Date: Tue, 26 Aug 2014 03:28:16 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Mateusz Guzik <mjg@freebsd.org> Subject: Re: svn commit: r270444 - in head/sys: kern sys Message-ID: <20140826012816.GC23088@dft-labs.eu> In-Reply-To: <1815651.yxLDiBYvJT@ralph.baldwin.cx> References: <201408240904.s7O949sI083660@svn.freebsd.org> <1724027.iWxFDWcg2R@ralph.baldwin.cx> <20140825170241.GA23088@dft-labs.eu> <1815651.yxLDiBYvJT@ralph.baldwin.cx>
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On Mon, Aug 25, 2014 at 01:35:58PM -0400, John Baldwin wrote: > On Monday, August 25, 2014 07:02:41 PM Mateusz Guzik wrote: > > On Mon, Aug 25, 2014 at 10:23:19AM -0400, John Baldwin wrote: > > > On Sunday, August 24, 2014 09:04:09 AM Mateusz Guzik wrote: > > > > Author: mjg > > > > Date: Sun Aug 24 09:04:09 2014 > > > > New Revision: 270444 > > > > URL: http://svnweb.freebsd.org/changeset/base/270444 > > > > > > > > Log: > > > > Fix getppid for traced processes. > > > > > > > > Traced processes always have the tracer set as the parent. > > > > Utilize proc_realparent to obtain the right process when needed. > > > > > > Are you sure this won't break things? I know of several applications that > > > expect a debugger to be the parent when attached and change behavior as a > > > result (e.g. inserting a breakpoint on an assertion failure rather than > > > generating a core). > > > > Well, this is what linux and solaris do. > > Interesting. > > > I don't feel strongly about this change. If you really want I'm happy to > > revert. > > In general I'd like to someday have the debugger-debuggee relationship not > override parent-child and this is a step in that direction. However, this > will break existing applications, so this needs to be clearly documented in > the release notes. In addition, we should probably advertise how a process > can correctly determine if it is being run under a debugger (right now you can > do 'getppid()' and use strcmp or strstr on the p_comm of that pid so you can > do different things for "gdb" vs "gcore", etc. so just checking P_TRACED from > kinfo_proc wouldn't be equivalent in functionality) > Is any of programs you mentioned opensource or at least publicly available? In linux they provide TracerPid in /proc/<pid>/status. We could add a specific sysctl or extend kinfo with the same data. -- Mateusz Guzik <mjguzik gmail.com>
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