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//------------------------------------------------------------------------------
// <copyright file="SharedUtils.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Diagnostics {
using System.Security.Permissions;
using System.Security;
using System.Threading;
using System.Text;
using Microsoft.Win32;
using System.Globalization;
using System.ComponentModel;
using System.Security.Principal;
using System.Security.AccessControl;
using System.Runtime.Versioning;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
using System.Diagnostics.CodeAnalysis;
internal static class SharedUtils {
internal const int UnknownEnvironment = 0;
internal const int W2kEnvironment = 1;
internal const int NtEnvironment = 2;
internal const int NonNtEnvironment = 3;
private static volatile int environment = UnknownEnvironment;
private static Object s_InternalSyncObject;
private static Object InternalSyncObject {
get {
if (s_InternalSyncObject == null) {
Object o = new Object();
Interlocked.CompareExchange(ref s_InternalSyncObject, o, null);
}
return s_InternalSyncObject;
}
}
internal static Win32Exception CreateSafeWin32Exception() {
return CreateSafeWin32Exception(0);
}
internal static Win32Exception CreateSafeWin32Exception(int error) {
Win32Exception newException = null;
// Need to assert SecurtiyPermission, otherwise Win32Exception
// will not be able to get the error message. At this point the right
// permissions have already been demanded.
SecurityPermission securityPermission = new SecurityPermission(PermissionState.Unrestricted);
securityPermission.Assert();
try {
if (error == 0)
newException = new Win32Exception();
else
newException = new Win32Exception(error);
}
finally {
SecurityPermission.RevertAssert();
}
return newException;
}
internal static int CurrentEnvironment {
get {
if (environment == UnknownEnvironment) {
lock (InternalSyncObject) {
if (environment == UnknownEnvironment) {
// Need to assert Environment permissions here
// the environment check is not exposed as a public method
if (Environment.OSVersion.Platform == PlatformID.Win32NT) {
if (Environment.OSVersion.Version.Major >= 5)
environment = W2kEnvironment;
else
environment = NtEnvironment;
}
else
environment = NonNtEnvironment;
}
}
}
return environment;
}
}
internal static void CheckEnvironment() {
if (CurrentEnvironment == NonNtEnvironment)
throw new PlatformNotSupportedException(SR.GetString(SR.WinNTRequired));
}
internal static void CheckNtEnvironment() {
if (CurrentEnvironment == NtEnvironment)
throw new PlatformNotSupportedException(SR.GetString(SR.Win2000Required));
}
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
internal static void EnterMutex(string name, ref Mutex mutex) {
string mutexName = null;
if (CurrentEnvironment == W2kEnvironment)
mutexName = "Global\\" + name;
else
mutexName = name;
EnterMutexWithoutGlobal(mutexName, ref mutex);
}
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
[SecurityPermission(SecurityAction.Assert, ControlPrincipal = true)]
[SuppressMessage("Microsoft.Security", "CA2106:SecureAsserts", Justification = "Microsoft: We pass fixed data into sec.AddAccessRule")]
internal static void EnterMutexWithoutGlobal(string mutexName, ref Mutex mutex) {
bool createdNew;
MutexSecurity sec = new MutexSecurity();
SecurityIdentifier everyoneSid = new SecurityIdentifier(WellKnownSidType.AuthenticatedUserSid, null);
sec.AddAccessRule(new MutexAccessRule(everyoneSid, MutexRights.Synchronize | MutexRights.Modify, AccessControlType.Allow));
Mutex tmpMutex = new Mutex(false, mutexName, out createdNew, sec);
SafeWaitForMutex(tmpMutex, ref mutex);
}
// We need to atomically attempt to acquire the mutex and record whether we took it (because we require thread affinity
// while the mutex is held and the two states must be kept in lock step). We can get atomicity with a CER, but we don't want
// to hold a CER over a call to WaitOne (this could cause deadlocks). The ---- is to provide a new API out of
// mscorlib that performs the wait and lets us know if it succeeded. But at this late stage we don't want to expose a new
// API out of mscorlib, so we'll build our own solution.
