dump core or not dump core

dump core or not dump core

Post by Ruppert R. Koc » Thu, 08 Jun 2000 04:00:00



Howdy,

Some of my programs dump core, others don't. I tried
it on RedHat 6.1 and Mandrake 7.0 with kernels 2.2.14
and 2.2.15. I tried tcsh and bash with coredumpsize
set to 1GB. It seems to be application specific.

Is there any other criteria when suppressing apart from
the type of signal and the size limitation?
The application that doesn't dump core contains signal
handlers for some signals, but not for SEGV or ABRT.

Ruppert

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

 Dept of Elec. & Comp. Engr.    http://alpha.ece.ucsb.edu/~ruppert
 University of California       Phone: (805) 893-7788
 Santa Barbara, CA 93106        Fax:   (805) 893-3262
 -----------------------------------------------------------------

 
 
 

dump core or not dump core

Post by Juergen Hein » Thu, 08 Jun 2000 04:00:00



>Howdy,

>Some of my programs dump core, others don't. I tried
>it on RedHat 6.1 and Mandrake 7.0 with kernels 2.2.14
>and 2.2.15. I tried tcsh and bash with coredumpsize
>set to 1GB. It seems to be application specific.

>Is there any other criteria when suppressing apart from
>the type of signal and the size limitation?
>The application that doesn't dump core contains signal
>handlers for some signals, but not for SEGV or ABRT.

[...]

Some options :

- an application can inhibit the generation of core dumps
using setrlimit(2). Some do for security reasons as else
passwords or other sensitive data might end up in a core file.
Ftp servers often do that for instance.

- an application can change its current working directory. If
the new working directory does not allow the writing of files
for the effective user id / group id the application is running
with, then no core dump will be written either. Daemons often
change their working directory to / before chaning their euid
to something other than 0.

- an application cannot dump a core if there is another file
named core and the permissions are such, that it cannot be
overwritten.

More here, but these two came to my mind right now 8-)

Cheers,
Juergen

--
\ Real name     : Jrgen Heinzl                 \       no flames      /


 
 
 

1. core dumps core dumps everywhere...

I've been setting up this particular FreeBSD 3.4-release to be the
file server for my little home network. Of the last month or so of
setting this sucker up, I only encountered handful of core dumps
(probably less than 5).

Over this weekend, I began to transfer all the files from MS-DOS (in
ZIPed form) to UFS. And while trying to mount that MS-DOS partition to
access the ZIP files, I came over that little interesting note
contained in mount_msdos -- saying in FreeBSD 2.x (or somethin')
earlier, mounting DOS partitions w/greater than 16KB cluster size will
corrupt other mounted file system under FreeBSD.

Funny as it may seem, I *could not* get 32KB-clustered, 2GB DOS
partition to mount. I had to re-partition to exactly 1GB (16KB cluster
size) and have that mount.

Anyway, after mounting the said partition in read-only state, I began
to notice awful lot of core dumps by FreeBSD. Over this two days, I
encounetered no less than 20, with at least one unannounced
spontaneous reboot (I wasn't there, so I didn't see what exactly
happened).

Now having all the file transfers done and no more having to mount
that DOS partition, I noticed there's still a good amount of core
dumps going on. The login prompt seemed to be the most suseptable -- I
enter the user ID at login, press [ENTER] and there's good chance of
voila -- a core dump. The record is 7 dumps straight while trying to
log on. It also looks like other programs running aren't immune
either, although I haven't seen any daemons dumping craps.

Did mounting and accessing MS-DOS partition permanently damaged this
copy of FreeBSD? The messages during boot-up didn't hint at any
anomalies...

2. using grep to find IP address...

3. Get "Segmentation fault (core dumped)" but no core file found

4. Q: metadb, swap space

5. Apache problem - core dumps (httpd.core) all over the place

6. BroadVision

7. XF86_SVGA core dumped, but where is the core file?

8. KDE

9. why are core dumps always named "core"?

10. GDB dumps core when given core?

11. want to dump core, then run the core later.

12. SIGBUS does not cause core dump

13. Why does lx99p13 not dumping core ?