[PATCH v2 3/9] unpack-trees: refuse to remove startup_info->original_cwd

["Elijah Newren via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Elijah Newren <newren@xxxxxxxxx>

In the past, when a directory needs to be removed to make room for a
file, we have always errored out when that directory contains any
untracked (but not ignored) files.  Add an extra condition on that: also
error out if the directory is the current working directory we inherited
from our parent process.

Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
---
 t/t2501-cwd-empty.sh | 10 +++++-----
 unpack-trees.c       | 17 +++++++++++++----
 unpack-trees.h       |  1 +
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/t/t2501-cwd-empty.sh b/t/t2501-cwd-empty.sh
index 5dfb456a691..212676d71c3 100755
--- a/t/t2501-cwd-empty.sh
+++ b/t/t2501-cwd-empty.sh
@@ -38,7 +38,7 @@ test_expect_failure 'checkout does not clean cwd incidentally' '
 	test_path_is_dir foo
 '
 
-test_expect_failure 'checkout fails if cwd needs to be removed' '
+test_expect_success 'checkout fails if cwd needs to be removed' '
 	git checkout foo/bar/baz &&
 	test_when_finished "git clean -fdx" &&
 
@@ -95,7 +95,7 @@ test_expect_failure 'merge does not remove cwd incidentally' '
 	test_path_is_dir subdir
 '
 
-test_expect_failure 'merge fails if cwd needs to be removed' '
+test_expect_success 'merge fails if cwd needs to be removed' '
 	git checkout foo/bar/baz &&
 	test_when_finished "git clean -fdx" &&
 
@@ -122,7 +122,7 @@ test_expect_failure 'cherry-pick does not remove cwd incidentally' '
 	test_path_is_dir subdir
 '
 
-test_expect_failure 'cherry-pick fails if cwd needs to be removed' '
+test_expect_success 'cherry-pick fails if cwd needs to be removed' '
 	git checkout foo/bar/baz &&
 	test_when_finished "git clean -fdx" &&
 
@@ -149,7 +149,7 @@ test_expect_failure 'rebase does not remove cwd incidentally' '
 	test_path_is_dir subdir
 '
 
-test_expect_failure 'rebase fails if cwd needs to be removed' '
+test_expect_success 'rebase fails if cwd needs to be removed' '
 	git checkout foo/bar/baz &&
 	test_when_finished "git clean -fdx" &&
 
@@ -176,7 +176,7 @@ test_expect_failure 'revert does not remove cwd incidentally' '
 	test_path_is_dir subdir
 '
 
-test_expect_failure 'revert fails if cwd needs to be removed' '
+test_expect_success 'revert fails if cwd needs to be removed' '
 	git checkout fd_conflict &&
 	git revert HEAD &&
 	test_when_finished "git clean -fdx" &&
diff --git a/unpack-trees.c b/unpack-trees.c
index 89ca95ce90b..6bc16f3a714 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -36,6 +36,9 @@ static const char *unpack_plumbing_errors[NB_UNPACK_TREES_WARNING_TYPES] = {
 	/* ERROR_NOT_UPTODATE_DIR */
 	"Updating '%s' would lose untracked files in it",
 
+	/* ERROR_CWD_IN_THE_WAY */
+	"Refusing to remove '%s' since it is the current working directory.",
+
 	/* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
 	"Untracked working tree file '%s' would be overwritten by merge.",
 
@@ -131,6 +134,9 @@ void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 	msgs[ERROR_NOT_UPTODATE_DIR] =
 		_("Updating the following directories would lose untracked files in them:\n%s");
 
+	msgs[ERROR_CWD_IN_THE_WAY] =
+		_("Refusing to remove the current working directory:\n%s");
+
 	if (!strcmp(cmd, "checkout"))
 		msg = advice_enabled(ADVICE_COMMIT_BEFORE_MERGE)
 		      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
@@ -2146,10 +2152,7 @@ static int verify_clean_subdirectory(const struct cache_entry *ce,
 		cnt++;
 	}
 
-	/*
-	 * Then we need to make sure that we do not lose a locally
-	 * present file that is not ignored.
-	 */
+	/* Do not lose a locally present file that is not ignored. */
 	pathbuf = xstrfmt("%.*s/", namelen, ce->name);
 
 	memset(&d, 0, sizeof(d));
@@ -2160,6 +2163,12 @@ static int verify_clean_subdirectory(const struct cache_entry *ce,
 	free(pathbuf);
 	if (i)
 		return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
+
+	/* Do not lose startup_info->original_cwd */
+	if (startup_info->original_cwd &&
+	    !strcmp(startup_info->original_cwd, ce->name))
+		return add_rejected_path(o, ERROR_CWD_IN_THE_WAY, ce->name);
+
 	return cnt;
 }
 
diff --git a/unpack-trees.h b/unpack-trees.h
index 71ffb7eeb0c..efb9edfbb27 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -19,6 +19,7 @@ enum unpack_trees_error_types {
 	ERROR_WOULD_OVERWRITE = 0,
 	ERROR_NOT_UPTODATE_FILE,
 	ERROR_NOT_UPTODATE_DIR,
+	ERROR_CWD_IN_THE_WAY,
 	ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN,
 	ERROR_WOULD_LOSE_UNTRACKED_REMOVED,
 	ERROR_BIND_OVERLAP,
-- 
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