Code:
/ Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / whidbey / NetFxQFE / ndp / clr / src / BCL / System / Threading / Mutex.cs / 1 / Mutex.cs
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*==============================================================================
**
** Class: Mutex
**
**
** Purpose: synchronization primitive that can also be used for interprocess synchronization
**
**
=============================================================================*/
namespace System.Threading
{
using System;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Security.Permissions;
using System.IO;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.Versioning;
using System.Security.Principal;
using System.Security;
#if !FEATURE_PAL
using System.Security.AccessControl;
#endif
[HostProtection(Synchronization=true, ExternalThreading=true)]
[ComVisible(true)]
public sealed class Mutex : WaitHandle
{
static bool dummyBool;
private const int WAIT_OBJECT_0 = 0;
private const int WAIT_ABANDONED_0 = 0x80;
private const uint WAIT_FAILED = 0xFFFFFFFF;
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex(bool initiallyOwned, String name, out bool createdNew)
#if !FEATURE_PAL
: this(initiallyOwned, name, out createdNew, null)
{
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public unsafe Mutex(bool initiallyOwned, String name, out bool createdNew, MutexSecurity mutexSecurity)
#endif
{
if(null != name && System.IO.Path.MAX_PATH < name.Length)
{
throw new ArgumentException(Environment.GetResourceString("Argument_WaitHandleNameTooLong",name));
}
Win32Native.SECURITY_ATTRIBUTES secAttrs = null;
#if !FEATURE_PAL
// For ACL's, get the security descriptor from the MutexSecurity.
if (mutexSecurity != null) {
secAttrs = new Win32Native.SECURITY_ATTRIBUTES();
secAttrs.nLength = (int)Marshal.SizeOf(secAttrs);
byte[] sd = mutexSecurity.GetSecurityDescriptorBinaryForm();
byte* pSecDescriptor = stackalloc byte[sd.Length];
Buffer.memcpy(sd, 0, pSecDescriptor, 0, sd.Length);
secAttrs.pSecurityDescriptor = pSecDescriptor;
}
#endif
SafeWaitHandle mutexHandle = null;
bool newMutex = false;
RuntimeHelpers.CleanupCode cleanupCode = new RuntimeHelpers.CleanupCode(MutexCleanupCode);
MutexCleanupInfo cleanupInfo = new MutexCleanupInfo(mutexHandle, false);
RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(
delegate(object userData) { // try block
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
if (initiallyOwned) {
cleanupInfo.inCriticalRegion = true;
Thread.BeginThreadAffinity();
Thread.BeginCriticalRegion();
}
}
int errorCode = 0;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
errorCode = CreateMutexHandle(initiallyOwned, name, secAttrs, out mutexHandle);
}
if (mutexHandle.IsInvalid) {
mutexHandle.SetHandleAsInvalid();
if(null != name && 0 != name.Length && Win32Native.ERROR_INVALID_HANDLE == errorCode)
throw new WaitHandleCannotBeOpenedException(Environment.GetResourceString("Threading.WaitHandleCannotBeOpenedException_InvalidHandle", name));
__Error.WinIOError(errorCode, name);
}
newMutex = errorCode != Win32Native.ERROR_ALREADY_EXISTS;
SetHandleInternal(mutexHandle);
hasThreadAffinity = true;
},
cleanupCode,
cleanupInfo);
createdNew = newMutex;
}
[PrePrepareMethod]
private void MutexCleanupCode(Object userData, bool exceptionThrown)
{
MutexCleanupInfo cleanupInfo = (MutexCleanupInfo) userData;
// If hasThreadAffinity isn’t true, we’ve thrown an exception in the above try, and we must free the mutex
// on this OS thread before ending our thread affninity.
