Load resources from a location relative to the main executable

[probonopd]

Currently Scribus is loading resources (e.g. some of the icons) from a location defined at compile time.

This makes the binary non-relocateable in the filesystem, which means it only works when it is installed to the $PREFIX it was compiled for.

However, for AppImage, we need to make a bundle that can run from any location in the filesystem.
For the past 2 years, we have been doing a crude binary patch as a workaround:

scribus/AppImage-package/bundle.sh

Lines 89 to 97 in 1ed8577

	########################################################################
	# Patch away absolute paths; it would be nice if they were relative
	########################################################################
	sed -i -e 's|/usr/share/scribus|././/share/scribus|g' usr/bin/scribus
	sed -i -e 's|/usr/lib/scribus|././/lib/scribus|g' usr/bin/scribus
	sed -i -e 's|/usr/share/doc/scribus/|././/share/doc/scribus/|g' usr/bin/scribus
	# Possibly need to patch additional hardcoded paths away, replace
	# "/usr" with "././" which means "usr/ in the AppDir"

At execution time, we change to the usr/ directory inside the AppImage.

This causes considerable pain. One cannot, for example, use relative paths to open documents anymore but needs to do things like

me@host:~$ ./Scribus-*-x86_64.AppImage $(readlink -f my_document.sla)

Even worse, one cannot use relative paths in Python scripts.

Hence, Scribus should be changed to load resources from a location relative to the main executable.

One could use QString QCoreApplication::applicationDirPath() instead and construct a relative path to ../share/... from there. This would have the advantage that for normal installations, nothing would change (all files would stay where they are now) but since they would be referenced relative to the main application, the application would be relocateable.

I wonder what is done for macOS, where the application also needs to be relocateable...

[probonopd]

Looks like it has been implemented in

scribus/scribus/scpaths.cpp

Lines 73 to 97 in e51649a

	#ifdef Q_OS_LINUX
	// Set the application name expliticly.
	QCoreApplication::setApplicationName("scribus");
	QString pathPtr = QCoreApplication::applicationDirPath() + QString("/..");
	m_shareDir = QString("%1/share/scribus/").arg(pathPtr);
	m_docDir = QString("%1/share/doc/scribus/").arg(pathPtr);
	//m_fontDir = QString("%1/share/scribus/fonts/").arg(pathPtr);
	m_iconDir = QString("%1/share/scribus/icons/").arg(pathPtr);
	m_sampleScriptDir = QString("%1/share/scribus/samples/").arg(pathPtr);
	m_scriptDir = QString("%1/share/scribus/scripts/").arg(pathPtr);
	m_templateDir = QString("%1/share/scribus/templates/").arg(pathPtr);
	m_libDir = QString("%1/lib/scribus/").arg(pathPtr);
	m_pluginDir = QString("%1/lib/scribus/plugins/").arg(pathPtr);
	m_qmlDir = QString("%1/share/scribus/qml/").arg(pathPtr);
	qDebug() << QString("scpaths: doc dir=%1").arg(m_docDir);
	qDebug() << QString("scpaths: icon dir=%1").arg(m_iconDir);
	//qDebug() << QString("scpaths: font dir=%1").arg(m_fontDir);
	qDebug() << QString("scpaths: sample dir=%1").arg(m_sampleScriptDir);
	qDebug() << QString("scpaths: script dir=%1").arg(m_scriptDir);
	qDebug() << QString("scpaths: template dir=%1").arg(m_templateDir);
	qDebug() << QString("scpaths: lib dir=%1").arg(m_libDir);
	qDebug() << QString("scpaths: plugins dir=%1").arg(m_pluginDir);
	qDebug() << QString("scpaths: qml dir=%1").arg(m_qmlDir);
	#endif

Thanks @LyzardKing.

However, it's not entirely working yet:

me@host:~/digital-handshake-master$ '/home/me/Downloads/Scribus-b5aa26c-x86_64.AppImage'
Run experimental bundle that bundles everything
"scpaths: doc dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/doc/scribus/"
"scpaths: icon dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/scribus/icons/"
"scpaths: sample dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/scribus/samples/"
"scpaths: script dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/scribus/scripts/"
"scpaths: template dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/scribus/templates/"
"scpaths: lib dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../lib/scribus/"
"scpaths: plugins dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../lib/scribus/plugins/"
"scpaths: qml dir=/tmp/.mount_ScribuAitwXX/lib/x86_64-linux-gnu/../share/scribus/qml/"
No icons found :(

Looks like for whatever reason it thinks the application directory applicationDirPath() is not usr/bin but lib/x86_64-linux-gnu/. Thanks to @jghali, we assume the reason is that applicationDirPath() trips over what we are doing in the AppRun:

exec "${HERE}/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2" --inhibit-cache --library-path "${LIBRARY_PATH}" "${MAIN}" "$@"

One can temporarily work around this by symlinking

( cd appdir/lib/ ; ln -s ../usr/share . ; ln -s ../usr/lib . )