submodule: rename and add flags to ok_to_remove_submodule

In different contexts the question "Is it ok to delete a submodule?"
may be answered differently.

In 293ab15eea (submodule: teach rm to remove submodules unless they
contain a git directory, 2012-09-26) a case was made that we can safely
ignore ignored untracked files for removal as we explicitely ask for the
removal of the submodule.

In a later patch we want to remove submodules even when the user doesn't
explicitly ask for it (e.g. checking out a tree-ish in which the submodule
doesn't exist).  In that case we want to be more careful when it comes
to deletion of untracked files. As of this patch it is unclear how this
will be implemented exactly, so we'll offer flags in which the caller
can specify how the different untracked files ought to be handled.

As the flags allow the function to not die on an error when spawning
a child process, we need to find an appropriate return code for the
case when the child process could not be started. As in that case we
cannot tell if the submodule is ok to remove, we'd want to return 'false'.

As only 0 is understood as false, rename the function to invert the
meaning, i.e. the return code of 0 signals the removal of the submodule
is fine, and other values can be used to return a more precise answer
what went wrong.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rm.c

@@ -187,7 +187,9 @@ static int check_local_mod(struct object_id *head, int index_only)
 		 */
 		if (ce_match_stat(ce, &st, 0) ||
 		    (S_ISGITLINK(ce->ce_mode) &&
-		     !ok_to_remove_submodule(ce->name)))
+		     bad_to_remove_submodule(ce->name,
+				SUBMODULE_REMOVAL_DIE_ON_ERROR |
+				SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED)))
 			local_changes = 1;
 
 		/*

submodule.c

@@ -1019,39 +1019,64 @@ int submodule_uses_gitfile(const char *path)
 	return 1;
 }
 
-int ok_to_remove_submodule(const char *path)
+/*
+ * Check if it is a bad idea to remove a submodule, i.e. if we'd lose data
+ * when doing so.
+ *
+ * Return 1 if we'd lose data, return 0 if the removal is fine,
+ * and negative values for errors.
+ */
+int bad_to_remove_submodule(const char *path, unsigned flags)
 {
 	ssize_t len;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
-	int ok_to_remove = 1;
+	int ret = 0;
 
 	if (!file_exists(path) || is_empty_dir(path))
-		return 1;
-
-	if (!submodule_uses_gitfile(path))
 		return 0;
 
-	argv_array_pushl(&cp.args, "status", "--porcelain", "-u",
+	if (!submodule_uses_gitfile(path))
+		return 1;
+
+	argv_array_pushl(&cp.args, "status", "--porcelain",
 				   "--ignore-submodules=none", NULL);
+
+	if (flags & SUBMODULE_REMOVAL_IGNORE_UNTRACKED)
+		argv_array_push(&cp.args, "-uno");
+	else
+		argv_array_push(&cp.args, "-uall");
+
+	if (!(flags & SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED))
+		argv_array_push(&cp.args, "--ignored");
+
 	prepare_submodule_repo_env(&cp.env_array);
 	cp.git_cmd = 1;
 	cp.no_stdin = 1;
 	cp.out = -1;
 	cp.dir = path;
-	if (start_command(&cp))
-		die(_("could not run 'git status --porcelain -u --ignore-submodules=none' in submodule %s"), path);
+	if (start_command(&cp)) {
+		if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
+			die(_("could not start 'git status in submodule '%s'"),
+				path);
+		ret = -1;
+		goto out;
+	}
 
 	len = strbuf_read(&buf, cp.out, 1024);
 	if (len > 2)
-		ok_to_remove = 0;
+		ret = 1;
 	close(cp.out);
 
-	if (finish_command(&cp))
-		die(_("'git status --porcelain -u --ignore-submodules=none' failed in submodule %s"), path);
-
+	if (finish_command(&cp)) {
+		if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
+			die(_("could not run 'git status in submodule '%s'"),
+				path);
+		ret = -1;
+	}
+out:
 	strbuf_release(&buf);
-	return ok_to_remove;
+	return ret;
 }
 
 static int find_first_merges(struct object_array *result, const char *path,

submodule.h

@@ -59,7 +59,11 @@ extern int fetch_populated_submodules(const struct argv_array *options,
 			       int quiet, int max_parallel_jobs);
 extern unsigned is_submodule_modified(const char *path, int ignore_untracked);
 extern int submodule_uses_gitfile(const char *path);
-extern int ok_to_remove_submodule(const char *path);
+
+#define SUBMODULE_REMOVAL_DIE_ON_ERROR (1<<0)
+#define SUBMODULE_REMOVAL_IGNORE_UNTRACKED (1<<1)
+#define SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED (1<<2)
+extern int bad_to_remove_submodule(const char *path, unsigned flags);
 extern int merge_submodule(unsigned char result[20], const char *path,
 			   const unsigned char base[20],
 			   const unsigned char a[20],