posix: Create /proc/filesystems

posix/subsystem/src/procfs.cpp

@@ -234,6 +234,7 @@ std::shared_ptr<Link> DirectoryNode::createRootDirectory() {
 	the_node->_entries.insert(std::move(self_thread_link));
 
 	the_node->directMkregular("uptime", std::make_shared<UptimeNode>());
+	the_node->directMkregular("filesystems", std::make_shared<FilesystemsNode>());
 
 	return link;
 }
@@ -358,6 +359,25 @@ async::result<void> UptimeNode::store(std::string) {
 	co_return;
 }
 
+async::result<std::string> FilesystemsNode::show() {
+	// See man 5 proc for more details.
+	// Based on the man page from Linux man-pages 6.01, updated on 2022-10-09.
+	std::stringstream stream;
+	stream << "nodev\tsysfs\n";
+	stream << "nodev\ttmpfs\n";
+	stream << "nodev\tproc\n";
+	stream << "nodev\tdevpts\n";
+	stream << "nodev\tdevtmpfs\n";
+	stream << "\text2\n";
+	co_return stream.str();
+}
+
+async::result<void> FilesystemsNode::store(std::string) {
+	// TODO: proper error reporting.
+	std::cout << "posix: Can't store to a /proc/filesystems file" << std::endl;
+	co_return;
+}
+
 VfsType SelfLink::getType() {
 	return VfsType::symlink;
 }

posix/subsystem/src/procfs.hpp

@@ -219,6 +219,13 @@ struct UptimeNode final : RegularNode {
 	async::result<void> store(std::string) override;
 };
 
+struct FilesystemsNode final : RegularNode {
+	FilesystemsNode() {}
+
+	async::result<std::string> show() override;
+	async::result<void> store(std::string) override;
+};
+
 struct CommNode final : RegularNode {
 	CommNode(Process *process)
 	: _process(process)