[PATCH] apply: support case-only renames in case-insensitive filesystems

From: Tao Klerks via GitGitGadget <gitgitgadget@gmail.com>
Date: Jun 11, 2022, 17:03 UTC
Message-ID: <pull.1257.git.1654967038802.gitgitgadget@gmail.com>

From: Tao Klerks <tao@klerks.biz>

"git apply" checks, when validating a patch, to ensure that any files being added aren't already in the worktree.

When this check runs on a case-only rename, in a case-insensitive filesystem, this leads to a false positive - the command fails with an error like: error: File1: already exists in working directory

Fix this existence check to allow the file to exist, for a case-only rename when config core.ignorecase is set.

Also add a test for this case, while verifying that conflicting file conditions are still caught correctly, including case-only conflicts on case-sensitive filesystems.

Signed-off-by: Tao Klerks <tao@klerks.biz>
---
    apply: support case-only renames in case-insensitive filesystems
    
    As suggested recently in thread
    CAPMMpojwV+f=z9sgc_GaUOTFBCUVdbrGW8WjatWWmC3WTcsoXw@mail.gmail.com,
    proposing a fix to git-apply for case-only renames on case-insensitive
    filesystems.
    
    Also including tests to check both the corrected behavior and the
    corresponding legitimate errors.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1257%2FTaoK%2Ftao-apply-case-insensitive-renames-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1257/TaoK/tao-apply-case-insensitive-renames-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1257

 apply.c                                  |  2 +
 t/t4141-apply-case-insensitive-rename.sh | 50 ++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100755 t/t4141-apply-case-insensitive-rename.sh

diff --git a/apply.c b/apply.c
index 2b7cd930efa..ccba7f90393 100644
--- a/apply.c
+++ b/apply.c
@@ -3942,6 +3942,8 @@ static int check_patch(struct apply_state *state, struct patch *patch)
 	if ((tpatch = in_fn_table(state, new_name)) &&
 	    (was_deleted(tpatch) || to_be_deleted(tpatch)))
 		ok_if_exists = 1;
+	else if (ignore_case && !strcasecmp(old_name, new_name))
+		ok_if_exists = 1;
 	else
 		ok_if_exists = 0;
 
diff --git a/t/t4141-apply-case-insensitive-rename.sh b/t/t4141-apply-case-insensitive-rename.sh
new file mode 100755
index 00000000000..6b394252ff8
--- /dev/null
+++ b/t/t4141-apply-case-insensitive-rename.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+
+test_description='git apply should handle case-only renames on case-insensitive filesystems'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+# Please note, this test assumes that core.ignorecase is set appropriately for the filesystem,
+# as tested in t0050. Case-only rename conflicts are only tested in case-sensitive filesystems.
+
+if ! test_have_prereq CASE_INSENSITIVE_FS
+then
+	test_set_prereq CASE_SENSITIVE_FS
+	echo nuts
+fi
+
+test_expect_success setup '
+	echo "This is some content in the file." > file1 &&
+	echo "A completely different file." > file2 &&
+	git update-index --add file1 &&
+	git update-index --add file2 &&
+	cat >case_only_rename_patch <<-\EOF
+	diff --git a/file1 b/File1
+	similarity index 100%
+	rename from file1
+	rename to File1
+	EOF
+'
+
+test_expect_success 'refuse to apply rename patch with conflict' '
+	cat >conflict_patch <<-\EOF &&
+	diff --git a/file1 b/file2
+	similarity index 100%
+	rename from file1
+	rename to file2
+	EOF
+	test_must_fail git apply --index conflict_patch
+'
+
+test_expect_success CASE_SENSITIVE_FS 'refuse to apply case-only rename patch with conflict, in case-sensitive FS' '
+	test_when_finished "git mv File1 file2" &&
+	git mv file2 File1 &&
+	test_must_fail git apply --index case_only_rename_patch
+'
+
+test_expect_success 'apply case-only rename patch without conflict' '
+	git apply --index case_only_rename_patch
+'
+
+test_done

base-commit: 1e59178e3f65880188caedb965e70db5ceeb2d64

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