hurd/fd-read.c

   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 }