Merge branch 'en/keep-cwd'

Many git commands that deal with working tree files try to remove a
directory that becomes empty (i.e. "git switch" from a branch that
has the directory to another branch that does not would attempt
remove all files in the directory and the directory itself).  This
drops users into an unfamiliar situation if the command was run in
a subdirectory that becomes subject to removal due to the command.
The commands have been taught to keep an empty directory if it is
the directory they were started in to avoid surprising users.

* en/keep-cwd:
  t2501: simplify the tests since we can now assume desired behavior
  dir: new flag to remove_dir_recurse() to spare the original_cwd
  dir: avoid incidentally removing the original_cwd in remove_path()
  stash: do not attempt to remove startup_info->original_cwd
  rebase: do not attempt to remove startup_info->original_cwd
  clean: do not attempt to remove startup_info->original_cwd
  symlinks: do not include startup_info->original_cwd in dir removal
  unpack-trees: add special cwd handling
  unpack-trees: refuse to remove startup_info->original_cwd
  setup: introduce startup_info->original_cwd
  t2501: add various tests for removing the current working directory

1 files changed, 277 insertions, 0 deletions

diff --git a/t/t2501-cwd-empty.sh b/t/t2501-cwd-empty.sh
new file mode 100755
index 0000000000..f6d8d7d03d
--- /dev/null
+++ b/t/t2501-cwd-empty.sh
@@ -0,0 +1,277 @@
+#!/bin/sh
+
+test_description='Test handling of the current working directory becoming empty'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit init &&
+
+	git branch fd_conflict &&
+
+	mkdir -p foo/bar &&
+	test_commit foo/bar/baz &&
+
+	git revert HEAD &&
+	git tag reverted &&
+
+	git checkout fd_conflict &&
+	mkdir dirORfile &&
+	test_commit dirORfile/foo &&
+
+	git rm -r dirORfile &&
+	echo not-a-directory >dirORfile &&
+	git add dirORfile &&
+	git commit -m dirORfile &&
+
+	git switch -c df_conflict HEAD~1 &&
+	test_commit random_file &&
+
+	git switch -c undo_fd_conflict fd_conflict &&
+	git revert HEAD
+'
+
+test_incidental_dir_removal () {
+	test_when_finished "git reset --hard" &&
+
+	git checkout foo/bar/baz^{commit} &&
+	test_path_is_dir foo/bar &&
+
+	(
+		cd foo &&
+		"$@" &&
+
+		# Make sure foo still exists, and commands needing it work
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+	test_path_is_missing foo/bar/baz &&
+	test_path_is_missing foo/bar &&
+
+	test_path_is_dir foo
+}
+
+test_required_dir_removal () {
+	git checkout df_conflict^{commit} &&
+	test_when_finished "git clean -fdx" &&
+
+	(
+		cd dirORfile &&
+
+		# Ensure command refuses to run
+		test_must_fail "$@" 2>../error &&
+		grep "Refusing to remove.*current working directory" ../error &&
+
+		# ...and that the index and working tree are left clean
+		git diff --exit-code HEAD &&
+
+		# Ensure that getcwd and git status do not error out (which
+		# they might if the current working directory had been removed)
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+
+	test_path_is_dir dirORfile
+}
+
+test_expect_success 'checkout does not clean cwd incidentally' '
+	test_incidental_dir_removal git checkout init
+'
+
+test_expect_success 'checkout fails if cwd needs to be removed' '
+	test_required_dir_removal git checkout fd_conflict
+'
+
+test_expect_success 'reset --hard does not clean cwd incidentally' '
+	test_incidental_dir_removal git reset --hard init
+'
+
+test_expect_success 'reset --hard fails if cwd needs to be removed' '
+	test_required_dir_removal git reset --hard fd_conflict
+'
+
+test_expect_success 'merge does not clean cwd incidentally' '
+	test_incidental_dir_removal git merge reverted
+'
+
+# This file uses some simple merges where
+#   Base: 'dirORfile/' exists
+#   Side1: random other file changed
+#   Side2: 'dirORfile/' removed, 'dirORfile' added
+# this should resolve cleanly, but merge-recursive throws merge conflicts
+# because it's dumb.  Add a special test for checking merge-recursive (and
+# merge-ort), then after this just hard require ort for all remaining tests.
+#
+test_expect_success 'merge fails if cwd needs to be removed; recursive friendly' '