// We'll P/Invoke out to the WaitForSingleObject inside a CER, but use a timeout to ensure we can't block a thread abort for
// an unlimited time (we do this in an infinite loop so the semantic of acquiring the mutex is unchanged, the timeout is
// just to allow us to poll for abort). A limitation of CERs in Whidbey (and part of the problem that put us in this
// position in the first place) is that a CER root in a method will cause the entire method to delay thread aborts. So we
// need to carefully partition the real CER part of out logic in a sub-method (and ensure the jit doesn't inline on us).
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
private static bool SafeWaitForMutex(Mutex mutexIn, ref Mutex mutexOut)
{
Debug.Assert(mutexOut == null, "You must pass in a null ref Mutex");
// Wait as long as necessary for the mutex.
while (true) {
// Attempt to acquire the mutex but timeout quickly if we can't.
if (!SafeWaitForMutexOnce(mutexIn, ref mutexOut))
return false;
if (mutexOut != null)
return true;
// We come out here to the outer method every so often so we're not in a CER and a thread abort can interrupt us.
// But the abort logic itself is poll based (in the this case) so we really need to check for a pending abort
// explicitly else the two timing windows will virtually never line up and we'll still end up stalling the abort
// attempt. Thread.Sleep checks for pending abort for us.
Thread.Sleep(0);
}
}
// The portion of SafeWaitForMutex that runs under a CER and thus must not block for a arbitrary period of time.
// This method must not be inlined (to stop the CER accidently spilling into the calling method).
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
[MethodImplAttribute(MethodImplOptions.NoInlining)]
private static bool SafeWaitForMutexOnce(Mutex mutexIn, ref Mutex mutexOut)
{
bool ret;
RuntimeHelpers.PrepareConstrainedRegions();
try {} finally {
// Wait for the mutex for half a second (long enough to gain the mutex in most scenarios and short enough to avoid
// impacting a thread abort for too long).
// Holding a mutex requires us to keep thread affinity and announce ourselves as a critical region.
Thread.BeginCriticalRegion();
Thread.BeginThreadAffinity();
int result = WaitForSingleObjectDontCallThis(mutexIn.SafeWaitHandle, 500);
switch (result) {
case NativeMethods.WAIT_OBJECT_0:
case NativeMethods.WAIT_ABANDONED:
// Mutex was obtained, atomically record that fact.
mutexOut = mutexIn;
ret = true;
break;
case NativeMethods.WAIT_TIMEOUT:
// Couldn't get mutex yet, simply return and we'll try again later.
ret = true;
break;
default:
// Some sort of failure return immediately all the way to the caller of SafeWaitForMutex.
ret = false;
break;
}
// If we're not leaving with the Mutex we don't require thread affinity and we're not a critical region any more.
if (mutexOut == null) {
Thread.EndThreadAffinity();
Thread.EndCriticalRegion();
}
}
return ret;
}
// P/Invoke for the methods above. Don't call this from anywhere else.
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
[System.Security.SuppressUnmanagedCodeSecurity]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[DllImport(ExternDll.Kernel32, ExactSpelling=true, SetLastError=true, EntryPoint="WaitForSingleObject")]
private static extern int WaitForSingleObjectDontCallThis(SafeWaitHandle handle, int timeout);
[ResourceExposure(ResourceScope.Machine)] // This is scoped to a Fx build dir.
[ResourceConsumption(ResourceScope.Machine)]
// What if an app is locked back? Why would we use this?
internal static string GetLatestBuildDllDirectory(string machineName) {
string dllDir = "";
RegistryKey baseKey = null;
RegistryKey complusReg = null;
//This property is retrieved only when creationg a new category,
// the calling code already demanded PerformanceCounterPermission.
// Therefore the assert below is safe.
//This property is retrieved only when creationg a new log,
// the calling code already demanded EventLogPermission.
// Therefore the assert below is safe.
