1  /* Determine whether two stat buffers are known to refer to the same file.
       2  
       3     Copyright (C) 2006, 2009-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  #ifndef SAME_INODE_H
      19  #define SAME_INODE_H 1
      20  
      21  /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE.  */
      22  #if !_GL_CONFIG_H_INCLUDED
      23   #error "Please include config.h first."
      24  #endif
      25  
      26  #include <sys/stat.h>
      27  
      28  _GL_INLINE_HEADER_BEGIN
      29  #ifndef SAME_INODE_INLINE
      30  # define SAME_INODE_INLINE _GL_INLINE
      31  #endif
      32  
      33  /* True if A and B point to structs with st_dev and st_ino members
      34     that are known to represent the same file.
      35  
      36     Use | and ^ to shorten generated code, and to lessen the
      37     probability of screwups if st_ino is an array.  */
      38  
      39  #if defined __VMS && __CRTL_VER < 80200000
      40  # define PSAME_INODE(a, b) (! (((a)->st_dev ^ (b)->st_dev) \
      41                                 | ((a)->st_ino[0] ^ (b)->st_ino[0]) \
      42                                 | ((a)->st_ino[1] ^ (b)->st_ino[1]) \
      43                                 | ((a)->st_ino[2] ^ (b)->st_ino[2])))
      44  #elif defined _WIN32 && ! defined __CYGWIN__
      45    /* Native Windows.  */
      46  # if _GL_WINDOWS_STAT_INODES
      47    /* stat() and fstat() set st_dev and st_ino to 0 if information about
      48       the inode is not available.  */
      49  #  if _GL_WINDOWS_STAT_INODES == 2
      50  #   define PSAME_INODE(a, b) \
      51       (! (! ((a)->st_dev | (a)->st_ino._gl_ino[0] | (a)->st_ino._gl_ino[1]) \
      52           | ((a)->st_dev ^ (b)->st_dev) \
      53           | ((a)->st_ino._gl_ino[0] ^ (b)->st_ino._gl_ino[0]) \
      54           | ((a)->st_ino._gl_ino[1] ^ (b)->st_ino._gl_ino[1])))
      55  #  else
      56  #   define PSAME_INODE(a, b) (! (! ((a)->st_dev | (a)->st_ino) \
      57                                   | ((a)->st_dev ^ (b)->st_dev) \
      58                                   | ((a)->st_ino ^ (b)->st_ino)))
      59  #  endif
      60  # else
      61    /* stat() and fstat() set st_ino to 0 always.  */
      62  #  define PSAME_INODE(a, b) 0
      63  # endif
      64  #else
      65    /* POSIX.  */
      66  # define PSAME_INODE(a, b) (! (((a)->st_dev ^ (b)->st_dev) \
      67                                 | ((a)->st_ino ^ (b)->st_ino)))
      68  #endif
      69  
      70  /* True if struct objects A and B are known to represent the same file.  */
      71  
      72  #define SAME_INODE(a, b) PSAME_INODE (&(a), &(b))
      73  
      74  /* True if *A and *B represent the same file.  Unlike PSAME_INODE,
      75     args are evaluated once and must point to struct stat.  */
      76  
      77  SAME_INODE_INLINE bool
      78  psame_inode (struct stat const *a, struct stat const *b)
      79  {
      80    return PSAME_INODE (a, b);
      81  }
      82  
      83  _GL_INLINE_HEADER_END
      84  
      85  #endif