[education/rkward] rkward/rbackend: Experimental: Prefer system libraries in backend, when running in an AppImage.

[Thomas Friedrichsmeier]

Git commit 43303039205a08480aa7baf58f71fa005f1d6fa1 by Thomas Friedrichsmeier.
Committed on 16/07/2022 at 21:02.
Pushed by tfry into branch 'master'.

Experimental: Prefer system libraries in backend, when running in an AppImage.

M  +24   -2    rkward/rbackend/rkfrontendtransmitter.cpp

https://invent.kde.org/education/rkward/commit/43303039205a08480aa7baf58f71fa005f1d6fa1

diff --git a/rkward/rbackend/rkfrontendtransmitter.cpp b/rkward/rbackend/rkfrontendtransmitter.cpp
index 6e84042b..3367a2e7 100644
--- a/rkward/rbackend/rkfrontendtransmitter.cpp
+++ b/rkward/rbackend/rkfrontendtransmitter.cpp
@@ -120,9 +120,31 @@ void RKFrontendTransmitter::run () {
 		qDebug("%s", qPrintable(args.join("\n")));
 	}
 
+	// Special handling for running inside an AppImage. In this case, we want the backend process to prefer system libraries.
+	// (R may even call system binaries)
+	QString appdir = QString::fromLocal8Bit(qgetenv("APPDIR"));
+	if (!appdir.isEmpty()) {
+		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+		QStringList keys_to_fix = QStringList() << "LD_LIBRARY_PATH" << "PATH";
+		for (const QString &key : keys_to_fix) {
+			QStringList parts = env.value(key).split(':');
+			QStringList append;
+			int i = 0;
+			while (i < parts.size()) {
+				if (parts.at(i).startsWith(appdir)) {
+					append.append(parts.takeAt(i));
+					continue;
+				}
+				++i;
+			}
+			env.insert(key, (parts + append).join(':'));
+		}
+		backend->setProcessEnvironment(env);
+	}
+
 #ifdef Q_OS_MACOS
 	// Resolving libR.dylib and friends is a pain on MacOS, and running through R CMD does not always seem to be enough.
-	// (Apparently DYLIB_FALLBACK_LIBRARY_PATH is ignored on newer versions of MacOS). Safest best seems to be to start in the lib directory, itself.
+	// (Apparently DYLIB_FALLBACK_LIBRARY_PATH is ignored on newer versions of MacOS). Safest bet seems to be to start in the lib directory, itself.
 	QProcess dummy;
 	dummy.start(RKSessionVars::RBinary(), QStringList() << "--slave" << "--no-save" << "--no-init-file" << "-e" << "cat(R.home('lib'))");
 	dummy.waitForFinished ();
@@ -131,7 +153,7 @@ void RKFrontendTransmitter::run () {
 	backend->setWorkingDirectory (r_home);
 #endif
 #if defined(Q_OS_WIN)
-	// added on a hunch, to be removed, should it have no effect, to be cleaned, otherwise:
+	// Quite a HACK, but it really works:
 	// On some windows systems, the _first_ invocation of the backend seems to fail as somehow process output from the backend (the token) never arrives.
 	// Could it help to start a dummy process, before that? And, if doing so, will we be able to read its output?
 	QProcess dummy;