RegistryPermission registryPermission = new RegistryPermission(PermissionState.Unrestricted);
registryPermission.Assert();
try {
if (machineName.Equals(".")) {
return GetLocalBuildDirectory();
}
else {
baseKey = RegistryKey.OpenRemoteBaseKey(RegistryHive.LocalMachine, machineName);
}
if (baseKey == null)
throw new InvalidOperationException(SR.GetString(SR.RegKeyMissingShort, "HKEY_LOCAL_MACHINE", machineName));
complusReg = baseKey.OpenSubKey("SOFTWARE\\Microsoft\\.NETFramework");
if (complusReg != null) {
string installRoot = (string)complusReg.GetValue("InstallRoot");
if (installRoot != null && installRoot != String.Empty) {
// the "policy" subkey contains a v{major}.{minor} subkey for each version installed. There are also
// some extra subkeys like "standards" and "upgrades" we want to ignore.
// first we figure out what version we are...
string versionPrefix = "v" + Environment.Version.Major + "." + Environment.Version.Minor;
RegistryKey policyKey = complusReg.OpenSubKey("policy");
// This is the full version string of the install on the remote machine we want to use (for example "v2.0.50727")
string version = null;
if (policyKey != null) {
try {
// First check to see if there is a version of the runtime with the same minor and major number:
RegistryKey bestKey = policyKey.OpenSubKey(versionPrefix);
if (bestKey != null) {
try {
version = versionPrefix + "." + GetLargestBuildNumberFromKey(bestKey);
} finally {
bestKey.Close();
}
} else {
// There isn't an exact match for our version, so we will look for the largest version
// installed.
string[] majorVersions = policyKey.GetSubKeyNames();
int[] largestVersion = new int[] { -1, -1, -1 };
for (int i = 0; i < majorVersions.Length; i++) {
string majorVersion = majorVersions[i];
// If this looks like a key of the form v{something}.{something}, we should see if it's a usable build.
if (majorVersion.Length > 1 && majorVersion[0] == 'v' && majorVersion.Contains(".")) {
int[] currentVersion = new int[] { -1, -1, -1 };
string[] splitVersion = majorVersion.Substring(1).Split('.');
if(splitVersion.Length != 2) {
continue;
}
if (!Int32.TryParse(splitVersion[0], out currentVersion[0]) || !Int32.TryParse(splitVersion[1], out currentVersion[1])) {
continue;
}
RegistryKey k = policyKey.OpenSubKey(majorVersion);
if (k == null) {
// We may be able to use another subkey
continue;
}
try {
currentVersion[2] = GetLargestBuildNumberFromKey(k);
if (currentVersion[0] > largestVersion[0]
|| ((currentVersion[0] == largestVersion[0]) && (currentVersion[1] > largestVersion[1]))) {
largestVersion = currentVersion;
}
} finally {
k.Close();
}
}
}
version = "v" + largestVersion[0] + "." + largestVersion[1] + "." + largestVersion[2];
}
} finally {
policyKey.Close();
}
if (version != null && version != String.Empty) {
StringBuilder installBuilder = new StringBuilder();
installBuilder.Append(installRoot);
if (!installRoot.EndsWith("\\", StringComparison.Ordinal))
installBuilder.Append("\\");
installBuilder.Append(version);
dllDir = installBuilder.ToString();
}
}
}
}
}
catch {
// ignore
}
finally {
if (complusReg != null)
complusReg.Close();
if (baseKey != null)
baseKey.Close();
RegistryPermission.RevertAssert();
}
return dllDir;
}
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
private static int GetLargestBuildNumberFromKey(RegistryKey rootKey) {
int largestBuild = -1;
string[] minorVersions = rootKey.GetValueNames();
for (int i = 0; i < minorVersions.Length; i++) {
int o;
if (Int32.TryParse(minorVersions[i], out o)) {
largestBuild = (largestBuild > o) ? largestBuild : o;
}
}
return largestBuild;
}
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
private static string GetLocalBuildDirectory() {
return RuntimeEnvironment.GetRuntimeDirectory();
}
}
}
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