+	git checkout foo/bar/baz &&
+	test_when_finished "git clean -fdx" &&
+
+	mkdir dirORfile &&
+	(
+		cd dirORfile &&
+
+		test_must_fail git merge fd_conflict 2>../error
+	) &&
+
+	test_path_is_dir dirORfile &&
+	grep "Refusing to remove the current working directory" error
+'
+
+GIT_TEST_MERGE_ALGORITHM=ort
+
+test_expect_success 'merge fails if cwd needs to be removed' '
+	test_required_dir_removal git merge fd_conflict
+'
+
+test_expect_success 'cherry-pick does not clean cwd incidentally' '
+	test_incidental_dir_removal git cherry-pick reverted
+'
+
+test_expect_success 'cherry-pick fails if cwd needs to be removed' '
+	test_required_dir_removal git cherry-pick fd_conflict
+'
+
+test_expect_success 'rebase does not clean cwd incidentally' '
+	test_incidental_dir_removal git rebase reverted
+'
+
+test_expect_success 'rebase fails if cwd needs to be removed' '
+	test_required_dir_removal git rebase fd_conflict
+'
+
+test_expect_success 'revert does not clean cwd incidentally' '
+	test_incidental_dir_removal git revert HEAD
+'
+
+test_expect_success 'revert fails if cwd needs to be removed' '
+	test_required_dir_removal git revert undo_fd_conflict
+'
+
+test_expect_success 'rm does not clean cwd incidentally' '
+	test_incidental_dir_removal git rm bar/baz.t
+'
+
+test_expect_success 'apply does not remove cwd incidentally' '
+	git diff HEAD HEAD~1 >patch &&
+	test_incidental_dir_removal git apply ../patch
+'
+
+test_incidental_untracked_dir_removal () {
+	test_when_finished "git reset --hard" &&
+
+	git checkout foo/bar/baz^{commit} &&
+	mkdir -p untracked &&
+	mkdir empty
+	>untracked/random &&
+
+	(
+		cd untracked &&
+		"$@" &&
+
+		# Make sure untracked still exists, and commands needing it work
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+	test_path_is_missing empty &&
+	test_path_is_missing untracked/random &&
+
+	test_path_is_dir untracked
+}
+
+test_expect_success 'clean does not remove cwd incidentally' '
+	test_incidental_untracked_dir_removal \
+		git -C .. clean -fd -e warnings . >warnings &&
+	grep "Refusing to remove current working directory" warnings
+'
+
+test_expect_success 'stash does not remove cwd incidentally' '
+	test_incidental_untracked_dir_removal \
+		git stash --include-untracked
+'
+
+test_expect_success '`rm -rf dir` only removes a subset of dir' '
+	test_when_finished "rm -rf a/" &&
+
+	mkdir -p a/b/c &&
+	>a/b/c/untracked &&
+	>a/b/c/tracked &&
+	git add a/b/c/tracked &&
+
+	(
+		cd a/b &&
+		git rm -rf ../b
+	) &&
+
+	test_path_is_dir a/b &&
+	test_path_is_missing a/b/c/tracked &&
+	test_path_is_file a/b/c/untracked
+'
+
+test_expect_success '`rm -rf dir` even with only tracked files will remove something else' '
+	test_when_finished "rm -rf a/" &&
+
+	mkdir -p a/b/c &&
+	>a/b/c/tracked &&
+	git add a/b/c/tracked &&
+
+	(
+		cd a/b &&
+		git rm -rf ../b
+	) &&
+
+	test_path_is_missing a/b/c/tracked &&
+	test_path_is_missing a/b/c &&
+	test_path_is_dir a/b
+'
+
+test_expect_success 'git version continues working from a deleted dir' '
+	mkdir tmp &&
+	(
+		cd tmp &&
+		rm -rf ../tmp &&
+		git version
+	)
+'
+
+test_submodule_removal () {
+	path_status=$1 &&
+	shift &&
+
+	test_status=
+	test "$path_status" = dir && test_status=test_must_fail
+
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_when_finished "rm -rf .git/modules/my_submodule" &&
+
+	git checkout foo/bar/baz &&
+
+	git init my_submodule &&
+	touch my_submodule/file &&
+	git -C my_submodule add file &&
+	git -C my_submodule commit -m "initial commit" &&
+	git submodule add ./my_submodule &&
+	git commit -m "Add the submodule" &&
+
+	(
+		cd my_submodule &&
+		$test_status "$@"
+	) &&
+
+	test_path_is_${path_status} my_submodule
+}
+
+test_expect_success 'rm -r with -C leaves submodule if cwd inside' '
+	test_submodule_removal dir git -C .. rm -r my_submodule/
+'
+
+test_expect_success 'rm -r leaves submodule if cwd inside' '
+	test_submodule_removal dir \
+		git --git-dir=../.git --work-tree=.. rm -r ../my_submodule/
+'
+
+test_expect_success 'rm -rf removes submodule even if cwd inside' '
+	test_submodule_removal missing \
+		git --git-dir=../.git --work-tree=.. rm -rf ../my_submodule/
+'
+
+test_done