Kernel/SVC: Partially implemented svcReplyAndReceive.

It behaves mostly as WaitSynchronizationN with wait_all = false, except for IPC buffer translation.

The target thread of an IPC response will now wake up when responding.
IPC buffer translation is currently not implemented.
Error passing back to svcSendSyncRequest is currently not implemented.

src/core/hle/function_wrappers.h

@@ -16,9 +16,6 @@ namespace HLE {
 
 #define PARAM(n) Core::CPU().GetReg(n)
 
-/// An invalid result code that is meant to be overwritten when a thread resumes from waiting
-static const ResultCode RESULT_INVALID(0xDEADC0DE);
-
 /**
  * HLE a function return from the current ARM11 userland process
  * @param res Result to return
@@ -68,10 +65,18 @@ void Wrap() {
                       (PARAM(3) != 0), (((s64)PARAM(4) << 32) | PARAM(0)))
                      .raw;
 
-    if (retval != RESULT_INVALID.raw) {
-        Core::CPU().SetReg(1, (u32)param_1);
-        FuncReturn(retval);
-    }
+    Core::CPU().SetReg(1, (u32)param_1);
+    FuncReturn(retval);
+}
+
+template <ResultCode func(s32*, u32*, s32, u32)>
+void Wrap() {
+    s32 param_1 = 0;
+    u32 retval =
+        func(&param_1, (Kernel::Handle*)Memory::GetPointer(PARAM(1)), (s32)PARAM(2), PARAM(3)).raw;
+
+    Core::CPU().SetReg(1, (u32)param_1);
+    FuncReturn(retval);
 }
 
 template <ResultCode func(u32, u32, u32, u32, s64)>
@@ -92,9 +97,7 @@ template <ResultCode func(u32, s64)>
 void Wrap() {
     s32 retval = func(PARAM(0), (((s64)PARAM(3) << 32) | PARAM(2))).raw;
 
-    if (retval != RESULT_INVALID.raw) {
-        FuncReturn(retval);
-    }
+    FuncReturn(retval);
 }
 
 template <ResultCode func(MemoryInfo*, PageInfo*, u32)>

src/core/hle/svc.cpp

@@ -25,6 +25,7 @@
 #include "core/hle/kernel/semaphore.h"
 #include "core/hle/kernel/server_port.h"
 #include "core/hle/kernel/server_session.h"
+#include "core/hle/kernel/session.h"
 #include "core/hle/kernel/shared_memory.h"
 #include "core/hle/kernel/thread.h"
 #include "core/hle/kernel/timer.h"
@@ -397,6 +398,112 @@ static ResultCode WaitSynchronizationN(s32* out, Kernel::Handle* handles, s32 ha
     }
 }
 
