876110 - Crashes before the crash reporter is available lack android traces in logcat

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: General, defect)

Description

[Mike Hommey [:glandium]]

When our crash reporter is not yet in place (so, before libxul is loaded and XRE_main called), crashes end up in the bionic segfault handler. The bionic segfault handler displays a very brief summary of the crash, and requests a dump to debuggerd. Then, debuggerd attaches to the crashed with ptrace, gets a dump and displays it in logcat, which is very helpful... except it doesn't work on nightlies.
As briefly mentioned in bug 857108, the reason this doesn't work is because we don't mark OFFICIAL_BUILDs with the debuggable flag in AndroidManifest.xml. The debuggable flag makes the zygote explicitely does PR_SET_DUMPABLE that allows to ptrace processes, which is not possible normally on android because application processes are forked and setuid'ed (the latter part blocking ptrace for good reason in the general context).
But since we're running native code, we can do PR_SET_DUMPABLE ourselves to allow debuggerd to work.

Comment 1

[Mike Hommey [:glandium]]

Attachment: Manually set fennec process dptraceable on non release builds

Comment 2

[Mike Hommey [:glandium]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/1c254da4d503

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/1c254da4d503