There was a problem where errno could be set in a signal handler
and cause bugs if other system calls were interrupted.
There isn't strong evidence this is causing any issues, but add this
proactively.
Bug: 31448909
Test: Ran the backtrace unit tests, backtraces few random processes,
Test: forced the ANR path for some zygote based processes.
Test: Ran the art ThreadStress test a few times.
Change-Id: I5abc9e330a5e86cea7015e2362f66044c6bc37d0
Remove the logging of an error if a thread disappears before the unwind
can begin. This can happen, so allow the caller to determine if this
is really a problem worth logging.
Bug: 27449879
(cherry picked from commit 206a3b9798)
Change-Id: If9e7cfeb6eb7b122679a734c1a9eacee8354ef18
If the signal handler doesn't fire in the given time when trying to unwind
a thread, put on a logging handler. This prevents crashes if the signal
does eventually fire.
Bug: 23783762
Change-Id: Ib7abb36b71d079a7043117697c41b535319586fd
If the signal to dump a thread is never delivered, then it's
possible for a deadlock. The signal handler is responsible for
unlocking and deleting the ThreadEntry created for the pid/tid
combination. This means if the signal is lost, the ThreadEntry
gets stuck locked and never deleted. If a second attempt to get
a backtrace of this thread occurs, there is a deadlock.
Also, decrease the timeout from 10 seconds to 5 seconds. The original
10 seconds was because the unwind was actually done in the signal
handler. Now the signal handler does nothing but copy the ucontext
structure and let the caller do the unwind.
Bug: 21086132
Change-Id: Idc735dbf6147ec879d35bd4f034c5d227e26a98d
Under some conditions, /proc/<pid>/maps might return nothing. If we
try and unwind in this case, we'll crash. Check this case and fail
the unwind.
Add checks that no other functions try and use map_ without
checking for nullptr.
Add logging when an unwind fails so it's clear what happened.
Bug: 21162746
Change-Id: I56ce51dda0cfc9db20475a441f118108196aa07c
Also simplifies the Darwin implementation of gettid, because
apparently libbacktrace had a better way of doing it.
Change-Id: I9e14f9176b167405a5aaa5b8a0db0327c7126271
When doing a local unwind, do not include the frames that come
from either libunwind or libbacktrace.
Bug: 11518609
Change-Id: I0ec8d823aebbfa0903e61b16b7e5663f3fd65e78
The object hierarchy was confusing and convoluted. This removes
a lot of unnecessary code, and consolidates the BacktraceCurrent
and BacktraceThread code into BacktraceCurrent.
Change-Id: I01c8407d493712a48169df49dd3ff46db4a7c3ae
