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/* 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/>. */
#include <file_change_detection.h>
#include <errno.h>
#include <stddef.h>
bool
__file_is_unchanged (const struct file_change_detection *left,
const struct file_change_detection *right)
{
if (left->size < 0 || right->size < 0)
/* Negative sizes are used as markers and never match. */
return false;
else if (left->size == 0 && right->size == 0)
/* Both files are empty or do not exist, so they have the same
content, no matter what the other fields indicate. */
return true;
else
return left->size == right->size
&& left->ino == right->ino
&& left->mtime.tv_sec == right->mtime.tv_sec
&& left->mtime.tv_nsec == right->mtime.tv_nsec
&& left->ctime.tv_sec == right->ctime.tv_sec
&& left->ctime.tv_nsec == right->ctime.tv_nsec;
}
libc_hidden_def (__file_is_unchanged)
void
__file_change_detection_for_stat (struct file_change_detection *file,
const struct stat64 *st)
{
if (S_ISDIR (st->st_mode))
/* Treat as empty file. */
file->size = 0;
else if (!S_ISREG (st->st_mode))
/* Non-regular files cannot be cached. */
file->size = -1;
else
{
file->size = st->st_size;
file->ino = st->st_ino;
file->mtime = st->st_mtim;
file->ctime = st->st_ctim;
}
}
libc_hidden_def (__file_change_detection_for_stat)
bool
__file_change_detection_for_path (struct file_change_detection *file,
const char *path)
{
struct stat64 st;
if (stat64 (path, &st) != 0)
switch (errno)
{
case EACCES:
case EISDIR:
case ELOOP:
case ENOENT:
case ENOTDIR:
case EPERM:
/* Ignore errors due to file system contents. Instead, treat
the file as empty. */
file->size = 0;
return true;
default:
/* Other errors are fatal. */
return false;
}
else /* stat64 was successfull. */
{
__file_change_detection_for_stat (file, &st);
return true;
}
}
libc_hidden_def (__file_change_detection_for_path)
bool
__file_change_detection_for_fp (struct file_change_detection *file,
FILE *fp)
{
if (fp == NULL)
{
/* The file does not exist. */
file->size = 0;
return true;
}
else
{
struct stat64 st;
if (fstat64 (__fileno (fp), &st) != 0)
/* If we already have a file descriptor, all errors are fatal. */
return false;
else
{
__file_change_detection_for_stat (file, &st);
return true;
}
}
}
libc_hidden_def (__file_change_detection_for_fp)
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