Function clean

commands.cpp:716–833

Encrypt contents of stdin and write to stdout

// Encrypt contents of stdin and write to stdout
int clean (int argc, const char** argv)
{
	const char*		key_name = 0;
	const char*		key_path = 0;
	const char*		legacy_key_path = 0;

	int			argi = parse_plumbing_options(&key_name, &key_path, argc, argv);
	if (argc - argi == 0) {
	} else if (!key_name && !key_path && argc - argi == 1) { // Deprecated - for compatibility with pre-0.4
		legacy_key_path = argv[argi];
	} else {
		std::clog << "Usage: git-crypt clean [--key-name=NAME] [--key-file=PATH]" << std::endl;
		return 2;
	}
	Key_file		key_file;
	load_key(key_file, key_name, key_path, legacy_key_path);

	const Key_file::Entry*	key = key_file.get_latest();
	if (!key) {
		std::clog << "git-crypt: error: key file is empty" << std::endl;
		return 1;
	}

	// Read the entire file

	Hmac_sha1_state	hmac(key->hmac_key, HMAC_KEY_LEN); // Calculate the file's SHA1 HMAC as we go
	uint64_t		file_size = 0;	// Keep track of the length, make sure it doesn't get too big
	std::string		file_contents;	// First 8MB or so of the file go here
	temp_fstream		temp_file;	// The rest of the file spills into a temporary file on disk
	temp_file.exceptions(std::fstream::badbit);

	char			buffer[1024];

	while (std::cin && file_size < Aes_ctr_encryptor::MAX_CRYPT_BYTES) {
		std::cin.read(buffer, sizeof(buffer));

		const size_t	bytes_read = std::cin.gcount();

		hmac.add(reinterpret_cast<unsigned char*>(buffer), bytes_read);
		file_size += bytes_read;

		if (file_size <= 8388608) {
			file_contents.append(buffer, bytes_read);
		} else {
			if (!temp_file.is_open()) {
				temp_file.open(std::fstream::in | std::fstream::out | std::fstream::binary | std::fstream::app);
			}
			temp_file.write(buffer, bytes_read);
		}
	}

	// Make sure the file isn't so large we'll overflow the counter value (which would doom security)
	if (file_size >= Aes_ctr_encryptor::MAX_CRYPT_BYTES) {
		std::clog << "git-crypt: error: file too long to encrypt securely" << std::endl;
		return 1;
	}

	// We use an HMAC of the file as the encryption nonce (IV) for CTR mode.