[Lldb-commits] [PATCH] D106226: [lldb] Improve error message when "lldb attach" fails

Tue Jul 20 10:56:51 PDT 2021

teemperor added a comment.

Congrats on getting started on your first patch! I improving this error message really seems like a good idea.

>From what I can see the error message here is identical to GDB's which is a different project with an incompatible license. No idea if this is large enough of a copy to bring us into the realm of copyright (not a lawyer), but I think formulating our own (maybe even better?) error message would anyway be a good idea. What about something along those lines:

  error: attach failed: <Whatever error we already would return here> (This line is just the normal LLDB attach error)
  Note that attaching might have failed due to the ptrace_scope security policy
  which restricts debuggers from attaching to other processes. See
  the ptrace_scope documentation for more information:
    https://www.kernel.org/doc/Documentation/security/Yama.txt
  The current ptrace_scope policy can be found here:
    /proc/sys/kernel/yama/ptrace_scope

(Not sure how I feel about linking to some internet URL, but I couldn't find any man page for Yama/ptrace_scope)

Also I wonder how we could make sure we emit this diagnostic in cases where the ptrace_scope is actually the reason for the failed attach. The proper way to check this seems to be checking the `errno` after we call `ptrace` and then propagate the error all the way back to `lldb` from `lldb-server`. >From the `lldb` side I don't think we have any way of knowing why the attach actually failed so we would emit this error speculatively which doesn't seem ideal. It still sounds like a better solution than having just this generic error message that doesn't help anyone, so I think David's suggestion + a FIXME is maybe a good compromise here.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106226/new/

https://reviews.llvm.org/D106226