+error_code canonicalize(const Twine &path, SmallVectorImpl<char> &result) {
+ assert(path::is_absolute(path) && "path must be absolute!");
+ SmallString<128> path_storage;
+ StringRef p = path.toStringRef(path_storage);
+ SmallVector<wchar_t, 128> path_utf16;
+ result.set_size(0);
+
+ // Convert path to UTF-16.
+ if (error_code ec = UTF8ToUTF16(p, path_utf16))
+ return ec;
+
+ DWORD size = ::GetShortPathNameW(c_str(path_utf16), NULL, 0);
+ SmallVector<wchar_t, 128> short_path;
+ short_path.reserve(size + 1);
+ size = ::GetShortPathNameW( c_str(path_utf16)
+ , short_path.data()
+ , short_path.capacity());
+ if (!size)
+ return windows_error(::GetLastError());
+
+ short_path.set_size(size);
+
+ size = ::GetLongPathNameW(c_str(short_path), NULL, 0);
+ path_utf16.reserve(size + 1);
+ size = ::GetLongPathNameW( c_str(short_path)
+ , path_utf16.data()
+ , path_utf16.capacity());
+ if (!size)
+ return windows_error(::GetLastError());
+
+ path_utf16.set_size(size);
+
+ if (error_code ec = UTF16ToUTF8(path_utf16.data(), path_utf16.size(), result))
+ return ec;
+
+ return success;
+}
+