mirror of
https://github.com/reactos/reactos.git
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327 lines
8 KiB
C
327 lines
8 KiB
C
/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS system libraries
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* FILE: lib/rtl/resource.c
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* PURPOSE: Resource (multiple-reader-single-writer lock) functions
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* PROGRAMMER: Partially takem from Wine:
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* Copyright 1996-1998 Marcus Meissner
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* 1999 Alex Korobka
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*/
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/* INCLUDES *****************************************************************/
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#include <rtl.h>
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#define NDEBUG
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#include <debug.h>
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/* FUNCTIONS ***************************************************************/
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlInitializeResource(PRTL_RESOURCE Resource)
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{
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NTSTATUS Status;
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Status = RtlInitializeCriticalSection(&Resource->Lock);
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if (!NT_SUCCESS(Status))
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{
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RtlRaiseStatus(Status);
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}
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Status = NtCreateSemaphore(&Resource->SharedSemaphore,
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SEMAPHORE_ALL_ACCESS,
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NULL,
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0,
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65535);
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if (!NT_SUCCESS(Status))
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{
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RtlRaiseStatus(Status);
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}
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Resource->SharedWaiters = 0;
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Status = NtCreateSemaphore(&Resource->ExclusiveSemaphore,
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SEMAPHORE_ALL_ACCESS,
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NULL,
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0,
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65535);
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if (!NT_SUCCESS(Status))
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{
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RtlRaiseStatus(Status);
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}
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Resource->ExclusiveWaiters = 0;
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Resource->NumberActive = 0;
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Resource->OwningThread = NULL;
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Resource->TimeoutBoost = 0; /* no info on this one, default value is 0 */
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}
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlDeleteResource(PRTL_RESOURCE Resource)
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{
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RtlDeleteCriticalSection(&Resource->Lock);
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NtClose(Resource->ExclusiveSemaphore);
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NtClose(Resource->SharedSemaphore);
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Resource->OwningThread = NULL;
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Resource->ExclusiveWaiters = 0;
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Resource->SharedWaiters = 0;
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Resource->NumberActive = 0;
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}
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/*
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* @implemented
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*/
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BOOLEAN
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NTAPI
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RtlAcquireResourceExclusive(
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PRTL_RESOURCE Resource,
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BOOLEAN Wait)
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{
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NTSTATUS Status;
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BOOLEAN retVal = FALSE;
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start:
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RtlEnterCriticalSection(&Resource->Lock);
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if (Resource->NumberActive == 0) /* lock is free */
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{
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Resource->NumberActive = -1;
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retVal = TRUE;
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}
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else if (Resource->NumberActive < 0) /* exclusive lock in progress */
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{
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if (Resource->OwningThread == NtCurrentTeb()->ClientId.UniqueThread)
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{
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retVal = TRUE;
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Resource->NumberActive--;
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goto done;
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}
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wait:
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if (Wait)
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{
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Resource->ExclusiveWaiters++;
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RtlLeaveCriticalSection(&Resource->Lock);
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Status = NtWaitForSingleObject(Resource->ExclusiveSemaphore,
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FALSE,
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NULL);
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if (!NT_SUCCESS(Status))
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goto done;
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goto start; /* restart the acquisition to avoid deadlocks */
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}
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}
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else /* one or more shared locks are in progress */
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{
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if (Wait)
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goto wait;
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}
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if (retVal)
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Resource->OwningThread = NtCurrentTeb()->ClientId.UniqueThread;
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done:
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RtlLeaveCriticalSection(&Resource->Lock);
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return retVal;
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}
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/*
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* @implemented
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*/
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BOOLEAN
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NTAPI
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RtlAcquireResourceShared(
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PRTL_RESOURCE Resource,
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BOOLEAN Wait)
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{
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NTSTATUS Status = STATUS_UNSUCCESSFUL;
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BOOLEAN retVal = FALSE;
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start:
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RtlEnterCriticalSection(&Resource->Lock);
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if (Resource->NumberActive < 0)
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{
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if (Resource->OwningThread == NtCurrentTeb()->ClientId.UniqueThread)
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{
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Resource->NumberActive--;
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retVal = TRUE;
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goto done;
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}
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if (Wait)
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{
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Resource->SharedWaiters++;
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RtlLeaveCriticalSection(&Resource->Lock);
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Status = NtWaitForSingleObject(Resource->SharedSemaphore,
