[GSoC] [PATCH v5 0/9] submodule: convert the rest of 'add' to C

NOTE: This series uses (ar/submodule-add-config):
https://lore.kernel.org/git/20210806140431.92018-1-raykar.ath@gmail.com/

Since v4:
* Rename a local variable in 'compute_submodule_clone_url()' to reduce ambiguity.
* Add a new patch that renames 'compute_submodule_clone_url()' to
  'resolve_relative_url()' to better convey its use. We add it at the end after
  the 'resolve-relative-url' subcommand is removed so that there is no confusion
  as to what that function name binds to.
* Fix incorrect example in the docstring for 'git_url_basename()'. Also add
  another example for more clarity.

Also since this query of mine got buried in the revisions, I shall include it here again:

Questions about the cache API used in [PATCH 5/9]:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  1. What is the difference between 'read_cache()' and 'read_cache_preload()'?
     From what I can tell, the latter optimistically preloads the index stat
     data. Is there any reason to use 'read_cache()' over
     'read_cache_preload()'?
  2. Which one is more appropriate for use in 'die_on_index_match()'?

Fetch-it-Via: git fetch https://github.com/tfidfwastaken/git submodule-helper-add-list-5

Atharva Raykar (9):
  submodule--helper: add options for compute_submodule_clone_url()
  submodule--helper: refactor resolve_relative_url() helper
  submodule--helper: remove repeated code in sync_submodule()
  dir: libify and export helper functions from clone.c
  submodule--helper: convert the bulk of cmd_add() to C
  submodule--helper: remove add-clone subcommand
  submodule--helper: remove add-config subcommand
  submodule--helper: remove resolve-relative-url subcommand
  submodule--helper: rename compute_submodule_clone_url()

 builtin/clone.c             | 118 +-------------
 builtin/submodule--helper.c | 307 +++++++++++++++++++-----------------
 dir.c                       | 114 +++++++++++++
 dir.h                       |  11 ++
 git-submodule.sh            |  96 +----------
 5 files changed, 291 insertions(+), 355 deletions(-)

Range-diff against v4:
 1:  75edf24186 !  1:  78e19c4b01 submodule--helper: add options for compute_submodule_clone_url()
    @@ Commit message
         `resolve_relative_url()` by using this function, something we will do in
         the next patch.
     
    +    We also rename the local variable 'relurl' to avoid potential confusion
    +    with the 'rel_url' parameter while we are at it.
    +
         Having this functionality factored out will be useful for converting the
         rest of `submodule add` in subsequent patches.
     
    @@ builtin/submodule--helper.c: static int module_foreach(int argc, const char **ar
     -static char *compute_submodule_clone_url(const char *rel_url)
     +static char *compute_submodule_clone_url(const char *rel_url, const char *up_path, int quiet)
      {
    - 	char *remoteurl, *relurl;
    +-	char *remoteurl, *relurl;
    ++	char *remoteurl, *resolved_url;
      	char *remote = get_default_remote();
    -@@ builtin/submodule--helper.c: static char *compute_submodule_clone_url(const char *rel_url)
    + 	struct strbuf remotesb = STRBUF_INIT;
      
      	strbuf_addf(&remotesb, "remote.%s.url", remote);
      	if (git_config_get_string(remotesb.buf, &remoteurl)) {
    @@ builtin/submodule--helper.c: static char *compute_submodule_clone_url(const char
      		remoteurl = xgetcwd();
      	}
     -	relurl = relative_url(remoteurl, rel_url, NULL);
    -+	relurl = relative_url(remoteurl, rel_url, up_path);
    ++	resolved_url = relative_url(remoteurl, rel_url, up_path);
      
      	free(remote);
      	free(remoteurl);
    + 	strbuf_release(&remotesb);
    + 
    +-	return relurl;
    ++	return resolved_url;
    + }
    + 
    + struct init_cb {
     @@ builtin/submodule--helper.c: static void init_submodule(const char *path, const char *prefix,
      		if (starts_with_dot_dot_slash(url) ||
      		    starts_with_dot_slash(url)) {
 2:  8e7a3e727a !  2:  faadf74ec1 submodule--helper: refactor resolve_relative_url() helper
    @@ builtin/submodule--helper.c: static char *relative_url(const char *remote_url,
     +static char *compute_submodule_clone_url(const char *rel_url, const char *up_path, int quiet)
      {
     -	char *remoteurl = NULL;
    -+	char *remoteurl, *relurl;
    ++	char *remoteurl, *resolved_url;
      	char *remote = get_default_remote();
     +	struct strbuf remotesb = STRBUF_INIT;
     +
    @@ builtin/submodule--helper.c: static char *relative_url(const char *remote_url,
     +				remotesb.buf);
     +		remoteurl = xgetcwd();
     +	}
    -+	relurl = relative_url(remoteurl, rel_url, up_path);
    ++	resolved_url = relative_url(remoteurl, rel_url, up_path);
     +
     +	free(remote);
     +	free(remoteurl);
     +	strbuf_release(&remotesb);
     +
    -+	return relurl;
    ++	return resolved_url;
     +}
     +
     +static int resolve_relative_url(int argc, const char **argv, const char *prefix)
    @@ builtin/submodule--helper.c: static int module_foreach(int argc, const char **ar
      
     -static char *compute_submodule_clone_url(const char *rel_url, const char *up_path, int quiet)
     -{
    --	char *remoteurl, *relurl;
    +-	char *remoteurl, *resolved_url;
     -	char *remote = get_default_remote();
     -	struct strbuf remotesb = STRBUF_INIT;
     -
    @@ builtin/submodule--helper.c: static int module_foreach(int argc, const char **ar
     -				remotesb.buf);
     -		remoteurl = xgetcwd();
     -	}
    --	relurl = relative_url(remoteurl, rel_url, up_path);
    +-	resolved_url = relative_url(remoteurl, rel_url, up_path);
     -
     -	free(remote);
     -	free(remoteurl);
     -	strbuf_release(&remotesb);
     -
    --	return relurl;
    +-	return resolved_url;
     -}
     -
      struct init_cb {
 3:  82961ddd02 =  3:  d2127bd09a submodule--helper: remove repeated code in sync_submodule()
 4:  fa97d6801e !  4:  4b05f93def dir: libify and export helper functions from clone.c
    @@ dir.h: static inline int is_dot_or_dotdot(const char *name)
     + *
     + * For example:
     + * 	/path/to/repo.git => "repo"
    -+ * 	host.xz.foo/.git => "foo"
    ++ * 	host.xz:foo/.git => "foo"
    ++ * 	http://example.com/user/bar.baz => "bar.baz"
     + */
     +char *git_url_basename(const char *repo, int is_bundle, int is_bare);
     +void strip_dir_trailing_slashes(char *dir);
 5:  a3aa25518d =  5:  1491a011b0 submodule--helper: convert the bulk of cmd_add() to C
 6:  9667159d4b =  6:  5d5d07a6ba submodule--helper: remove add-clone subcommand
 7:  dc87b5627a =  7:  0ea27c2a15 submodule--helper: remove add-config subcommand
 8:  ea08e4fbad !  8:  6bd2571f73 submodule--helper: remove resolve-relative-url subcommand
    @@ Commit message
     
      ## builtin/submodule--helper.c ##
     @@ builtin/submodule--helper.c: static char *compute_submodule_clone_url(const char *rel_url, const char *up_pat
    - 	return relurl;
    + 	return resolved_url;
      }
      
     -static int resolve_relative_url(int argc, const char **argv, const char *prefix)
 -:  ---------- >  9:  14a05a0c1d submodule--helper: rename compute_submodule_clone_url()