1  /* Copyright (C) 1993-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <unistd.h>
      20  #include <hurd.h>
      21  #include <hurd/fd.h>
      22  #include <string.h>
      23  
      24  error_t
      25  _hurd_fd_read (struct hurd_fd *fd, void *buf, size_t *nbytes, loff_t offset)
      26  {
      27    error_t err;
      28    char *data;
      29    mach_msg_type_number_t nread;
      30  
      31    error_t readfd (io_t port)
      32      {
      33        return __io_read (port, &data, &nread, offset, *nbytes);
      34      }
      35  
      36    data = buf;
      37    nread = *nbytes;
      38    if (err = HURD_FD_PORT_USE_CANCEL (fd, _hurd_ctty_input (port, ctty, readfd)))
      39      return err;
      40  
      41    if (data != buf)
      42      {
      43        if (nread > *nbytes)	/* Sanity check for bogus server.  */
      44  	{
      45  	  __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread);
      46  	  return EGRATUITOUS;
      47  	}
      48        memcpy (buf, data, nread);
      49        __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread);
      50      }
      51  
      52    *nbytes = nread;
      53    return 0;
      54  }