Add symlink API support for Windows, expose symlink methods.

Author: bruvzg

core/io/dir_access.cpp

@@ -582,6 +582,10 @@ void DirAccess::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("remove", "path"), &DirAccess::remove);
 	ClassDB::bind_static_method("DirAccess", D_METHOD("remove_absolute", "path"), &DirAccess::remove_absolute);
 
+	ClassDB::bind_method(D_METHOD("is_link", "path"), &DirAccess::is_link);
+	ClassDB::bind_method(D_METHOD("read_link", "path"), &DirAccess::read_link);
+	ClassDB::bind_method(D_METHOD("create_link", "source", "target"), &DirAccess::create_link);
+
 	ClassDB::bind_method(D_METHOD("set_include_navigational", "enable"), &DirAccess::set_include_navigational);
 	ClassDB::bind_method(D_METHOD("get_include_navigational"), &DirAccess::get_include_navigational);
 	ClassDB::bind_method(D_METHOD("set_include_hidden", "enable"), &DirAccess::set_include_hidden);

doc/classes/DirAccess.xml

@@ -94,6 +94,16 @@
 				Static version of [method copy]. Supports only absolute paths.
 			</description>
 		</method>
+		<method name="create_link">
+			<return type="int" enum="Error" />
+			<param index="0" name="source" type="String" />
+			<param index="1" name="target" type="String" />
+			<description>
+				Creates symbolic link between files or folders.
+				[b]Note:[/b] On Windows, this method works only if the application is running with elevated privileges or Developer Mode is enabled.
+				[b]Note:[/b] This method is implemented on macOS, Linux, and Windows.
+			</description>
+		</method>
 		<method name="current_is_dir" qualifiers="const">
 			<return type="bool" />
 			<description>
@@ -212,6 +222,14 @@
 				[b]Note:[/b] This method is implemented on macOS, Linux (for EXT4 and F2FS filesystems only) and Windows. On other platforms, it always returns [code]true[/code].
 			</description>
 		</method>
+		<method name="is_link">
+			<return type="bool" />
+			<param index="0" name="path" type="String" />
+			<description>
+				Returns [code]true[/code] if the file or directory is a symbolic link, directory junction, or other reparse point.
+				[b]Note:[/b] This method is implemented on macOS, Linux, and Windows.
+			</description>
+		</method>
 		<method name="list_dir_begin">
 			<return type="int" enum="Error" />
 			<description>
@@ -264,6 +282,14 @@
 				Returns [code]null[/code] if opening the directory failed. You can use [method get_open_error] to check the error that occurred.
 			</description>
 		</method>
+		<method name="read_link">
+			<return type="String" />
+			<param index="0" name="path" type="String" />
+			<description>
+				Returns target of the symbolic link.
+				[b]Note:[/b] This method is implemented on macOS, Linux, and Windows.
+			</description>
+		</method>
 		<method name="remove">
 			<return type="int" enum="Error" />
 			<param index="0" name="path" type="String" />

drivers/windows/dir_access_windows.cpp

@@ -396,6 +396,66 @@ bool DirAccessWindows::is_case_sensitive(const String &p_path) const {
 	}
 }
 
+bool DirAccessWindows::is_link(String p_file) {
+	String f = p_file;
+
+	if (!f.is_absolute_path()) {
+		f = get_current_dir().path_join(f);
+	}
+	f = fix_path(f);
+
+	DWORD attr = GetFileAttributesW((LPCWSTR)(f.utf16().get_data()));
+	if (attr == INVALID_FILE_ATTRIBUTES) {
+		return false;
+	}
+
+	return (attr & FILE_ATTRIBUTE_REPARSE_POINT);
+}
+
+String DirAccessWindows::read_link(String p_file) {
+	String f = p_file;
+
+	if (!f.is_absolute_path()) {
+		f = get_current_dir().path_join(f);
+	}
+	f = fix_path(f);
+
+	HANDLE hfile = CreateFileW((LPCWSTR)(f.utf16().get_data()), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
+	if (hfile == INVALID_HANDLE_VALUE) {
+		return f;
+	}
+
+	DWORD ret = GetFinalPathNameByHandleW(hfile, nullptr, 0, VOLUME_NAME_DOS | FILE_NAME_NORMALIZED);
+	if (ret == 0) {
+		return f;
+	}
+	Char16String cs;
+	cs.resize(ret + 1);
+	GetFinalPathNameByHandleW(hfile, (LPWSTR)cs.ptrw(), ret, VOLUME_NAME_DOS | FILE_NAME_NORMALIZED);
+	CloseHandle(hfile);
+
+	return String::utf16((const char16_t *)cs.ptr(), ret).trim_prefix(R"(\\?\)");
+}
+
+Error DirAccessWindows::create_link(String p_source, String p_target) {
+	if (p_target.is_relative_path()) {
+		p_target = get_current_dir().path_join(p_target);
+	}
+
+	p_source = fix_path(p_source);
+	p_target = fix_path(p_target);
+
+	DWORD file_attr = GetFileAttributesW((LPCWSTR)(p_source.utf16().get_data()));
+	bool is_dir = (file_attr & FILE_ATTRIBUTE_DIRECTORY);
+
+	DWORD flags = ((is_dir) ? SYMBOLIC_LINK_FLAG_DIRECTORY : 0) | SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE;
+	if (CreateSymbolicLinkW((LPCWSTR)p_target.utf16().get_data(), (LPCWSTR)p_source.utf16().get_data(), flags) != 0) {
+		return OK;
+	} else {
+		return FAILED;
+	}
+}
+
 DirAccessWindows::DirAccessWindows() {
 	p = memnew(DirAccessWindowsPrivate);
 	p->h = INVALID_HANDLE_VALUE;

drivers/windows/dir_access_windows.h

@@ -77,9 +77,9 @@ class DirAccessWindows : public DirAccess {
 	virtual Error rename(String p_path, String p_new_path) override;
 	virtual Error remove(String p_path) override;
 
-	virtual bool is_link(String p_file) override { return false; };
-	virtual String read_link(String p_file) override { return p_file; };
-	virtual Error create_link(String p_source, String p_target) override { return FAILED; };
+	virtual bool is_link(String p_file) override;
+	virtual String read_link(String p_file) override;
+	virtual Error create_link(String p_source, String p_target) override;
 
 	uint64_t get_space_left() override;