Warn on null pointer in callback in Font.cpp

[daleglass]

This was found by the address sanitizer, see below:

I added some debug info, which results in this pattern of calls:

[04/13 19:43:40] [INFO] [default] readHelper: dst 0x7b5463e5f770 ; len 112 data 0x7b54488a9818
[04/13 19:43:40] [INFO] [default] readHelper: dst 0x7b5463e5f800 ; len 192 data 0x7b54488a9818
[04/13 19:43:40] [INFO] [default] readHelper: dst 0x7d6519a60d00 ; len 4560 data 0x7b54488a9818
[04/13 19:43:40] [INFO] [default] readHelper: dst 0x0 ; len 0 data 0x7b54488a9818

Turns out passing a 0 as the first argument to memset isn't supposed to be done.

I'm not sure if this is a bug in the library or an indication of something special that should be reacted to in a special manner. Maybe an "end" indication. If that's it, then we should just remove the logged warning.

[04/13 19:43:40] [WARNING] [default] readHelper called with NULL pointer as first argument: dst =  0x0 ; length =  0 ; data = 0x7b54488a9818
[04/13 19:43:40] [DEBUG] [default] Font "https://files.thingvellir.net/Poppins-Medium.arfont" failed to decode.


#1  0x00007fffd8005151 in handleNonNullArg (Data=Data@entry=0x7fffe867e480, Opts=..., IsAttr=IsAttr@entry=true) at ../../../../libsanitizer/ubsan/ubsan_handlers.cpp:750
#2  0x00007fffd8008084 in __ubsan::__ubsan_handle_nonnull_arg (Data=Data@entry=0x7fffe867e480) at ../../../../libsanitizer/ubsan/ubsan_handlers.cpp:754
#3  0x00007fffe5e0474d in readHelper (dst=<optimized out>, length=length@entry=0, data=data@entry=0x7bfed518c818) at /home/dale/git/overte/overte-master/libraries/render-utils/src/text/Font.cpp:111
#4  0x00007fffe5e49de5 in artery_font::decode<&(readHelper(void*, int, void*)), float, artery_font::StdList, artery_font::StdList<unsigned char>, artery_font::StdString> (font=..., userData=<optimized out>)
    at /home/dale/git/overte/overte-master/libraries/render-utils/src/text/Font.cpp:123
#5  0x00007fffe5e0fb5b in Font::read (this=this@entry=0x7cdfa2374ad0, in=...) at /home/dale/git/overte/overte-master/libraries/render-utils/src/text/Font.cpp:123
#6  0x00007fffe5e15281 in Font::load (family=..., fontFile=...) at /home/dale/git/overte/overte-master/libraries/render-utils/src/text/Font.cpp:88
#7  0x00007fffe5e1696b in Font::load (family=...) at /home/dale/git/overte/overte-master/libraries/render-utils/src/text/Font.cpp:289
#8  0x00007fffe5d42ffd in TextRenderer3D::TextRenderer3D (this=0x7cefa05d7ae0, family=<optimized out>) at /home/dale/git/overte/overte-master/libraries/render-utils/src/TextRenderer3D.cpp:22
#9  0x00007fffe5d436ab in TextRenderer3D::getInstance (family=family@entry=0x7ffff1a636e0 "Roboto") at /home/dale/git/overte/overte-master/libraries/render-utils/src/TextRenderer3D.cpp:17
#10 0x00007ffff200ebf3 in render::entities::TextEntityRenderer::TextEntityRenderer (this=this@entry=0x7d8fa44b0680, entity=⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'
⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'
std::shared_ptr<EntityItem> (use count 6, weak count 3) = {...})
    at /home/dale/git/overte/overte-master/libraries/entities-renderer/src/RenderableTextEntityItem.cpp:32
#11 0x00007ffff1d4dac4 in make_renderer<render::entities::TextEntityRenderer> (entity=⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'
⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'
std::shared_ptr<EntityItem> (use count 6, weak count 3) = {...})
    at /home/dale/git/overte/overte-master/libraries/entities-renderer/src/RenderableEntityItem.cpp:136
#12 0x00007ffff1d00cf1 in render::entities::EntityRenderer::addToScene (renderer=..., entity=⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'
⚠️ warning: RTTI symbol not found for class 'std::_Sp_counted_deleter<TextEntityItem*, TextEntityItem::factory(EntityItemID const&, EntityItemProperties const&)::{lambda(TextEntityItem*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>'