if(!hasThreadAffinity) {
if (cleanupInfo.mutexHandle != null && !cleanupInfo.mutexHandle.IsInvalid) {
if( cleanupInfo.inCriticalRegion) {
Win32Native.ReleaseMutex(cleanupInfo.mutexHandle);
}
cleanupInfo.mutexHandle.Dispose();
}
if( cleanupInfo.inCriticalRegion) {
Thread.EndCriticalRegion();
Thread.EndThreadAffinity();
}
}
}
internal class MutexCleanupInfo
{
internal SafeWaitHandle mutexHandle;
internal bool inCriticalRegion;
internal MutexCleanupInfo(SafeWaitHandle mutexHandle, bool inCriticalRegion)
{
this.mutexHandle = mutexHandle;
this.inCriticalRegion = inCriticalRegion;
}
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public Mutex(bool initiallyOwned, String name) : this(initiallyOwned, name, out dummyBool) {
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex(bool initiallyOwned) : this(initiallyOwned, null, out dummyBool)
{
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex() : this(false, null, out dummyBool)
{
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
private Mutex(SafeWaitHandle handle)
{
SetHandleInternal(handle);
hasThreadAffinity = true;
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand,Flags=SecurityPermissionFlag.UnmanagedCode)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public static Mutex OpenExisting(string name)
{
#if !FEATURE_PAL
return OpenExisting(name, MutexRights.Modify | MutexRights.Synchronize);
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand,Flags=SecurityPermissionFlag.UnmanagedCode)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public static Mutex OpenExisting(string name, MutexRights rights)
{
#endif // !FEATURE_PAL
if (name == null)
{
throw new ArgumentNullException("name", Environment.GetResourceString("ArgumentNull_WithParamName"));
}
if(name.Length == 0)
{
throw new ArgumentException(Environment.GetResourceString("Argument_EmptyName"), "name");
}
if(System.IO.Path.MAX_PATH < name.Length)
{
throw new ArgumentException(Environment.GetResourceString("Argument_WaitHandleNameTooLong",name));
}
// To allow users to view & edit the ACL's, call OpenMutex
// with parameters to allow us to view & edit the ACL. This will
// fail if we don't have permission to view or edit the ACL's.
// If that happens, ask for less permissions.
#if FEATURE_PAL
SafeWaitHandle myHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
#else
SafeWaitHandle myHandle = Win32Native.OpenMutex((int) rights, false, name);
#endif
int errorCode = 0;
if (myHandle.IsInvalid)
{
errorCode = Marshal.GetLastWin32Error();
if(Win32Native.ERROR_FILE_NOT_FOUND == errorCode || Win32Native.ERROR_INVALID_NAME == errorCode)
{
throw new WaitHandleCannotBeOpenedException();
}
if(null != name && 0 != name.Length && Win32Native.ERROR_INVALID_HANDLE == errorCode)
{
throw new WaitHandleCannotBeOpenedException(Environment.GetResourceString("Threading.WaitHandleCannotBeOpenedException_InvalidHandle", name));
}
// this is for passed through Win32Native Errors
__Error.WinIOError(errorCode,name);
}
return new Mutex(myHandle);
}
// Note: To call ReleaseMutex, you must have an ACL granting you
// MUTEX_MODIFY_STATE rights (0x0001). The other interesting value
// in a Mutex's ACL is MUTEX_ALL_ACCESS (0x1F0001).
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
public void ReleaseMutex()
{
if (Win32Native.ReleaseMutex(safeWaitHandle))
{
Thread.EndCriticalRegion();
Thread.EndThreadAffinity();
}
else
{
throw new ApplicationException(Environment.GetResourceString("Arg_SynchronizationLockException"));
}
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
static int CreateMutexHandle(bool initiallyOwned, String name, Win32Native.SECURITY_ATTRIBUTES securityAttribute, out SafeWaitHandle mutexHandle) {
int errorCode;
bool fAffinity = false;
bool fHitRace = false;
bool fRetry = false;
while(true) {
fHitRace = false;
fRetry = false;
mutexHandle = Win32Native.CreateMutex(securityAttribute, initiallyOwned, name);
errorCode = Marshal.GetLastWin32Error();
if( !mutexHandle.IsInvalid) {
break;
}
if( errorCode == Win32Native.ERROR_ACCESS_DENIED) {
// If a mutex with the name already exists, OS will try to open it with FullAccess.
// It might fail if we don't have enough access. In that case, we try to open the mutex will modify and synchronize access.
