115 lines
3.8 KiB
C
115 lines
3.8 KiB
C
/*
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* FreeRDP: A Remote Desktop Protocol Client
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* Mutex Utils
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*
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* Copyright 2011 Vic Lee
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <winpr/windows.h>
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#include <freerdp/utils/memory.h>
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#include <freerdp/utils/mutex.h>
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#ifdef _WIN32
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#define freerdp_mutex_t HANDLE
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#else
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#include <pthread.h>
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#define freerdp_mutex_t pthread_mutex_t
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#endif
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/**
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* Mutex are used to prevent concurrent accesses to specific portions of code.
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* This funciton and the other freerdp_mutex_*() function are defining a portable API
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* to get mutex for both Windows and Linux, where the lower level implementation is very different.
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*
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* This function creates a new freerdp_mutex object.
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* Use freerdp_mutex_lock() to get exclusive ownership of the mutex, and lock a given (protected) portion of code.
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* Use freerdp_mutex_unlock() to release your ownership on a mutex.
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* Use freerdp_mutex_free() to release the resources associated with the mutex when it is no longer needed.
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*
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* @return a freerdp_mutex pointer. This should be considered opaque, as the implementation is platform dependent.
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* NULL is returned if an allocation or initialization error occurred.
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*
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* @see pthread documentation for Linux implementation of mutexes
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* @see MSDN http://msdn.microsoft.com/en-us/library/windows/desktop/ms682411%28v=vs.85%29.aspx for Windows implementation
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*/
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freerdp_mutex freerdp_mutex_new(void)
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{
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#ifdef _WIN32
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freerdp_mutex_t mutex;
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mutex = CreateMutex(NULL, FALSE, NULL);
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return (freerdp_mutex) mutex;
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#else
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freerdp_mutex_t* mutex;
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mutex = xnew(freerdp_mutex_t);
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if (mutex)
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pthread_mutex_init(mutex, 0);
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return mutex;
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#endif
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}
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/**
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* This function is used to deallocate all resources associated with a freerdp_mutex object.
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*
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* @param mutex [in] - Pointer to the mutex that needs to be deallocated.
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* On return, this object is not valid anymore.
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*/
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void freerdp_mutex_free(freerdp_mutex mutex)
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{
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#ifdef _WIN32
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CloseHandle((freerdp_mutex_t) mutex);
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#else
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pthread_mutex_destroy((freerdp_mutex_t*) mutex);
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xfree(mutex);
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#endif
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}
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/**
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* Use this function to get exclusive ownership of the mutex.
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* This should be called before entering a portion of code that needs to be protected against concurrent accesses.
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* Use the freerdp_mutex_unlock() call to release ownership when you leave this protected code.
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*
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* @param mutex [in] - An initialized freerdp_mutex object, as returned from a call to freerdp_mutex_new().
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* This function will suspend the running thread when called, until the mutex is available.
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* Only one thread at a time will be allowed to continue execution.
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*/
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void freerdp_mutex_lock(freerdp_mutex mutex)
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{
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#ifdef _WIN32
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WaitForSingleObject((freerdp_mutex_t) mutex, INFINITE);
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#else
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pthread_mutex_lock(mutex);
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#endif
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}
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/**
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* Use this function to release your ownership on a mutex.
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* This should be called when leaving a portion of code that needs to be protected against concurrent accesses.
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* DO NOT use this call on a mutex that you do not own. See freerdp_mutex_lock() for getting ownership on a mutex.
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*
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* @param mutex [in] - Pointer to a mutex that was locked by a call to freerdp_mutex_lock().
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*/
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void freerdp_mutex_unlock(freerdp_mutex mutex)
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{
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#ifdef _WIN32
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ReleaseMutex((freerdp_mutex_t) mutex);
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#else
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pthread_mutex_unlock(mutex);
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#endif
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}
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