mirror of https://github.com/dahall/Vanara.git
51 lines
2.5 KiB
C#
51 lines
2.5 KiB
C#
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using System;
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using Microsoft.Win32.SafeHandles;
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using System.Runtime.InteropServices;
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namespace Vanara.InteropServices
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{
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/// <summary>A <see cref="SafeHandle"/> that takes a delegate in the constructor that closes the supplied handle.</summary>
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/// <seealso cref="SafeHandle"/>
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public class GenericSafeHandle : SafeHandleZeroOrMinusOneIsInvalid
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{
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/// <summary>Initializes a new instance of the <see cref="GenericSafeHandle"/> class.</summary>
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protected GenericSafeHandle() : base(true) { }
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/// <summary>Initializes a new instance of the <see cref="GenericSafeHandle"/> class.</summary>
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/// <param name="closeMethod">The delegate method for closing the handle.</param>
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public GenericSafeHandle(Func<IntPtr, bool> closeMethod) : this(IntPtr.Zero, closeMethod, true) { }
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/// <summary>Initializes a new instance of the <see cref="GenericSafeHandle"/> class.</summary>
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/// <param name="ptr">The PTR.</param>
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/// <param name="closeMethod">The delegate method for closing the handle.</param>
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/// <param name="ownsHandle">if set to <c>true</c> [owns handle].</param>
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/// <exception cref="System.ArgumentNullException">closeMethod</exception>
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public GenericSafeHandle(IntPtr ptr, Func<IntPtr, bool> closeMethod, bool ownsHandle = true) : base(ownsHandle)
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{
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SetHandle(ptr);
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CloseMethod = closeMethod ?? throw new ArgumentNullException(nameof(closeMethod));
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}
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/// <summary>Gets or sets the close method.</summary>
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/// <value>The close method.</value>
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protected virtual Func<IntPtr, bool> CloseMethod { get; }
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/// <summary>Performs an implicit conversion from <see cref="GenericSafeHandle"/> to <see cref="IntPtr"/>.</summary>
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/// <param name="h">The <see cref="GenericSafeHandle"/> instance.</param>
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/// <returns>The value of the handle. Use caution when using this value as it can be closed by the disposal of the parent <see cref="GenericSafeHandle"/>.</returns>
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public static implicit operator IntPtr(GenericSafeHandle h) => h.DangerousGetHandle();
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/// <summary>When overridden in a derived class, executes the code required to free the handle.</summary>
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/// <returns>
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/// true if the handle is released successfully; otherwise, in the event of a catastrophic failure, false. In this case, it generates a
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/// releaseHandleFailed MDA Managed Debugging Assistant.
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/// </returns>
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protected override bool ReleaseHandle()
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{
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if (IsInvalid) return true;
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var ret = CloseMethod?.Invoke(handle) ?? true;
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SetHandle(IntPtr.Zero);
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return ret;
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}
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}
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}
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