Handle git_path() with lock files correctly in worktrees

I stumbled over this during my recent work in Git GUI
[https://github.com/gitgitgadget/git/pull/361] that was originally really only intended to use the correct hooks directory.

It turns out that my fears that index.lock was mishandled were unfounded, hence this patch series has a lot lower priority for me than "OMG we must push this into v2.24.0!".

Technically, the first patch is not needed (because I decided against adding a test to t1400 in the end, in favor of t1500), but it shouldn't hurt, either.

I verified locally that this patch pair does not conflict with sg/dir-trie-fixes.

Changes since v3:

* Instead of duplicating the path when it has a .lock suffix, we now use strbuf manipulation to strip the suffix temporarily.
* The test case in t1500 was scrapped in favor of a much simpler pair of test cases in t0060.

Changes since v2:

* Adjusted the commit message to really not talk about index.lock.
* Instead of modifying the code inside trie_find() to special-case .lock, I now copy the string without the suffix .lock (if any) before handing it off to trie_find().

Changes since v1:

* Clarified the commit message to state that index.lock is fine, it is logs/HEAD.lock that isn't.

Johannes Schindelin (2):
t1400: wrap setup code in test case
git_path(): handle .lock files correctly

 path.c                |  6 ++++++
 t/t0060-path-utils.sh |  2 ++
 t/t1400-update-ref.sh | 18 ++++++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)

base-commit: 108b97dc372828f0e72e56bbb40cae8e1e83ece6
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-401%2Fdscho%2Flock-files-in-worktrees-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-401/dscho/lock-files-in-worktrees-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/401

Range-diff vs v3:

 1:  cf97c5182e = 1:  cf97c5182e t1400: wrap setup code in test case
 2:  8b1f4f089a ! 2:  d98810875e git_path(): handle `.lock` files correctly
     @@ -28,46 +28,40 @@
       --- a/path.c
       +++ b/path.c
      @@
     - static void update_common_dir(struct strbuf *buf, int git_dir_len,
     + #include "path.h"
     + #include "packfile.h"
     + #include "object-store.h"
     ++#include "lockfile.h"
     + 
     + static int get_st_mode_bits(const char *path, int *mode)
     + {
     +@@
       			      const char *common_dir)
       {
     --	char *base = buf->buf + git_dir_len;
     -+	char *base = buf->buf + git_dir_len, *base2 = NULL;
     -+
     -+	if (ends_with(base, ".lock"))
     -+		base = base2 = xstrndup(base, strlen(base) - 5);
     + 	char *base = buf->buf + git_dir_len;
     ++	int has_lock_suffix = strbuf_strip_suffix(buf, LOCK_SUFFIX);
      +
       	init_common_trie();
       	if (trie_find(&common_trie, base, check_common, NULL) > 0)
       		replace_dir(buf, git_dir_len, common_dir);
      +
     -+	free(base2);
     ++	if (has_lock_suffix)
     ++		strbuf_addstr(buf, LOCK_SUFFIX);
       }
       
       void report_linked_checkout_garbage(void)
      
     - diff --git a/t/t1500-rev-parse.sh b/t/t1500-rev-parse.sh
     - --- a/t/t1500-rev-parse.sh
     - +++ b/t/t1500-rev-parse.sh
     + diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
     + --- a/t/t0060-path-utils.sh
     + +++ b/t/t0060-path-utils.sh
      @@
     - 	test_cmp expect actual
     - '
     - 
     -+test_expect_success 'git-path in worktree' '
     -+	test_tick &&
     -+	git commit --allow-empty -m empty &&
     -+	git worktree add --detach wt &&
     -+	test_write_lines >expect \
     -+		"$(pwd)/.git/worktrees/wt/logs/HEAD" \
     -+		"$(pwd)/.git/worktrees/wt/logs/HEAD.lock" \
     -+		"$(pwd)/.git/worktrees/wt/index" \
     -+		"$(pwd)/.git/worktrees/wt/index.lock" &&
     -+	git -C wt rev-parse >actual \
     -+		--git-path logs/HEAD --git-path logs/HEAD.lock \
     -+		--git-path index --git-path index.lock &&
     -+	test_cmp expect actual
     -+'
     -+
     - test_expect_success 'rev-parse --is-shallow-repository in shallow repo' '
     - 	test_commit test_commit &&
     - 	echo true >expect &&
     + test_git_path GIT_OBJECT_DIRECTORY=foo objects2 .git/objects2
     + test_expect_success 'setup common repository' 'git --git-dir=bar init'
     + test_git_path GIT_COMMON_DIR=bar index                    .git/index
     ++test_git_path GIT_COMMON_DIR=bar index.lock               .git/index.lock
     + test_git_path GIT_COMMON_DIR=bar HEAD                     .git/HEAD
     + test_git_path GIT_COMMON_DIR=bar logs/HEAD                .git/logs/HEAD
     ++test_git_path GIT_COMMON_DIR=bar logs/HEAD.lock           .git/logs/HEAD.lock
     + test_git_path GIT_COMMON_DIR=bar logs/refs/bisect/foo     .git/logs/refs/bisect/foo
     + test_git_path GIT_COMMON_DIR=bar logs/refs/bisec/foo      bar/logs/refs/bisec/foo
     + test_git_path GIT_COMMON_DIR=bar logs/refs/bisec          bar/logs/refs/bisec

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