170 lines
7.9 KiB
C#
170 lines
7.9 KiB
C#
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//------------------------------------------------------------------------------
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// <copyright file="Win32Exception.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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/*
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*/
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namespace System.ComponentModel {
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using Microsoft.Win32;
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using System;
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using System.Diagnostics;
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using System.Runtime.InteropServices;
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using System.Runtime.Remoting;
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using System.Runtime.Serialization;
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using System.Security;
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using System.Security.Permissions;
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using System.Text;
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/// <devdoc>
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/// <para>The exception that is thrown for a Win32 error code.</para>
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/// </devdoc>
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// Code already shipped - safe to place link demand on derived class constructor when base doesn't have it - Suppress message.
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[HostProtection(SharedState = true)]
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]
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[Serializable]
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[SuppressUnmanagedCodeSecurity]
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public partial class Win32Exception : ExternalException, ISerializable {
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/// <devdoc>
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/// <para>Represents the Win32 error code associated with this exception. This
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/// field is read-only.</para>
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/// </devdoc>
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private readonly int nativeErrorCode;
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/// <devdoc>
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/// <para>Initializes a new instance of the <see cref='System.ComponentModel.Win32Exception'/> class with the last Win32 error
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/// that occured.</para>
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/// </devdoc>
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[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
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public Win32Exception() : this(Marshal.GetLastWin32Error()) {
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}
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/// <devdoc>
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/// <para>Initializes a new instance of the <see cref='System.ComponentModel.Win32Exception'/> class with the specified error.</para>
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/// </devdoc>
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[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
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public Win32Exception(int error) : this(error, GetErrorMessage(error)) {
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}
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/// <devdoc>
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/// <para>Initializes a new instance of the <see cref='System.ComponentModel.Win32Exception'/> class with the specified error and the
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/// specified detailed description.</para>
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/// </devdoc>
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[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
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public Win32Exception(int error, string message)
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: base(message) {
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nativeErrorCode = error;
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}
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/// <devdoc>
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/// Initializes a new instance of the Exception class with a specified error message.
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/// FxCop CA1032: Multiple constructors are required to correctly implement a custom exception.
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/// </devdoc>
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[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
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public Win32Exception( string message ) : this(Marshal.GetLastWin32Error(), message) {
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}
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/// <devdoc>
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/// Initializes a new instance of the Exception class with a specified error message and a
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/// reference to the inner exception that is the cause of this exception.
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/// FxCop CA1032: Multiple constructors are required to correctly implement a custom exception.
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/// </devdoc>
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[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
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public Win32Exception( string message, Exception innerException ) : base(message, innerException) {
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nativeErrorCode = Marshal.GetLastWin32Error();
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}
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protected Win32Exception(SerializationInfo info, StreamingContext context) : base (info, context) {
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#if FEATURE_MONO_CAS
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IntSecurity.UnmanagedCode.Demand();
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#endif
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nativeErrorCode = info.GetInt32("NativeErrorCode");
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}
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/// <devdoc>
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/// <para>Represents the Win32 error code associated with this exception. This
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/// field is read-only.</para>
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/// </devdoc>
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public int NativeErrorCode {
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get {
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return nativeErrorCode;
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}
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}
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#if !MONO
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private static bool TryGetErrorMessage(int error, StringBuilder sb, out string errorMsg)
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{
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errorMsg = "";
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int result = SafeNativeMethods.FormatMessage(
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SafeNativeMethods.FORMAT_MESSAGE_IGNORE_INSERTS |
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SafeNativeMethods.FORMAT_MESSAGE_FROM_SYSTEM |
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SafeNativeMethods.FORMAT_MESSAGE_ARGUMENT_ARRAY,
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IntPtr.Zero, (uint) error, 0, sb, sb.Capacity + 1,
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null);
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if (result != 0) {
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int i = sb.Length;
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while (i > 0) {
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char ch = sb[i - 1];
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if (ch > 32 && ch != '.') break;
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i--;
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}
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errorMsg = sb.ToString(0, i);
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}
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else if (Marshal.GetLastWin32Error() == SafeNativeMethods.ERROR_INSUFFICIENT_BUFFER) {
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return false;
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}
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else {
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errorMsg ="Unknown error (0x" + Convert.ToString(error, 16) + ")";
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}
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return true;
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}
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// Windows API FormatMessage lets you format a message string given an errocode.
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// Unlike other APIs this API does not support a way to query it for the total message size.
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//
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// So the API can only be used in one of these two ways.
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// a. You pass a buffer of appropriate size and get the resource.
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// b. Windows creates a buffer and passes the address back and the onus of releasing the bugffer lies on the caller.
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//
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// Since the error code is coming from the user, it is not possible to know the size in advance.
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// Unfortunately we can't use option b. since the buffer can only be freed using LocalFree and it is a private API on onecore.
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// Also, using option b is ugly for the manged code and could cause memory leak in situations where freeing is unsuccessful.
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//
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// As a result we use the following approach.
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// We initially call the API with a buffer size of 256 and then gradually increase the size in case of failure until we reach the max allowed size of 65K bytes.
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private const int MaxAllowedBufferSize = 65 * 1024;
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private static string GetErrorMessage(int error) {
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string errorMsg;
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StringBuilder sb = new StringBuilder(256);
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do {
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if (TryGetErrorMessage(error, sb, out errorMsg))
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return errorMsg;
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else {
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// increase the capacity of the StringBuilder by 4 times.
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sb.Capacity *= 4;
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}
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}
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while (sb.Capacity < MaxAllowedBufferSize);
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// If you come here then a size as large as 65K is also not sufficient and so we give the generic errorMsg.
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return "Unknown error (0x" + Convert.ToString(error, 16) + ")";
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}
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#endif
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// Even though all we're exposing is the nativeErrorCode (which is also available via public property)
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// it's not a bad idea to have this in place. Later, if more fields are added to this exception,
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// we won't need to worry about accidentaly exposing them through this interface.
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[SecurityPermissionAttribute(SecurityAction.Demand,SerializationFormatter=true)]
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public override void GetObjectData(SerializationInfo info, StreamingContext context) {
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if (info==null) {
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throw new ArgumentNullException("info");
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}
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info.AddValue("NativeErrorCode", nativeErrorCode);
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base.GetObjectData(info, context);
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}
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}
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}
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