1  /* Detecting file changes using modification times.
       2     Copyright (C) 2017-2023 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  #ifndef _FILE_CHANGE_DETECTION_H
      20  #define _FILE_CHANGE_DETECTION_H
      21  
      22  #include <stdbool.h>
      23  #include <stdio.h>
      24  #include <sys/stat.h>
      25  #include <sys/types.h>
      26  
      27  /* Items for identifying a particular file version.  Excerpt from
      28     struct stat64.  */
      29  struct file_change_detection
      30  {
      31    /* Special values: 0 if file does not exist.  -1 to force mismatch
      32       with the next comparison.  */
      33    off64_t size;
      34  
      35    ino64_t ino;
      36    struct __timespec64 mtime;
      37    struct __timespec64 ctime;
      38  };
      39  
      40  /* Returns true if *LEFT and *RIGHT describe the same version of the
      41     same file.  */
      42  bool __file_is_unchanged (const struct file_change_detection *left,
      43                            const struct file_change_detection *right);
      44  
      45  /* Extract file change information to *FILE from the stat buffer
      46     *ST.  */
      47  void __file_change_detection_for_stat (struct file_change_detection *file,
      48                                         const struct __stat64_t64 *st);
      49  
      50  /* Writes file change information for PATH to *FILE.  Returns true on
      51     success.  For benign errors, *FILE is cleared, and true is
      52     returned.  For errors indicating resource outages and the like,
      53     false is returned.  */
      54  bool __file_change_detection_for_path (struct file_change_detection *file,
      55                                         const char *path);
      56  
      57  /* Writes file change information for the stream FP to *FILE.  Returns
      58     true on success, false on failure.  If FP is NULL, treat the file
      59     as non-existing.  */
      60  bool __file_change_detection_for_fp (struct file_change_detection *file,
      61                                       FILE *fp);
      62  
      63  #ifndef _ISOMAC
      64  libc_hidden_proto (__file_is_unchanged)
      65  libc_hidden_proto (__file_change_detection_for_stat)
      66  libc_hidden_proto (__file_change_detection_for_path)
      67  libc_hidden_proto (__file_change_detection_for_fp)
      68  #endif
      69  
      70  #endif /* _FILE_CHANGE_DETECTION_H */