Re: [PATCH 1/1][RFC][GSoC] submodule: using 'is_writing_gitmodules_ok()' for a stricter check

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Shourya,

On Tue, 11 Feb 2020, Shourya Shukla wrote:

> The if conditions of the functions 'update_path_in_gitmodules()'
> and 'remove_path_from_gitmodules()' are not catering to every
> condition encountered by the function. On detailed observation,
> one can notice that .gitmodules cannot be changed (i.e. removal
> of a path or updation of a path) until these conditions are satisfied:
>
>     1. The file exists
>     2. The file, if it does not exist, should be absent from
>        the index and other branches as well.

I don't think that other branches matter in this context.

>     3. There should not be any unmerged changes in the file.
>     4. The submodules do not exist or if the submodule name
>        does not match.
>
> Only the conditions 1, 3 and 4 were being satisfied earlier. Now
> on changing the if statement in one of the places, the condition
> 2 is satisfied as well.

Let's see how this is done...

> Signed-off-by: Shourya Shukla <shouryashukla.oo@gmail.com>
> ---
>  submodule.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/submodule.c b/submodule.c
> index 3a184b66ab..f7836a6851 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -107,7 +107,13 @@ int update_path_in_gitmodules(const char *oldpath, const char *newpath)
>  	const struct submodule *submodule;
>  	int ret;
>
> -	if (!file_exists(GITMODULES_FILE)) /* Do nothing without .gitmodules */
> +	/* If .gitmodules file is not safe to write(update a path) i.e.
> +	 * if it does not exist or if it is not present in the working tree
> +	 * but lies in the index or in the current branch.
> +	 * The function 'is_writing_gitmodules_ok()' checks for the same.
> +	 * and exits with failure if above conditions are not satisfied
> +	*/

Style: we always begin and end multi-line comments with `/*` and `*/` on
their own line.

> +	if (is_writing_gitmodules_ok())

Hmm. This function is defined thusly:

int is_writing_gitmodules_ok(void)
{
	struct object_id oid;
	return file_exists(GITMODULES_FILE) ||
		(get_oid(GITMODULES_INDEX, &oid) < 0 && get_oid(GITMODULES_HEAD, &oid) < 0);
}

Aha! So this tries to ensure that the `.gitmodules` file exists on disk,
or if it does not, then it should not exist in the index nor in the
_current_ branch.

But we're in the function called `update_path_in_gitmodules()` which
suggests that we're working on an existing, valid `.gitmodules`.

So I do not think that we can proceed if `.gitmodules` is absent from
disk, even if in case that it is _also_ absent from the index and from the
current branch.

>  		return -1;
>
>  	if (is_gitmodules_unmerged(the_repository->index))
> @@ -136,7 +142,13 @@ int remove_path_from_gitmodules(const char *path)
>  	struct strbuf sect = STRBUF_INIT;
>  	const struct submodule *submodule;
>
> -	if (!file_exists(GITMODULES_FILE)) /* Do nothing without .gitmodules */
> +	/* If .gitmodules file is not safe to write(remove a path) i.e.
> +	 * if it does not exist or if it is not present in the working tree
> +	 * but lies in the index or in the current branch.
> +	 * The function 'is_writing_gitmodules_ok()' checks for the same.
> +	 * and exits with failure if above conditions are not satisfied
> +	*/
> +	if (is_writing_gitmodules_ok())

Here, we want to remove a path from `.gitmodules`, so I think that the
same analysis applies as above.

In other words, I think that the existing code is correct and does not
need to be patched.

Ciao,
Johannes

>  		return -1;
>
>  	if (is_gitmodules_unmerged(the_repository->index))
> --
> 2.20.1
>
>