demo/translation: new demo program

Author: MaxKellermann

demo/meson.build

@@ -7,6 +7,7 @@ subdir('lua')
 subdir('net')
 subdir('spawn')
 subdir('systemd')
+subdir('translation')
 subdir('uring')
 subdir('was')
 subdir('zlib')

demo/translation/Translate.cxx

@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright CM4all GmbH
+// author: Max Kellermann <max.kellermann@ionos.com>
+
+#include "AllocatorPtr.hxx"
+#include "translation/Protocol.hxx"
+#include "translation/PReader.hxx"
+#include "translation/String.hxx"
+#include "net/ConnectSocket.hxx"
+#include "net/LocalSocketAddress.hxx"
+#include "net/SocketError.hxx"
+#include "net/SocketProtocolError.hxx"
+#include "net/UniqueSocketDescriptor.hxx"
+#include "util/SpanCast.hxx"
+#include "util/StringSplit.hxx"
+#include "util/PrintException.hxx"
+
+#include <fmt/core.h>
+
+#include <sysexits.h> // for EX_*
+
+using std::string_view_literals::operator""sv;
+
+static void
+AppendPacket(std::string &request, const TranslationHeader &header, std::string_view payload) noexcept
+{
+	request += ToStringView(ReferenceAsBytes(header));
+	request += payload;
+}
+
+static std::string
+ParseRequest(std::span<const char * const> args)
+{
+	std::string request;
+
+	// Add implicit BEGIN packet
+	static constexpr TranslationHeader begin_header{
+		.length = 0,
+		.command = TranslationCommand::BEGIN,
+	};
+	AppendPacket(request, begin_header, {});
+
+	// Parse and add command line packets
+	for (const char *arg : args) {
+		std::string_view arg_view = arg;
+		auto [cmd_str, payload] = Split(arg_view, '=');
+		if (payload.data() == nullptr)
+			throw std::runtime_error(fmt::format("Invalid packet format (expected COMMAND=PAYLOAD): {:?}", arg));
+
+		TranslationCommand command = ParseTranslationCommand(cmd_str);
+
+		TranslationHeader header{
+			.length = static_cast<uint16_t>(payload.size()),
+			.command = command,
+		};
+		AppendPacket(request, header, payload);
+	}
+
+	// Add END packet
+	static constexpr TranslationHeader end_header{
+		.length = 0,
+		.command = TranslationCommand::END,
+	};
+	AppendPacket(request, end_header, {});
+
+	return request;
+}
+
+static void
+DumpPacket(TranslationCommand command, std::span<const std::byte> payload)
+{
+	if (payload.empty())
+		fmt::print("{}\n", ToString(command));
+	else
+		fmt::print("{} = {:?}\n", ToString(command), ToStringView(payload));
+}
+
+static void
+ReadAndProcessResponse(SocketDescriptor socket, AllocatorPtr alloc)
+{
+	TranslatePacketReader reader;
+
+	while (true) {
+		std::array<std::byte, 4096> buffer;
+		ssize_t bytes_read = socket.Read(buffer);
+		if (bytes_read <= 0) [[unlikely]] {
+			if (bytes_read < 0)
+				throw MakeSocketError("Failed to read from socket");
+			else
+				throw SocketClosedPrematurelyError{};
+		}
+
+		auto received = std::span{buffer}.first(bytes_read);
+		while (true) {
+			const auto consumed = reader.Feed(alloc, received);
+			if (consumed == 0)
+				// Need more data
+				break;
+
+			received = received.subspan(consumed);
+
+			if (reader.IsComplete()) {
+				const auto command = reader.GetCommand();
+				DumpPacket(command, reader.GetPayload());
+
+				if (command == TranslationCommand::END)
+					return;
+			}
+		}
+	}
+}
+
+
+int
+main(int argc, char **argv)
+try {
+	if (argc < 2) {
+		fmt::print(stderr,
+			   "Usage: {} SOCKET_PATH [COMMAND=PAYLOAD] ...\nExample: {} /tmp/translation.sock HOST=example.com URI=/path"sv,
+			   argv[0], argv[0]);
+		return EX_USAGE;
+	}
+
+	const char *const socket_path = argv[1];
+	const auto request = ParseRequest({argv + 2, static_cast<size_t>(argc - 2)});
+
+	auto socket = CreateConnectSocket(LocalSocketAddress{socket_path}, SOCK_STREAM);
+	socket.FullWrite(AsBytes(request));
+
+	Allocator allocator_instance;
+	AllocatorPtr alloc{allocator_instance};
+	ReadAndProcessResponse(socket, alloc);
+
+	return EXIT_SUCCESS;
+} catch (...) {
+	PrintException(std::current_exception());
+	return EXIT_FAILURE;
+}

demo/translation/meson.build

@@ -0,0 +1,11 @@
+executable(
+  'Translate',
+  'Translate.cxx',
+  include_directories: inc,
+  dependencies: [
+    fmt_dep,
+    net_dep,
+    translation_dep,
+    util_dep,
+  ],
+)