   std::shared_ptr<EntityItem> (use count 6, weak count 3) = {...}, scene=std::shared_ptr<render::Scene> (use count 5, weak count 0) = {...}, transaction=...)
    at /home/dale/git/overte/overte-master/libraries/entities-renderer/src/RenderableEntityItem.cpp:440
#13 0x00007ffff1bad627 in EntityTreeRenderer::addPendingEntities (this=this@entry=0x7d8fa1e65980, scene=std::shared_ptr<render::Scene> (use count 5, weak count 0) = {...}, transaction=...)
    at /home/dale/git/overte/overte-master/libraries/entities-renderer/src/EntityTreeRenderer.cpp:494
#14 0x00007ffff1bc51ff in EntityTreeRenderer::update (this=this@entry=0x7d8fa1e65980, simulate=simulate@entry=false) at /home/dale/git/overte/overte-master/libraries/entities-renderer/src/EntityTreeRenderer.cpp:634
#15 0x0000000000d53fbc in Application::update (this=this@entry=0x7bff9f604790, deltaTime=<optimized out>) at /home/dale/git/overte/overte-master/interface/src/Application.cpp:2306
#16 0x0000000000d5eaef in Application::idle (this=this@entry=0x7bff9f604790) at /home/dale/git/overte/overte-master/interface/src/Application.cpp:1875
#17 0x0000000000f54455 in Application::event (this=0x7bff9f604790, event=0x7c2fa1027420) at /home/dale/git/overte/overte-master/interface/src/Application_Events.cpp:103
#18 0x00007fffb1240ef7 in QApplicationPrivate::notify_helper (this=this@entry=0x7d2fa02a4740, receiver=receiver@entry=0x7bff9f604790, e=e@entry=0x7c2fa1027420) at kernel/qapplication.cpp:3640
#19 0x00007fffb12477c3 in QApplication::notify (this=this@entry=0x7bff9f604790, receiver=receiver@entry=0x7bff9f604790, e=e@entry=0x7c2fa1027420) at kernel/qapplication.cpp:3386
#20 0x0000000000f4c023 in Application::notify (this=0x7bff9f604790, object=<optimized out>, event=<optimized out>) at /home/dale/git/overte/overte-master/interface/src/Application_Events.cpp:61
#21 0x00007fffe8c1f778 in QCoreApplication::notifyInternal2 (receiver=0x7bff9f604790, event=0x7c2fa1027420) at kernel/qcoreapplication.cpp:1064
#22 0x00007fffe8c1f992 in QCoreApplication::sendEvent (receiver=<optimized out>, event=<optimized out>) at kernel/qcoreapplication.cpp:1462
#23 0x00007fffe8c22ca8 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=event_type@entry=0, data=0x7cbfa0207f40) at kernel/qcoreapplication.cpp:1821
#24 0x00007fffe8c22f50 in QCoreApplication::sendPostedEvents (receiver=<optimized out>, event_type=0) at kernel/qcoreapplication.cpp:1680
--Type <RET> for more, q to quit, c to continue without paging--
#25 0x00007fffe8c754cf in postEventSourceDispatch (s=0x7cafa02d0360) at kernel/qeventdispatcher_glib.cpp:277
#26 0x00007fffe14eb323 in g_main_dispatch (context=0x7d0fa0282480) at ../glib/gmain.c:3565
#27 g_main_context_dispatch_unlocked (context=0x7d0fa0282480) at ../glib/gmain.c:4425
#28 0x00007fffe14f4278 in g_main_context_iterate_unlocked (context=context@entry=0x7d0fa0282480, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4490
#29 0x00007fffe14f4423 in g_main_context_iteration (context=0x7d0fa0282480, may_block=1) at ../glib/gmain.c:4556
#30 0x00007fffe8c74f67 in QEventDispatcherGlib::processEvents (this=0x7c2fa0907f00, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#31 0x00007fffe8c1e0e2 in QEventLoop::exec (this=this@entry=0x7fffffff6fb0, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#32 0x00007fffe8c264c4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1375
#33 0x00007fffc7c61bad in QGuiApplication::exec () at kernel/qguiapplication.cpp:1863
#34 0x00007fffb1240e69 in QApplication::exec () at kernel/qapplication.cpp:2832
#35 0x00000000017e4876 in main (argc=<optimized out>, argv=<optimized out>) at /home/dale/git/overte/overte-master/interface/src/main.cpp:850

@HifiExperiments I think you should have a better idea of how this is supposed to work, your feedback would be great.

[HifiExperiments]

hm yeah can you catch where in the library the problem is coming from? https://github.com/Chlumsky/artery-font-format/blob/af79386abe0857fe1c30be97eec760dbd84022c5/artery-font/serialization.hpp#L109

maybe something about the footer? I think we’re safe to just ignore

possibly related to https://github.com/overte-org/overte/pull/937/changes#r1567943126

[daleglass]

hm yeah can you catch where in the library the problem is coming from? https://github.com/Chlumsky/artery-font-format/blob/af79386abe0857fe1c30be97eec760dbd84022c5/artery-font/serialization.hpp#L109

maybe something about the footer? I think we’re safe to just ignore

possibly related to https://github.com/overte-org/overte/pull/937/changes#r1567943126

Dang, I was hoping you'd know something about this, because I hate everything about this library.

It's all in a header, there's that #define mess, no comments and no documentation I can find.

How did you figure out how to use this thing? Is there docs somewhere?

I don't think it's the footer, because in what circumstances would &footer ever be null?

        internal::ArteryFontFooter footer;
        ARTERY_FONT_DECODE_READ(&footer, sizeof(footer)-sizeof(footer.checksum));

[ksuprynowicz]

Thank you!

[HifiExperiments]

How did you figure out how to use this thing? Is there docs somewhere?

I don't think it's the footer, because in what circumstances would &footer ever be null?

        internal::ArteryFontFooter footer;
        ARTERY_FONT_DECODE_READ(&footer, sizeof(footer)-sizeof(footer.checksum));

haha trial and error and luck. iirc I had found some other projects that used it and based our solution off of those, but the versions were all slightly different and there was some weirdness with Qt

yeah you're right that doesn't make sense. must be one of the other fields for whatever reason. I'll try to investigate more at some point but I think this solution is totally sufficient