Re: [PATCH v1 1/2] refs: extract function to normalize partial refs

> On Sat, Nov 04, 2017 at 11:27:39AM +0900, Junio C Hamano wrote:
>> I however notice that addition of /* to the tail is trying to be
>> careful by using strbuf_complete('/'), but prefixing with "refs/"
>> does not and we would end up with a double-slash if pattern begins
>> with a slash.  The contract between the caller of this function (or
>> its original, which is for_each_glob_ref_in()) and the callee is
>> that prefix must not begin with '/', so it may be OK, but we might
>> want to add "if (*pattern == '/') BUG(...)" at the beginning.
>>
>> I dunno.  In any case, that is totally outside the scope of this two
>> patch series.
> 
> I do think it's a good idea to make future readers of the code aware of
> this contract, and adding a BUG assert does that quite well. Here is a
> patch that implements it.
> 
> This applies of course on top of this patch series.
> 
> -- >8 --
> Subject: [PATCH] normalize_glob_ref: assert implicit contract of prefix
> 
> normalize_glob_ref has an implicit contract of expecting 'prefix' to not
> start with a '/', otherwise the pattern would end up with a
> double-slash.
> 
> Mark it as a BUG when the prefix argument of normalize_glob_ref starts
> with a '/' so that future callers will be aware of this contract.
> 
> Signed-off-by: Kevin Daudt <me@ikke.info>
> ---
>  refs.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/refs.c b/refs.c
> index e9ae659ae..6747981d1 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -372,6 +372,8 @@ int head_ref_namespaced(each_ref_fn fn, void *cb_data)
>  void normalize_glob_ref(struct strbuf *normalized_pattern, const char *prefix,
>  		const char *pattern, int flags)
>  {
> +	if (prefix && *prefix == '/') BUG("prefix cannot not start with '/'");