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From Sam Talebbeik <sae...@ix.netcom.com>
Subject Re: Solaris 2.7 and getting a clean coredump
Date Sat, 04 Dec 1999 04:00:14 GMT
I am glad that the problem is resolved. Last that I checked, the issue
of setuid() was indeed discussed in Apache's debugging page. That
is why I pointed you to the page. Here is a cut and paste from that page
about setuid(). The "coreadm" utility is something that I was not
aware of. Thanks for pointing it out.

    ST.

-----------------------------------------------------------------------------

Getting the server to dump core

Strangely enough, sometimes you actually want to force the server to crash
so that you can get a
look at some nutty behavior. Normally this can be done simply by using the
gcore command.
However, for security reasons, most Unix systems do not allow a setuid
process to dump core, since
the file contents might reveal something that is supposed to be protected
in memory.

Here is one way to get a core file from a setuid Apache httpd process on
Solaris, without knowing
which httpd child might be the one to die [note: it is probably easier to
use the MaxClients trick in the
first section above].

    # for pid in `ps -eaf | fgrep httpd | cut -d' ' -f4`
    do
      truss -f -l -t\!all -S SIGSEGV -p $pid 2>&1 | egrep SIGSEGV &
    done

The undocumented '-S' flag to truss will halt the process in place upon
receipt of a given signal
(SIGSEGV in this case). At this point you can use:

    # gcore PID

and then look at the backtrace as discussed above for gdb.
-----------------------------------------------------------------------------

Dirk-Willem van Gulik wrote:

> On Thu, 2 Dec 1999, Sam Talebbeik wrote:
>
> > You will fine some very good debugging tips at Apache's
> > own developer web site. Try the following link:
> >
> > http://dev.apache.org/debugging.html
>
> But not the setuid() and coreadm information which actually solved the
> problem. I've commet an updated version to cvs.
>
> DW.


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