bookmarkfs/src/watcher.h
2024-12-31 18:09:03 +08:00

88 lines
2.2 KiB
C

/**
* bookmarkfs/src/watcher.h
* ----
*
* Copyright (C) 2024 CismonX <admin@cismon.net>
*
* This file is part of BookmarkFS.
*
* BookmarkFS is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* BookmarkFS 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with BookmarkFS. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef BOOKMARKFS_WATCHER_H_
#define BOOKMARKFS_WATCHER_H_
#include <stdint.h>
/**
* A watcher_poll() call returning WATCHER_POLL_ERR
* most likely means that the file being watched has gone.
*
* When the file is back, calling watcher_poll() again should
* return WATCHER_POLL_CHANGED, and the watcher should continue to work.
*/
#define WATCHER_POLL_ERR -1
#define WATCHER_POLL_NOCHANGE 0
#define WATCHER_POLL_CHANGED 1
/**
* Always use fstat() to detect file change.
*/
#define WATCHER_FALLBACK ( 1u << 0 )
/**
* Nothing is performed on the filesystem,
* and watcher_poll() always returns WATCHER_POLL_NOCHANGE.
*/
#define WATCHER_NOOP ( 1u << 1 )
/**
* Bit to shift when applying sandbox flags to the watcher.
*/
#define WATCHER_SANDBOX_FLAGS_OFFSET 16
struct watcher;
/**
* Creates a watcher that watches for changes of a single file.
*
* The `flags` argument is a bit combination of watcher flags
* and sandbox flags. The latter is used for
* initializing the sandbox for the internal worker thread.
*/
struct watcher *
watcher_create (
int dirfd,
char const *name,
uint32_t flags
);
void
watcher_destroy (
struct watcher *w
);
/**
* Check whether the file associated with the watcher
* has changed since the last watcher_poll() call
* (or, if not yet called, since watcher initialization).
*
* Returns one of WATCHER_POLL_*.
*/
int
watcher_poll (
struct watcher *w
);
#endif /* !defined(BOOKMARKFS_WATCHER_H_) */