From 5129c29a865c5014a8cc89e0f8e7a2bec1fc9f99 Mon Sep 17 00:00:00 2001
From: Andrew Belt <andrewpbelt@gmail.com>
Date: Sat, 25 Jan 2020 16:51:05 -0500
Subject: [PATCH] Use -rpath=. for plugins. Set cwd when loading plugins.

---
 plugin.mk      | 10 ++++----
 src/plugin.cpp | 69 ++++++++++++++++++++++++++++++--------------------
 2 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/plugin.mk b/plugin.mk
index 21e23f53..bd6dd49b 100644
--- a/plugin.mk
+++ b/plugin.mk
@@ -20,24 +20,24 @@ FLAGS += -I$(RACK_DIR)/include -I$(RACK_DIR)/dep/include
 # I don't really understand the side effects (see GCC manual), but so far tests are positive.
 FLAGS += -fno-gnu-unique
 
+LDFLAGS += -shared
+LDFLAGS += -Wl,-rpath=.
+LDFLAGS += -L$(RACK_DIR) -lRack
+
 include $(RACK_DIR)/arch.mk
 
 ifdef ARCH_LIN
-	LDFLAGS += -shared
 	TARGET := plugin.so
 	RACK_USER_DIR ?= $(HOME)/.Rack
-	# Link to glibc 2.23
-# 	FLAGS += -include force_link_glibc_2.23.h
 endif
 
 ifdef ARCH_MAC
-	LDFLAGS += -shared -undefined dynamic_lookup
 	TARGET := plugin.dylib
+	LDFLAGS += -undefined dynamic_lookup
 	RACK_USER_DIR ?= $(HOME)/Documents/Rack
 endif
 
 ifdef ARCH_WIN
-	LDFLAGS += -shared -L$(RACK_DIR) -lRack
 	TARGET := plugin.dll
 	RACK_USER_DIR ?= "$(USERPROFILE)"/Documents/Rack
 endif
diff --git a/src/plugin.cpp b/src/plugin.cpp
index 916b1839..1f9e551c 100644
--- a/src/plugin.cpp
+++ b/src/plugin.cpp
@@ -43,51 +43,66 @@ namespace plugin {
 // private API
 ////////////////////
 
+static void* loadLibrary(std::string libraryPath) {
+	#if defined ARCH_WIN
+		SetErrorMode(SEM_NOOPENFILEERRORBOX | SEM_FAILCRITICALERRORS);
+		std::wstring libraryFilenameW = string::toWstring(libraryPath);
+		HINSTANCE handle = LoadLibraryW(libraryFilenameW.c_str());
+		SetErrorMode(0);
+		if (!handle) {
+			int error = GetLastError();
+			throw Exception(string::f("Failed to load library %s: code %d", libraryPath.c_str(), error));
+		}
+	#else
+		// Plugin uses -rpath=. so change working directory so it can find libRack.
+		char cwd[PATH_MAX];
+		cwd[0] = '\0';
+		getcwd(cwd, sizeof(cwd));
+		chdir(asset::systemDir.c_str());
+		// And then change it back
+		DEFER({
+			chdir(cwd);
+		});
+		// Load library with dlopen
+		void* handle = dlopen(libraryPath.c_str(), RTLD_NOW | RTLD_LOCAL);
+		if (!handle) {
+			throw Exception(string::f("Failed to load library %s: %s", libraryPath.c_str(), dlerror()));
+		}
+	#endif
+		return handle;
+}
+
 typedef void (*InitCallback)(Plugin*);
 
-static InitCallback loadLibrary(Plugin* plugin) {
+static InitCallback loadPluginCallback(Plugin* plugin) {
 	// Load plugin library
-	std::string libraryFilename;
+	std::string libraryExt;
 #if defined ARCH_LIN
-	libraryFilename = plugin->path + "/" + "plugin.so";
+	libraryExt = "so";
 #elif defined ARCH_WIN
-	libraryFilename = plugin->path + "/" + "plugin.dll";
+	libraryExt = "dll";
 #elif ARCH_MAC
-	libraryFilename = plugin->path + "/" + "plugin.dylib";
+	libraryExt = "dylib";
 #endif
+	std::string libraryPath = plugin->path + "/plugin." + libraryExt;
 
 	// Check file existence
-	if (!system::isFile(libraryFilename)) {
-		throw Exception(string::f("Library %s does not exist", libraryFilename.c_str()));
+	if (!system::isFile(libraryPath)) {
+		throw Exception(string::f("Library %s does not exist", libraryPath.c_str()));
 	}
 
 	// Load dynamic/shared library
-#if defined ARCH_WIN
-	SetErrorMode(SEM_NOOPENFILEERRORBOX | SEM_FAILCRITICALERRORS);
-	std::wstring libraryFilenameW = string::toWstring(libraryFilename);
-	HINSTANCE handle = LoadLibraryW(libraryFilenameW.c_str());
-	SetErrorMode(0);
-	if (!handle) {
-		int error = GetLastError();
-		throw Exception(string::f("Failed to load library %s: code %d", libraryFilename.c_str(), error));
-	}
-#else
-	void* handle = dlopen(libraryFilename.c_str(), RTLD_NOW | RTLD_LOCAL);
-	if (!handle) {
-		throw Exception(string::f("Failed to load library %s: %s", libraryFilename.c_str(), dlerror()));
-	}
-#endif
-	plugin->handle = handle;
+	plugin->handle = loadLibrary(libraryPath);
 
 	// Get plugin's init() function
 	InitCallback initCallback;
 #if defined ARCH_WIN
-	initCallback = (InitCallback) GetProcAddress(handle, "init");
+	initCallback = (InitCallback) GetProcAddress(plugin->handle, "init");
 #else
-	initCallback = (InitCallback) dlsym(handle, "init");
+	initCallback = (InitCallback) dlsym(plugin->handle, "init");
 #endif
 	if (!initCallback) {
-		throw Exception(string::f("Failed to read init() symbol in %s", libraryFilename.c_str()));
+		throw Exception(string::f("Failed to read init() symbol in %s", libraryPath.c_str()));
 	}
 
 	return initCallback;
@@ -139,7 +154,7 @@ static Plugin* loadPlugin(std::string path) {
 			initCallback = core::init;
 		}
 		else {
-			initCallback = loadLibrary(plugin);
+			initCallback = loadPluginCallback(plugin);
 		}
 		initCallback(plugin);