//
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try
{
}
finally
{
Thread.BeginThreadAffinity();
fAffinity = true;
}
mutexHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
if(!mutexHandle.IsInvalid)
{
errorCode = Win32Native.ERROR_ALREADY_EXISTS;
#if !FEATURE_PAL
if (Environment.IsW2k3)
{
//Enables workaround for known OS bug at
//http://support.microsoft.com/default.aspx?scid=kb;en-us;889318
//Workaround suggested by NeillC (The previous workaround of a acquiring a global mutex was not secure):
//1)Open the mutex twice.
//2)Call WaitForMultipleObjects with bWaitAll=TRUE and a zero timeout
//3)If this call returns with ERROR_INVALID_PARAMETER then the two objects are the same and you can close one and use the other
//4)If it returns timeout then you hit the ----
//5)If it returns success then you hit the ---- but you have to release before close.
SafeWaitHandle tempMutexHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
if(!tempMutexHandle.IsInvalid)
{
RuntimeHelpers.PrepareConstrainedRegions();
try
{
uint originalRetCode = 0;
IntPtr mutexPtr = mutexHandle.DangerousGetHandle();
IntPtr tempMutexPtr = tempMutexHandle.DangerousGetHandle();
IntPtr[] waitHandles = new IntPtr[] {mutexPtr, tempMutexPtr};
//We directly Pinvoke to WaitForMultipleObjects for two reasons:
//1. The VM method WaitForMultiple does not support doing WaitForMultipleObjects
// for COM STA threads.
//2. We call the method in such a way that it's guaranteed to not block, so
// it should not lead to any COM pumping/rentrancy issues.
originalRetCode = Win32Native.WaitForMultipleObjects(2,waitHandles,true, 0);
GC.KeepAlive(waitHandles);
if(originalRetCode == WAIT_FAILED)
{
uint retCode = (uint) Marshal.GetLastWin32Error();
BCLDebug.Assert(retCode == Win32Native.ERROR_INVALID_PARAMETER, "Expected Invalid Parameter return code");
//Some weird transient error?
if(retCode != Win32Native.ERROR_INVALID_PARAMETER)
{
mutexHandle.Dispose();
fRetry = true;
}
}
else
{
fHitRace = true;
if((originalRetCode >= WAIT_OBJECT_0) && (originalRetCode < (WAIT_OBJECT_0+2)))
{
Win32Native.ReleaseMutex(mutexHandle);
Win32Native.ReleaseMutex(tempMutexHandle);
}
else if((originalRetCode >= WAIT_ABANDONED_0) && (originalRetCode < (WAIT_ABANDONED_0+2)))
{
Win32Native.ReleaseMutex(mutexHandle);
Win32Native.ReleaseMutex(tempMutexHandle);
}
mutexHandle.Dispose();
}
}
finally
{
tempMutexHandle.Dispose();
}
}
else
{
mutexHandle.Dispose();
fRetry = true;
}
}
#endif //!FEATURE_PAL
}
else
{
errorCode = Marshal.GetLastWin32Error();
}
}
finally
{
if (fAffinity)
Thread.EndThreadAffinity();
}
if(fHitRace || fRetry)
continue;
// There could be a ---- here, the other owner of the mutex can free the mutex,
// We need to retry creation in that case.
