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 <marcandre.lureau@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
129 lines
4 KiB
C
129 lines
4 KiB
C
/*
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* QEMU file monitor helper
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*
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* Copyright (c) 2018 Red Hat, Inc.
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*
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* This 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 of the License, or (at your option) any later version.
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*
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* This 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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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef QEMU_FILE_MONITOR_H
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#define QEMU_FILE_MONITOR_H
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#include "qemu-common.h"
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typedef struct QFileMonitor QFileMonitor;
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typedef enum {
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/* File has been created in a dir */
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QFILE_MONITOR_EVENT_CREATED,
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/* File has been modified in a dir */
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QFILE_MONITOR_EVENT_MODIFIED,
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/* File has been deleted in a dir */
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QFILE_MONITOR_EVENT_DELETED,
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/* File has attributes changed */
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QFILE_MONITOR_EVENT_ATTRIBUTES,
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/* Dir is no longer being monitored (due to deletion) */
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QFILE_MONITOR_EVENT_IGNORED,
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} QFileMonitorEvent;
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/**
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* QFileMonitorHandler:
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* @id: id from qemu_file_monitor_add_watch()
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* @event: the file change that occurred
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* @filename: the name of the file affected
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* @opaque: opaque data provided to qemu_file_monitor_add_watch()
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*
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* Invoked whenever a file changes. If @event is
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* QFILE_MONITOR_EVENT_IGNORED, @filename will be
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* empty.
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*
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*/
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typedef void (*QFileMonitorHandler)(int id,
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QFileMonitorEvent event,
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const char *filename,
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void *opaque);
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/**
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* qemu_file_monitor_new:
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a handle for a file monitoring object.
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*
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* This object does locking internally to enable it to be
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* safe to use from multiple threads
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*
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* If the platform does not support file monitoring, an
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* error will be reported. Likewise if file monitoring
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* is supported, but cannot be initialized
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*
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* Currently this is implemented on Linux platforms with
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* the inotify subsystem.
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*
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* Returns: the new monitoring object, or NULL on error
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*/
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QFileMonitor *qemu_file_monitor_new(Error **errp);
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/**
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* qemu_file_monitor_free:
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* @mon: the file monitor context
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*
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* Free resources associated with the file monitor,
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* including any currently registered watches.
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*/
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void qemu_file_monitor_free(QFileMonitor *mon);
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/**
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* qemu_file_monitor_add_watch:
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* @mon: the file monitor context
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* @dirpath: the directory whose contents to watch
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* @filename: optional filename to filter on
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* @cb: the function to invoke when @dirpath has changes
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* @opaque: data to pass to @cb
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* @errp: pointer to a NULL-initialized error object
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*
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* Register to receive notifications of changes
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* in the directory @dirpath. All files in the
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* directory will be monitored. If the caller is
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* only interested in one specific file, @filename
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* can be used to filter events.
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*
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* Returns: a positive integer watch ID, or -1 on error
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*/
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int qemu_file_monitor_add_watch(QFileMonitor *mon,
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const char *dirpath,
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const char *filename,
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QFileMonitorHandler cb,
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void *opaque,
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Error **errp);
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/**
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* qemu_file_monitor_remove_watch:
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* @mon: the file monitor context
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* @dirpath: the directory whose contents to unwatch
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* @id: id of the watch to remove
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*
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* Removes the file monitoring watch @id, associated
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* with the directory @dirpath. This must never be
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* called from a QFileMonitorHandler callback, or a
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* deadlock will result.
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*/
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void qemu_file_monitor_remove_watch(QFileMonitor *mon,
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const char *dirpath,
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int id);
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#endif /* QEMU_FILE_MONITOR_H */
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