Subject: [PATCH v3] Teach rm to remove submodules unless they contain a git directory

From: Jens Lehmann <[email-masked]>
Date: Tue, 11 Sep 2012 20:34:15 +0200

Currently using "git rm" on a submodule - populated or not - fails with
this error:
	fatal: git rm: '<submodule path>': Is a directory
This made sense in the past as there was no way to remove a submodule
without possibly removing unpushed parts of the submodule's history
contained in its .git directory too, so erroring out here protected the
user from possible loss of data.

But submodules cloned with a recent git version do not contain the .git
directory anymore, they use a gitfile to point to their git directory
which is safely stored inside the superproject's .git directory. The work
tree of these submodules can safely be removed without loosing history, so
let's teach git to do so.

Using rm on an unpopulated submodule now removes the empty directory from
the work tree and the gitlink from the index. If the submodule's directory
is missing from the work tree, it will still be removed from the index.

Using rm on a populated submodule using a gitfile will apply the usual
checks for work tree modification adapted to submodules (unless forced).
For a submodule that means that the HEAD is the same as recorded in the
index, no tracked files are modified and no untracked files that aren't
ignored are present in the submodules work tree (ignored files are deemed
expendable and won't stop a submodule's work tree from being removed).
That logic has to be applied in all nested submodules too.

Using rm on a submodule which has its .git directory inside the work trees
top level directory will just error out like it did before to protect the
repository, even when forced. In the future git could either provide a
message informing the user to convert the submodule to use a gitfile or
even attempt to do the conversion itself, but that is not part of this
change.

Signed-off-by: Jens Lehmann <[email-masked]>
---

Am 11.09.2012 01:55, schrieb Junio C Hamano:
> * jl/submodule-rm (2012-08-27) 1 commit
>  - Teach rm to remove submodules unless they contain a git directory
> 
> "git rm submodule" cannot blindly remove a submodule directory as
> its working tree may have local changes, and worse yet, it may even
> have its repository embedded in it.  Teach it some special cases
> where it is safe to remove a submodule, specifically, when there is
> no local changes in the submodule working tree, and its repository
> is not embedded in its working tree but is elsewhere and uses the
> gitfile mechanism to point at it.
> 
> I lost track; what is the doneness of the discussion on this patch?

The review of v2 revealed that in case of submodule merge conflicts
the necessary checks weren't done. This (and the minor issues raised
in http://permalink.gmane.org/gmane.comp.version-control.git/204370)
is fixed in this version.

 Documentation/git-rm.txt |  15 +++
 builtin/rm.c             | 107 ++++++++++++++---
 submodule.c              |  80 +++++++++++++
 submodule.h              |   2 +
 t/t3600-rm.sh            | 291 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 480 insertions(+), 15 deletions(-)

diff --git a/Documentation/git-rm.txt b/Documentation/git-rm.txt
index 5d31860..882cb11 100644
--- a/Documentation/git-rm.txt
+++ b/Documentation/git-rm.txt
@@ -107,6 +107,21 @@ as well as modifications of existing paths.
 Typically you would first remove all tracked files from the working
 tree using this command:

+Submodules
+~~~~~~~~~~
+Only submodules using a gitfile (which means they were cloned
+with a git version 1.7.8 or newer) will be removed from the work
+tree, as their repository lives inside the .git directory of the
+superproject. If a submodule (or one of those nested inside it)
+still uses a .git directory, `git rm` will fail - no matter if forced
+or not - to protect the submodule's history.
+
+A submodule is considered up-to-date when the HEAD is the same as
+recorded in the index, no tracked files are modified and no untracked
+files that aren't ignored are present in the submodules work tree.
+Ignored files are deemed expendable and won't stop a submodule's work
+tree from being removed.
+
 ----------------
 git ls-files -z | xargs -0 rm -f
 ----------------
diff --git a/builtin/rm.c b/builtin/rm.c
index b384c4c..0e7ea7c 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -9,6 +9,7 @@
 #include "cache-tree.h"
 #include "tree-walk.h"
 #include "parse-options.h"
+#include "submodule.h"

 static const char * const builtin_rm_usage[] = {
 	N_("git rm [options] [--] <file>..."),
@@ -17,9 +18,43 @@ static const char * const builtin_rm_usage[] = {

 static struct {
 	int nr, alloc;
-	const char **name;
+	struct {
+		const char *name;
+		char is_submodule;
+	} *entry;
 } list;