if( errorCode != Win32Native.ERROR_FILE_NOT_FOUND) {
if( errorCode == Win32Native.ERROR_SUCCESS) {
errorCode = Win32Native.ERROR_ALREADY_EXISTS;
}
break;
}
}
else {
break;
}
}
return errorCode;
}
#if !FEATURE_PAL
public MutexSecurity GetAccessControl()
{
return new MutexSecurity(safeWaitHandle, AccessControlSections.Access | AccessControlSections.Owner | AccessControlSections.Group);
}
public void SetAccessControl(MutexSecurity mutexSecurity)
{
if (mutexSecurity == null)
throw new ArgumentNullException("mutexSecurity");
mutexSecurity.Persist(safeWaitHandle);
}
#endif
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*==============================================================================
**
** Class: Mutex
**
**
** Purpose: synchronization primitive that can also be used for interprocess synchronization
**
**
=============================================================================*/
namespace System.Threading
{
using System;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Security.Permissions;
using System.IO;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.Versioning;
using System.Security.Principal;
using System.Security;
#if !FEATURE_PAL
using System.Security.AccessControl;
#endif
[HostProtection(Synchronization=true, ExternalThreading=true)]
[ComVisible(true)]
public sealed class Mutex : WaitHandle
{
static bool dummyBool;
private const int WAIT_OBJECT_0 = 0;
private const int WAIT_ABANDONED_0 = 0x80;
private const uint WAIT_FAILED = 0xFFFFFFFF;
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex(bool initiallyOwned, String name, out bool createdNew)
#if !FEATURE_PAL
: this(initiallyOwned, name, out createdNew, null)
{
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public unsafe Mutex(bool initiallyOwned, String name, out bool createdNew, MutexSecurity mutexSecurity)
#endif
{
if(null != name && System.IO.Path.MAX_PATH < name.Length)
{
throw new ArgumentException(Environment.GetResourceString("Argument_WaitHandleNameTooLong",name));
}
Win32Native.SECURITY_ATTRIBUTES secAttrs = null;
#if !FEATURE_PAL
// For ACL's, get the security descriptor from the MutexSecurity.
if (mutexSecurity != null) {
secAttrs = new Win32Native.SECURITY_ATTRIBUTES();
secAttrs.nLength = (int)Marshal.SizeOf(secAttrs);
byte[] sd = mutexSecurity.GetSecurityDescriptorBinaryForm();
byte* pSecDescriptor = stackalloc byte[sd.Length];
Buffer.memcpy(sd, 0, pSecDescriptor, 0, sd.Length);
secAttrs.pSecurityDescriptor = pSecDescriptor;
}
#endif
SafeWaitHandle mutexHandle = null;
bool newMutex = false;
RuntimeHelpers.CleanupCode cleanupCode = new RuntimeHelpers.CleanupCode(MutexCleanupCode);
MutexCleanupInfo cleanupInfo = new MutexCleanupInfo(mutexHandle, false);
RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(
delegate(object userData) { // try block
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
if (initiallyOwned) {
cleanupInfo.inCriticalRegion = true;
Thread.BeginThreadAffinity();
Thread.BeginCriticalRegion();
}
}
int errorCode = 0;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
errorCode = CreateMutexHandle(initiallyOwned, name, secAttrs, out mutexHandle);
}
if (mutexHandle.IsInvalid) {
mutexHandle.SetHandleAsInvalid();
if(null != name && 0 != name.Length && Win32Native.ERROR_INVALID_HANDLE == errorCode)
throw new WaitHandleCannotBeOpenedException(Environment.GetResourceString("Threading.WaitHandleCannotBeOpenedException_InvalidHandle", name));
__Error.WinIOError(errorCode, name);
}
newMutex = errorCode != Win32Native.ERROR_ALREADY_EXISTS;
SetHandleInternal(mutexHandle);
hasThreadAffinity = true;
},
cleanupCode,
cleanupInfo);
createdNew = newMutex;
}
[PrePrepareMethod]
private void MutexCleanupCode(Object userData, bool exceptionThrown)
{
MutexCleanupInfo cleanupInfo = (MutexCleanupInfo) userData;
// If hasThreadAffinity isn’t true, we’ve thrown an exception in the above try, and we must free the mutex
// on this OS thread before ending our thread affninity.
