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121 lines
3.6 KiB
C
121 lines
3.6 KiB
C
/* Detecting file changes using modification times.
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Copyright (C) 2017-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <file_change_detection.h>
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#include <errno.h>
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#include <stddef.h>
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bool
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__file_is_unchanged (const struct file_change_detection *left,
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const struct file_change_detection *right)
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{
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if (left->size < 0 || right->size < 0)
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/* Negative sizes are used as markers and never match. */
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return false;
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else if (left->size == 0 && right->size == 0)
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/* Both files are empty or do not exist, so they have the same
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content, no matter what the other fields indicate. */
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return true;
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else
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return left->size == right->size
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&& left->ino == right->ino
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&& left->mtime.tv_sec == right->mtime.tv_sec
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&& left->mtime.tv_nsec == right->mtime.tv_nsec
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&& left->ctime.tv_sec == right->ctime.tv_sec
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&& left->ctime.tv_nsec == right->ctime.tv_nsec;
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}
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libc_hidden_def (__file_is_unchanged)
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void
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__file_change_detection_for_stat (struct file_change_detection *file,
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const struct __stat64_t64 *st)
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{
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if (S_ISDIR (st->st_mode))
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/* Treat as empty file. */
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file->size = 0;
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else if (!S_ISREG (st->st_mode))
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/* Non-regular files cannot be cached. */
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file->size = -1;
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else
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{
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file->size = st->st_size;
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file->ino = st->st_ino;
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file->mtime = (struct __timespec64) { st->st_mtim.tv_sec,
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st->st_mtim.tv_nsec };
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file->ctime = (struct __timespec64) { st->st_ctim.tv_sec,
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st->st_ctim.tv_nsec };
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}
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}
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libc_hidden_def (__file_change_detection_for_stat)
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bool
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__file_change_detection_for_path (struct file_change_detection *file,
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const char *path)
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{
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struct __stat64_t64 st;
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if (__stat64_time64 (path, &st) != 0)
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switch (errno)
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{
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case EACCES:
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case EISDIR:
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case ELOOP:
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case ENOENT:
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case ENOTDIR:
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case EPERM:
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/* Ignore errors due to file system contents. Instead, treat
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the file as empty. */
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file->size = 0;
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return true;
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default:
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/* Other errors are fatal. */
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return false;
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}
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else /* stat64 was successfull. */
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{
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__file_change_detection_for_stat (file, &st);
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return true;
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}
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}
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libc_hidden_def (__file_change_detection_for_path)
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bool
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__file_change_detection_for_fp (struct file_change_detection *file,
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FILE *fp)
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{
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if (fp == NULL)
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{
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/* The file does not exist. */
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file->size = 0;
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return true;
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}
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else
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{
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struct __stat64_t64 st;
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if (__fstat64_time64 (__fileno (fp), &st) != 0)
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/* If we already have a file descriptor, all errors are fatal. */
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return false;
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else
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{
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__file_change_detection_for_stat (file, &st);
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return true;
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}
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}
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}
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libc_hidden_def (__file_change_detection_for_fp)
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