ktrace as a replacement for strace

[Chris Hodgins]

Dan Nelson wrote:
> In the last episode (Feb 08), Loren M. Lang said:
> 
>>I'm looking for a replacement for the strace program I used to use on
>>linux; freebsd has a port of strace, but it just hangs everytime I
>>use it.  It looks like the bsd version of strace would be
>>ktrace/kdump.  I was able to get these to print a trace of the
>>program I ran, but it doesn't do all the nice substatuting that
>>strace was able to do. Mainly, I just want the first argument of open
>>to look like a string instead of a 32 bit pointer that I can't read. 
>>I'm trying to figure out what files this program is trying to read so
>>I can edit it's configuration file.
> 
> 
> The string in the NAMI line immediately after an open() call is the
> filename in kdump output.
> 
> strace actually does work, but I think it's losing a race when it
> forks the child process.  Try suspending and resuming strace:
> 
> (dan at dan.4) /home/dan> strace date
> <hangs here, hit ^Z>
> ^Z
> zsh: 62219 suspended  strace date
> [1]  + suspended  strace date
> (dan at dan.4) /home/dan> fg
> [1]  + continued  strace date
> execve(0xbfbfdef4, [0xbfbfe3b8], [/* 0 vars */]) = 0
> mmap(0, 3920, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0) = 0x28071000
> munmap(0x28071000, 3920)                = 0
> ...
> 
> strace hasn't been updated in a while, though, and has problems parsing
> newer syscalls.  Take a look at the truss command in the base system,
> which does about the same thing as strace.  Ktrace has the advantage
> that it's less intrusive; both strace and truss have to stop the
> process to print out data, which really slow it down.
> 

Is truss still being fixed to work without procfs or is ktrace a better 
replacement?

Chris