improve symlink handling in Ping (#79323)

* improve symlink handling in Ping

* update comment

* feedback from review

Author: wfurt

src/libraries/Common/src/System/Net/NetworkInformation/UnixCommandLinePing.cs

@@ -40,10 +40,8 @@ private static bool IsBusyboxPing(string? pingBinary)
         {
             if (pingBinary != null)
             {
-                string? linkedName = Interop.Sys.ReadLink(pingBinary);
-
-                // If pingBinary is not link linkedName will be null
-                if (linkedName != null && linkedName.EndsWith("busybox", StringComparison.Ordinal))
+                System.IO.FileSystemInfo? linkInfo = File.ResolveLinkTarget(pingBinary, returnFinalTarget: true);
+                if (linkInfo?.Name.EndsWith("busybox", StringComparison.Ordinal) == true)
                 {
                     return true;
                 }

src/libraries/System.Net.Ping/src/System.Net.Ping.csproj

@@ -56,8 +56,6 @@
              Link="Common\Interop\Unix\Interop.Libraries.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Close.cs"
              Link="Common\Interop\Unix\System.Native\Interop.Close.cs" />
-    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.ReadLink.cs"
-             Link="Common\Interop\Unix\System.Native\Interop.ReadLink.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Socket.cs"
              Link="Common\Interop\Unix\System.Native\Interop.Socket.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.SocketAddress.cs"