Re: SEGFAULT on increment_row_positions

[JD Smith]

On Mon, 06 Jun 2005 10:17:26 -0700, JD Smith wrote:

> On Sat, 04 Jun 2005 01:57:49 +0200, Kim F. Storm wrote:
> 
>> JD Smith <address@hidden> writes:
>> 
>>> Program received signal SIGSEGV, Segmentation fault.
>>> 0x0804fdf8 in increment_row_positions (row=0x86905a4, delta=-17, 
>>> delta_bytes=4)
>>>     at dispnew.c:1188
>> 
>> I recall fixing a problem like that in CVS emacs (22.0) some time ago.
>> 
>> 
>>> This is GNU Emacs 21.3.1 (i386-redhat-linux-gnu, X toolkit, Xaw3d
>>> scroll bars) of 2005-02-04 on bugs.build.redhat.com running under FC3.
>> 
>> Can you test your code with CVS emacs, to see if it fails there too?
> 
> Thanks Kim.  I compiled a CVS version 22.0.50.1, and indeed the problem
> seems to have been solved (with about 3 hours of similar testing down).

Well, I spoke too soon.  I got a very similar SEGFAULT under
22.0.50.1:

Program received signal SIGSEGV, Segmentation fault.
0x08050c27 in increment_row_positions (row=0x888d384, delta=-1, delta_bytes=4)
    at dispnew.c:1190
1190          if (BUFFERP (row->glyphs[area][i].object)
(gdb) bt
#0  0x08050c27 in increment_row_positions (row=0x888d384, delta=-1,
    delta_bytes=4) at dispnew.c:1190
#1  0x08050ca6 in increment_matrix_positions (matrix=0x851a2e0, start=37,
    end=64, delta=-1, delta_bytes=-1) at dispnew.c:929
#2  0x0806e09a in try_window_id (w=0x94d10b0) at xdisp.c:13977
#3  0x08073b15 in redisplay_window (window=156045492, just_this_one_p=1)
    at xdisp.c:12260
#4  0x0807593d in redisplay_window_1 (window=156045492) at xdisp.c:10975
#5  0x0813a69c in internal_condition_case_1 (
    bfun=0x8075910 <redisplay_window_1>, arg=156045492, handlers=137328837,
    hfun=0x806b168 <redisplay_window_error>) at eval.c:1430
#6  0x08076bf0 in redisplay_internal (preserve_echo_area=4) at xdisp.c:10574
#7  0x080e6049 in read_char (commandflag=1, nmaps=2, maps=0xbfffed40,
    prev_event=137302033, used_mouse_menu=0xbfffed88) at keyboard.c:2539
#8  0x080e8bf6 in read_key_sequence (keybuf=0xbfffeea0, bufsize=30,
    prompt=137302033, dont_downcase_last=0, can_return_switch_frame=1,
    fix_current_buffer=1) at keyboard.c:8818
#9  0x080ea4fb in command_loop_1 () at keyboard.c:1527
#10 0x0813a5aa in internal_condition_case (bfun=0x80ea368 <command_loop_1>,
    handlers=137363001, hfun=0x80e4384 <cmd_error>) at eval.c:1389
#11 0x080ded52 in command_loop_2 () at keyboard.c:1318
#12 0x0813a4b9 in internal_catch (tag=4, func=0x80ded34 <command_loop_2>,
    arg=137302033) at eval.c:1148
#13 0x080deb61 in command_loop () at keyboard.c:1297
#14 0x080debfb in recursive_edit_1 () at keyboard.c:990
#15 0x080decf6 in Frecursive_edit () at keyboard.c:1051
#16 0x080de07d in main (argc=2, argv=0xbffff4a4) at emacs.c:1775

(gdb) p row->glyphs[area][i]
$2 = {
  charpos = 4980,
  object = 148914700,
  pixel_width = 10,
  ascent = 12,
  descent = 3,
  voffset = 0,
  type = 0,
  multibyte_p = 1,
  left_box_line_p = 0,
  right_box_line_p = 0,
  overlaps_vertically_p = 0,
  padding_p = 0,
  glyph_not_available_p = 0,
  face_id = 18,
  font_type = 0,
  slice = {
    x = 0,
    y = 0,
    width = 0,
    height = 0
  },
  u = {
    ch = 119,
    cmp_id = 119,
    img_id = 119,
    stretch = {
      height = 119,
      ascent = 0
    },
    val = 119
  }
}

I am using glyphs in the margin to mark breakpoints, and it appears
that these glyphs must be active to trip this bug (so my several hours
of uptime I reported before didn't count).  I had used these
breakpoint glyphs for an hour before experiencing the crash, so it's
not a simple one.  Any recommendations?

JD