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Refactor DllImports in Microsoft.Extensions.Hosting.Systemd #63421

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Merged
tarekgh merged 1 commit into from
Jan 6, 2022
Merged

Refactor DllImports in Microsoft.Extensions.Hosting.Systemd #63421

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2 changes: 2 additions & 0 deletions src/libraries/Common/src/Interop/Unix/Interop.Libraries.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@ internal static partial class Interop
{
internal static partial class Libraries
{
internal const string Libc = "libc";

// Shims
internal const string SystemNative = "libSystem.Native";
internal const string NetSecurityNative = "libSystem.Net.Security.Native";
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13 changes: 13 additions & 0 deletions src/libraries/Common/src/Interop/Unix/libc/Interop.GetParentPid.cs
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@@ -0,0 +1,13 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Runtime.InteropServices;

internal static partial class Interop
{
internal static partial class libc
{
[GeneratedDllImport(Libraries.Libc, EntryPoint = "getppid")]
internal static partial int GetParentPid();
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@am11 am11 Jan 6, 2022

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It would be nice to add this file next to

runtime/src/libraries/Common/src/Interop/Unix/System.Native/Interop.GetPid.cs

Lines 10 to 11 in e46ae80

[GeneratedDllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetPid")]
internal static partial int GetPid();
and export SystemNative_GetParentPid symbol from System.Native (see: https://grep.app/search?q=SystemNative_GetPid&regexp=true&filter[repo][0]=dotnet/runtime). If I remember it correctly, we intentionally try not to import symbol from libc directly (except for tests). getppid was indeed an exceptional case.

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@jkoritzinsky jkoritzinsky Jan 6, 2022

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We try not to use SystemNative_* APIs from out-of-box assemblies like the Microsoft.Extensions.* assemblies as they're considered private APIs for the Microsoft.NETCore.App framework.

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@am11 am11 Jan 6, 2022

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I saw that libc was once removed from Interop.Libraries.cs 27bc21d#diff-c1db2d15cd6bf99da7a388eca0ae209ff70f2708d8c4ee6f10d11ad320bdb917, not sure if it makes sense to add it back for OOTB assemblies. (e.g. System.Drawing interop code is still maintained under its own hierarchy)

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@eerhardt eerhardt Jan 6, 2022

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We try not to use SystemNative_* APIs from out-of-box assemblies like the Microsoft.Extensions.* assemblies as they're considered private APIs for the Microsoft.NETCore.App framework.

It is even more of a stronger statement than "try not to". We explicitly can't. This is because the Microsoft.Extensions.* assemblies target netfx where the System.Native shim isn't present. (Note the netfx assembly would also be used on traditional Mono). And also new Extension assemblies can run on older .NET Core versions. In that case the System.Native shim will be present, but it won't have the new shim method.

So for assemblies that aren't in the Microsoft.NETCore.App shared framework, we can't use the System.Native shims.

}
}
5 changes: 5 additions & 0 deletions ...ries/Microsoft.Extensions.Hosting.Systemd/src/Microsoft.Extensions.Hosting.Systemd.csproj
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Expand Up @@ -18,6 +18,11 @@
<Compile Remove="SystemdLifetime.netstandard.cs" />
</ItemGroup>

<ItemGroup>
<Compile Include="$(CommonPath)Interop\Unix\libc\Interop.GetParentPid.cs" Link="Common\Interop\Unix\libc\Interop.GetParentPid.cs" />
<Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs" Link="Common\Interop\Unix\Interop.Libraries.cs" />
</ItemGroup>

<ItemGroup>
<ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Hosting\src\Microsoft.Extensions.Hosting.csproj" />
</ItemGroup>
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6 changes: 1 addition & 5 deletions src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdHelpers.cs
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Expand Up @@ -4,7 +4,6 @@
using System;
using System.Globalization;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace Microsoft.Extensions.Hosting.Systemd
Expand Down Expand Up @@ -34,7 +33,7 @@ private static bool CheckParentIsSystemd()
try
{
// Check whether our direct parent is 'systemd'.
int parentPid = GetParentPid();
int parentPid = Interop.libc.GetParentPid();
string ppidString = parentPid.ToString(NumberFormatInfo.InvariantInfo);
byte[] comm = File.ReadAllBytes("/proc/" + ppidString + "/comm");
return comm.AsSpan().SequenceEqual(Encoding.ASCII.GetBytes("systemd\n"));
Expand All @@ -45,8 +44,5 @@ private static bool CheckParentIsSystemd()

return false;
}

[GeneratedDllImport("libc", EntryPoint = "getppid")]
private static partial int GetParentPid();
}
}