dirRenameWindowsInner

fn dirRenameWindowsInner(
    old_dir: Dir,
    old_sub_path: []const u8,
    new_dir: Dir,
    new_sub_path: []const u8,
    replace_if_exists: bool,
) Dir.RenamePreserveError!void {
    const w = windows;
    const old_path_w_buf = try sliceToPrefixedFileW(old_dir.handle, old_sub_path, .{});
    const old_path_w = old_path_w_buf.span();
    const new_path_w_buf = try sliceToPrefixedFileW(new_dir.handle, new_sub_path, .{});
    const new_path_w = new_path_w_buf.span();

    const src_fd = src_fd: {
        if (OpenFile(old_path_w, .{
            .dir = old_dir.handle,
            .access_mask = .{
                .GENERIC = .{ .WRITE = true },
                .STANDARD = .{
                    .RIGHTS = .{ .DELETE = true },
                    .SYNCHRONIZE = true,
                },
            },
            .creation = .OPEN,
            .filter = .any, // This function is supposed to rename both files and directories.
            .follow_symlinks = false,
        })) |handle| {
            break :src_fd handle;
        } else |err| switch (err) {
            error.WouldBlock => unreachable, // Not possible without `.share_access_nonblocking = true`.
            else => |e| return e,
        }
    };
    defer w.CloseHandle(src_fd);

    var rc: w.NTSTATUS = undefined;
    // FileRenameInformationEx has varying levels of support:
    // - FILE_RENAME_INFORMATION_EX requires >= win10_rs1
    //   (INVALID_INFO_CLASS is returned if not supported)
    // - Requires the NTFS filesystem
    //   (on filesystems like FAT32, INVALID_PARAMETER is returned)
    // - FILE_RENAME_POSIX_SEMANTICS requires >= win10_rs1
    // - FILE_RENAME_IGNORE_READONLY_ATTRIBUTE requires >= win10_rs5
    //   (NOT_SUPPORTED is returned if a flag is unsupported)
    //
    // The strategy here is just to try using FileRenameInformationEx and fall back to
    // FileRenameInformation if the return value lets us know that some aspect of it is not supported.
    const need_fallback = need_fallback: {
        var rename_info: w.FILE.RENAME_INFORMATION = .init(.{
            .Flags = .{
                .REPLACE_IF_EXISTS = replace_if_exists,
                .POSIX_SEMANTICS = true,
                .IGNORE_READONLY_ATTRIBUTE = true,
            },
            .RootDirectory = if (Dir.path.isAbsoluteWindowsWtf16(new_path_w)) null else new_dir.handle,
            .FileName = new_path_w,
        });
        var io_status_block: w.IO_STATUS_BLOCK = undefined;
        const rename_info_buf = rename_info.toBuffer();
        rc = w.ntdll.NtSetInformationFile(
            src_fd,
            &io_status_block,
            rename_info_buf.ptr,
            @intCast(rename_info_buf.len),
            .RenameEx,
        );
        switch (rc) {
            .SUCCESS => return,
            // The filesystem does not support FileDispositionInformationEx
            .INVALID_PARAMETER,
            // The operating system does not support FileDispositionInformationEx
            .INVALID_INFO_CLASS,
            // The operating system does not support one of the flags
            .NOT_SUPPORTED,
            => break :need_fallback true,
            // For all other statuses, fall down to the switch below to handle them.
            else => break :need_fallback false,
        }
    };

    if (need_fallback) {
        var rename_info: w.FILE.RENAME_INFORMATION = .init(.{
            .Flags = .{ .REPLACE_IF_EXISTS = replace_if_exists },
            .RootDirectory = if (Dir.path.isAbsoluteWindowsWtf16(new_path_w)) null else new_dir.handle,
            .FileName = new_path_w,
        });
        var io_status_block: w.IO_STATUS_BLOCK = undefined;
        const rename_info_buf = rename_info.toBuffer();
        rc = w.ntdll.NtSetInformationFile(
            src_fd,
            &io_status_block,
            rename_info_buf.ptr,
            @intCast(rename_info_buf.len),
            .Rename,
        );
    }

    switch (rc) {
        .SUCCESS => {},
        .INVALID_HANDLE => |err| return w.statusBug(err),
        .INVALID_PARAMETER => |err| return w.statusBug(err),
        .OBJECT_PATH_SYNTAX_BAD => |err| return w.statusBug(err),
        .ACCESS_DENIED => return error.AccessDenied,
        .OBJECT_NAME_NOT_FOUND => return error.FileNotFound,
        .OBJECT_PATH_NOT_FOUND => return error.FileNotFound,
        .NOT_SAME_DEVICE => return error.CrossDevice,
        .OBJECT_NAME_COLLISION => return error.PathAlreadyExists,
        .DIRECTORY_NOT_EMPTY => return error.DirNotEmpty,
        .FILE_IS_A_DIRECTORY => return error.IsDir,
        .NOT_A_DIRECTORY => return error.NotDir,
        else => return w.unexpectedStatus(rc),
    }
}