+static int check_submodules_use_gitfiles(void)
+{
+	int i;
+	int errs = 0;
+
+	for (i = 0; i < list.nr; i++) {
+		const char *name = list.entry[i].name;
+		int pos;
+		struct cache_entry *ce;
+		struct stat st;
+
+		pos = cache_name_pos(name, strlen(name));
+		if (pos < 0)
+			pos = -pos-1;
+		ce = active_cache[pos];
+
+		if (!S_ISGITLINK(ce->ce_mode) ||
+		    (lstat(ce->name, &st) < 0) ||
+		    is_empty_dir(name))
+			continue;
+
+		if (!submodule_uses_gitfile(name))
+			errs = error(_("submodule '%s' (or one of its nested "
+				     "submodules) uses a .git directory\n"
+				     "(use 'rm -rf' if you really want to remove "
+				     "it including all of its history)"), name);
+	}
+
+	return errs;
+}
+
 static int check_local_mod(unsigned char *head, int index_only)
 {
 	/*
@@ -37,15 +72,23 @@ static int check_local_mod(unsigned char *head, int index_only)
 		struct stat st;
 		int pos;
 		struct cache_entry *ce;
-		const char *name = list.name[i];
+		const char *name = list.entry[i].name;
 		unsigned char sha1[20];
 		unsigned mode;
 		int local_changes = 0;
 		int staged_changes = 0;

 		pos = cache_name_pos(name, strlen(name));
-		if (pos < 0)
-			continue; /* removing unmerged entry */
+		if (pos < 0) {
+			/*
+			 * Skip unmerged entries except for populated submodules
+			 * that could loose history when removed.
+			 */
+			pos = -pos-1;
+			if (!S_ISGITLINK(active_cache[pos]->ce_mode) ||
+			    is_empty_dir(name))
+				continue;
+		}
 		ce = active_cache[pos];

 		if (lstat(ce->name, &st) < 0) {
@@ -58,9 +101,10 @@ static int check_local_mod(unsigned char *head, int index_only)
 			/* if a file was removed and it is now a
 			 * directory, that is the same as ENOENT as
 			 * far as git is concerned; we do not track
-			 * directories.
+			 * directories unless they are submodules.
 			 */
-			continue;
+			if (!S_ISGITLINK(ce->ce_mode))
+				continue;
 		}

 		/*
@@ -80,8 +124,11 @@ static int check_local_mod(unsigned char *head, int index_only)

 		/*
 		 * Is the index different from the file in the work tree?
+		 * If it's a submodule, is its work tree modified?
 		 */
-		if (ce_match_stat(ce, &st, 0))
+		if (ce_match_stat(ce, &st, 0) ||
+		    (S_ISGITLINK(ce->ce_mode) &&
+		     !ok_to_remove_submodule(ce->name)))
 			local_changes = 1;

 		/*
@@ -115,10 +162,18 @@ static int check_local_mod(unsigned char *head, int index_only)
 				errs = error(_("'%s' has changes staged in the index\n"
 					     "(use --cached to keep the file, "
 					     "or -f to force removal)"), name);
-			if (local_changes)
-				errs = error(_("'%s' has local modifications\n"
-					     "(use --cached to keep the file, "
-					     "or -f to force removal)"), name);
+			if (local_changes) {
+				if (S_ISGITLINK(ce->ce_mode) &&
+				    !submodule_uses_gitfile(name)) {
+					errs = error(_("submodule '%s' (or one of its nested "
+						     "submodules) uses a .git directory\n"
+						     "(use 'rm -rf' if you really want to remove "
+						     "it including all of its history)"), name);
+				} else
+					errs = error(_("'%s' has local modifications\n"
+						     "(use --cached to keep the file, "
+						     "or -f to force removal)"), name);
+			}
 		}
 	}
 	return errs;
@@ -173,8 +228,9 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 		struct cache_entry *ce = active_cache[i];
 		if (!match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, seen))
 			continue;
-		ALLOC_GROW(list.name, list.nr + 1, list.alloc);
-		list.name[list.nr++] = ce->name;
+		ALLOC_GROW(list.entry, list.nr + 1, list.alloc);
+		list.entry[list.nr].name = ce->name;
+		list.entry[list.nr++].is_submodule = S_ISGITLINK(ce->ce_mode);
 	}

 	if (pathspec) {
@@ -215,6 +271,9 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 			hashclr(sha1);
 		if (check_local_mod(sha1, index_only))
 			exit(1);
+	} else if (!index_only) {
+		if (check_submodules_use_gitfiles())
+			exit(1);
 	}

