From 94ca4e7a03aa274cb32e1e90278f5620d57017ef Mon Sep 17 00:00:00 2001
From: Rolf Bjarne Kvinge <rolf@xamarin.com>
Date: Thu, 22 Apr 2021 11:57:41 +0200
Subject: [PATCH] [ObjCRuntime] Print to stderr if using xamarin_log fails.
 Fixes #11239. (#11262)

* [ObjCRuntime] Print to stderr if using xamarin_log fails. Fixes #11239.

Fixes https://github.com/xamarin/xamarin-macios/issues/11239.

* Update xtro.
---
 src/ObjCRuntime/Runtime.CoreCLR.cs            |  2 +-
 src/ObjCRuntime/Runtime.cs                    | 20 ++++++++++++++++---
 .../xtro-sharpie/common-CoreFoundation.ignore |  1 +
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/ObjCRuntime/Runtime.CoreCLR.cs b/src/ObjCRuntime/Runtime.CoreCLR.cs
index 5be9151b0c..c27794f20b 100644
--- a/src/ObjCRuntime/Runtime.CoreCLR.cs
+++ b/src/ObjCRuntime/Runtime.CoreCLR.cs
@@ -27,7 +27,7 @@ namespace ObjCRuntime {
 		[System.Diagnostics.Conditional ("UNDEFINED")]
 		static void log_coreclr (string message)
 		{
-			xamarin_log (message);
+			NSLog (message);
 		}
 
 		// Returns a retained MonoObject. Caller must release.
diff --git a/src/ObjCRuntime/Runtime.cs b/src/ObjCRuntime/Runtime.cs
index 5faa213e17..b801be966d 100644
--- a/src/ObjCRuntime/Runtime.cs
+++ b/src/ObjCRuntime/Runtime.cs
@@ -14,6 +14,7 @@ using System.IO;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Text;
 
 using Foundation;
 using Registrar;
@@ -1617,16 +1618,29 @@ namespace ObjCRuntime {
 		}
 
 		[DllImport ("__Internal", CharSet = CharSet.Unicode)]
-		internal extern static void xamarin_log (string s);
+		extern static void xamarin_log (string s);
+
+		[DllImport (Constants.libcLibrary)]
+		extern static nint write (int filedes, byte[] buf, nint nbyte);
 
 		internal static void NSLog (string value)
 		{
-			xamarin_log (value);
+			try {
+				xamarin_log (value);
+			} catch {
+				// Append a newline like NSLog does
+				if (!value.EndsWith ('\n'))
+					value += "\n";
+				// Don't use Console.WriteLine, since that brings in a lot of supporting code and may bloat apps.
+				var utf8 = Encoding.UTF8.GetBytes (value);
+				write (2 /* STDERR */, utf8, utf8.Length);
+				// Ignore any errors writing to stderr (might happen on devices if the developer tools haven't been mounted, but xamarin_log should always work on devices).
+			}
 		}
 
 		internal static void NSLog (string format, params object[] args)
 		{
-			xamarin_log (string.Format (format, args));
+			NSLog (string.Format (format, args));
 		}
 #endif // !COREBUILD
 
diff --git a/tests/xtro-sharpie/common-CoreFoundation.ignore b/tests/xtro-sharpie/common-CoreFoundation.ignore
index 05a20c8878..780044da1a 100644
--- a/tests/xtro-sharpie/common-CoreFoundation.ignore
+++ b/tests/xtro-sharpie/common-CoreFoundation.ignore
@@ -981,6 +981,7 @@
 !unknown-pinvoke! dispatch_walltime bound
 !unknown-pinvoke! dispatch_write bound
 !unknown-pinvoke! open bound
+!unknown-pinvoke! write bound
 !missing-field! kCFStreamErrorDomainSOCKS not bound
 !missing-field! kCFStreamErrorDomainSSL not bound
 !missing-field! kCFStreamPropertyShouldCloseNativeSocket not bound