[PATCH v1] name-hash: properly fold directory names in adjust_dirname_case()

[Ben Peart <benpeart@microsoft.com>]

Correct the pointer arithmetic in adjust_dirname_case() so that it calls
find_dir_entry() with the correct string length.  Previously passing in
"dir1/foo" would pass a length of 6 instead of the correct 4.  This resulted in
find_dir_entry() never finding the entry and so the subsequent memcpy that would
fold the name to the version with the correct case never executed.

Add a test to validate the corrected behavior with name folding of directories.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---

Notes:
    Base Ref: v2.16.1
    Web-Diff: https://github.com/benpeart/git/commit/2944970f4e
    Checkout: git fetch https://github.com/benpeart/git adjust_dirname-v1 && git checkout 2944970f4e

 name-hash.c           |  6 +++---
 t/t0050-filesystem.sh | 12 +++++++++++-
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/name-hash.c b/name-hash.c
index 45c98db0a0..2ddbb72647 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -696,12 +696,12 @@ void adjust_dirname_case(struct index_state *istate, char *name)
 		if (*ptr == '/') {
 			struct dir_entry *dir;
 
-			ptr++;
-			dir = find_dir_entry(istate, name, ptr - name + 1);
+			dir = find_dir_entry(istate, name, ptr - name);
 			if (dir) {
 				memcpy((void *)startPtr, dir->name + (startPtr - name), ptr - startPtr);
-				startPtr = ptr;
+				startPtr = ptr + 1;
 			}
+			ptr++;
 		}
 	}
 }
diff --git a/t/t0050-filesystem.sh b/t/t0050-filesystem.sh
index b29d749bb7..219c96594c 100755
--- a/t/t0050-filesystem.sh
+++ b/t/t0050-filesystem.sh
@@ -80,7 +80,17 @@ test_expect_success 'merge (case change)' '
 	git merge topic
 '
 
-
+test_expect_success CASE_INSENSITIVE_FS 'add directory (with different case)' '
+	git reset --hard initial &&
+	mkdir -p dir1 &&
+	mkdir -p dir1/dir2 &&
+	touch dir1/dir2/a &&
+	touch dir1/dir2/b &&
+	git add dir1/dir2/a &&
+	git add dir1/DIR2/b &&
+	camel=$(git ls-files | grep dir2) &&
+	test $(echo "$camel" | wc -l) = 2
+'
 
 test_expect_failure CASE_INSENSITIVE_FS 'add (with different case)' '
 	git reset --hard initial &&

base-commit: 8279ed033f703d4115bee620dccd32a9ec94d9aa
-- 
2.15.0.windows.1