 	/*
@@ -222,7 +281,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	 * the index unless all of them succeed.
 	 */
 	for (i = 0; i < list.nr; i++) {
-		const char *path = list.name[i];
+		const char *path = list.entry[i].name;
 		if (!quiet)
 			printf("rm '%s'\n", path);

@@ -244,7 +303,25 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	if (!index_only) {
 		int removed = 0;
 		for (i = 0; i < list.nr; i++) {
-			const char *path = list.name[i];
+			const char *path = list.entry[i].name;
+			if (list.entry[i].is_submodule) {
+				if (is_empty_dir(path)) {
+					if (!rmdir(path)) {
+						removed = 1;
+						continue;
+					}
+				} else {
+					struct strbuf buf = STRBUF_INIT;
+					strbuf_addstr(&buf, path);
+					if (!remove_dir_recursively(&buf, 0)) {
+						removed = 1;
+						strbuf_release(&buf);
+						continue;
+					}
+					strbuf_release(&buf);
+					/* Fallthrough and let remove_path() fail. */
+				}
+			}
 			if (!remove_path(path)) {
 				removed = 1;
 				continue;
diff --git a/submodule.c b/submodule.c
index 19dc6a6..acb2fe0 100644
--- a/submodule.c
+++ b/submodule.c
@@ -758,6 +758,86 @@ unsigned is_submodule_modified(const char *path, int ignore_untracked)
 	return dirty_submodule;
 }

+int submodule_uses_gitfile(const char *path)
+{
+	struct child_process cp;
+	const char *argv[] = {
+		"submodule",
+		"foreach",
+		"--quiet",
+		"--recursive",
+		"test -f .git",
+		NULL,
+	};
+	struct strbuf buf = STRBUF_INIT;
+	const char *git_dir;
+
+	strbuf_addf(&buf, "%s/.git", path);
+	git_dir = read_gitfile(buf.buf);
+	if (!git_dir) {
+		strbuf_release(&buf);
+		return 0;
+	}
+	strbuf_release(&buf);
+
+	/* Now test that all nested submodules use a gitfile too */
+	memset(&cp, 0, sizeof(cp));
+	cp.argv = argv;
+	cp.env = local_repo_env;
+	cp.git_cmd = 1;
+	cp.no_stdin = 1;
+	cp.no_stderr = 1;
+	cp.no_stdout = 1;
+	cp.dir = path;
+	if (run_command(&cp))
+		return 0;
+
+	return 1;
+}
+
+int ok_to_remove_submodule(const char *path)
+{
+	struct stat st;
+	ssize_t len;
+	struct child_process cp;
+	const char *argv[] = {
+		"status",
+		"--porcelain",
+		"-u",
+		"--ignore-submodules=none",
+		NULL,
+	};
+	struct strbuf buf = STRBUF_INIT;
+	int ok_to_remove = 1;
+
+	if ((lstat(path, &st) < 0) || is_empty_dir(path))
+		return 1;
+
+	if (!submodule_uses_gitfile(path))
+		return 0;
+
+	memset(&cp, 0, sizeof(cp));
+	cp.argv = argv;
+	cp.env = local_repo_env;
+	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 -uall --ignore-submodules=none' in submodule %s", path);
+
+	len = strbuf_read(&buf, cp.out, 1024);
+	if (len > 2)
+		ok_to_remove = 0;
+	close(cp.out);
+
+	if (finish_command(&cp))
+		die("'git status --porcelain -uall --ignore-submodules=none' failed in submodule %s", path);
+
+	strbuf_release(&buf);
+	return ok_to_remove;
+}
+
 static int find_first_merges(struct object_array *result, const char *path,
 		struct commit *a, struct commit *b)
 {
diff --git a/submodule.h b/submodule.h
index e105b0e..9c0f6a4 100644
--- a/submodule.h
+++ b/submodule.h
@@ -27,6 +27,8 @@ int fetch_populated_submodules(int num_options, const char **options,
 			       const char *prefix, int command_line_option,
 			       int quiet);
 unsigned is_submodule_modified(const char *path, int ignore_untracked);
+int submodule_uses_gitfile(const char *path);
+int ok_to_remove_submodule(const char *path);
 int merge_submodule(unsigned char result[20], const char *path, const unsigned char base[20],
 		    const unsigned char a[20], const unsigned char b[20], int search);
 int find_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_name,
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index 9fd28bc..61ef529 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -262,4 +262,295 @@ test_expect_success 'rm removes subdirectories recursively' '
 	! test -d dir
 '

