dovecot - Oct 2004 - assertion failed and debugging dovecot

I'm getting this error on a particular message in my Maildir:

   Oct 11 21:59:48 aurora dovecot: IMAP(doug): file ostream-file.c: line 
646 (_send_istream): assertion failed: (instream->v_offset <= in_size)

To me, more import than the question "why is this happening" is
"how can I
debug this?"  Attaching gdb to the running imap process doesn't give me
access to the proper function names to set up breakpoints and get a stack 
trace.

Can someone with the experience give a quick how-to on debugging functions 
deep in dovecot?

Thanks,

Doug

On 12.10.2004, at 08:17, Doug Luce wrote:
> I'm getting this error on a particular message in my Maildir:
>
>   Oct 11 21:59:48 aurora dovecot: IMAP(doug): file ostream-file.c: 
> line 646 (_send_istream): assertion failed: (instream->v_offset <= 
> in_size)
I heard about the same problem today from someone else. Apparently this 
can be reproduced every time with some mail. Still waiting for that 
mail :)
> To me, more import than the question "why is this happening" is
"how
> can I debug this?"  Attaching gdb to the running imap process
doesn't
> give me access to the proper function names to set up breakpoints and 
> get a stack trace.
>
> Can someone with the experience give a quick how-to on debugging 
> functions deep in dovecot?
You should be able to attach gdb normally into it, as long as the 
binary isn't stripped, ie.:

gdb /usr/local/libexec/dovecot/imap pid
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It's not stripped, but I think I need additional clues.  Why does the
"where" fail to tell me where I am?

Thanks,

Doug

My session:

aurora# ps ax | grep imap
83842  ??  S      0:00.06 imap-login
83849  ??  S      0:00.24 imap
aurora# gdb /usr/local/dovecot-nightly/libexec/dovecot/imap 83849
GNU gdb 5.2.1 (FreeBSD)
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for
details.
This GDB was configured as "alpha-unknown-freebsd"...
Attaching to program: /usr/local/dovecot-nightly/libexec/dovecot/imap, process
83849
0x130234c60 in ?? ()
(gdb) where
#0  0x130234c60 in ?? ()
#1  0x12006e3a8 in _read (stream=0x1200aa080) at istream-mmap.c:91
#2  0x12006e3a8 in _read (stream=0x0) at istream-mmap.c:91
Error accessing memory address 0x40: Bad address.
(gdb) cont
Continuing. [[ Then it bombs with the log message I posted earlier ]]

Program received signal SIGABRT, Aborted.
warning: Hit heuristic-fence-post without finding
warning: enclosing function for address 0x130235908
This warning occurs if you are debugging a function without any symbols
(for example, in a stripped executable).  In that case, you may wish to
increase the size of the search with the `set heuristic-fence-post' command.

Otherwise, you told GDB there was a function where there isn't one, or
(more likely) you have encountered a bug in GDB.
0x130235908 in ?? ()
(gdb) where
#0  0x130235908 in ?? ()
warning: Hit heuristic-fence-post without finding
warning: enclosing function for address 0x130226e18
(gdb) c
Continuing.

Program terminated with signal SIGABRT, Aborted.
The program no longer exists.
(gdb)

On Wed, 13 Oct 2004, Timo Sirainen wrote:
> On 12.10.2004, at 08:17, Doug Luce wrote:
>
> > I'm getting this error on a particular message in my Maildir:
> >
> >   Oct 11 21:59:48 aurora dovecot: IMAP(doug): file ostream-file.c:
> > line 646 (_send_istream): assertion failed: (instream->v_offset
<> > in_size)
>
> I heard about the same problem today from someone else. Apparently this
> can be reproduced every time with some mail. Still waiting for that
> mail :)
>
> > To me, more import than the question "why is this happening"
is "how
> > can I debug this?"  Attaching gdb to the running imap process
doesn't
> > give me access to the proper function names to set up breakpoints and
> > get a stack trace.
> >
> > Can someone with the experience give a quick how-to on debugging
> > functions deep in dovecot?
>
> You should be able to attach gdb normally into it, as long as the
> binary isn't stripped, ie.:
>
> gdb /usr/local/libexec/dovecot/imap pid
>