From c8f36e32ca6b27ec1d0432fef070ab24925ab6dd Mon Sep 17 00:00:00 2001
From: Piotrek Marciniak <piotrek@ptrm.eu>
Date: Fri, 6 Jan 2023 14:24:28 +0100
Subject: [PATCH] Unhardcode Apple M1 brew paths for SDL2

---
 ffi/SDL2_0.lua |  3 +--
 ffi/util.lua   | 19 ++++++++++++++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/ffi/SDL2_0.lua b/ffi/SDL2_0.lua
index 83ccc5dcb8..51ec7d56c5 100644
--- a/ffi/SDL2_0.lua
+++ b/ffi/SDL2_0.lua
@@ -25,8 +25,7 @@ local SDL = util.ffiLoadCandidates{
     -- this unfortunately needs to be written in full due to the . in the name
     "libSDL2-2.0.so",
     "libSDL2-2.0.so.0",
-    "/usr/local/opt/lib/libSDL2.dylib",
-    "/opt/homebrew/lib/libSDL2.dylib",
+    util.KO_DYLD_PREFIX .. "/lib/libSDL2.dylib",
 }
 
 -- Some features (like SDL_GameControllerRumble) may require a minimum version
diff --git a/ffi/util.lua b/ffi/util.lua
index fc48a8e412..e505eefe75 100644
--- a/ffi/util.lua
+++ b/ffi/util.lua
@@ -60,10 +60,27 @@ int WideCharToMultiByte(
 );
 ]]
 
+local getlibprefix = function()
+    -- Apple M1 homebrew installs libraries outside of default searchpaths,
+    -- and dyld environment variables are sip-protected on MacOS, cf. https://github.com/Homebrew/brew/issues/13481#issuecomment-1181592842
+    local libprefix = os.getenv("KO_DYLD_PREFIX");
+
+    if not libprefix then
+        local std_out = io.popen("brew --prefix", "r")
+            if std_out then
+                libprefix = std_out:read("*line")
+                std_out:close()
+            end
+    end
+
+    return libprefix or "";
+end
+
 require("ffi/posix_h")
 
 local util = {}
 
+util.KO_DYLD_PREFIX = getlibprefix()
 
 if ffi.os == "Windows" then
     util.gettime = function()
@@ -619,7 +636,7 @@ function util.haveSDL2()
     if haveSDL2 == nil then
         local candidates
         if jit.os == "OSX" then
-            candidates = {"libs/libSDL2.dylib", "/opt/homebrew/lib/libSDL2.dylib", "SDL2"}
+            candidates = {"libs/libSDL2.dylib", "SDL2", util.KO_DYLD_PREFIX .. "/lib/libSDL2.dylib"}
         else
             candidates = {"SDL2", "libSDL2-2.0.so", "libSDL2-2.0.so.0"}
         end