Function decrypt_reverse_longname

libcppcryptfs/filename/cryptfilename.cpp:404–486

const WCHAR *
decrypt_reverse_longname(CryptContext *con, LPCWSTR filename, LPCWSTR plain_path, const BYTE *dir_iv, wstring& decrypted_name)
{
	HANDLE hFind = INVALID_HANDLE_VALUE;
	bool found = false;

	try {
		
		wstring storage = plain_path;

		wstring base64_hash;
		if (!extract_lfn_base64_hash(filename /* &s[0] */, base64_hash))
			throw(-1);
		wstring lfn_path;
		if (con->m_lfn_cache.lookup(&base64_hash[0], &lfn_path, NULL)) {
			const WCHAR *ps = wcsrchr(&lfn_path[0], '\\');
			decrypted_name = ps ? ps + 1 : &lfn_path[0];
			found = true;
		} else {
			// go through all the files in the dir
			// if the name is long enough to be a long file name (> 175 chars in utf8)
			// then encrypt it and see if it matches the one we're looking for

			// store any we generate in the lfn cache for later use

			WIN32_FIND_DATA fdata;
			wstring findspec = storage;
			findspec += L"*";
			hFind = FindFirstFile(&findspec[0], &fdata);
			if (hFind == INVALID_HANDLE_VALUE)
				throw(-1);

			string utf8name;
			wstring find_enc;
			string actual_encrypted;
			wstring find_base64_hash;
			wstring find_path;

			do {

				if (!wcscmp(fdata.cFileName, L".") || !wcscmp(fdata.cFileName, L".."))
					continue;
				
				if (!unicode_to_utf8(fdata.cFileName, utf8name))
					throw(-1);

				if (utf8name.length() <= static_cast<size_t>(con->m_shortNameMax))
					continue;				

				if (!encrypt_filename(con, dir_iv, fdata.cFileName, find_enc, &actual_encrypted))
					throw(-1);
	
				extract_lfn_base64_hash(&find_enc[0], find_base64_hash);

				find_path = storage;
				find_path += fdata.cFileName;

				con->m_lfn_cache.store_if_not_there(&find_base64_hash[0], &find_path[0], &actual_encrypted[0]);