fdopen.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

#include <precomp.h>

#include <tchar.h>

/*
 * @implemented
 */
FILE* _tfdopen(int handle,
#ifndef _UNICODE
   const
#endif
   _TCHAR* mode)
{
  FILE* file;
  int rw;

  if (handle == 0)
    return stdin;

  if (handle == 1)
    return stdout;

  if (handle == 2)
    return stderr;

  file = __alloc_file();
  if (file == NULL)
    return NULL;
  file->_file = handle;

  rw = (mode[1] == '+') || (mode[1] && (mode[2] == '+'));

  if (*mode == 'a')
    _lseek(handle, 0, SEEK_END);

  file->_cnt = 0;
  file->_file = handle;
  file->_bufsiz = 0;

// The mode of the stream must be compatible with the mode of the file descriptor.
// this should be checked.

  if (rw)
    file->_flag = _IOREAD | _IOWRT;
  else if (*mode == 'r')
    file->_flag = _IOREAD;
  else
    file->_flag = _IOWRT;

  file->_base = file->_ptr = NULL;

  return file;
}