debug/fgetws_chk.c

   1 /* Copyright (C) 1993-2018 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include "libioP.h"
  19 #include <wchar.h>
  20 #include <sys/param.h>
  21
  22 wchar_t *
  23 __fgetws_chk (wchar_t *buf, size_t size, int n, FILE *fp)
  24 {
  25   size_t count;
  26   wchar_t *result;
  27   int old_error;
  28   CHECK_FILE (fp, NULL);
  29   if (n <= 0)
  30     return NULL;
  31   _IO_acquire_lock (fp);
  32   /* This is very tricky since a file descriptor may be in the
  33      non-blocking mode. The error flag doesn't mean much in this
  34      case. We return an error only when there is a new error. */
  35   old_error = fp->_flags & _IO_ERR_SEEN;
  36   fp->_flags &= ~_IO_ERR_SEEN;
  37   count = _IO_getwline (fp, buf, MIN ((size_t) n - 1, size), L'\n', 1);
  38   /* If we read in some bytes and errno is EAGAIN, that error will
  39      be reported for next read. */
  40   if (count == 0 || (_IO_ferror_unlocked (fp) && errno != EAGAIN))
  41     result = NULL;
  42   else if (count >= size)
  43     __chk_fail ();
  44   else
  45     {
  46       buf[count] = '\0';
  47       result = buf;
  48     }
  49   fp->_flags |= old_error;
  50   _IO_release_lock (fp);
  51   return result;
  52 }