[CB-11355] initPlugins() abuse borking plugins on (ajax) loads, and potential fix

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: cordova-lib, cordova-ubuntu (DEPRECATED)
• Labels: easyfix plugins segfault triaged ubuntu

Environment

Ubuntu 15.10

$ cordova -v
6.1.1

$ nodejs -v
v6.2.0

• Assignee: David Barth
• Reporter: Pat Deegan
• Created: 01/Jun/16 18:11
• Updated: 23/Aug/18 07:51
• Resolved: 05/May/18 06:53

Description

I'm working on an (ubuntu) plugin that is thread-safe but was causing segfaults everytime I'd (asynch) load a new page or component.

Trying to run it under gdb, I found that as long as I avoided moving around there were no issues, but every load of a new page or (html) popup would spawn a new thread and somehow re-init my plugin (which is stateful and needs to stay alive).

The traces looked like so:
======================== snip ========================
[New Thread 0x7fffcf8a9700 (LWP 26618)]
Debug: Enable plugin "com.example.MyPlugin"
Debug: Enable plugin "File"
Debug: Enable plugin "Notification"
Debug: Enable plugin "com.cordova.Device"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/logo.png"
[Thread 0x7fffcf8a9700 (LWP 26618) exited]
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/cordova.js"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/cordova_plugins.js"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/pageA.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/pageB.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/index.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/libcoreplugins.so"
[New Thread 0x7fffcf8a9700 (LWP 26619)]
[Thread 0x7fffcf8a9700 (LWP 26619) exited]
Debug: Enable plugin "com.example.MyPlugin"
Debug: Enable plugin "File"
Debug: Enable plugin "Notification"
Debug: Enable plugin "com.cordova.Device"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/logo.png"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/cordova.js"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/cordova_plugins.js"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/pageA.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/pageB.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/index.html"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/libcoreplugins.so"
[New Thread 0x7fffcf8a9700 (LWP 26621)]
Debug: Enable plugin "com.example.MyPlugin"
Debug: Enable plugin "File"
Debug: Enable plugin "Notification"
Debug: Enable plugin "com.cordova.Device"
Debug: Testing "/path/to/project/platforms/ubuntu/native/prefix/www/logo.png"
[Thread 0x7fffcf8a9700 (LWP 26621) exited]
Program received signal SIGSEGV, Segmentation fault.
======================== /snip ========================

I tracked down the reason for all the (redundant?) "Enable plugin" events to initPlugins() calls in loadFinished() (in the Ubuntu package/src/cordova.cpp):

void Cordova::loadFinished(bool ok) {
Q_UNUSED(ok)
initPlugins();
}

I'm not certain what the purpose of this call is, as the init already happens in Cordova::appLoaded().

In any case, I've disabled the call and loadFinished() and my plugin is both persistent and has stopped causing segfaults.

Is there a reason to keep this initPlugins() call in loadFinished()? If so, could we add some kind of

virtual bool loadOnlyOnce()

{ return false;}

to the CPlugin base class so we can check for and skip plugins that override it? Or is there some other technique I'm not aware of?

Thanks,
Pat Deegan