Introduce CLI

main: Parse args using getopt_long() in main().

Begin implementation of a CLI. It can be launched
using ./qswiki config --cli.

Allow connecting to another instance using "attach" command.
This uses Unix domain sockets, and in the future can be used
to drop caches, reload template, etc.

Closes: #21

cliconsole.cpp

@@ -0,0 +1,137 @@
+#include "cliconsole.h"
+
+CLIConsole::CLIConsole(CLIHandler &cliHandler, std::string socketPath)
+{
+	this->handler = &cliHandler;
+	this->socketPath = socketPath;
+}
+
+std::pair<bool, std::string> CLIConsole::send(std::string input)
+{
+	ssize_t ret =
+		sendto(this->sock, input.c_str(), input.size(), 0, (const sockaddr *)&this->server, sizeof(this->server));
+	if((size_t)ret != input.size())
+	{
+		return {false, "sendto failed: " + std::to_string(ret) + " " + std::string(strerror(errno))};
+	}
+	char buffer[1024] = {0};
+	ret = recvfrom(this->sock, buffer, sizeof(buffer) - 1, 0, NULL, NULL);
+	if(ret == -1)
+	{
+		return {false, "recvfrom failed: " + std::string(strerror(errno))};
+	}
+
+	bool success = false;
+	std::string_view view = buffer;
+	if(view[0] == '1')
+	{
+		success = true;
+	}
+	view.remove_prefix(1);
+	std::string msg = std::string{view};
+
+	return {success, msg};
+}
+
+void CLIConsole::attach()
+{
+	if(attached)
+	{
+		std::cout << "Already attached" << std::endl;
+		return;
+	}
+	if(socketPath.size() > sizeof(this->server.sun_path) - 1)
+	{
+		std::cout << "Socket path too long" << std::endl;
+		return;
+	}
+	memset(&this->server, 0, sizeof(this->server));
+	this->server.sun_family = AF_UNIX;
+	memcpy(&this->server.sun_path, socketPath.c_str(), socketPath.size());
+	this->server.sun_path[socketPath.size()] = 0;
+
+	int s = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if(s == -1)
+	{
+		std::cout << "Failed to create socket" << strerror(errno) << std::endl;
+		return;
+	}
+	this->sock = s;
+
+	struct sockaddr_un client;
+	client.sun_family = AF_UNIX;
+	client.sun_path[0] = '\0';
+
+	int ret = bind(this->sock, (struct sockaddr *)&client, sizeof(client));
+	if(ret != 0)
+	{
+		std::cout << "bind() failed: " << strerror(errno) << std::endl;
+		return;
+	}
+	auto result = this->send("attach");
+	if(result.first)
+	{
+		std::cout << "Attached successfully: " << result.second << std::endl;
+		this->attached = true;
+	}
+	else
+	{
+		std::cout << "Attached unsuccessfully: " << result.second << std::endl;
+	}
+}
+
+void CLIConsole::startInteractive()
+{
+	std::cout << "qswiki CLI" << std::endl;
+	std::cout << "not attached - use 'attach' to connect to running instance" << std::endl;
+
+	while(true)
+	{
+		std::string input;
+		std::cout << "> ";
+		std::getline(std::cin, input);
+
+		if(std::cin.bad() || std::cin.eof())
+		{
+			std::cout << "Exiting" << std::endl;
+			return;
+		}
+		if(input.empty())
+		{
+			continue;
+		}
+
+		auto pair = CLIHandler::splitCommand(input);
+		if(pair.first == "exit")
+		{
+			std::cout << "Exiting CLI";
+			exit(EXIT_SUCCESS);
+		}
+		if(pair.first == "attach")
+		{
+			attach();
+			continue;
+		}
+
+		std::pair<bool, std::string> result;
+		if(!attached)
+		{
+			result = handler->processCommand(pair.first, pair.second);
+		}
+		else
+		{
+			result = this->send(input);
+		}
+
+		if(!result.second.empty())
+		{
+			std::cout << result.second << std::endl;
+		}
+		if(!result.first)
+		{
+			std::cout << "Command failed" << std::endl;
+		}
+	}
+
+	std::cout << "\n";
+}