meso: Implement ConnectLight

mesosphere/source/processes/KClientPort.cpp

@@ -2,6 +2,7 @@
 #include <mesosphere/threading/KScopedCriticalSection.hpp>
 #include <mesosphere/threading/KThread.hpp>
 #include <mesosphere/core/KCoreContext.hpp>
+#include <mesosphere/core/make_object.hpp>
 
 namespace mesosphere
 {
@@ -14,7 +15,30 @@ KClientPort::~KClientPort()
 
 bool KClientPort::IsSignaled() const
 {
-    return false; // TODO
+    return numSessions.load() < maxSessions;
+}
+
+std::tuple<Result, SharedPtr<KLightClientSession>> KClientPort::ConnectLight()
+{
+    using RetType = std::tuple<Result, SharedPtr<KLightClientSession>>;
+    // Official kernel first checks reslimit then session max count. We will do the opposite.
+    int curCount = numSessions.load();
+    while (curCount < maxSessions || !numSessions.compare_exchange_weak(curCount, curCount + 1));
+
+    if (curCount >= maxSessions) {
+        return RetType{ResultKernelOutOfSessions(), nullptr};
+    }
+
+    auto [res, serverSession, clientSession] = MakeObject<KLightSession>(parent.get());
+    if (res.IsSuccess()) {
+        serverSession.detach(); // Lifetime is now managed my KServerPort session list
+        return RetType{ResultSuccess(), clientSession};
+    } else {
+        if (numSessions.fetch_sub(1) == maxSessions) {
+            NotifyWaiters();
+        }
+        return RetType{res, nullptr};
+    }
 }
 
 }

mesosphere/source/processes/KLightSession.cpp

@@ -1,4 +1,5 @@
 #include <mesosphere/processes/KLightSession.hpp>
+#include <mesosphere/processes/KPort.hpp>
 #include <mesosphere/core/KCoreContext.hpp>
 
 namespace mesosphere
@@ -8,14 +9,24 @@ KLightSession::~KLightSession()
 {
 }
 
-Result KLightSession::Initialize()
+Result KLightSession::Initialize(KPort *parentPort)
 {
     SetClientServerParent();
     isClientAlive = true;
     isServerAlive = true;
 
     SetResourceOwner(KCoreContext::GetCurrentInstance().GetCurrentProcess());
-    return ResultSuccess();
+
+    if (parentPort == nullptr) {
+        return ResultSuccess();
+    } else {
+        // Another difference with official kernel: if adding the session fails, the session isn't added to allocator set (since it'll be deleted right away).
+        Result res = parentPort->AddLightServerSession(server);
+        if (res.IsSuccess()) {
+            client.parentClientPort = &parentPort->GetClient(); 
+        }
+        return res;
+    }
 }
 
 void KLightSession::Terminate(bool fromServer)

mesosphere/source/processes/KPort.cpp

@@ -21,13 +21,13 @@ Result KPort::Initialize(int maxSessions, bool isLight)
     return ResultSuccess();
 }
 
-Result KPort::AddServerSession(KLightServerSession &lightServerSession)
+Result KPort::AddLightServerSession(KLightServerSession &lightServerSession)
 {
     KScopedCriticalSection critsec{};
     if (isClientAlive || isServerAlive) {
         return ResultKernelConnectionRefused();
     } else {
-        return server.AddServerSession(lightServerSession);
+        return server.AddLightServerSession(lightServerSession);
     }
 }
 

mesosphere/source/processes/KServerPort.cpp

@@ -10,6 +10,7 @@ KServerPort::~KServerPort()
 {
     KScopedCriticalSection critsec{};
     parent->isServerAlive = false;
+    // TODO
 }
 
 bool KServerPort::IsSignaled() const
@@ -21,7 +22,7 @@ bool KServerPort::IsSignaled() const
     }
 }
 
-Result KServerPort::AddServerSession(KLightServerSession &lightServerSession)
+Result KServerPort::AddLightServerSession(KLightServerSession &lightServerSession)
 {
     KScopedCriticalSection critsec{};
     bool wasEmpty = lightServerSessions.empty();