[PATCH 08/16] update submodules: add depopulate_submodule

[Stefan Beller <sbeller@google.com>]

Implement the functionality needed to enable work tree manipulating
commands to that a deleted submodule should not only affect the index
(leaving all the files of the submodule in the work tree) but also to
remove the work tree of the superproject (including any untracked
files).

To do so, we need an equivalent of "rm -rf", which is already found in
entry.c, so expose that and for clarity add a suffix "_or_dir" to it.

That will only work properly when the submodule uses a gitfile instead of
a .git directory and no untracked files are present. Otherwise the removal
will fail with a warning (which is just what happened until now).

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 cache.h     |  2 ++
 entry.c     |  8 ++++++++
 submodule.c | 25 +++++++++++++++++++++++++
 submodule.h |  1 +
 4 files changed, 36 insertions(+)

diff --git a/cache.h b/cache.h
index a50a61a..65c47e4 100644
--- a/cache.h
+++ b/cache.h
@@ -2018,4 +2018,6 @@ void sleep_millisec(int millisec);
  */
 void safe_create_dir(const char *dir, int share);
 
+void remove_subtree_or_die(const char *path);
+
 #endif /* CACHE_H */
diff --git a/entry.c b/entry.c
index c6eea24..019826b 100644
--- a/entry.c
+++ b/entry.c
@@ -73,6 +73,14 @@ static void remove_subtree(struct strbuf *path)
 		die_errno("cannot rmdir '%s'", path->buf);
 }
 
+void remove_subtree_or_die(const char *path)
+{
+	struct strbuf sb = STRBUF_INIT;
+	strbuf_addstr(&sb, path);
+	remove_subtree(&sb);
+	strbuf_release(&sb);
+}
+
 static int create_file(const char *path, unsigned int mode)
 {
 	mode = (mode & 0100) ? 0777 : 0666;
diff --git a/submodule.c b/submodule.c
index d34b721..0fa4613 100644
--- a/submodule.c
+++ b/submodule.c
@@ -308,6 +308,31 @@ static void print_submodule_summary(struct rev_info *rev, FILE *f,
 	strbuf_release(&sb);
 }
 
+int depopulate_submodule(const char *path)
+{
+	int ret = 0;
+	char *dot_git = xstrfmt("%s/.git", path);
+
+	/* Is it populated? */
+	if (!resolve_gitdir(dot_git))
+		goto out;
+
+	/* Does it have a .git directory? */
+	if (!submodule_uses_gitfile(path)) {
+		warning(_("cannot remove submodule '%s' because it (or one of "
+			  "its nested submodules) uses a .git directory"),
+			  path);
+		ret = -1;
+		goto out;
+	}
+
+	remove_subtree_or_die(path);
+
+out:
+	free(dot_git);
+	return ret;
+}
+
 /* Helper function to display the submodule header line prior to the full
  * summary output. If it can locate the submodule objects directory it will
  * attempt to lookup both the left and right commits and put them into the
diff --git a/submodule.h b/submodule.h
index 3df6881..8518cf3 100644
--- a/submodule.h
+++ b/submodule.h
@@ -65,6 +65,7 @@ extern void set_config_update_recurse_submodules(int value);
  */
 extern int submodule_is_interesting(const char *path, const unsigned char *sha1);
 extern int submodules_interesting_for_update(void);
+extern int depopulate_submodule(const char *path);
 extern void check_for_new_submodule_commits(unsigned char new_sha1[20]);
 extern int fetch_populated_submodules(const struct argv_array *options,
 			       const char *prefix, int command_line_option,
-- 
2.10.1.469.g00a8914