From 90e33dfec651c04d75f20a4e5c20593145c5d90e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Fri, 8 Jun 2018 17:24:57 +0100 Subject: util: add helper APIs for dealing with inotify in portable manner MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The inotify userspace API for reading events is quite horrible, so it is useful to wrap it in a more friendly API to avoid duplicating code across many users in QEMU. Wrapping it also allows introduction of a platform portability layer, so that we can add impls for non-Linux based equivalents in future. Reviewed-by: Marc-André Lureau Signed-off-by: Daniel P. Berrangé --- include/qemu/filemonitor.h | 128 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 128 insertions(+) create mode 100644 include/qemu/filemonitor.h (limited to 'include/qemu') diff --git a/include/qemu/filemonitor.h b/include/qemu/filemonitor.h new file mode 100644 index 0000000..cd03183 --- /dev/null +++ b/include/qemu/filemonitor.h @@ -0,0 +1,128 @@ +/* + * QEMU file monitor helper + * + * Copyright (c) 2018 Red Hat, Inc. + * + * This 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 of the License, or (at your option) any later version. + * + * This 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 this library; if not, see . + * + */ + +#ifndef QEMU_FILE_MONITOR_H +#define QEMU_FILE_MONITOR_H + +#include "qemu-common.h" + + +typedef struct QFileMonitor QFileMonitor; + +typedef enum { + /* File has been created in a dir */ + QFILE_MONITOR_EVENT_CREATED, + /* File has been modified in a dir */ + QFILE_MONITOR_EVENT_MODIFIED, + /* File has been deleted in a dir */ + QFILE_MONITOR_EVENT_DELETED, + /* File has attributes changed */ + QFILE_MONITOR_EVENT_ATTRIBUTES, + /* Dir is no longer being monitored (due to deletion) */ + QFILE_MONITOR_EVENT_IGNORED, +} QFileMonitorEvent; + + +/** + * QFileMonitorHandler: + * @id: id from qemu_file_monitor_add_watch() + * @event: the file change that occurred + * @filename: the name of the file affected + * @opaque: opaque data provided to qemu_file_monitor_add_watch() + * + * Invoked whenever a file changes. If @event is + * QFILE_MONITOR_EVENT_IGNORED, @filename will be + * empty. + * + */ +typedef void (*QFileMonitorHandler)(int id, + QFileMonitorEvent event, + const char *filename, + void *opaque); + +/** + * qemu_file_monitor_new: + * @errp: pointer to a NULL-initialized error object + * + * Create a handle for a file monitoring object. + * + * This object does locking internally to enable it to be + * safe to use from multiple threads + * + * If the platform does not support file monitoring, an + * error will be reported. Likewise if file monitoring + * is supported, but cannot be initialized + * + * Currently this is implemented on Linux platforms with + * the inotify subsystem. + * + * Returns: the new monitoring object, or NULL on error + */ +QFileMonitor *qemu_file_monitor_new(Error **errp); + +/** + * qemu_file_monitor_free: + * @mon: the file monitor context + * + * Free resources associated with the file monitor, + * including any currently registered watches. + */ +void qemu_file_monitor_free(QFileMonitor *mon); + +/** + * qemu_file_monitor_add_watch: + * @mon: the file monitor context + * @dirpath: the directory whose contents to watch + * @filename: optional filename to filter on + * @cb: the function to invoke when @dirpath has changes + * @opaque: data to pass to @cb + * @errp: pointer to a NULL-initialized error object + * + * Register to receive notifications of changes + * in the directory @dirpath. All files in the + * directory will be monitored. If the caller is + * only interested in one specific file, @filename + * can be used to filter events. + * + * Returns: a positive integer watch ID, or -1 on error + */ +int qemu_file_monitor_add_watch(QFileMonitor *mon, + const char *dirpath, + const char *filename, + QFileMonitorHandler cb, + void *opaque, + Error **errp); + +/** + * qemu_file_monitor_remove_watch: + * @mon: the file monitor context + * @dirpath: the directory whose contents to unwatch + * @id: id of the watch to remove + * + * Removes the file monitoring watch @id, associated + * with the directory @dirpath. This must never be + * called from a QFileMonitorHandler callback, or a + * deadlock will result. + */ +void qemu_file_monitor_remove_watch(QFileMonitor *mon, + const char *dirpath, + int id); + +#endif /* QEMU_FILE_MONITOR_H */ -- cgit v1.1