From d9d17737c3ea3cc6dd27e48b351e7b9036113b9c Mon Sep 17 00:00:00 2001
From: nmzik <Nmzik@mail.ru>
Date: Sun, 6 Sep 2026 05:07:44 +0400
Subject: [PATCH] net: return native SO_ERROR

---
 src/libs/network.cpp            | 34 ++++++++++++++++++++++-----------
 tests/KernelFileSystemTests.cpp |  7 +++++++
 2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/libs/network.cpp b/src/libs/network.cpp
index 0198e6f72..369ba2a6e 100644
--- a/src/libs/network.cpp
+++ b/src/libs/network.cpp
@@ -918,7 +918,10 @@ static int SetGuestSocketError(int error) {
 	return -1;
 }
 
-static int SetHostSocketError(int error) {
+static int ConvertHostSocketError(int error) {
+	if (error == 0) {
+		return 0;
+	}
 	int posix_error = Posix::POSIX_EIO;
 #if defined(_WIN32)
 	switch (error) {
@@ -971,14 +974,14 @@ static int SetHostSocketError(int error) {
 		default: break;
 	}
 #endif
-	return SetGuestSocketError(posix_error);
+	return posix_error;
 }
 
 static int SetHostSocketError() {
 #if defined(_WIN32)
-	return SetHostSocketError(WSAGetLastError());
+	return SetGuestSocketError(ConvertHostSocketError(WSAGetLastError()));
 #else
-	return SetHostSocketError(errno);
+	return SetGuestSocketError(ConvertHostSocketError(errno));
 #endif
 }
 
@@ -1873,18 +1876,27 @@ int KYTY_SYSV_ABI Getsockopt(int s, int level, int optname, void* optval, uint32
 		return -1;
 	}
 
-#if defined(_WIN32)
-	int len = static_cast<int>(*optlen);
+	// Guest socket options: SOL_SOCKET=0xffff, SO_ERROR=0x1007.
+	const bool socket_error = (level == 0xffff && optname == 0x1007);
+#if !defined(_WIN32)
+	if (!socket_error) {
+		return SetGuestSocketError(Posix::POSIX_ENOPROTOOPT);
+	}
+#endif
+	if (socket_error) {
+		optname = SO_ERROR;
+	}
+	SocketLength len = static_cast<SocketLength>(*optlen);
 	if (::getsockopt(socket, ConvertSocketOptionLevel(level), optname, static_cast<char*>(optval),
-	                 &len) == SOCKET_ERROR) {
+	                 &len) != 0) {
 		return SetHostSocketError();
 	}
+	if (socket_error && len >= static_cast<SocketLength>(sizeof(int))) {
+		auto* error = static_cast<int*>(optval);
+		*error = ConvertHostSocketError(*error);
+	}
 	*optlen = static_cast<uint32_t>(len);
 	return 0;
-#else
-	*Posix::GetErrorAddr() = Posix::POSIX_ENOSYS;
-	return -1;
-#endif
 }
 
 int KYTY_SYSV_ABI Setsockopt(int s, int level, int optname, const void* optval, uint32_t optlen) {
diff --git a/tests/KernelFileSystemTests.cpp b/tests/KernelFileSystemTests.cpp
index da26ee421..e9ce956c2 100644
--- a/tests/KernelFileSystemTests.cpp
+++ b/tests/KernelFileSystemTests.cpp
@@ -99,6 +99,13 @@ void CheckSocketWakeup() {
   const int enabled = 1;
   Check(Net::Setsockopt(writer, 6, 1, &enabled, sizeof(enabled)) == 0,
         "enable TCP_NODELAY");
+  int socket_error = -1;
+  uint32_t error_size = sizeof(socket_error);
+  *Libs::Posix::GetErrorAddr() = Libs::Posix::POSIX_EINVAL;
+  Check(Net::Getsockopt(writer, 0xffff, 0x1007, &socket_error, &error_size) == 0 &&
+            socket_error == 0 && error_size == sizeof(socket_error) &&
+            *Libs::Posix::GetErrorAddr() == Libs::Posix::POSIX_EINVAL,
+        "SO_ERROR reports socket status without changing guest errno");
 
   std::array<uint64_t, 16> readable {};
   const auto bit = uint64_t {1} << (reader % 64);