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

   1 /* Overflow tests for stat, statfs, and lseek functions.
   2    Copyright (C) 2011-2020 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 #include <sys/types.h>
  23
  24 /* Test for overflows of structures where we ask the kernel to fill them
  25    in with standard 64-bit syscalls but return them through APIs that
  26    only expose the low 32 bits of some fields.  */
  27
  28 static inline off_t lseek_overflow (loff_t res)
  29 {
  30   off_t retval = (off_t) res;
  31   if (retval == res)
  32     return retval;
  33
  34   __set_errno (EOVERFLOW);
  35   return (off_t) -1;
  36 }
  37
  38 static inline int stat_overflow (struct stat *buf)
  39 {
  40 #if defined __INO_T_MATCHES_INO64_T
  41   return 0;
  42 #else
  43   if (buf->__st_ino_pad == 0 && buf->__st_size_pad == 0
  44       && buf->__st_blocks_pad == 0)
  45     return 0;
  46
  47   __set_errno (EOVERFLOW);
  48   return -1;
  49 #endif
  50 }
  51
  52 /* Note that f_files and f_ffree may validly be a sign-extended -1.  */
  53 static inline int statfs_overflow (struct statfs *buf)
  54 {
  55 #if __STATFS_MATCHES_STATFS64
  56   return 0;
  57 #else
  58   if (buf->__f_blocks_pad == 0 && buf->__f_bfree_pad == 0
  59       && buf->__f_bavail_pad == 0
  60       && (buf->__f_files_pad == 0
  61           || (buf->f_files == -1U && buf->__f_files_pad == -1))
  62       && (buf->__f_ffree_pad == 0
  63           || (buf->f_ffree == -1U && buf->__f_ffree_pad == -1)))
  64     return 0;
  65
  66   __set_errno (EOVERFLOW);
  67   return -1;
  68 #endif
  69 }