assertion failed; looks like a bug
In XEmacs 21.2 (beta32) "Kastor & Polydeukes" [Lucid]
(sparc-sun-solaris2.7) of Fri Mar 31 2000 on rhea
configured using `configure --prefix=/export/users/hamishm/xemacs
--site-prefixes=/export/users/hamishm/gnome:/export/users/hamishm --pdump'
CVS updated at 9:10am EST March 31 2000.
Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:
I recently started playing around with eshell by John Wiegley
(http://www.emacs.org/~johnw/eshell.html) I'm using version 2.2.1,
with a couple of bug fixes for my non-MULE XEmacs:
(defun process-coding-system (blug)
(cons nil nil))
(defun coding-system-eol-type (coding)
nil)
I discovered that when attempting to do some piping in eshell
(e.g. "ls | head"), my XEmacs was dying. I started to do some
investigation.
I got the following backtrace:
#0 assert_failed (file=0x22bda8 "lstream.h", line=33,
expr=0x22bdb8 "RECORD_TYPEP (obj, lrecord_type_lstream)") at emacs.c:2748
#1 0xdace4 in unix_send_process (proc=5188096, lstream=0x37fc00)
at lstream.h:33
#2 0x167b38 in send_process (proc=5188096, relocatable=5573876,
nonrelocatable=0x0, start=0, len=315) at process.c:988
#3 0x16a2a8 in Fprocess_send_string (process=5188096, string=5573876,
from=-24697440, to=-24697440) at process.c:1118
This backtrace is actually somewhat misleading, since the lstream
passed in to unix_send_process is perfectly valid. The lstream that is
being barfed on in p->pipe_outstream (where p is the process structure
referred to by Lisp_Object argument proc.
It looks like the problem is that "head" exits before reading all its
input (pretty normal for "head", I think).
It turns out that the following loop (lines 1148-1158 of
process-unix.c) is the culprit:
while (Lstream_was_blocked_p (XLSTREAM (p->pipe_outstream)))
{
/* Buffer is full. Wait, accepting input;
that may allow the program
to finish doing output and read more. */
Faccept_process_output (Qnil, make_int (1), Qnil);
old_sigpipe =
(SIGTYPE (*) (int)) signal (SIGPIPE, send_process_trap);
Lstream_flush (XLSTREAM (p->pipe_outstream));
signal (SIGPIPE, old_sigpipe);
}
The following backtrace shows p->pipe_outstream being set to Qnil as
part of the above call to Faccept_process_output:
#0 deactivate_process (proc=5698048) at process.c:1865
#1 0x169ed8 in remove_process (proc=5698048) at process.c:1878
#2 0x16802c in status_notify () at process.c:1408
#3 0xe0ad4 in execute_internal_event (event=5698048) at event-stream.c:3045
#4 0xdfd84 in Faccept_process_output (process=-24697440, timeout_secs=165,
timeout_msecs=3406848) at event-stream.c:2641
#5 0xdaca4 in unix_send_process (proc=5698048, lstream=0x37f600)
at process-unix.c:1175
#6 0x167b38 in send_process (proc=5698048, relocatable=5985204,
nonrelocatable=0x0, start=0, len=315) at process.c:988
Subsequently, at line 1156, Lstream_flush is called, using
XLSTREAM(p->pipe_outstream) as an argument. At this point,
p->p->pipe_outstream is no longer an lstream, but is nil;
the assertion fails, BOOM.
I'm not sure what the correct fix is here.
Regards,
Hamish.