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#region Copyright notice and license
// Copyright 2015, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using System;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Threading;
using Grpc.Core.Logging;
using Grpc.Core.Utils;
namespace Grpc.Core.Internal
{
/// <summary>
/// Represents a dynamically loaded unmanaged library in a (partially) platform independent manner.
/// An important difference in library loading semantics is that on Windows, once we load a dynamic library using LoadLibrary,
/// that library becomes instantly available for <c>DllImport</c> P/Invoke calls referring to the same library name.
/// On Unix systems, dlopen has somewhat different semantics, so we need to use dlsym and <c>Marshal.GetDelegateForFunctionPointer</c>
/// to obtain delegates to native methods.
/// See http://stackoverflow.com/questions/13461989/p-invoke-to-dynamically-loaded-library-on-mono.
/// </summary>
internal class UnmanagedLibrary
{
static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<UnmanagedLibrary>();
// flags for dlopen
const int RTLD_LAZY = 1;
const int RTLD_GLOBAL = 8;
readonly string libraryPath;
readonly IntPtr handle;
public UnmanagedLibrary(string[] libraryPathAlternatives)
{
this.libraryPath = FirstValidLibraryPath(libraryPathAlternatives);
Logger.Debug("Attempting to load native library \"{0}\"", this.libraryPath);
this.handle = PlatformSpecificLoadLibrary(this.libraryPath);
if (this.handle == IntPtr.Zero)
{
throw new IOException(string.Format("Error loading native library \"{0}\"", this.libraryPath));
}
}
/// <summary>
/// Loads symbol in a platform specific way.
/// </summary>
/// <param name="symbolName"></param>
/// <returns></returns>
public IntPtr LoadSymbol(string symbolName)
{
if (PlatformApis.IsLinux)
{
if (PlatformApis.IsMono)
{
return Mono.dlsym(this.handle, symbolName);
}
return Linux.dlsym(this.handle, symbolName);
}
if (PlatformApis.IsMacOSX)
{
return MacOSX.dlsym(this.handle, symbolName);
}
throw new InvalidOperationException("Unsupported platform.");
}
public T GetNativeMethodDelegate<T>(string methodName)
where T : class
{
var ptr = LoadSymbol(methodName);
if (ptr == IntPtr.Zero)
{
throw new MissingMethodException(string.Format("The native method \"{0}\" does not exist", methodName));
}
return Marshal.GetDelegateForFunctionPointer(ptr, typeof(T)) as T;
}
/// <summary>
/// Loads library in a platform specific way.
/// </summary>
private static IntPtr PlatformSpecificLoadLibrary(string libraryPath)
{
if (PlatformApis.IsWindows)
{
return Windows.LoadLibrary(libraryPath);
}
if (PlatformApis.IsLinux)
{
if (PlatformApis.IsMono)
{
return Mono.dlopen(libraryPath, RTLD_GLOBAL + RTLD_LAZY);
}
return Linux.dlopen(libraryPath, RTLD_GLOBAL + RTLD_LAZY);
}
if (PlatformApis.IsMacOSX)
{
return MacOSX.dlopen(libraryPath, RTLD_GLOBAL + RTLD_LAZY);
}
throw new InvalidOperationException("Unsupported platform.");
}
private static string FirstValidLibraryPath(string[] libraryPathAlternatives)
{
GrpcPreconditions.CheckArgument(libraryPathAlternatives.Length > 0, "libraryPathAlternatives cannot be empty.");
foreach (var path in libraryPathAlternatives)
{
if (File.Exists(path))
{
return path;
}
}
throw new FileNotFoundException(String.Format("Error loading native library. Not found in any of the possible locations {0}", libraryPathAlternatives));
}
private static class Windows
{
[DllImport("kernel32.dll")]
internal static extern IntPtr LoadLibrary(string filename);
}
private static class Linux
{
[DllImport("libdl.so")]
internal static extern IntPtr dlopen(string filename, int flags);
[DllImport("libdl.so")]
internal static extern IntPtr dlsym(IntPtr handle, string symbol);
}
private static class MacOSX
{
[DllImport("libSystem.dylib")]
internal static extern IntPtr dlopen(string filename, int flags);
[DllImport("libSystem.dylib")]
internal static extern IntPtr dlsym(IntPtr handle, string symbol);
}
/// <summary>
/// On Linux systems, using using dlopen and dlsym results in
/// DllNotFoundException("libdl.so not found") if libc6-dev
/// is not installed. As a workaround, we load symbols for
/// dlopen and dlsym from the current process as on Linux
/// Mono sure is linked against these symbols.
/// </summary>
private static class Mono
{
[DllImport("__Internal")]
internal static extern IntPtr dlopen(string filename, int flags);
[DllImport("__Internal")]
internal static extern IntPtr dlsym(IntPtr handle, string symbol);
}
}
}
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