core dump size means what?

core dump size means what?

Post by Adam Skegg » Fri, 10 Jan 2003 13:19:03



Hi,

I have a core dump for a dced process. It's huge at 269Mb. Normally the
running dced is much smaller. Can I assume from this that dced was
leaking memory? or does the core file include other stuff? The core was
due to a SEGV.

PS: Is there a dedicated dce newsgroup? I had a bit of a look but found
didly.

Thanks,
Adam.

 
 
 

core dump size means what?

Post by all mail refus » Sat, 11 Jan 2003 06:28:00



>Hi,

>I have a core dump for a dced process. It's huge at 269Mb. Normally the
>running dced is much smaller. Can I assume from this that dced was
>leaking memory? or does the core file include other stuff? The core was
>due to a SEGV.

>PS: Is there a dedicated dce newsgroup? I had a bit of a look but found
>didly.

A core dump is usually a sparse file - does the size as shown by "du"
correspond better with the size when running ?

--
decoy mail addresses: obtain username via 0x4f/tcp or 0x50/tcp

 
 
 

core dump size means what?

Post by Dennis Hand » Sat, 11 Jan 2003 20:28:20


: I have a core dump for a dced process. It's huge at 269Mb. Normally the
: running dced is much smaller.  or does the core file include other stuff?

The core file contains all of the data (heap/stack/etc.) and registers for
a process.  You can use adb(1) to see what the sizes of each part are:

$ adb core
$m
$q

(The $m and $q are commands.  There may be no adb prompts.)

 
 
 

1. newgrp sets core dump size limit to 0 on HP-UX 11

Hello,

I noticed today that using newgrp(1) on HP-UX 11.0 and 11.i results in the
hard limit for core dump size getting set to 0:

        hp% uname -a
        HP-UX hp B.11.11 U 9000/780 unknown
        hp% limit coredumpsize 12345
        hp% limit coredumpsize
        coredumpsize    12345 kbytes
        hp% limit -h coredumpsize
        coredumpsize    unlimited

        hp% newgrp users
        hp% limit coredumpsize
        coredumpsize    0 kbytes
        hp% limit -h coredumpsize
        coredumpsize    0 kbytes

Since it sets the hard limit to 0, it is not possible for to create a core
dump under any circumstances after running newgrp.

This seems to be hard coded in the newgrp binary, I did a system call
trace using tusc:

        # tusc /usr/bin/newgrp

        ... snip ...
        setrlimit(RLIMIT_CORE, 0x680f0804) ....................... = 0
        setgid(3) ................................................ = 0
        setresuid(0, 0, 0) ....................................... = 0
        setresuid(0, 0, 0) ....................................... = 0
        getpid() ................................................. = 21227 (21226)
        audwrite(0x680f0874) ..................................... = 0
        audswitch(0) ............................................. = 0
        setuid(0) ................................................ = 0
        execve("/sbin/sh", 0x680f0878, 0x680f0674) ............... = 0 [32-bit]
        ...

Note the call to setrlimit() right before it exec()s the shell.

/usr/bin/newgrp on HP-UX 10.20 does not seem to have this behavior. It
preserves the existing limits as you'd expect, and doesn't call
setrlimit(). However, 11.0 and 11.i both do.

Does anyone know if this is a feature or a bug?

Thanks,

Chris Wing

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