//===----- RemoteTargetExternal.h - LLVM out-of-process JIT execution -----===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Definition of the RemoteTargetExternal class which executes JITed code in a
// separate process from where it was built.
//
//===----------------------------------------------------------------------===//

#ifndef LLI_REMOTETARGETEXTERNAL_H
#define LLI_REMOTETARGETEXTERNAL_H

#include "RPCChannel.h"
#include "RemoteTarget.h"
#include "RemoteTargetMessage.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Config/config.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Memory.h"
#include <stdlib.h>
#include <string>

namespace llvm {

class RemoteTargetExternal : public RemoteTarget {
  RPCChannel RPC;

  bool WriteBytes(const void *Data, size_t Size) {
    return RPC.WriteBytes(Data, Size);
  }

  bool ReadBytes(void *Data, size_t Size) { return RPC.ReadBytes(Data, Size); }

public:
  /// Allocate space in the remote target address space.
  ///
  /// @param      Size      Amount of space, in bytes, to allocate.
  /// @param      Alignment Required minimum alignment for allocated space.
  /// @param[out] Address   Remote address of the allocated memory.
  ///
  /// @returns True on success. On failure, ErrorMsg is updated with
  ///          descriptive text of the encountered error.
  bool allocateSpace(size_t Size, unsigned Alignment,
                     uint64_t &Address) override;

  /// Load data into the target address space.
  ///
  /// @param      Address   Destination address in the target process.
  /// @param      Data      Source address in the host process.
  /// @param      Size      Number of bytes to copy.
  ///
  /// @returns True on success. On failure, ErrorMsg is updated with
  ///          descriptive text of the encountered error.
  bool loadData(uint64_t Address, const void *Data, size_t Size) override;

  /// Load code into the target address space and prepare it for execution.
  ///
  /// @param      Address   Destination address in the target process.
  /// @param      Data      Source address in the host process.
  /// @param      Size      Number of bytes to copy.
  ///
  /// @returns True on success. On failure, ErrorMsg is updated with
  ///          descriptive text of the encountered error.
  bool loadCode(uint64_t Address, const void *Data, size_t Size) override;

  /// Execute code in the target process. The called function is required
  /// to be of signature int "(*)(void)".
  ///
  /// @param      Address   Address of the loaded function in the target
  ///                       process.
  /// @param[out] RetVal    The integer return value of the called function.
  ///
  /// @returns True on success. On failure, ErrorMsg is updated with
  ///          descriptive text of the encountered error.
  bool executeCode(uint64_t Address, int &RetVal) override;

  /// Minimum alignment for memory permissions. Used to separate code and
  /// data regions to make sure data doesn't get marked as code or vice
  /// versa.
  ///
  /// @returns Page alignment return value. Default of 4k.
  unsigned getPageAlignment() override { return 4096; }

  bool create() override {
    RPC.ChildName = ChildName;
    if (!RPC.createServer())
      return true;

    // We must get Ack from the client (blocking read)
    if (!Receive(LLI_ChildActive)) {
      ErrorMsg += ", (RPCChannel::create) - Stopping process!";
      stop();
      return false;
    }

    return true;
  }

  /// Terminate the remote process.
  void stop() override;

  RemoteTargetExternal(std::string &Name) : RemoteTarget(), ChildName(Name) {}
  virtual ~RemoteTargetExternal() {}

private:
  std::string ChildName;

  bool SendAllocateSpace(uint32_t Alignment, uint32_t Size);
  bool SendLoadSection(uint64_t Addr,
                       const void *Data,
                       uint32_t Size,
                       bool IsCode);
  bool SendExecute(uint64_t Addr);
  bool SendTerminate();

  // High-level wrappers for receiving data
  bool Receive(LLIMessageType Msg);
  bool Receive(LLIMessageType Msg, int32_t &Data);
  bool Receive(LLIMessageType Msg, uint64_t &Data);

  // Lower level target-independent read/write to deal with errors
  bool ReceiveHeader(LLIMessageType Msg);
  bool ReceivePayload();
  bool SendHeader(LLIMessageType Msg);
  bool SendPayload();

  // Functions to append/retrieve data from the payload
  SmallVector<const void *, 2> SendData;
  SmallVector<void *, 1> ReceiveData; // Future proof
  SmallVector<int, 2> Sizes;
  void AppendWrite(const void *Data, uint32_t Size);
  void AppendRead(void *Data, uint32_t Size);
};

} // end namespace llvm

#endif // LLI_REMOTETARGETEXTERNAL_H