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FALSE,
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NULL);
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if (!NT_SUCCESS(Status))
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goto done;
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goto start;
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}
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}
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else
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{
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if (Status != STATUS_WAIT_0) /* otherwise RtlReleaseResource() has already done it */
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Resource->NumberActive++;
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retVal = TRUE;
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}
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done:
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RtlLeaveCriticalSection(&Resource->Lock);
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return retVal;
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}
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlConvertExclusiveToShared(PRTL_RESOURCE Resource)
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{
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RtlEnterCriticalSection(&Resource->Lock);
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if (Resource->NumberActive == -1)
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{
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Resource->OwningThread = NULL;
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if (Resource->SharedWaiters > 0)
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{
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ULONG n;
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/* prevent new writers from joining until
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* all queued readers have done their thing */
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n = Resource->SharedWaiters;
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Resource->NumberActive = Resource->SharedWaiters + 1;
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Resource->SharedWaiters = 0;
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NtReleaseSemaphore(Resource->SharedSemaphore,
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n,
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NULL);
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}
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else
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{
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Resource->NumberActive = 1;
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}
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}
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RtlLeaveCriticalSection(&Resource->Lock);
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}
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlConvertSharedToExclusive(PRTL_RESOURCE Resource)
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{
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NTSTATUS Status;
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RtlEnterCriticalSection(&Resource->Lock);
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if (Resource->NumberActive == 1)
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{
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Resource->OwningThread = NtCurrentTeb()->ClientId.UniqueThread;
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Resource->NumberActive = -1;
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}
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else
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{
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Resource->ExclusiveWaiters++;
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RtlLeaveCriticalSection(&Resource->Lock);
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Status = NtWaitForSingleObject(Resource->ExclusiveSemaphore,
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FALSE,
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NULL);
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if (!NT_SUCCESS(Status))
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return;
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RtlEnterCriticalSection(&Resource->Lock);
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Resource->OwningThread = NtCurrentTeb()->ClientId.UniqueThread;
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Resource->NumberActive = -1;
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}
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RtlLeaveCriticalSection(&Resource->Lock);
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}
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlReleaseResource(PRTL_RESOURCE Resource)
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{
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RtlEnterCriticalSection(&Resource->Lock);
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if (Resource->NumberActive > 0) /* have one or more readers */
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{
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Resource->NumberActive--;
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if (Resource->NumberActive == 0)
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{
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if (Resource->ExclusiveWaiters > 0)
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{
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wake_exclusive:
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Resource->ExclusiveWaiters--;
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NtReleaseSemaphore(Resource->ExclusiveSemaphore,
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1,
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NULL);
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}
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}
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}
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else if (Resource->NumberActive < 0) /* have a writer, possibly recursive */
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{
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Resource->NumberActive++;
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if (Resource->NumberActive == 0)
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{
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Resource->OwningThread = 0;
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if (Resource->ExclusiveWaiters > 0)
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{
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goto wake_exclusive;
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}
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else
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{
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if (Resource->SharedWaiters > 0)
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{
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ULONG n;
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/* prevent new writers from joining until
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* all queued readers have done their thing */
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n = Resource->SharedWaiters;
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Resource->NumberActive = Resource->SharedWaiters;
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Resource->SharedWaiters = 0;
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NtReleaseSemaphore(Resource->SharedSemaphore,
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n,
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NULL);
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}
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}
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}
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}
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RtlLeaveCriticalSection(&Resource->Lock);
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}
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/*
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* @implemented
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*/
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VOID
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NTAPI
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RtlDumpResource(PRTL_RESOURCE Resource)
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{
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DbgPrint("RtlDumpResource(%p):\n\tactive count = %d\n\twaiting readers = %u\n\twaiting writers = %u\n",
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Resource,
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Resource->NumberActive,
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Resource->SharedWaiters,
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Resource->ExclusiveWaiters);
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if (Resource->NumberActive != 0)
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{
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DbgPrint("\towner thread = %p\n",
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Resource->OwningThread);
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}
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}
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/* EOF */
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