Merge pull request #2504 from dscho/access-repo-via-junction

Handle `git add <file>` where <file> traverses an NTFS junction

abspath.c

@@ -93,6 +93,9 @@ static char *strbuf_realpath_1(struct strbuf *resolved, const char *path,
 			goto error_out;
 	}
 
+	if (platform_strbuf_realpath(resolved, path))
+		return resolved->buf;
+
 	strbuf_addstr(&remaining, path);
 	get_root_part(resolved, &remaining);
 

compat/mingw.c

@@ -1238,6 +1238,82 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
 }
 #endif
 
+char *mingw_strbuf_realpath(struct strbuf *resolved, const char *path)
+{
+	wchar_t wpath[MAX_PATH];
+	HANDLE h;
+	DWORD ret;
+	int len;
+	const char *last_component = NULL;
+	char *append = NULL;
+
+	if (xutftowcs_path(wpath, path) < 0)
+		return NULL;
+
+	h = CreateFileW(wpath, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+
+	/*
+	 * strbuf_realpath() allows the last path component to not exist. If
+	 * that is the case, now it's time to try without last component.
+	 */
+	if (h == INVALID_HANDLE_VALUE &&
+	    GetLastError() == ERROR_FILE_NOT_FOUND) {
+		/* cut last component off of `wpath` */
+		wchar_t *p = wpath + wcslen(wpath);
+
+		while (p != wpath)
+			if (*(--p) == L'/' || *p == L'\\')
+				break; /* found start of last component */
+
+		if (p != wpath && (last_component = find_last_dir_sep(path))) {
+			append = xstrdup(last_component + 1); /* skip directory separator */
+			/*
+			 * Do not strip the trailing slash at the drive root, otherwise
+			 * the path would be e.g. `C:` (which resolves to the
+			 * _current_ directory on that drive).
+			 */
+			if (p[-1] == L':')
+				p[1] = L'\0';
+			else
+				*p = L'\0';
+			h = CreateFileW(wpath, 0, FILE_SHARE_READ |
+					FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+					NULL, OPEN_EXISTING,
+					FILE_FLAG_BACKUP_SEMANTICS, NULL);
+		}
+	}
+
+	if (h == INVALID_HANDLE_VALUE) {
+realpath_failed:
+		FREE_AND_NULL(append);
+		return NULL;
+	}
+
+	ret = GetFinalPathNameByHandleW(h, wpath, ARRAY_SIZE(wpath), 0);
+	CloseHandle(h);
+	if (!ret || ret >= ARRAY_SIZE(wpath))
+		goto realpath_failed;
+
+	len = wcslen(wpath) * 3;
+	strbuf_grow(resolved, len);
+	len = xwcstoutf(resolved->buf, normalize_ntpath(wpath), len);
+	if (len < 0)
+		goto realpath_failed;
+	resolved->len = len;
+
+	if (append) {
+		/* Use forward-slash, like `normalize_ntpath()` */
+		strbuf_complete(resolved, '/');
+		strbuf_addstr(resolved, append);
+		FREE_AND_NULL(append);
+	}
+
+	return resolved->buf;
+
+}
+
 char *mingw_getcwd(char *pointer, int len)
 {
 	wchar_t cwd[MAX_PATH], wpointer[MAX_PATH];

compat/mingw.h

@@ -43,6 +43,9 @@ int mingw_is_mount_point(struct strbuf *path);
 #define PATH_SEP ';'
 char *mingw_query_user_email(void);
 #define query_user_email mingw_query_user_email
+struct strbuf;
+char *mingw_strbuf_realpath(struct strbuf *resolved, const char *path);
+#define platform_strbuf_realpath mingw_strbuf_realpath
 
 /**
  * Verifies that the specified path is owned by the user running the

git-compat-util.h

@@ -391,6 +391,10 @@ static inline int git_has_dir_sep(const char *path)
 #define query_user_email() NULL
 #endif
 
+#ifndef platform_strbuf_realpath
+#define platform_strbuf_realpath(resolved, path) NULL
+#endif
+
 #ifdef __TANDEM
 #include <floss.h(floss_execl,floss_execlp,floss_execv,floss_execvp)>
 #include <floss.h(floss_getpwuid)>

t/t0060-path-utils.sh

@@ -281,6 +281,14 @@ test_expect_success SYMLINKS 'real path works on symlinks' '
 	test_cmp expect actual
 '
 
+test_expect_success MINGW 'real path works near drive root' '
+	# we need a non-existing path at the drive root; simply skip if C:/xyz exists
+	if test ! -e C:/xyz
+	then
+		test C:/xyz = $(test-tool path-utils real_path C:/xyz)
+	fi
+'
+
 test_expect_success SYMLINKS 'prefix_path works with absolute paths to work tree symlinks' '
 	ln -s target symlink &&
 	echo "symlink" >expect &&

t/t3700-add.sh

@@ -548,4 +548,15 @@ test_expect_success CASE_INSENSITIVE_FS 'path is case-insensitive' '
 	git add "$downcased"
 '
 
+test_expect_success MINGW 'can add files via NTFS junctions' '
+	test_when_finished "cmd //c rmdir junction && rm -rf target" &&
+	test_create_repo target &&
+	cmd //c "mklink /j junction target" &&
+	>target/via-junction &&
+	git -C junction add "$(pwd)/junction/via-junction" &&
+	echo via-junction >expect &&
+	git -C target diff --cached --name-only >actual &&
+	test_cmp expect actual
+'
+
 test_done

t/t5601-clone.sh

@@ -78,6 +78,13 @@ test_expect_success 'clone respects GIT_WORK_TREE' '
 
 '
 
+test_expect_success CASE_INSENSITIVE_FS 'core.worktree is not added due to path case' '
+
+	mkdir UPPERCASE &&
+	git clone src "$(pwd)/uppercase" &&
+	test "unset" = "$(git -C UPPERCASE config --default unset core.worktree)"
+'
+
 test_expect_success 'clone from hooks' '
 
 	test_create_repo r0 &&