sysdeps/unix/sysv/linux/generic/wordsize-32/overflow.h

   1 /* Overflow tests for stat, statfs, and lseek functions.
   2    Copyright (C) 2011-2019 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <sys/stat.h>
  21 #include <sys/statfs.h>
  22
  23 /* Test for overflows of structures where we ask the kernel to fill them
  24    in with standard 64-bit syscalls but return them through APIs that
  25    only expose the low 32 bits of some fields.  */
  26
  27 static inline off_t lseek_overflow (loff_t res)
  28 {
  29   off_t retval = (off_t) res;
  30   if (retval == res)
  31     return retval;
  32
  33   __set_errno (EOVERFLOW);
  34   return (off_t) -1;
  35 }
  36
  37 static inline int stat_overflow (struct stat *buf)
  38 {
  39   if (buf->__st_ino_pad == 0 && buf->__st_size_pad == 0
  40       && buf->__st_blocks_pad == 0)
  41     return 0;
  42
  43   __set_errno (EOVERFLOW);
  44   return -1;
  45 }
  46
  47 /* Note that f_files and f_ffree may validly be a sign-extended -1.  */
  48 static inline int statfs_overflow (struct statfs *buf)
  49 {
  50   if (buf->__f_blocks_pad == 0 && buf->__f_bfree_pad == 0
  51       && buf->__f_bavail_pad == 0
  52       && (buf->__f_files_pad == 0
  53           || (buf->f_files == -1U && buf->__f_files_pad == -1))
  54       && (buf->__f_ffree_pad == 0
  55           || (buf->f_ffree == -1U && buf->__f_ffree_pad == -1)))
  56     return 0;
  57
  58   __set_errno (EOVERFLOW);
  59   return -1;
  60 }