Re: 5.1-R: zero byte core file.

On Wed, 20 Aug 2003, Yogeshwar Shenoy wrote:

> While using 5.1-RELEASE, I find that if my application program seg
> faults, it produces "programname.core"; but it is 0 bytes.  I ran the
> exact same program on another machine that was running 4.4-RELEASE, and
> I do get a core file that I can use with gdb.  I'd really appreciate if
> someone could help me resolve this. 
> 
> Additional details:  - It is not specific to the application program. I
> tried a 2 line program: 
>     char p[8]; 
>     memcpy(p, "1234567890123456789012345678901234567890", 40); 
>  with same results on 5.1-R(0 byte core file) and 4.4-R(usable core
> file) 
> 
> - "ulimit -a" on the 5.1-R machine gives
>    core file size (blocks, -c) unlimited
> 
> - Just to be sure I used getrlimit() to find what the limit for
> RLIMIT_CORE is in my processes, and it is RLIM_INFINITY. 
> 
> - I did the basic checks like write permission on current directory, it
> looks fine. 
> 
> Can someone help me resolve this? 

With 5.1-CURRENT from July, I get:

paprika:~/tmp/core> ./tmp 
Segmentation fault (core dumped)
paprika:~/tmp/core> ls -l
total 348
drwxr-xr-x  2 rwatson  rwatson     512 Aug 20 17:23 ./
drwxr-xr-x  9 rwatson  rwatson     512 Aug 20 17:23 ../
-rwxr-xr-x  1 rwatson  rwatson    4677 Aug 20 17:23 tmp*
-rw-r--r--  1 rwatson  rwatson     131 Aug 20 17:23 tmp.c
-rw-------  1 rwatson  rwatson  323584 Aug 20 17:23 tmp.core

The corefile isn't very useful, since the stack is completely hosed by the
operations, but I do get a core that I can point gdb at.  Some elements of
core file generation are platform-specific: what architecture are you
running on?  And, just to confirm, "df ." indicates you have space, right? 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert_at_fledge.watson.org      Network Associates Laboratories