在函数中分配内存以返回给用户

Question

我有一个函数,它通过串行发送命令,然后接收未知大小的响应.运用

(ioctl(fd_, FIONREAD, &bytes_in_buffer);

我确定需要为阅读分配多少内存.

//This code calls the function below
unsigned char CheckRefresh[] = {254, 124, 0};
unsigned char * response;
unsigned int size;
relay_board->SendCustomCommand(CheckRefresh, 3, &response, size);

ErrorCode SendCustomCommand(unsigned char * command, unsigned int command_size, unsigned char **response, unsigned int &response_size)
{
  //Send the command
  write(fd_, command, command_size);

  // ... Omitting Polling Code to Get correct number of bytes ...
  (ioctl(fd_, FIONREAD, &bytes_in_buffer);

  //Now getting the response
  response_size = (unsigned int)bytes_in_buffer;
  (*response) = new unsigned char(response_size);
  if(read(fd_, *response, response_size) < 0)
  {
    std::cout << "[ProXRSerial] SendCustomCommand: Read failed... -- Errno: " << errno << std::endl;
    return Failed;
  };
  return Success;
}

我相信这会破坏我的堆栈,因为我的下一个函数调用会中断

unsigned char * command = new unsigned char(3);

以下内容:

sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) -
__builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) 
(old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 
* (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && 
((unsigned long)old_end & pagemask) == 0)' failed.

有人可以提供一些建议吗？我很茫然,我认为传递双指针会让我为用户分配内存......

先感谢您.

Answer 1

这条线

(*response) = new unsigned char(response_size);

应该读

(*response) = new unsigned char[response_size];

您的版本分配一个无符号字符,并使用该值进行初始化response_size.