Summary:
Previously `AtosSymbolizer` would set the PID to examine in the
constructor which is called early on during sanitizer init. This can
lead to incorrect behaviour in the case of a fork() because if the
symbolizer is launched in the child it will be told examine the parent
process rather than the child.
To fix this the PID is determined just before the symbolizer is
launched.
A test case is included that triggers the buggy behaviour that existed
prior to this patch. The test observes the PID that `atos` was called
on. It also examines the symbolized stacktrace. Prior to this patch
`atos` failed to symbolize the stacktrace giving output that looked
like...
```
#0 0x100fc3bb5 in __sanitizer_print_stack_trace asan_stack.cpp:86
#1 0x10490dd36 in PrintStack+0x56 (/path/to/print-stack-trace-in-code-loaded-after-fork.cpp.tmp_shared_lib.dylib:x86_64+0xd36)
#2 0x100f6f986 in main+0x4a6 (/path/to/print-stack-trace-in-code-loaded-after-fork.cpp.tmp_loader:x86_64+0x100001986)
#3 0x7fff714f1cc8 in start+0x0 (/usr/lib/system/libdyld.dylib:x86_64+0x1acc8)
```
After this patch stackframes `#1` and `#2` are fully symbolized.
This patch is also a pre-requisite refactor for rdar://problem/58789439.
Reviewers: kubamracek, yln
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D77623
Summary:
The sanitizer symbolizers support printing the function offset
(difference between pc and function start) of a stackframe using the
`%q` format specifier.
Unfortunately this didn't actually work because neither the atos
or dladdr symbolizer set the `AddressInfo::function_offset` field.
This patch teaches both symbolizers to try to compute the function
offset. In the case of the atos symbolizer, atos might not report the
function offset (e.g. it reports a source location instead) so in this
case it fallsback to using `dladdr()` to compute the function offset.
Two test cases are included.
rdar://problem/56695185
Reviewers: kubamracek, yln
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D69549
On Darwin, we currently use forkpty to communicate with the "atos"
symbolizer. There are several problems that fork[pty] has, e.g. that
after fork, interceptors are still active and this sometimes causes
crashes or hangs. This is especially problematic for TSan, which uses
interceptors for OS-provided locks and mutexes, and even Libc functions
use those.
This patch replaces forkpty with posix_spawn on Darwin. Since
posix_spawn doesn't fork (at least on Darwin), the interceptors are not
a problem. Another benefit is that we'll handle post-fork failures (e.g.
sandbox disallows "exec") gracefully now.
Related revisions and previous attempts that were blocked by or had to
be revered due to test failures:
https://reviews.llvm.org/D48451https://reviews.llvm.org/D40032
Reviewed By: kubamracek
Differential Revision: https://reviews.llvm.org/D65253
llvm-svn: 368947
See https://reviews.llvm.org/D58620 for discussion, and for the commands
I ran. In addition I also ran
for f in $(svn diff | diffstat | grep .cc | cut -f 2 -d ' '); do rg $f . ; done
and manually updated (many) references to renamed files found by that.
llvm-svn: 367463
Dan Liew