Logging: Redirect StdErr into logging system (#4427)

* Logging: Redirect StdErr into logging system

* Remove Mono.Unix

* Apply suggestions from code review

Co-authored-by: riperiperi <rhy3756547@hotmail.com>

* Address comments

---------

Co-authored-by: Mary <thog@protonmail.com>
Co-authored-by: riperiperi <rhy3756547@hotmail.com>
Co-authored-by: Mary <mary@mary.zone>

Ryujinx.Common/SystemInterop/StdErrAdapter.cs

@@ -0,0 +1,93 @@
+using System;
+using System.IO;
+using System.Runtime.Versioning;
+using System.Threading;
+using Ryujinx.Common.Logging;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Common.SystemInterop
+{
+    public partial class StdErrAdapter : IDisposable
+    {
+        private bool _disposable = false;
+        private UnixStream _pipeReader;
+        private UnixStream _pipeWriter;
+        private Thread _worker;
+
+        public StdErrAdapter()
+        {
+            if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
+            {
+                RegisterPosix();
+            }
+        }
+
+        [SupportedOSPlatform("linux")]
+        [SupportedOSPlatform("macos")]
+        private void RegisterPosix()
+        {
+            const int stdErrFileno = 2;
+
+            (int readFd, int writeFd) = MakePipe();
+            dup2(writeFd, stdErrFileno);
+
+            _pipeReader = new UnixStream(readFd);
+            _pipeWriter = new UnixStream(writeFd);
+
+            _worker = new Thread(EventWorker);
+            _disposable = true;
+            _worker.Start();
+        }
+
+        [SupportedOSPlatform("linux")]
+        [SupportedOSPlatform("macos")]
+        private void EventWorker()
+        {
+            TextReader reader = new StreamReader(_pipeReader);
+            string line;
+            while ((line = reader.ReadLine()) != null)
+            {
+                Logger.Error?.PrintRawMsg(line);
+            }
+        }
+
+        private void Dispose(bool disposing)
+        {
+            if (_disposable)
+            {
+                if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
+                {
+                    _pipeReader?.Close();
+                    _pipeWriter?.Close();
+                }
+
+                _disposable = false;
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
+
+        [LibraryImport("libc", SetLastError = true)]
+        private static partial int dup2(int fd, int fd2);
+
+        [LibraryImport("libc", SetLastError = true)]
+        private static unsafe partial int pipe(int* pipefd);
+
+        private static unsafe (int, int) MakePipe()
+        {
+            int *pipefd = stackalloc int[2];
+
+            if (pipe(pipefd) == 0)
+            {
+                return (pipefd[0], pipefd[1]);
+            }
+            else
+            {
+                throw new();
+            }
+        }
+    }
+}