Ruby

Now development version of MRI (RUBY_DEVEL macro enabled binary) supports RUBY_ON_BUG environment variable.
It kicks the specified process with PID of the Ruby process when rb_bug() function is called, like:

$ RUBY_ON_BUG='gdb -p' ./miniruby -e 'Process.kill(:SEGV, $$)'
-e:1: [BUG] Segmentation fault at 0x000003e800000512
ruby 3.2.0dev (2022-01-12T02:02:24Z master dcb02cb28a) [x86_64-linux]

GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2
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Attaching to process 1298
Reading symbols from /home/ko1/ruby/build/trunk/miniruby...
Reading symbols from /lib/x86_64-linux-gnu/libz.so.1...
(No debugging symbols found in /lib/x86_64-linux-gnu/libz.so.1)
Reading symbols from /lib/x86_64-linux-gnu/libpthread.so.0...
Reading symbols from /usr/lib/debug/.build-id/e5/4761f7b554d0fcc1562959665d93dffbebdaf0.debug...
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Reading symbols from /lib/x86_64-linux-gnu/librt.so.1...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/librt-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libgmp.so.10...
(No debugging symbols found in /lib/x86_64-linux-gnu/libgmp.so.10)
Reading symbols from /lib/x86_64-linux-gnu/libcapstone.so.3...
(No debugging symbols found in /lib/x86_64-linux-gnu/libcapstone.so.3)
Reading symbols from /lib/x86_64-linux-gnu/libdl.so.2...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libdl-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libcrypt.so.1...
(No debugging symbols found in /lib/x86_64-linux-gnu/libcrypt.so.1)
Reading symbols from /lib/x86_64-linux-gnu/libm.so.6...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libm-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libc.so.6...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.31.so...
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007fc0a0099dba in __GI___wait4 (pid=1299, stat_loc=stat_loc@entry=0x558e2382b5d8, options=options@entry=0, usage=usage@entry=0x0)
    at ../sysdeps/unix/sysv/linux/wait4.c:27
27      ../sysdeps/unix/sysv/linux/wait4.c: No such file or directory.
(gdb)

This feature is convenient for CI and so on.
Again, this feature is only enabled on RUBY_DEVEL. This is because I'm not sure it can be a security issue.
However, we discussed about this feature and we concluded it is not a problem to contain this kind of feature (if RUBYOPT is modified, it is already issue).

So I want to enable this feature.

Two points we need to discuss.

• anyone have security concern about this feature on release version?
• RUBY_ON_BUG is named without any discussion because it is only MRI development. However if it is enabled on release version, the name should be discussed. Any good name?

Thanks,
Koichi