From 5b587d199ed6a08a79102f6efc9fd21ae54eb0e5 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 8 Aug 2025 01:14:11 +0300
Subject: [PATCH] Kernel/LibC: Implement FIONREAD for tcp and udp sockets

---
 kernel/include/kernel/Networking/TCPSocket.h |  3 +++
 kernel/include/kernel/Networking/UDPSocket.h |  4 +++-
 kernel/kernel/Networking/TCPSocket.cpp       | 13 +++++++++++++
 kernel/kernel/Networking/UDPSocket.cpp       | 19 +++++++++++++++++++
 userspace/libraries/LibC/include/sys/ioctl.h |  2 ++
 5 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/kernel/include/kernel/Networking/TCPSocket.h b/kernel/include/kernel/Networking/TCPSocket.h
index 746dcf03..0a0b63d7 100644
--- a/kernel/include/kernel/Networking/TCPSocket.h
+++ b/kernel/include/kernel/Networking/TCPSocket.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <BAN/HashMap.h>
 #include <BAN/Endianness.h>
 #include <BAN/Queue.h>
 #include <kernel/Lock/Mutex.h>
@@ -63,6 +64,8 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> recvfrom_impl(BAN::ByteSpan, sockaddr*, socklen_t*) override;
 		virtual BAN::ErrorOr<void> getpeername_impl(sockaddr*, socklen_t*) override;
 
+		virtual BAN::ErrorOr<long> ioctl_impl(int, void*) override;
+
 		virtual void receive_packet(BAN::ConstByteSpan, const sockaddr* sender, socklen_t sender_len) override;
 
 		virtual bool can_read_impl() const override;
diff --git a/kernel/include/kernel/Networking/UDPSocket.h b/kernel/include/kernel/Networking/UDPSocket.h
index 4ded8d98..6e39381e 100644
--- a/kernel/include/kernel/Networking/UDPSocket.h
+++ b/kernel/include/kernel/Networking/UDPSocket.h
@@ -38,6 +38,8 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> recvfrom_impl(BAN::ByteSpan buffer, sockaddr* address, socklen_t* address_len) override;
 		virtual BAN::ErrorOr<void> getpeername_impl(sockaddr*, socklen_t*) override { return BAN::Error::from_errno(ENOTCONN); }
 
+		virtual BAN::ErrorOr<long> ioctl_impl(int, void*) override;
+
 		virtual bool can_read_impl() const override { return !m_packets.empty(); }
 		virtual bool can_write_impl() const override { return true; }
 		virtual bool has_error_impl() const override { return false; }
@@ -59,7 +61,7 @@ namespace Kernel
 		BAN::CircularQueue<PacketInfo, 32>	m_packets;
 		size_t								m_packet_total_size { 0 };
 		SpinLock							m_packet_lock;
-		ThreadBlocker							m_packet_thread_blocker;
+		ThreadBlocker						m_packet_thread_blocker;
 
 		friend class BAN::RefPtr<UDPSocket>;
 	};
diff --git a/kernel/kernel/Networking/TCPSocket.cpp b/kernel/kernel/Networking/TCPSocket.cpp
index a04535b2..b91b2d55 100644
--- a/kernel/kernel/Networking/TCPSocket.cpp
+++ b/kernel/kernel/Networking/TCPSocket.cpp
@@ -8,6 +8,7 @@
 #include <fcntl.h>
 #include <netinet/in.h>
 #include <sys/epoll.h>
+#include <sys/ioctl.h>
 
 namespace Kernel
 {
@@ -255,6 +256,18 @@ namespace Kernel
 		return {};
 	}
 
+	BAN::ErrorOr<long> TCPSocket::ioctl_impl(int request, void* argument)
+	{
+		switch (request)
+		{
+			case FIONREAD:
+				*static_cast<int*>(argument) = m_recv_window.data_size;
+				return 0;
+		}
+
+		return NetworkSocket::ioctl_impl(request, argument);
+	}
+
 	bool TCPSocket::can_read_impl() const
 	{
 		if (m_has_connected && !m_has_sent_zero && m_state != State::Established && m_state != State::Listen)
diff --git a/kernel/kernel/Networking/UDPSocket.cpp b/kernel/kernel/Networking/UDPSocket.cpp
index ce0b9fba..763ab4ec 100644
--- a/kernel/kernel/Networking/UDPSocket.cpp
+++ b/kernel/kernel/Networking/UDPSocket.cpp
@@ -4,6 +4,7 @@
 #include <kernel/Thread.h>
 
 #include <sys/epoll.h>
+#include <sys/ioctl.h>
 
 namespace Kernel
 {
@@ -138,4 +139,22 @@ namespace Kernel
 		return TRY(m_network_layer.sendto(*this, message, address, address_len));
 	}
 
+	BAN::ErrorOr<long> UDPSocket::ioctl_impl(int request, void* argument)
+	{
+		switch (request)
+		{
+			case FIONREAD:
+			{
+				SpinLockGuard guard(m_packet_lock);
+				if (m_packets.empty())
+					*static_cast<int*>(argument) = 0;
+				else
+					*static_cast<int*>(argument) = m_packets.front().packet_size;
+				return 0;
+			}
+		}
+
+		return NetworkSocket::ioctl_impl(request, argument);
+	}
+
 }
diff --git a/userspace/libraries/LibC/include/sys/ioctl.h b/userspace/libraries/LibC/include/sys/ioctl.h
index 33a0a781..fe7627c7 100644
--- a/userspace/libraries/LibC/include/sys/ioctl.h
+++ b/userspace/libraries/LibC/include/sys/ioctl.h
@@ -37,6 +37,8 @@ __BEGIN_DECLS
 
 #define KDLOADFONT	30
 
+#define FIONREAD	40 /* get number of input bytes available */
+
 struct winsize
 {
 	unsigned short ws_row;