text: /*
   * Copyright (c) 2003-2005 The Regents of The University of Michigan
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met: redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer;
   * redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution;
   * neither the name of the copyright holders nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef __SIM_SYSCALL_EMUL_BUF_HH__
  #define __SIM_SYSCALL_EMUL_BUF_HH__
  
  ///
  /// @file syscall_emul_buf.hh
  ///
  /// This file defines buffer classes used to handle pointer arguments
  /// in emulated syscalls.
  
  #include <cstring>
  
  #include "base/types.hh"
  #include "mem/se_translating_port_proxy.hh"
  
  namespace gem5
  {
  
  /**
   * Base class for BufferArg and TypedBufferArg, Not intended to be
   * used directly.
   *
   * The BufferArg classes represent buffers in target user space that
   * are passed by reference to an (emulated) system call.  Each
   * instance provides an internal (simulator-space) buffer of the
   * appropriate size and tracks the user-space address.  The copyIn()
   * and copyOut() methods copy the user-space buffer to and from the
   * simulator-space buffer, respectively.
   */
  class BaseBufferArg
  {
  
    public:
  
      /**
       * Allocate a buffer of size 'size' representing the memory at
       * target address 'addr'.
       */
      BaseBufferArg(Addr _addr, int _size)
          : addr(_addr), size(_size), bufPtr(new uint8_t[size])
      {
          // clear out buffer: in case we only partially populate this,
          // and then do a copyOut(), we want to make sure we don't
          // introduce any random junk into the simulated address space
          memset(bufPtr, 0, size);
      }
  
      ~BaseBufferArg() { delete [] bufPtr; }
  
      /**
       * copy data into simulator space (read from target memory)
       */
      bool
      copyIn(const PortProxy &memproxy)
      {
          memproxy.readBlob(addr, bufPtr, size);
          return true;    // no EFAULT detection for now
      }
  
      /**
       * copy data out of simulator space (write to target memory)
       */
      bool
      copyOut(const PortProxy &memproxy)
      {
          memproxy.writeBlob(addr, bufPtr, size);
          return true;    // no EFAULT detection for now
      }
  
    protected:
      const Addr addr;        ///< address of buffer in target address space
      const int size;         ///< buffer size
      uint8_t * const bufPtr; ///< pointer to buffer in simulator space
  };
  
  /**
   * BufferArg represents an untyped buffer in target user space that is
   * passed by reference to an (emulated) system call.
   */
  class BufferArg : public BaseBufferArg
  {
    public:
      /**
       * Allocate a buffer of size 'size' representing the memory at
       * target address 'addr'.
       */
      BufferArg(Addr _addr, int _size) : BaseBufferArg(_addr, _size) { }
  
      /**
       * Return a pointer to the internal simulator-space buffer.
       */
      void *bufferPtr() { return bufPtr; }
  };
  
  /**
   * TypedBufferArg is a class template; instances of this template
   * represent typed buffers in target user space that are passed by
   * reference to an (emulated) system call.
   *
   * This template provides operator overloads for convenience, allowing
   * for example the use of '->' to reference fields within a struct
   * type.
   */
  template <class T>
  class TypedBufferArg : public BaseBufferArg
  {
    public:
      /**
       * Allocate a buffer of type T representing the memory at target
       * address 'addr'. The user can optionally specify a specific
       * number of bytes to allocate to deal with structs that have
       * variable-size arrays at the end.
       */
      TypedBufferArg(Addr _addr, int _size = sizeof(T))
          : BaseBufferArg(_addr, _size)
      { }
  
      /**
       * Convert TypedBufferArg<T> to a pointer to T that points to the
       * internal buffer.
       */
      operator T*() { return (T *)bufPtr; }
  
      /**
       * Convert TypedBufferArg<T> to a reference to T that references the
       * internal buffer value.
       */
      T &operator*()       { return *((T *)bufPtr); }
  
  
      /**
       * Enable the use of '->' to reference fields where T is a struct
       * type.
       */
      T* operator->()      { return (T *)bufPtr; }
  
      /**
       * Enable the use of '[]' to reference fields where T is an array
       * type.
       */
      T &operator[](int i) { return ((T *)bufPtr)[i]; }
  };
  
  } // namespace gem5
  
  #endif // __SIM_SYSCALL_EMUL_BUF_HH__
  