Kernel/IPC: Added a function to translate the IPC command buffer from one process to another.

Currently only CopyHandle, MoveHandle and CallingPid descriptors are implemented.

src/core/CMakeLists.txt

@@ -61,6 +61,7 @@ set(SRCS
             hle/kernel/timer.cpp
             hle/kernel/vm_manager.cpp
             hle/kernel/wait_object.cpp
+            hle/kernel/ipc.cpp
             hle/lock.cpp
             hle/romfs.cpp
             hle/service/ac/ac.cpp
@@ -247,6 +248,7 @@ set(HEADERS
             hle/kernel/event.h
             hle/kernel/handle_table.h
             hle/kernel/hle_ipc.h
+            hle/kernel/ipc.h
             hle/kernel/kernel.h
             hle/kernel/memory.h
             hle/kernel/mutex.h

src/core/hle/kernel/errors.h

@@ -7,7 +7,6 @@
 #include "core/hle/result.h"
 
 namespace Kernel {
-
 namespace ErrCodes {
 enum {
     OutOfHandles = 19,
@@ -18,6 +17,7 @@ enum {
     WrongPermission = 46,
     InvalidBufferDescriptor = 48,
     MaxConnectionsReached = 52,
+    CommandTooLarge = 54,
 };
 }
 

src/core/hle/kernel/ipc.cpp

@@ -0,0 +1,93 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/hle/ipc.h"
+#include "core/hle/kernel/handle_table.h"
+#include "core/hle/kernel/ipc.h"
+#include "core/hle/kernel/kernel.h"
+#include "core/hle/kernel/memory.h"
+#include "core/hle/kernel/process.h"
+#include "core/hle/kernel/thread.h"
+#include "core/memory.h"
+
+namespace Kernel {
+
+ResultCode TranslateCommandBuffer(SharedPtr<Thread> src_thread, SharedPtr<Thread> dst_thread,
+                                  VAddr src_address, VAddr dst_address) {
+
+    auto& src_process = src_thread->owner_process;
+
+    IPC::Header header;
+    // TODO(Subv): Replace by Memory::Read32 when possible.
+    Memory::ReadBlock(*src_process, src_address, &header.raw, sizeof(header.raw));
+
+    size_t untranslated_size = 1u + header.normal_params_size;
+    size_t command_size = untranslated_size + header.translate_params_size;
+
+    // Note: The real kernel does not check that the command length fits into the IPC buffer area.
+    ASSERT(command_size <= IPC::COMMAND_BUFFER_LENGTH);
+
+    std::array<u32, IPC::COMMAND_BUFFER_LENGTH> cmd_buf;
+    Memory::ReadBlock(*src_process, src_address, cmd_buf.data(), command_size * sizeof(u32));
+
+    size_t i = untranslated_size;
+    while (i < command_size) {
+        u32 descriptor = cmd_buf[i];
+        i += 1;
+
+        switch (IPC::GetDescriptorType(descriptor)) {
+        case IPC::DescriptorType::CopyHandle:
+        case IPC::DescriptorType::MoveHandle: {
+            u32 num_handles = IPC::HandleNumberFromDesc(descriptor);
+            // Note: The real kernel does not check that the number of handles fits into the command
+            // buffer before writing them, only after finishing.
+            if (i + num_handles > command_size) {
+                return ResultCode(ErrCodes::CommandTooLarge, ErrorModule::OS,
+                                  ErrorSummary::InvalidState, ErrorLevel::Status);
+            }
+
+            for (u32 j = 0; j < num_handles; ++j) {
+                Handle handle = cmd_buf[i];
+                SharedPtr<Object> object = nullptr;
+                // Perform pseudo-handle detection here because by the time this function is called,
+                // the current thread and process are no longer the ones which created this IPC
+                // request, but the ones that are handling it.
+                if (handle == CurrentThread) {
+                    object = src_thread;
+                } else if (handle == CurrentProcess) {
+                    object = src_process;
+                } else if (handle != 0) {
+                    object = g_handle_table.GetGeneric(handle);
+                    if (descriptor == IPC::DescriptorType::MoveHandle) {
+                        g_handle_table.Close(handle);
+                    }
+                }
+
+                if (object == nullptr) {
+                    // Note: The real kernel sets invalid translated handles to 0 in the target
+                    // command buffer.
+                    cmd_buf[i++] = 0;
+                    continue;
+                }
+
+                auto result = g_handle_table.Create(std::move(object));
+                cmd_buf[i++] = result.ValueOr(0);
+            }
+            break;
+        }
+        case IPC::DescriptorType::CallingPid: {
+            cmd_buf[i++] = src_process->process_id;
+            break;
+        }
+        default:
+            UNIMPLEMENTED_MSG("Unsupported handle translation: 0x%08X", descriptor);
+        }
+    }
+
+    Memory::WriteBlock(*dst_thread->owner_process, dst_address, cmd_buf.data(),
+                       command_size * sizeof(u32));
+
+    return RESULT_SUCCESS;
+}
+} // namespace Kernel

src/core/hle/kernel/ipc.h

@@ -0,0 +1,14 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+#include "core/hle/kernel/thread.h"
+
+namespace Kernel {
+/// Performs IPC command buffer translation from one process to another.
+ResultCode TranslateCommandBuffer(SharedPtr<Thread> src_thread, SharedPtr<Thread> dst_thread,
+                                  VAddr src_address, VAddr dst_address);
+} // namespace Kernel