+/// In a single operation, sends a IPC reply and waits for a new request.
+static ResultCode ReplyAndReceive(s32* index, Kernel::Handle* handles, s32 handle_count,
+                                  Kernel::Handle reply_target) {
+    // 'handles' has to be a valid pointer even if 'handle_count' is 0.
+    if (handles == nullptr)
+        return Kernel::ERR_INVALID_POINTER;
+
+    // Check if 'handle_count' is invalid
+    if (handle_count < 0)
+        return Kernel::ERR_OUT_OF_RANGE;
+
+    using ObjectPtr = SharedPtr<Kernel::WaitObject>;
+    std::vector<ObjectPtr> objects(handle_count);
+
+    for (int i = 0; i < handle_count; ++i) {
+        auto object = Kernel::g_handle_table.Get<Kernel::WaitObject>(handles[i]);
+        if (object == nullptr)
+            return ERR_INVALID_HANDLE;
+        objects[i] = object;
+    }
+
+    // We are also sending a command reply.
+    // Do not send a reply if the command id in the command buffer is 0xFFFF.
+    u32* cmd_buff = Kernel::GetCommandBuffer();
+    IPC::Header header{cmd_buff[0]};
+    if (reply_target != 0 && header.command_id != 0xFFFF) {
+        auto session = Kernel::g_handle_table.Get<Kernel::ServerSession>(reply_target);
+        if (session == nullptr)
+            return ERR_INVALID_HANDLE;
+
+        auto request_thread = std::move(session->currently_handling);
+
+        // Mark the request as "handled".
+        session->currently_handling = nullptr;
+
+        // Error out if there's no request thread or the session was closed.
+        // TODO(Subv): Is the same error code (ClosedByRemote) returned for both of these cases?
+        if (request_thread == nullptr || session->parent->client == nullptr) {
+            *index = -1;
+            return Kernel::ERR_SESSION_CLOSED_BY_REMOTE;
+        }
+
+        // TODO(Subv): Perform IPC translation from the current thread to request_thread.
+
+        // Note: The scheduler is not invoked here.
+        request_thread->ResumeFromWait();
+    }
+
+    if (handle_count == 0) {
+        *index = 0;
+        // The kernel uses this value as a placeholder for the real error, and returns it when we
+        // pass no handles and do not perform any reply.
+        if (reply_target == 0 || header.command_id == 0xFFFF)
+            return ResultCode(0xE7E3FFFF);
+
+        return RESULT_SUCCESS;
+    }
+
+    auto thread = Kernel::GetCurrentThread();
+
+    // Find the first object that is acquirable in the provided list of objects
+    auto itr = std::find_if(objects.begin(), objects.end(), [thread](const ObjectPtr& object) {
+        return !object->ShouldWait(thread);
+    });
+
+    if (itr != objects.end()) {
+        // We found a ready object, acquire it and set the result value
+        Kernel::WaitObject* object = itr->get();
+        object->Acquire(thread);
+        *index = std::distance(objects.begin(), itr);
+
+        if (object->GetHandleType() == Kernel::HandleType::ServerSession) {
+            auto server_session = static_cast<Kernel::ServerSession*>(object);
+            if (server_session->parent->client == nullptr)
+                return Kernel::ERR_SESSION_CLOSED_BY_REMOTE;
+
+            // TODO(Subv): Perform IPC translation from the ServerSession to the current thread.
+        }
+        return RESULT_SUCCESS;
+    }
+
+    // No objects were ready to be acquired, prepare to suspend the thread.
+
+    // TODO(Subv): Perform IPC translation upon wakeup.
+
+    // Put the thread to sleep
+    thread->status = THREADSTATUS_WAIT_SYNCH_ANY;
+
+    // Add the thread to each of the objects' waiting threads.
+    for (size_t i = 0; i < objects.size(); ++i) {
+        Kernel::WaitObject* object = objects[i].get();
+        object->AddWaitingThread(thread);
+    }
+
+    thread->wait_objects = std::move(objects);
+
+    Core::System::GetInstance().PrepareReschedule();
+
+    // Note: The output of this SVC will be set to RESULT_SUCCESS if the thread resumes due to a
+    // signal in one of its wait objects, or to 0xC8A01836 if there was a translation error.
+    // By default the index is set to -1.
+    thread->wait_set_output = true;
+    *index = -1;
+    return RESULT_SUCCESS;
+}
+
 /// Create an address arbiter (to allocate access to shared resources)
 static ResultCode CreateAddressArbiter(Kernel::Handle* out_handle) {
     using Kernel::AddressArbiter;
@@ -1128,7 +1235,7 @@ static const FunctionDef SVC_Table[] = {
     {0x4C, nullptr, "ReplyAndReceive2"},
     {0x4D, nullptr, "ReplyAndReceive3"},
     {0x4E, nullptr, "ReplyAndReceive4"},
-    {0x4F, nullptr, "ReplyAndReceive"},
+    {0x4F, HLE::Wrap<ReplyAndReceive>, "ReplyAndReceive"},
     {0x50, nullptr, "BindInterrupt"},
     {0x51, nullptr, "UnbindInterrupt"},
     {0x52, nullptr, "InvalidateProcessDataCache"},