sysdeps/unix/sysv/linux/xstatover.h

   1 /* Overflow tests for stat, statfs, and lseek functions.
   2    Copyright (C) 2020-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/stat.h>
  20 #include <sys/statfs.h>
  21
  22 /* Test for overflows of structures where we ask the kernel to fill them
  23    in with standard 64-bit syscalls but return them through APIs that
  24    only expose the low 32 bits of some fields.  */
  25
  26 static inline off_t lseek_overflow (loff_t res)
  27 {
  28   off_t retval = (off_t) res;
  29   if (retval == res)
  30     return retval;
  31
  32   __set_errno (EOVERFLOW);
  33   return (off_t) -1;
  34 }
  35
  36 static inline int stat_overflow (struct stat *buf)
  37 {
  38 #if defined __INO_T_MATCHES_INO64_T || !STAT_IS_KERNEL_STAT
  39   return 0;
  40 #else
  41   if (buf->__st_ino_pad == 0 && buf->__st_size_pad == 0
  42       && buf->__st_blocks_pad == 0)
  43     return 0;
  44
  45   __set_errno (EOVERFLOW);
  46   return -1;
  47 #endif
  48 }
  49
  50 /* Note that f_files and f_ffree may validly be a sign-extended -1.  */
  51 static inline int statfs_overflow (struct statfs *buf)
  52 {
  53 #if __STATFS_MATCHES_STATFS64 || !STAT_IS_KERNEL_STAT
  54   return 0;
  55 #else
  56   if (buf->__f_blocks_pad == 0 && buf->__f_bfree_pad == 0
  57       && buf->__f_bavail_pad == 0
  58       && (buf->__f_files_pad == 0
  59           || (buf->f_files == -1U && buf->__f_files_pad == -1))
  60       && (buf->__f_ffree_pad == 0
  61           || (buf->f_ffree == -1U && buf->__f_ffree_pad == -1)))
  62     return 0;
  63
  64   __set_errno (EOVERFLOW);
  65   return -1;
  66 #endif
  67 }