Date: Thu, 03 Sep 2020 11:40:50 -0400 From: "Stefan O'Rear" <sorear@...tmail.com> To: musl@...ts.openwall.com Subject: Re: [PATCH 07/14] Emulate wait4 using waitid On Thu, Sep 3, 2020, at 11:36 AM, Arnd Bergmann wrote: > On Thu, Sep 3, 2020 at 4:56 PM Stefan O'Rear <sorear@...tmail.com> wrote: > > > > On Thu, Sep 3, 2020, at 7:23 AM, Stefan O'Rear wrote: > > > + case CLD_STOPPED: > > > + case CLD_TRAPPED: > > > + sw = ((info.si_status&0xff) << 8) + 0x7f; > > > + break; > > > > This is trying to be defensive but it is the cause of the strace issue > > in the cover letter since the ptrace interface generates si_status > > greater than 8 bits which must be visible in WSTOPSIG; the v2 will not > > mask here. > > Ah, I was trying to find out what exactly the masking was for since > I did not have that in my original version of the same function for Arm: Where is this coming from? I didn't want to blindly copy code from glibc and I couldn't find any documentation of how the mapping is supposed to work other than the POSIX descriptions of the wait and waitid functions (which is why I missed the non-POSIX ptrace cases). If there's an authoritative description of the mapping I would like to match it exactly. -s
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