/* Detecting file changes using modification times.

   Copyright (C) 2017-2020 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <https://www.gnu.org/licenses/>.  */

#ifndef _FILE_CHANGE_DETECTION_H

#define _FILE_CHANGE_DETECTION_H

#include <stdbool.h>

#include <stdio.h>

#include <sys/stat.h>

#include <sys/types.h>

/* Items for identifying a particular file version.  Excerpt from

   struct stat64.  */

struct file_change_detection

{

  /* Special values: 0 if file does not exist.  -1 to force mismatch

     with the next comparison.  */

  off64_t size;

  ino64_t ino;

  struct timespec mtime;

  struct timespec ctime;

};

/* Returns true if *LEFT and *RIGHT describe the same version of the

   same file.  */

bool __file_is_unchanged (const struct file_change_detection *left,

                          const struct file_change_detection *right);

/* Extract file change information to *FILE from the stat buffer

   *ST.  */

void __file_change_detection_for_stat (struct file_change_detection *file,

                                       const struct stat64 *st);

/* Writes file change information for PATH to *FILE.  Returns true on

   success.  For benign errors, *FILE is cleared, and true is

   returned.  For errors indicating resource outages and the like,

   false is returned.  */

bool __file_change_detection_for_path (struct file_change_detection *file,

                                       const char *path);

/* Writes file change information for the stream FP to *FILE.  Returns

   ture on success, false on failure.  If FP is NULL, treat the file

   as non-existing.  */

bool __file_change_detection_for_fp (struct file_change_detection *file,

                                     FILE *fp);

#ifndef _ISOMAC

libc_hidden_proto (__file_is_unchanged)

libc_hidden_proto (__file_change_detection_for_stat)

libc_hidden_proto (__file_change_detection_for_path)

libc_hidden_proto (__file_change_detection_for_fp)

#endif

#endif /* _FILE_CHANGE_DETECTION_H */