Date: Tue, 4 May 2010 11:02:40 -0500 From: Dan McNulty <dkmcnulty@gmail.com> To: Dan Nelson <dnelson@allantgroup.com> Cc: freebsd-questions@freebsd.org Subject: Re: Finding out when a child process forks or calls exec Message-ID: <s2l1efdac3e1005040902wf483d2afr7af5d4435dc7f30d@mail.gmail.com> In-Reply-To: <20100503213936.GL14572@dan.emsphone.com> References: <i2i1efdac3e1005031339zb359cc7bseca1556bf80615@mail.gmail.com> <20100503213936.GL14572@dan.emsphone.com>
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Great! This was what I was looking for. Thanks. -Dan On Mon, May 3, 2010 at 4:39 PM, Dan Nelson <dnelson@allantgroup.com> wrote: > In the last episode (May 03), Dan McNulty said: >> I am trying to port a debugging tool that uses the ptrace interface from >> Linux to FreeBSD. =A0From what I can tell, the ptrace interface on FreeB= SD >> is pretty similar to the Linux interface; however, it doesn't appear tha= t >> the FreeBSD interface generate events when the child process forks, call= s >> exec, creates a new LWP, etc. =A0My question then is: >> >> Does FreeBSD provide any way to determine from a parent/tracing >> process if a child process has called fork, exec, exit, or created a >> new LWP? > > /usr/bin/truss watches for syscalls named "fork", "rfork", and "vfork", a= nd > when they return it forks another copy of itself to watch the child. =A0S= ee > /usr/src/usr.bin/truss/i386-fbsd.c and main.c (search for "in_fork"). > > You can tell when a new lwp is created because lwpid changes. =A0In setup= .c > the waitevent() function calls ptrace(PT_LWPINFO...) on every syscall > entry/exit so it's easy to track; it then calls the find_thread() functio= n > which allocates a new helper struct every time a new lwp appears. > > -- > =A0 =A0 =A0 =A0Dan Nelson > =A0 =A0 =A0 =A0dnelson@allantgroup.com > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.o= rg" >
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