Refactor remote support

This moves the logic into a separate file and also implements proper
caching.

src/Util/util.cpp

@@ -6,9 +6,7 @@
 #include <unistd.h>
 
 #ifdef Q_OS_UNIX
-#include <netdb.h>
 #include <pwd.h>
-#include <unistd.h>
 #endif
 
 namespace Util {
@@ -34,79 +32,4 @@ std::string pwd() {
 	}
 	return result;
 }
-
-bool get_local_domain(std::string &result) {
-	static std::string cached_result;
-	if (!cached_result.empty()) {
-		result = cached_result;
-		return true;
-	}
-
-#ifndef Q_OS_UNIX
-	return false;
-#else
-	char host[HOST_NAME_MAX];
-	if (gethostname(host, HOST_NAME_MAX)) {
-		std::cerr << "gethostname failed" << std::endl;
-		return false;
-	}
-
-	// got the host, try to get the FQDN
-	struct addrinfo hints, *res;
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_family = AF_UNSPEC;
-	hints.ai_socktype = SOCK_STREAM;
-	hints.ai_flags = AI_CANONNAME;
-
-	int err = getaddrinfo(host, "http", &hints, &res);
-	if (err) {
-		std::cerr << "getaddrinfo failed: " << gai_strerror(err) << std::endl;
-		return false;
-	}
-
-	const auto fqdn = res->ai_canonname;
-	bool success = true;
-
-	if (!strncmp(fqdn, host, HOST_NAME_MAX)) {
-		std::cerr << "failed to retreive a proper FQDN for " << host << std::endl;
-		success = false;
-	} else {
-		result = fqdn;
-
-		// remove possible leading dot
-		if (result.starts_with('.')) {
-			result = result.substr(1);
-		}
-
-		cached_result = result;
-	}
-
-	freeaddrinfo(res);
-	return success;
-#endif
-}
-
-std::string get_username() {
-#ifdef Q_OS_UNIX
-	return getlogin();
-#else
-	return {};
-#endif
-}
-
-int get_port() {
-	const auto env = std::getenv("SSH_CONNECTION");
-	if (env) {
-		std::string ssh_connection {env};
-		const auto n = ssh_connection.rfind(' ');
-		if (n != std::string::npos) {
-			try {
-				return std::stoi(ssh_connection.substr(n + 1));
-			} catch (std::invalid_argument const &) {
-				std::cerr << "Failed to parse port number " << ssh_connection << std::endl;
-			}
-		}
-	}
-	return -1;
-}
 }

src/Util/util.hpp

@@ -14,7 +14,4 @@ namespace Util {
 
 const char *home_dir();
 std::string pwd();
-bool get_local_domain(std::string &result);
-std::string get_username();
-int get_port();
 }

src/path.cpp

@@ -4,6 +4,7 @@
 
 #include "Util/util.hpp"
 #include "mimedb.hpp"
+#include "remote.hpp"
 #include "settings.hpp"
 
 Path::Path(const std::string &p)
@@ -30,15 +31,7 @@ QUrl Path::get_url() const {
 	auto res = QUrl::fromLocalFile(QString::fromStdString(path.string()));
 
 	if (Settings::get()->remote) {
-		std::string host;
-		if (Util::get_local_domain(host)) {
-			res.setScheme("sftp");
-			res.setUserName(QString::fromStdString(Util::get_username()));
-			res.setHost(QString::fromStdString(host));
-			res.setPort(Util::get_port());
-		} else {
-			std::cerr << "Failed deducing remote prefix" << std::endl;
-		}
+		std::ignore = Remote::get()->rewire_url(res);
 	}
 
 	return res;

src/remote.cpp

@@ -0,0 +1,111 @@
+#include "remote.hpp"
+
+#include <iostream>
+
+#ifdef Q_OS_UNIX
+#include <netdb.h>
+#include <unistd.h>
+#endif
+
+bool Remote::rewire_url(QUrl &url) {
+	if (!init_done) {
+		init();
+	}
+	if (!ok) {
+		return false;
+	}
+
+	url.setScheme("sftp");
+	url.setUserName(username);
+	url.setHost(host);
+	url.setPort(port);
+
+	return true;
+}
+
+void Remote::init() {
+	init_done = true;
+
+	username = get_username();
+	if (username.isEmpty()) {
+		std::cerr << "Could not read username" << std::endl;
+		return;
+	}
+
+	host = get_local_domain();
+	if (host.isEmpty()) {
+		std::cerr << "Could not read host" << std::endl;
+		return;
+	}
+
+	// not a big deal if this fails, usually it still works without an explicit port
+	port = get_port();
+
+	ok = true;
+}
+
+QString Remote::get_local_domain() {
+#ifndef Q_OS_UNIX
+	return {};
+#else
+	char host[HOST_NAME_MAX];
+	if (gethostname(host, HOST_NAME_MAX)) {
+		std::cerr << "gethostname failed" << std::endl;
+		return {};
+	}
+
+	// got the host, try to get the FQDN
+	struct addrinfo hints, *res;
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_CANONNAME;
+
+	int err = getaddrinfo(host, "http", &hints, &res);
+	if (err) {
+		std::cerr << "getaddrinfo failed: " << gai_strerror(err) << std::endl;
+		return {};
+	}
+
+	const auto fqdn = res->ai_canonname;
+	std::string result;
+
+	if (!strncmp(fqdn, host, HOST_NAME_MAX)) {
+		std::cerr << "failed to retreive a proper FQDN for " << host << std::endl;
+	} else {
+		result = fqdn;
+
+		// remove possible leading dot
+		if (result.starts_with('.')) {
+			result = result.substr(1);
+		}
+	}
+
+	freeaddrinfo(res);
+	return QString::fromStdString(result);
+#endif
+}
+
+QString Remote::get_username() {
+#ifdef Q_OS_UNIX
+	return getlogin();
+#else
+	return {};
+#endif
+}
+
+int Remote::get_port() {
+	const auto env = std::getenv("SSH_CONNECTION");
+	if (env) {
+		std::string ssh_connection {env};
+		const auto n = ssh_connection.rfind(' ');
+		if (n != std::string::npos) {
+			try {
+				return std::stoi(ssh_connection.substr(n + 1));
+			} catch (std::invalid_argument const &) {
+				std::cerr << "Failed to parse port number " << ssh_connection << std::endl;
+			}
+		}
+	}
+	return -1;
+}

src/remote.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <QUrl>
+
+#include "Util/util.hpp"
+
+class Remote {
+public:
+	SINGLETON(Remote)
+	bool rewire_url(QUrl &url);
+private:
+	void init();
+	QString get_local_domain();
+	QString get_username();
+	int get_port();
+
+	bool init_done = false;
+	bool ok = false;
+
+	QString username;
+	QString host;
+	int port = -1;
+};