Fixed current working directory on macOS Sierra, probably

http://stackoverflow.com/questions/42600770/chdir-to-the-location-of-the-app-bundle-in-c-macos-application#comment72481655_42637115

src/main.cpp

@@ -1,30 +1,88 @@
-#if defined(APPLE)
-	#include "CoreFoundation/CoreFoundation.h"
-	#include <unistd.h>
-	#include <libgen.h>
-#endif
-
 #include "engine.hpp"
 #include "gui.hpp"
 #include "app.hpp"
 #include "plugin.hpp"
 
 
+#if defined(APPLE)
+#include <CoreFoundation/CoreFoundation.h>
+#include <unistd.h> // for chdir and access
+#include <libgen.h> // for dirname
+// #include <string.h>
+#include <mach-o/dyld.h> // for _NSGetExecutablePath
+#include <limits.h> // for PATH_MAX?
+#include <dirent.h> // for opendir
+
+void alert(std::string header, std::string message, int level) {
+	CFStringRef headerRef = CFStringCreateWithCString(NULL, header.c_str(), header.size());
+	CFStringRef messageRef = CFStringCreateWithCString(NULL, message.c_str(), message.size());
+	CFOptionFlags result;
+
+	CFUserNotificationDisplayAlert(
+		0, // no timeout
+		level, // flags for alert level
+		NULL, // iconURL
+		NULL, // soundURL
+		NULL, // localizationURL
+		headerRef,
+		messageRef,
+		NULL, // default "OK"
+		NULL, // alternative button
+		NULL, // other button
+		&result
+		);
+
+	CFRelease(headerRef);
+	CFRelease(messageRef);
+}
+
+bool isCorrectCwd() {
+	DIR *dir = opendir("res");
+	if (dir) {
+		closedir(dir);
+		return true;
+	}
+	else {
+		return false;
+	}
+}
+
+/** macOS workaround for setting the working directory to the location of the .app */
+void fixCwd() {
+	// Check if the cwd is already set correctly (e.g. launched from the command line or gdb)
+	if (isCorrectCwd())
+		return;
+
+	// Get path of binary inside the app bundle
+	// It should be something like */Rack.app/Contents/MacOS
+	char path[PATH_MAX];
+	uint32_t pathLen = sizeof(path);
+	int err = _NSGetExecutablePath(path, &pathLen);
+	assert(!err);
+
+	// Switch to the directory of the actual binary
+	chdir(dirname(path));
+	// and then go up three directories to get to the parent directory
+	chdir("../../../");
+	if (isCorrectCwd())
+		return;
+
+	// Switch to a default absolute path
+	chdir("/Applications/Rack");
+	if (isCorrectCwd())
+		return;
+
+	alert("Install Rack", "To install Rack, please move the Rack directory to your /Applications folder.", 2);
+	exit(1);
+}
+#endif
+
+
 using namespace rack;
 
 int main() {
 #if defined(APPLE)
-	// macOS workaround for setting the working directory to the location of the .app
-	{
-		CFBundleRef bundle = CFBundleGetMainBundle();
-		CFURLRef bundleURL = CFBundleCopyBundleURL(bundle);
-		char path[PATH_MAX];
-		Boolean success = CFURLGetFileSystemRepresentation(bundleURL, TRUE, (UInt8 *)path, PATH_MAX);
-		assert(success);
-		CFRelease(bundleURL);
-
-		chdir(dirname(path));
-	}
+	fixCwd();
 #endif
 
 	pluginInit();