4 files changed, 38 insertions, 9 deletions
diff --git a/src/core/hle/kernel/errors.h b/src/core/hle/kernel/errors.h
index b3b60e7df..64aa61460 100644
--- a/src/core/hle/kernel/errors.h
+++ b/src/core/hle/kernel/errors.h
@@ -13,6 +13,7 @@ enum {
     OutOfHandles = 19,
     SessionClosedByRemote = 26,
     PortNameTooLong = 30,
+    NoPendingSessions = 35,
     WrongPermission = 46,
     InvalidBufferDescriptor = 48,
     MaxConnectionsReached = 52,
@@ -94,5 +95,9 @@ constexpr ResultCode ERR_OUT_OF_RANGE_KERNEL(ErrorDescription::OutOfRange, Error
                                              ErrorLevel::Permanent); // 0xD8E007FD
 constexpr ResultCode RESULT_TIMEOUT(ErrorDescription::Timeout, ErrorModule::OS,
                                     ErrorSummary::StatusChanged, ErrorLevel::Info);
+/// Returned when Accept() is called on a port with no sessions to be accepted.
+constexpr ResultCode ERR_NO_PENDING_SESSIONS(ErrCodes::NoPendingSessions, ErrorModule::OS,
+                                             ErrorSummary::WouldBlock,
+                                             ErrorLevel::Permanent); // 0xD8401823
 
 } // namespace Kernel
diff --git a/src/core/hle/kernel/hle_ipc.cpp b/src/core/hle/kernel/hle_ipc.cpp
index 1cac1d0c9..5ebe2eca4 100644
--- a/src/core/hle/kernel/hle_ipc.cpp
+++ b/src/core/hle/kernel/hle_ipc.cpp
@@ -67,10 +67,13 @@ ResultCode HLERequestContext::PopulateFromIncomingCommandBuffer(const u32_le* sr
             ASSERT(i + num_handles <= command_size); // TODO(yuriks): Return error
             for (u32 j = 0; j < num_handles; ++j) {
                 Handle handle = src_cmdbuf[i];
-                SharedPtr<Object> object = src_table.GetGeneric(handle);
-                ASSERT(object != nullptr); // TODO(yuriks): Return error
-                if (descriptor == IPC::DescriptorType::MoveHandle) {
-                    src_table.Close(handle);
+                SharedPtr<Object> object = nullptr;
+                if (handle != 0) {
+                    object = src_table.GetGeneric(handle);
+                    ASSERT(object != nullptr); // TODO(yuriks): Return error
+                    if (descriptor == IPC::DescriptorType::MoveHandle) {
+                        src_table.Close(handle);
+                    }
                 }
 
                 cmd_buf[i++] = AddOutgoingHandle(std::move(object));
@@ -112,9 +115,11 @@ ResultCode HLERequestContext::WriteToOutgoingCommandBuffer(u32_le* dst_cmdbuf, P
             ASSERT(i + num_handles <= command_size);
             for (u32 j = 0; j < num_handles; ++j) {
                 SharedPtr<Object> object = GetIncomingHandle(cmd_buf[i]);
-
-                // TODO(yuriks): Figure out the proper error handling for if this fails
-                Handle handle = dst_table.Create(object).Unwrap();
+                Handle handle = 0;
+                if (object != nullptr) {
+                    // TODO(yuriks): Figure out the proper error handling for if this fails
+                    handle = dst_table.Create(object).Unwrap();
+                }
                 dst_cmdbuf[i++] = handle;
             }
             break;
diff --git a/src/core/hle/kernel/server_port.cpp b/src/core/hle/kernel/server_port.cpp
index 4d20c39a1..49a9cdfa3 100644
--- a/src/core/hle/kernel/server_port.cpp
+++ b/src/core/hle/kernel/server_port.cpp
@@ -5,8 +5,10 @@
 #include <tuple>
 #include "common/assert.h"
 #include "core/hle/kernel/client_port.h"
+#include "core/hle/kernel/errors.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/kernel/server_port.h"
+#include "core/hle/kernel/server_session.h"
 #include "core/hle/kernel/thread.h"
 
 namespace Kernel {
@@ -14,6 +16,16 @@ namespace Kernel {
 ServerPort::ServerPort() {}
 ServerPort::~ServerPort() {}
 
+ResultVal<SharedPtr<ServerSession>> ServerPort::Accept() {
+    if (pending_sessions.empty()) {
+        return ERR_NO_PENDING_SESSIONS;
+    }
+
+    auto session = std::move(pending_sessions.back());
+    pending_sessions.pop_back();
+    return MakeResult(std::move(session));
+}
+
 bool ServerPort::ShouldWait(Thread* thread) const {
     // If there are no pending sessions, we wait until a new one is added.
     return pending_sessions.size() == 0;
diff --git a/src/core/hle/kernel/server_port.h b/src/core/hle/kernel/server_port.h
index f1419cd46..6fe7c7f2f 100644
--- a/src/core/hle/kernel/server_port.h
+++ b/src/core/hle/kernel/server_port.h
@@ -14,6 +14,7 @@
 namespace Kernel {
 
 class ClientPort;
+class ServerSession;
 class SessionRequestHandler;
 
 class ServerPort final : public WaitObject {
@@ -41,6 +42,12 @@ public:
     }
 
     /**
+     * Accepts a pending incoming connection on this port. If there are no pending sessions, will
+     * return ERR_NO_PENDING_SESSIONS.
+     */
+    ResultVal<SharedPtr<ServerSession>> Accept();
+
+    /**
      * Sets the HLE handler template for the port. ServerSessions crated by connecting to this port
      * will inherit a reference to this handler.
      */
@@ -50,8 +57,8 @@ public:
 
     std::string name; ///< Name of port (optional)
 
-    std::vector<SharedPtr<WaitObject>>
-        pending_sessions; ///< ServerSessions waiting to be accepted by the port
+    /// ServerSessions waiting to be accepted by the port
+    std::vector<SharedPtr<ServerSession>> pending_sessions;
 
     /// This session's HLE request handler template (optional)
     /// ServerSessions created from this port inherit a reference to this handler.