xrdp/sesman/lock_uds.h

60 lines
1.9 KiB
C

/**
* xrdp: A Remote Desktop Protocol server.
*
* Copyright (C) 2022 Matt Burt, all xrdp contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
*
* @file lock_uds.h
* @brief Providing a locking facility for Unix Domain Sockets
* @author Matt Burt
*
* It is difficult for a server to determine whether a socket it wishes
* to listen on is already active or not. The purpose of this module is to
* provide a locking facility which can be used as a proxy for this.
*/
#ifndef LOCK_UDS_H
#define LOCK_UDS_H
struct lock_uds;
/**
* Take out a lock for the specified Unix Domain socket
* @param sockname Name of socket. Must start with a '/'
* @return A struct lock_uds instance if the lock was successfully acquired.
*
* A NULL return may indicate a lack of memory, or that another
* process has the lock.
*
* A file is created in the same directory as the socket. The name
* of the file is ".${basename}.lock", where basename is the base name
* of the socket. THE file is removed when the lock is relinquished. */
struct lock_uds *
lock_uds(const char *sockname);
/**
* Relinquish a lock on the specified Unix Domain Socket.
* @param lock to relinquish
*
* If the process which has originally taken out the lock forks, this
* routine should be called from the child process to prevent the lock
* inadvertently being passed to the child. */
void
unlock_uds(struct lock_uds *lock);
#endif // LOCK_UDS_H