On Sun, Dec 23, 2018 at 11:40:59PM +0000, Stan Hu wrote:
> Previously, calling ls-tree with a revision such as
> `master^{tree}:foo/{{path}}` would show the root tree instead of the
> correct tree pointed by foo/{{path}}. If a colon is present in the revision
> name, peel_onion() should assume that the presence of a bracket
> at the end of the string belongs to the filename.
> 
> Signed-off-by: Stan Hu <stanhu@gmail.com>
> ---
>  sha1-name.c               | 14 +++++++++++++-
>  t/t3104-ls-tree-braces.sh | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 43 insertions(+), 1 deletion(-)
>  create mode 100755 t/t3104-ls-tree-braces.sh
> 
> diff --git a/sha1-name.c b/sha1-name.c
> index faa60f69e3..588b7a53cc 100644
> --- a/sha1-name.c
> +++ b/sha1-name.c
> @@ -1001,9 +1001,21 @@ static int peel_onion(const char *name, int len, struct object_id *oid,
>  	 * "ref^{commit}".  "commit^{tree}" could be used to find the
>  	 * top-level tree of the given commit.
>  	 */
> -	if (len < 4 || name[len-1] != '}')
> +	if (len < 4)
>  		return -1;
>  
> +	/* Check for names in ref:path format in case the path includes
> +	 * brackets (e.g. ref^{type}:foo/{{bar}}).
> +	 */
> +	for (sp = name; sp < name + len; sp++) {
> +		if (*sp == ':')
> +			return -1;
> +	}
> +
> +	if (name[len-1] != '}') {
> +		return -1;
> +	}

Instead of replacing one loose check (find '}' at the end) with
another one, how about tighten the parsing? peel_onion() is supposed
to consume all "len" characters or none so checking something like
this may be better.

Note that it also shows another corner case we need to be careful
about: master^{/regex} syntax _can_ contain colons in regex. I suppose
doing strchr to find the closing '}' here is better than what I did
below.

--8<--
diff --git a/sha1-name.c b/sha1-name.c
index faa60f69e3..c9e26206ce 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -989,7 +989,7 @@ static int peel_onion(const char *name, int len, struct object_id *oid,
 		      unsigned lookup_flags)
 {
 	struct object_id outer;
-	const char *sp;
+	const char *sp, *end;
 	unsigned int expected_type = 0;
 	struct object *o;
 
@@ -1013,21 +1013,26 @@ static int peel_onion(const char *name, int len, struct object_id *oid,
 		return -1;
 
 	sp++; /* beginning of type name, or closing brace for empty */
-	if (starts_with(sp, "commit}"))
+	if (skip_prefix(sp, "commit}", &end))
 		expected_type = OBJ_COMMIT;
-	else if (starts_with(sp, "tag}"))
+	else if (skip_prefix(sp, "tag}", &end))
 		expected_type = OBJ_TAG;
-	else if (starts_with(sp, "tree}"))
+	else if (skip_prefix(sp, "tree}", &end))
 		expected_type = OBJ_TREE;
-	else if (starts_with(sp, "blob}"))
+	else if (skip_prefix(sp, "blob}", &end))
 		expected_type = OBJ_BLOB;
-	else if (starts_with(sp, "object}"))
+	else if (skip_prefix(sp, "object}", &end))
 		expected_type = OBJ_ANY;
-	else if (sp[0] == '}')
+	else if (sp[0] == '}') {
 		expected_type = OBJ_NONE;
-	else if (sp[0] == '/')
+		end = sp + 1;
+	} else if (sp[0] == '/') {
 		expected_type = OBJ_COMMIT;
-	else
+		end = name + len;
+	} else
+		return -1;
+
+	if (end != name + len)
 		return -1;
 
 	lookup_flags &= ~GET_OID_DISAMBIGUATORS;
--8<--

--
Duy