NamedPipeServerStream.Unix: GetImpersonationUserName tweaks. (#88125)

* NamedPipeServerStream.Unix: GetImpersonationUserName tweaks.

When the user name is not found, return an empty string like Environment.UserName.

Add EINTR handling.

* Remove GetNameFromUid and use GetUserNameFromPasswd.

src/libraries/Common/src/Interop/Unix/System.Native/Interop.GetPeerUserName.cs

-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System;
-using System.Diagnostics;
-using System.Runtime.InteropServices;
-
-internal static partial class Interop
-{
-    internal static partial class Sys
-    {
-        [LibraryImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetPeerUserName", StringMarshalling = StringMarshalling.Utf8, SetLastError = true)]
-        internal static partial string GetPeerUserName(SafeHandle socket);
-    }
-}

src/libraries/System.IO.Pipes/src/System.IO.Pipes.csproj

@@ -145,14 +145,14 @@
              Link="Common\Interop\Unix\Interop.FLock.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetHostName.cs"
              Link="Common\Interop\Unix\Interop.GetHostName.cs" />
-    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetPeerUserName.cs"
-             Link="Common\Interop\Unix\Interop.GetPeerUserName.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Open.cs"
              Link="Common\Interop\Unix\Interop.Open.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.OpenFlags.cs"
              Link="Common\Interop\Unix\Interop.OpenFlags.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Pipe.cs"
              Link="Common\Interop\Unix\Interop.Pipe.cs" />
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetPwUid.cs"
+             Link="Common\Interop\Unix\System.Native\Interop.GetPwUid.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Read.Pipe.cs"
              Link="Common\Interop\Unix\Interop.Read.Pipe.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Unlink.cs"

src/libraries/System.IO.Pipes/src/System/IO/Pipes/NamedPipeServerStream.Unix.cs

@@ -167,13 +167,13 @@ public string GetImpersonationUserName()
                 throw new InvalidOperationException(SR.InvalidOperation_PipeHandleNotSet);
             }
 
-            string name = Interop.Sys.GetPeerUserName(handle);
-            if (name != null)
+            uint peerID;
+            if (Interop.Sys.GetPeerID(handle, out peerID) == -1)
             {
-                return name;
+                throw CreateExceptionForLastError(_instance?.PipeName);
             }
 
-            throw CreateExceptionForLastError(_instance?.PipeName);
+            return Interop.Sys.GetUserNameFromPasswd(peerID);
         }
 
         public override int InBufferSize

src/native/libs/System.Native/entrypoints.c

@@ -183,7 +183,6 @@ static const Entry s_sysNative[] =
     DllImportEntry(SystemNative_TryChangeSocketEventRegistration)
     DllImportEntry(SystemNative_WaitForSocketEvents)
     DllImportEntry(SystemNative_PlatformSupportsDualModeIPv4PacketInfo)
-    DllImportEntry(SystemNative_GetPeerUserName)
     DllImportEntry(SystemNative_GetDomainSocketSizes)
     DllImportEntry(SystemNative_GetMaximumAddressSize)
     DllImportEntry(SystemNative_SendFile)

src/native/libs/System.Native/pal_networking.c

@@ -3036,51 +3036,6 @@ int32_t SystemNative_PlatformSupportsDualModeIPv4PacketInfo(void)
 #endif
 }
 
-static char* GetNameFromUid(uid_t uid)
-{
-    size_t bufferLength = 512;
-    while (1)
-    {
-        char *buffer = (char*)malloc(bufferLength);
-        if (buffer == NULL)
-            return NULL;
-
-        struct passwd pw;
-        struct passwd* result;
-        if (getpwuid_r(uid, &pw, buffer, bufferLength, &result) == 0)
-        {
-            if (result == NULL)
-            {
-                errno = ENOENT;
-                free(buffer);
-                return NULL;
-            }
-            else
-            {
-                char* name = strdup(pw.pw_name);
-                free(buffer);
-                return name;
-            }
-        }
-
-        free(buffer);
-        size_t tmpBufferLength;
-        if (errno != ERANGE || !multiply_s(bufferLength, (size_t)2, &tmpBufferLength))
-        {
-            return NULL;
-        }
-        bufferLength = tmpBufferLength;
-    }
-}
-
-char* SystemNative_GetPeerUserName(intptr_t socket)
-{
-    uid_t euid;
-    return SystemNative_GetPeerID(socket, &euid) == 0 ?
-        GetNameFromUid(euid) :
-        NULL;
-}
-
 void SystemNative_GetDomainSocketSizes(int32_t* pathOffset, int32_t* pathSize, int32_t* addressSize)
 {
     assert(pathOffset != NULL);

src/native/libs/System.Native/pal_networking.h

@@ -411,8 +411,6 @@ PALEXPORT int32_t SystemNative_WaitForSocketEvents(intptr_t port, SocketEvent* b
 
 PALEXPORT int32_t SystemNative_PlatformSupportsDualModeIPv4PacketInfo(void);
 
-PALEXPORT char* SystemNative_GetPeerUserName(intptr_t socket);
-
 PALEXPORT void SystemNative_GetDomainSocketSizes(int32_t* pathOffset, int32_t* pathSize, int32_t* addressSize);
 
 PALEXPORT int32_t SystemNative_GetMaximumAddressSize(void);

src/native/libs/System.Native/pal_networking_wasi.c

@@ -411,12 +411,6 @@ int32_t SystemNative_PlatformSupportsDualModeIPv4PacketInfo(void)
     return 0;
 }
 
-
-char* SystemNative_GetPeerUserName(intptr_t socket)
-{
-    return NULL;
-}
-
 void SystemNative_GetDomainSocketSizes(int32_t* pathOffset, int32_t* pathSize, int32_t* addressSize)
 {
     *pathOffset = -1;