if(!hasThreadAffinity) {
if (cleanupInfo.mutexHandle != null && !cleanupInfo.mutexHandle.IsInvalid) {
if( cleanupInfo.inCriticalRegion) {
Win32Native.ReleaseMutex(cleanupInfo.mutexHandle);
}
cleanupInfo.mutexHandle.Dispose();
}
if( cleanupInfo.inCriticalRegion) {
Thread.EndCriticalRegion();
Thread.EndThreadAffinity();
}
}
}
internal class MutexCleanupInfo
{
internal SafeWaitHandle mutexHandle;
internal bool inCriticalRegion;
internal MutexCleanupInfo(SafeWaitHandle mutexHandle, bool inCriticalRegion)
{
this.mutexHandle = mutexHandle;
this.inCriticalRegion = inCriticalRegion;
}
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public Mutex(bool initiallyOwned, String name) : this(initiallyOwned, name, out dummyBool) {
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex(bool initiallyOwned) : this(initiallyOwned, null, out dummyBool)
{
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public Mutex() : this(false, null, out dummyBool)
{
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
private Mutex(SafeWaitHandle handle)
{
SetHandleInternal(handle);
hasThreadAffinity = true;
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand,Flags=SecurityPermissionFlag.UnmanagedCode)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public static Mutex OpenExisting(string name)
{
#if !FEATURE_PAL
return OpenExisting(name, MutexRights.Modify | MutexRights.Synchronize);
}
[SecurityPermissionAttribute(SecurityAction.LinkDemand,Flags=SecurityPermissionFlag.UnmanagedCode)]
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public static Mutex OpenExisting(string name, MutexRights rights)
{
#endif // !FEATURE_PAL
if (name == null)
{
throw new ArgumentNullException("name", Environment.GetResourceString("ArgumentNull_WithParamName"));
}
if(name.Length == 0)
{
throw new ArgumentException(Environment.GetResourceString("Argument_EmptyName"), "name");
}
if(System.IO.Path.MAX_PATH < name.Length)
{
throw new ArgumentException(Environment.GetResourceString("Argument_WaitHandleNameTooLong",name));
}
// To allow users to view & edit the ACL's, call OpenMutex
// with parameters to allow us to view & edit the ACL. This will
// fail if we don't have permission to view or edit the ACL's.
// If that happens, ask for less permissions.
#if FEATURE_PAL
SafeWaitHandle myHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
#else
SafeWaitHandle myHandle = Win32Native.OpenMutex((int) rights, false, name);
#endif
int errorCode = 0;
if (myHandle.IsInvalid)
{
errorCode = Marshal.GetLastWin32Error();
if(Win32Native.ERROR_FILE_NOT_FOUND == errorCode || Win32Native.ERROR_INVALID_NAME == errorCode)
{
throw new WaitHandleCannotBeOpenedException();
}
if(null != name && 0 != name.Length && Win32Native.ERROR_INVALID_HANDLE == errorCode)
{
throw new WaitHandleCannotBeOpenedException(Environment.GetResourceString("Threading.WaitHandleCannotBeOpenedException_InvalidHandle", name));
}
// this is for passed through Win32Native Errors
__Error.WinIOError(errorCode,name);
}
return new Mutex(myHandle);
}
// Note: To call ReleaseMutex, you must have an ACL granting you
// MUTEX_MODIFY_STATE rights (0x0001). The other interesting value
// in a Mutex's ACL is MUTEX_ALL_ACCESS (0x1F0001).
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
public void ReleaseMutex()
{
if (Win32Native.ReleaseMutex(safeWaitHandle))
{
Thread.EndCriticalRegion();
Thread.EndThreadAffinity();
}
else
{
throw new ApplicationException(Environment.GetResourceString("Arg_SynchronizationLockException"));
}
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
static int CreateMutexHandle(bool initiallyOwned, String name, Win32Native.SECURITY_ATTRIBUTES securityAttribute, out SafeWaitHandle mutexHandle) {
int errorCode;
bool fAffinity = false;
bool fHitRace = false;
bool fRetry = false;
while(true) {
fHitRace = false;
fRetry = false;
mutexHandle = Win32Native.CreateMutex(securityAttribute, initiallyOwned, name);
errorCode = Marshal.GetLastWin32Error();
if( !mutexHandle.IsInvalid) {
break;
}
if( errorCode == Win32Native.ERROR_ACCESS_DENIED) {
// If a mutex with the name already exists, OS will try to open it with FullAccess.
// It might fail if we don't have enough access. In that case, we try to open the mutex will modify and synchronize access.
