Date: Tue, 18 Jun 1996 16:30:23 GMT From: James Raynard <fcurrent@jraynard.demon.co.uk> To: freebsd-current@freebsd.org Subject: strace [Was Re: ktrace...] Message-ID: <199606181630.QAA01838@jraynard.demon.co.uk>
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Sorry, I seem to have lost the original mail but someone was asking about porting strace to FreeBSD. I pulled down the source for strace-3.1 from the Incoming directory of my local Sunsite mirror this afternoon and had a look at it. Here's an extract from the PORTING file that comes with it:- The number one question is ``Does the native operating support a concept which enables even the mere possibility of tracing?''. So far I have seen two mechanisms which support system call tracing. They are the SunOS originated feature of the PTRACE_SYSCALL argument to the ptrace system call and the PIOCSENTRY/PIOCSEXIT ioctl for the /proc filesystem under System V release 4 style Unix derived systems. There may be others (surely a better one could be devised :-) but innovation is a rare commodity so unless one of these is supported you may be SOL. Now, FreeBSD has both ptrace() and a /proc filesystem, but neither of them support system call tracing as far as I can tell (and I checked through the source just in case there was anything undocumented). OTH ktrace() does support system call tracing, but does it all inside the kernel, which is no use to a program in userland. We're SOL 8-) -- James Raynard, Edinburgh, Scotland james@jraynard.demon.co.uk
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