Introducing cpptrace as the primary backtrace library broke the
backtrace fallback during the code move. This commit properly links AK
to libbacktrace.
It also fixes the function signatures for the fallback backtrace
handlers.
This commit replaces the default backtrace logic with cpptrace, for
nicer, colored backtraces. Cpptrace runs on all of our supported
platforms excpet android. As such backtrace.h is left in place.
All the backtrace functions are made noinline to have a consistent
number of frames. A maximum depth parameter is added to dump_backtrace
with a default of 100. This should be enough, and can be easily
changed, and allows for limiting the maximum depth.
Setting the LADYBIRD_BACKTRACE_SNIPPETS environment variable enables
surrouding code snippets in the backtrace. Specifically 2 lines above
and below. This number can be changed by calling snippet_context on the
formatter. For the whole list of options of what can be done with
formatting see the cpptrace repository.
On Windows we skipped frames when verification fails and when
dump_backtrace was added the logic was wrong and would have skipped
frames we care about.
This commit also implements skipping frames on Linux.
The only time where this does not skip all frames is when the call to
backtrace gets intercepted. Then we will end up skipping one frame less
than needed.
To keep delayload on Windows a patch and overlay port is used. When
upstream accepts these changes and vcpkg bumps the version the patch
could be removed to have just the cmake define.
When a `VERIFY()` assertion fails `ak_verification_failed` is invoked
which means the program will invoke `__builtin_trap` and immediately
quit. But with this change we have now allowed for an optional hook
into `ak_*_failed` that lets us perform some custom
action before program exits. This foundation is what we will
(ab)use to implement death tests without the process cloning
CrashTest infrastructure.
At this point, I've repeatedly felt the desire to be able to log
stacktraces to be able to see more easily what kind of call-sites exist
for a given piece of code. So this commit exposes `dump_backtrace()` in
the header so it can be used for this purpose.
This commit adds support for using the standard library implementation
of <stacktrace> if libbacktrace is not found. This can also be
explicitly enabled through ENABLE_STD_STACKTRACE for platforms that have
libbacktrace available.
Co-Authored-By: Andrew Kaster <andrew@ladybird.org>
```
VERIFICATION FAILED: !_temporary_result.is_error()
```
is not really a helpful error message.
When we are including `AK/Format.h`, which is most of the time,
we can easily print a much more useful error message:
```
UNEXPECTED ERROR: Cannot allocate memory (errno=12)
```
As recommended by the CMake docs, let's tolerate systems or setups that
don't have backtrace(3) in the `<execinfo.h>` header file, such as those
using libbacktrace directly.
The backtrace execinfo API takes the number of addresses the result
buffer can hold instead of its size, for some reason. Previously
backtraces larger than 256 frames deep would write past the end of the
result buffer.
While macOS backtrace(3) puts a space directly after the mangled symbol
name, some versions of glibc put a + directly after it. This new logic
accounts for both situations when trying to demangle.
Co-Authored-By: Andreas Kling <kling@serenityos.org>
On platforms that support it, enable using ``<execinfo.h>`` to get
backtrace(3) to dump a backtrace on assertion failure. This should make
debugging things like WebContent crashes in Lagom much easier.
Just because we may compile serenity with or without NDEBUG doesn't
mean that consuming projects or Ports will share the setting.
Always define the custom assertion function so that we don't have to
keep the same debug settings between all projects.
Until now, VERIFY() failures would just cause a __builtin_trap() in
release builds, which made them a bit too harsh. This commit adds an
out-of-line helper function that prints the error before trapping.
