From 72eb2ee84a4f397c5887159e288894778ea316a9 Mon Sep 17 00:00:00 2001
From: monojenkins <jo.shields+jenkins@xamarin.com>
Date: Thu, 23 May 2019 10:56:37 -0400
Subject: [PATCH] [Android] Fix runtime loading of DSOs for 64-bit processes
 (#14577)

[Android] Fix runtime loading of DSOs for 64-bit processes

Context: https://github.com/xamarin/xamarin-android/issues/2780

On Android the executable for the application is going to be
`/system/bin/app_process{32,64}` depending on the application's architecture.
However, libraries for the different architectures live in different
subdirectories of `/system`: `lib` for 32-bit apps and `lib64` for 64-bit ones.
Thus appending `/lib` below will fail to load the DSO for a 64-bit app, even if
it exists there, because it will have a different architecture. The quickest fix
is to use `lib64` explicitly for 64-bit Android apps.



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Backport of #13281.

/cc @lambdageek @grendello
---
 mono/metadata/loader.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/mono/metadata/loader.c b/mono/metadata/loader.c
index b6072e55e6a..dac5ee298ec 100644
--- a/mono/metadata/loader.c
+++ b/mono/metadata/loader.c
@@ -1667,8 +1667,20 @@ pinvoke_probe_for_module_relative_directories (MonoImage *image, const char *fil
 
 							base = g_path_get_dirname (resolvedname);
 							newbase = g_path_get_dirname(base);
-							mdirname = g_strdup_printf ("%s/lib", newbase);
 
+							// On Android the executable for the application is going to be /system/bin/app_process{32,64} depending on
+							// the application's architecture. However, libraries for the different architectures live in different
+							// subdirectories of `/system`: `lib` for 32-bit apps and `lib64` for 64-bit ones. Thus appending `/lib` below
+							// will fail to load the DSO for a 64-bit app, even if it exists there, because it will have a different
+							// architecture. This is the cause of https://github.com/xamarin/xamarin-android/issues/2780 and the ifdef
+							// below is the fix.
+							mdirname = g_strdup_printf (
+#if defined(TARGET_ANDROID) && (defined(TARGET_ARM64) || defined(TARGET_AMD64))
+									"%s/lib64",
+#else
+									"%s/lib",
+#endif
+									newbase);
 							g_free (resolvedname);
 							g_free (base);
 							g_free (newbase);
-- 
2.11.4.GIT