+cat >expect <<EOF
+D  submod
+EOF
+
+cat >expect.modified <<EOF
+ M submod
+EOF
+
+test_expect_success 'rm removes empty submodules from work tree' '
+	mkdir submod &&
+	git update-index --add --cacheinfo 160000 $(git rev-parse HEAD) submod &&
+	git config -f .gitmodules submodule.sub.url ./. &&
+	git config -f .gitmodules submodule.sub.path submod &&
+	git submodule init &&
+	git add .gitmodules &&
+	git commit -m "add submodule" &&
+	git rm submod &&
+	test ! -e submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm removes removed submodule from index' '
+	git reset --hard &&
+	git submodule update &&
+	rm -rf submod &&
+	git rm submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm removes work tree of unmodified submodules' '
+	git reset --hard &&
+	git submodule update &&
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with different HEAD fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		git checkout HEAD^
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with modifications fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >empty
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with untracked files fails unless forced' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		echo X >untracked
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'setup submodule conflict' '
+	git reset --hard &&
+	git submodule update &&
+	git checkout -b branch1 &&
+	echo 1 >nitfol &&
+	git add nitfol &&
+	git commit -m "added nitfol 1" &&
+	git checkout -b branch2 master &&
+	echo 2 >nitfol &&
+	git add nitfol &&
+	git commit -m "added nitfol 2" &&
+	git checkout -b conflict1 master &&
+	(cd submod &&
+		git fetch &&
+		git checkout branch1
+	) &&
+	git add submod &&
+	git commit -m "submod 1" &&
+	git checkout -b conflict2 master &&
+	(cd submod &&
+		git checkout branch2
+	) &&
+	git add submod &&
+	git commit -m "submod 2"
+'
+
+cat >expect.conflict <<EOF
+UU submod
+EOF
+
+test_expect_success 'rm of a conflicted populated submodule fails unless forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a conflicted populated submodule with a .git directory fails even when forced' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		rm .git &&
+		cp -a ../.git/modules/sub .git &&
+		GIT_WORK_TREE=. git config --unset core.worktree
+	) &&
+	test_must_fail git merge conflict2 &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	test_must_fail git rm -f submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.conflict actual &&
+	git merge --abort &&
+	rm -rf submod
+'
+
+test_expect_success 'rm of a conflicted unpopulated submodule succeeds' '
+	git checkout conflict1 &&
+	git reset --hard &&
+	test_must_fail git merge conflict2 &&
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated submodule with a .git directory fails even when forced' '
+	git checkout -f master &&
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		rm .git &&
+		cp -a ../.git/modules/sub .git &&
+		GIT_WORK_TREE=. git config --unset core.worktree
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	! test -s actual &&
+	test_must_fail git rm -f submod &&
+	test -d submod &&
+	test -d submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	! test -s actual &&
+	rm -rf submod
+'
+
+cat >expect.deepmodified <<EOF
+ M submod/subsubmod
+EOF
+
+test_expect_success 'setup subsubmodule' '
+	git reset --hard &&
+	git submodule update &&
+	(cd submod &&
+		git update-index --add --cacheinfo 160000 $(git rev-parse HEAD) subsubmod &&
+		git config -f .gitmodules submodule.sub.url ../. &&
+		git config -f .gitmodules submodule.sub.path subsubmod &&
+		git submodule init &&
+		git add .gitmodules &&
+		git commit -m "add subsubmodule" &&
+		git submodule update subsubmod
+	) &&
+	git commit -a -m "added deep submodule"
+'
+
+test_expect_success 'rm recursively removes work tree of unmodified submodules' '
+	git rm submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with different nested HEAD fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		git checkout HEAD^
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with nested modifications fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		echo X >empty
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with nested untracked files fails unless forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		echo X >untracked
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -f submod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect.modified actual &&
+	git rm -f submod &&
+	test ! -d submod &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rm of a populated nested submodule with a nested .git directory fails even when forced' '
+	git reset --hard &&
+	git submodule update --recursive &&
+	(cd submod/subsubmod &&
+		rm .git &&
+		cp -a ../../.git/modules/sub/modules/sub .git &&
+		GIT_WORK_TREE=. git config --unset core.worktree
+	) &&
+	test_must_fail git rm submod &&
+	test -d submod &&
+	test -d submod/subsubmod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	! test -s actual &&
+	test_must_fail git rm -f submod &&
+	test -d submod &&
+	test -d submod/subsubmod/.git &&
+	git status -s -uno --ignore-submodules=none > actual &&
+	! test -s actual &&
+	rm -rf submod
+'
+
 test_done
-- 
1.7.12.316.gac65367