Re: [GSoC][PATCH 13/13] submodule: port submodule subcommand 'foreach' from shell to C

> This aims to make git-submodule foreach a builtin. This is the very
> first step taken in this direction. Hence, 'foreach' is ported to
> submodule--helper, and submodule--helper is called from git-submodule.sh.
> The code is split up to have one function to obtain all the list of
> submodules. This function acts as the front-end of git-submodule foreach
> subcommand. It calls the function for_each_submodule_list, which basically
> loops through the list and calls function fn, which in this case is
> runcommand_in_submodule. This third function is a calling function that
> takes care of running the command in that submodule, and recursively
> perform the same when --recursive is flagged.
>
> The first function module_foreach first parses the options present in
> argv, and then with the help of module_list_compute, generates the list of
> submodules present in the current working tree.
>
> The second function for_each_submodule_list traverses through the
> list, and calls function fn (which in case of submodule subcommand
> foreach is runcommand_in_submodule) is called for each entry.
>
> The third function runcommand_in_submodule, generates a submodule struct sub
> for $name, value and then later prepends name=sub->name; and other
> value assignment to the env argv_array structure of a child_process.
> Also the <command> of submodule-foreach is push to args argv_array
> structure and finally, using run_command the commands are executed
> using a shell.
>
> The third function also takes care of the recursive flag, by creating
> a separate child_process structure and prepending "--super-prefix displaypath",
> to the args argv_array structure. Other required arguments and the
> input <command> of submodule-foreach is also appended to this argv_array.
>
> Helped-by: Brandon Williams <bmwill@google.com>
> Mentored-by: Christian Couder <christian.couder@gmail.com>
> Mentored-by: Stefan Beller <sbeller@google.com>
> Signed-off-by: Prathamesh Chavan <pc44800@gmail.com>
> ---
> In this new version, the following changes have been made:
> * Comment style is improved in the function runcommand_in_submodule()
>
> * Comment in added about why the variable "path" was exposed via args
>   argv_array instead of exposing it via the env_array.
>
> * This patch exposes the various variables when argc == 1 only, just
>   for maintaining a faithful porting. You can also find discussion about
>   the same at [1].
>
> [1]: https://public-inbox.org/git/CAME+mvUSGAFbN5j-_hv7QpAS57hq4wgH+yZ7XJMPuyQN1gALaA@mail.gmail.com/