//
RuntimeHelpers.PrepareConstrainedRegions();
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try
{
}
finally
{
Thread.BeginThreadAffinity();
fAffinity = true;
}
mutexHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
if(!mutexHandle.IsInvalid)
{
errorCode = Win32Native.ERROR_ALREADY_EXISTS;
#if !FEATURE_PAL
if (Environment.IsW2k3)
{
//Enables workaround for known OS bug at
//http://support.microsoft.com/default.aspx?scid=kb;en-us;889318
//Workaround suggested by NeillC (The previous workaround of a acquiring a global mutex was not secure):
//1)Open the mutex twice.
//2)Call WaitForMultipleObjects with bWaitAll=TRUE and a zero timeout
//3)If this call returns with ERROR_INVALID_PARAMETER then the two objects are the same and you can close one and use the other
//4)If it returns timeout then you hit the ----
//5)If it returns success then you hit the ---- but you have to release before close.
SafeWaitHandle tempMutexHandle = Win32Native.OpenMutex(Win32Native.MUTEX_MODIFY_STATE | Win32Native.SYNCHRONIZE, false, name);
if(!tempMutexHandle.IsInvalid)
{
RuntimeHelpers.PrepareConstrainedRegions();
try
{
uint originalRetCode = 0;
IntPtr mutexPtr = mutexHandle.DangerousGetHandle();
IntPtr tempMutexPtr = tempMutexHandle.DangerousGetHandle();
IntPtr[] waitHandles = new IntPtr[] {mutexPtr, tempMutexPtr};
//We directly Pinvoke to WaitForMultipleObjects for two reasons:
//1. The VM method WaitForMultiple does not support doing WaitForMultipleObjects
// for COM STA threads.
//2. We call the method in such a way that it's guaranteed to not block, so
// it should not lead to any COM pumping/rentrancy issues.
originalRetCode = Win32Native.WaitForMultipleObjects(2,waitHandles,true, 0);
GC.KeepAlive(waitHandles);
if(originalRetCode == WAIT_FAILED)
{
uint retCode = (uint) Marshal.GetLastWin32Error();
BCLDebug.Assert(retCode == Win32Native.ERROR_INVALID_PARAMETER, "Expected Invalid Parameter return code");
//Some weird transient error?
if(retCode != Win32Native.ERROR_INVALID_PARAMETER)
{
mutexHandle.Dispose();
fRetry = true;
}
}
else
{
fHitRace = true;
if((originalRetCode >= WAIT_OBJECT_0) && (originalRetCode < (WAIT_OBJECT_0+2)))
{
Win32Native.ReleaseMutex(mutexHandle);
Win32Native.ReleaseMutex(tempMutexHandle);
}
else if((originalRetCode >= WAIT_ABANDONED_0) && (originalRetCode < (WAIT_ABANDONED_0+2)))
{
Win32Native.ReleaseMutex(mutexHandle);
Win32Native.ReleaseMutex(tempMutexHandle);
}
mutexHandle.Dispose();
}
}
finally
{
tempMutexHandle.Dispose();
}
}
else
{
mutexHandle.Dispose();
fRetry = true;
}
}
#endif //!FEATURE_PAL
}
else
{
errorCode = Marshal.GetLastWin32Error();
}
}
finally
{
if (fAffinity)
Thread.EndThreadAffinity();
}
if(fHitRace || fRetry)
continue;
// There could be a ---- here, the other owner of the mutex can free the mutex,
// We need to retry creation in that case.
if( errorCode != Win32Native.ERROR_FILE_NOT_FOUND) {
if( errorCode == Win32Native.ERROR_SUCCESS) {
errorCode = Win32Native.ERROR_ALREADY_EXISTS;
}
break;
}
}
else {
break;
}
}
return errorCode;
}
#if !FEATURE_PAL
public MutexSecurity GetAccessControl()
{
return new MutexSecurity(safeWaitHandle, AccessControlSections.Access | AccessControlSections.Owner | AccessControlSections.Group);
}
public void SetAccessControl(MutexSecurity mutexSecurity)
{
if (mutexSecurity == null)
throw new ArgumentNullException("mutexSecurity");
mutexSecurity.Persist(safeWaitHandle);
}
#endif
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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- CapacityStreamGeometryContext.cs
- DynamicExpression.cs
- Visual3D.cs
- PropertyInformation.cs
- ConfigurationLocationCollection.cs
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- EntitySqlQueryState.cs
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