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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
/*============================================================
**
** Class: SafeHandle
**
**
** Purpose: The unmanaged implementation of the SafeHandle
** class
**
===========================================================*/
#include "common.h"
#include "vars.hpp"
#include "object.h"
#include "excep.h"
#include "frames.h"
#include "eecontract.h"
#include "typestring.h"
WORD SafeHandle::s_IsInvalidHandleMethodSlot = MethodTable::NO_SLOT;
WORD SafeHandle::s_ReleaseHandleMethodSlot = MethodTable::NO_SLOT;
void SafeHandle::Init()
{
CONTRACTL {
THROWS;
GC_TRIGGERS;
MODE_ANY;
} CONTRACTL_END;
// For reliability purposes, we need to eliminate all possible failure
// points before making a call to a CER method. IsInvalidHandle, and
// ReleaseHandle methods are critical calls that are already prepared (code:
// PrepareCriticalFinalizerObject). As a performance optimization, we are
// calling these methods through a fast macro that assumes the method slot
// has been already cached. Since figuring out the method slot for these 2
// methods involves calling .GetMethod which can fail, we are doing this
// eagerly here, Otherwise we will have to do it at the time of the call,
// and this could be at risk if .GetMethod failed.
MethodDesc* pMD = MscorlibBinder::GetMethod(METHOD__SAFE_HANDLE__GET_IS_INVALID);
s_IsInvalidHandleMethodSlot = pMD->GetSlot();
pMD = MscorlibBinder::GetMethod(METHOD__SAFE_HANDLE__RELEASE_HANDLE);
s_ReleaseHandleMethodSlot = pMD->GetSlot();
}
// These AddRef and Release methods (and supporting functions) also exist with equivalent
// code in SafeHandle.cs. Those implementations are the primary ones used by most code
// and exposed publicly; the implementations here are only for use by the runtime, without
// having to call out to the managed implementations.
void SafeHandle::AddRef()
{
CONTRACTL {
THROWS;
GC_TRIGGERS;
MODE_COOPERATIVE;
INSTANCE_CHECK;
} CONTRACTL_END;
// Cannot use "this" after Release, which toggles the GC mode.
SAFEHANDLEREF sh(this);
_ASSERTE(sh->IsFullyInitialized());
// See comments in SafeHandle.cs
INT32 oldState, newState;
do {
oldState = sh->m_state;
if (oldState & SH_State_Closed)
COMPlusThrow(kObjectDisposedException, IDS_EE_SAFEHANDLECLOSED);
newState = oldState + SH_RefCountOne;
} while (InterlockedCompareExchange((LONG*)&sh->m_state, newState, oldState) != oldState);
}
void SafeHandle::Release(bool fDispose)
{
CONTRACTL {
THROWS;
GC_TRIGGERS;
MODE_COOPERATIVE;
INSTANCE_CHECK;
} CONTRACTL_END;
// Cannot use "this" after RunReleaseMethod, which toggles the GC mode.
SAFEHANDLEREF sh(this);
_ASSERTE(sh->IsFullyInitialized());
// See comments in SafeHandle.cs
bool fPerformRelease = false;
INT32 oldState, newState;
do {
oldState = sh->m_state;
if (fDispose && (oldState & SH_State_Disposed))
return;
if ((oldState & SH_State_RefCount) == 0)
COMPlusThrow(kObjectDisposedException, IDS_EE_SAFEHANDLECLOSED);
fPerformRelease = ((oldState & (SH_State_RefCount | SH_State_Closed)) == SH_RefCountOne) && m_ownsHandle;
if (fPerformRelease)
{
GCPROTECT_BEGIN(sh);
CLR_BOOL fIsInvalid = FALSE;
DECLARE_ARGHOLDER_ARRAY(args, 1);
args[ARGNUM_0] = OBJECTREF_TO_ARGHOLDER(sh);
PREPARE_SIMPLE_VIRTUAL_CALLSITE_USING_SLOT(s_IsInvalidHandleMethodSlot, sh);
CRITICAL_CALLSITE;
CALL_MANAGED_METHOD(fIsInvalid, CLR_BOOL, args);
if (fIsInvalid)
{
fPerformRelease = false;
}
GCPROTECT_END();
}
newState = (oldState - SH_RefCountOne) |
((oldState & SH_State_RefCount) == SH_RefCountOne ? SH_State_Closed : 0) |
(fDispose ? SH_State_Disposed : 0);
} while (InterlockedCompareExchange((LONG*)&sh->m_state, newState, oldState) != oldState);
if (fPerformRelease)
RunReleaseMethod((SafeHandle*) OBJECTREFToObject(sh));
}
void SafeHandle::SetHandle(LPVOID handle)
{
CONTRACTL {
THROWS;
MODE_COOPERATIVE;
INSTANCE_CHECK;
} CONTRACTL_END;
_ASSERTE(IsFullyInitialized());
// The SafeHandle's handle field can only be set it if the SafeHandle isn't
// closed or disposed and its ref count is 1.
if (m_state != (LONG)SH_RefCountOne)
COMPlusThrow(kObjectDisposedException, IDS_EE_SAFEHANDLECANNOTSETHANDLE);
m_handle = handle;
}
void AcquireSafeHandle(SAFEHANDLEREF* s)
{
WRAPPER_NO_CONTRACT;
GCX_COOP();
_ASSERTE(s != NULL && *s != NULL);
(*s)->AddRef();
}
void ReleaseSafeHandle(SAFEHANDLEREF* s)
{
WRAPPER_NO_CONTRACT;
GCX_COOP();
_ASSERTE(s != NULL && *s != NULL);
(*s)->Release(false);
}
// This could theoretically be an instance method, but we'd need to
// somehow GC protect the this pointer or never dereference any
// field within the object. It's a lot simpler if we simply make
// this method static.
void SafeHandle::RunReleaseMethod(SafeHandle* psh)
{
CONTRACTL {
THROWS;
GC_TRIGGERS;
MODE_COOPERATIVE;
} CONTRACTL_END;
SAFEHANDLEREF sh(psh);
_ASSERTE(sh != NULL);
_ASSERTE(sh->m_ownsHandle);
_ASSERTE(sh->IsFullyInitialized());
GCPROTECT_BEGIN(sh);
// Save last error from P/Invoke in case the implementation of ReleaseHandle
// trashes it (important because this ReleaseHandle could occur implicitly
// as part of unmarshaling another P/Invoke).
Thread *pThread = GetThread();
DWORD dwSavedError = pThread->m_dwLastError;
CLR_BOOL fReleaseHandle = FALSE;
DECLARE_ARGHOLDER_ARRAY(args, 1);
args[ARGNUM_0] = OBJECTREF_TO_ARGHOLDER(sh);
PREPARE_SIMPLE_VIRTUAL_CALLSITE_USING_SLOT(s_ReleaseHandleMethodSlot, sh);
CRITICAL_CALLSITE;
CALL_MANAGED_METHOD(fReleaseHandle, CLR_BOOL, args);
pThread->m_dwLastError = dwSavedError;
GCPROTECT_END();
}
FCIMPL1(void, CriticalHandle::FireCustomerDebugProbe, CriticalHandle* refThisUNSAFE)
{
FCALL_CONTRACT;
CRITICALHANDLEREF ch(refThisUNSAFE);
HELPER_METHOD_FRAME_BEGIN_1(ch);
FCUnique(0x53);
HELPER_METHOD_FRAME_END();
}
FCIMPLEND
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