Re: [PATCH v7 4/7] submodule: allow do_submodule_path to work if given gitdir directly

[Junio C Hamano <gitster@pobox.com>]

Jacob Keller <jacob.e.keller@intel.com> writes:

> From: Jacob Keller <jacob.keller@gmail.com>
>
> Currently, do_submodule_path relies on read_gitfile, which will die() if
> it can't read from the specified gitfile. Unfortunately, this means that
> do_submodule_path will not work when given the path to a submodule which
> is checked out directly, such as a newly added submodule which you
> cloned and then "git submodule add". 

Hmm, are you sure about that?

A call to read_gitfile() turns into a call to read_gitfile_gently()
with the return_error_code parameter set to NULL.  The function does
a stat(2), and if the given path is not a file (e.g. we created the
submodule working tree and repository in-place ourselves, instead of
cloning an existing project from elsewhere, in which case we would
see a directory there), it says READ_GIT_FILE_ERR_NOT_A_FILE and
returns NULL, because that is not a fatal error condition.  The same
thing happens if path does not yet exist.

This caller is given <path>, prepares "<path>/.git" in buf, and
calls read_gitfile().  If it returns a non-NULL, it replaces what is
in buf and continues, but if it returns a NULL (i.e. the two cases I
mentioned in the above paragraph), it continues with "<path>/.git".

While I do not think changing it to resolve_gitdir() is wrong per-se,
I am not sure if it is necessary.

I must be misreading something in the existing code.

> Instead, replace the call with
> resolve_gitdir. This first checks to see if we've been given a gitdir
> already.
>
> Because resolve_gitdir may return the same buffer it was passed, we have
> to check for this case as well, since strbuf_reset() will not work as
> expected here, and indeed is not necessary.
>
> Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
> ---
>  path.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/path.c b/path.c
> index 17551c483476..d1af029152a2 100644
> --- a/path.c
> +++ b/path.c
> @@ -477,8 +477,8 @@ static void do_submodule_path(struct strbuf *buf, const char *path,
>  	strbuf_complete(buf, '/');
>  	strbuf_addstr(buf, ".git");
>  
> -	git_dir = read_gitfile(buf->buf);
> -	if (git_dir) {
> +	git_dir = resolve_gitdir(buf->buf);
> +	if (git_dir && git_dir != buf->buf) {
>  		strbuf_reset(buf);
>  		strbuf_addstr(buf, git_dir);
>  	}