unpack-trees: add special cwd handling

When running commands such as `git reset --hard` from a subdirectory, if
that subdirectory is in the way of adding needed files, bail with an
error message.

Note that this change looks kind of like it duplicates the new lines of
code from the previous commit in verify_clean_subdirectory().  However,
when we are preserving untracked files, we would rather any error
messages about untracked files being in the way take precedence over
error messages about a subdirectory that happens to be the_original_cwd
being in the way.  But in the UNPACK_RESET_OVERWRITE_UNTRACKED case,
there is no untracked checking to be done, so we simply add a special
case near the top of verify_absent_1.

Acked-by: Derrick Stolee <stolee@gmail.com>
Acked-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/unpack-trees.c b/unpack-trees.c
index 6bc16f3..5852807 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -2261,10 +2261,19 @@ static int verify_absent_1(const struct cache_entry *ce,
 	int len;
 	struct stat st;
 
-	if (o->index_only || !o->update ||
-	    o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED)
+	if (o->index_only || !o->update)
 		return 0;
 
+	if (o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED) {
+		/* Avoid nuking 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);
+		/* ...but nuke anything else. */
+		return 0;
+	}
+
 	len = check_leading_path(ce->name, ce_namelen(ce), 0);
 	if (!len)
 		return 0;