* infinite loop in scroll-up
@ 2003-03-21 16:48 Sergey Vlasov
0 siblings, 0 replies; only message in thread
From: Sergey Vlasov @ 2003-03-21 16:48 UTC (permalink / raw)
In GNU Emacs 21.3.1 (i686-pc-linux-gnu, X toolkit)
of 2003-03-20 on center4.mivlgu.local
configured using `configure --prefix=/home/vsu/opt/emacs --with-x --without-toolkit-scroll-bars'
Important settings:
value of $LC_ALL: nil
value of $LC_COLLATE: ru_RU.KOI8-R
value of $LC_CTYPE: ru_RU.KOI8-R
value of $LC_MESSAGES: ru_RU.KOI8-R
value of $LC_MONETARY: ru_RU.KOI8-R
value of $LC_NUMERIC: ru_RU.KOI8-R
value of $LC_TIME: ru_RU.KOI8-R
value of $LANG: ru_RU.KOI8-R
locale-coding-system: cyrillic-koi8
default-enable-multibyte-characters: t
I have tried to use the following configuration in my ~/.emacs:
(setq scroll-conservatively 1000)
(setq scroll-margin 1)
(temp-buffer-resize-mode 1)
(mwheel-install)
In some cases when I try to use the mouse wheel Emacs gets stuck
eating all CPU; C-g does not work; killing the Emacs process with
SIGFPE breaks the loop.
I have reduced the problem to the following test case (freshly started
'emacs -q --no-site-file', no X resources):
M-x set-variable RET scroll-conservatively RET 1000 RET
M-x set-variable RET scroll-margin RET 1 RET
M-x temp-buffer-resize-mode RET
C-h f mwheel-install RET
(this produces a buffer with 4 lines of text, last line does not
end with '\n)
C-x o
(switches to the *Help* buffer)
M-: (scroll-up 3) RET
(the number is 1 less than the buffer height)
At this point Emacs does not respond even to C-g. Examination using
gdb reveals that it is stuck in the loop in
src/window.c:window_scroll_pixel_based():
0x0807c935 in window_scroll_pixel_based (window=13, n=3, whole=0, noerror=0)
at window.c:4127
4127 move_it_by_lines (&it, 1, 1);
(gdb) l
4122 {
4123 /* We moved the window start towards ZV, so PT may be now
4124 in the scroll margin at the top. */
4125 move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
4126 while (it.current_y < this_scroll_margin)
4127 move_it_by_lines (&it, 1, 1);
4128 SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
4129 }
4130 else if (n < 0)
4131 {
(More detailed gdb output is at the end of message.)
The same behavior can be reproduced by adding one character at the end
of the initial *scratch* buffer (there will be 5 lines of text (one of
them empty), the last line not ending with '\n'), splitting the window
(C-x 2) and resizing the window to 5 lines (so that the whole text
will just fit), then doing (scroll-up 4). In fact, splitting is not
absolutely necessary - the same infinite loop happens when the frame
is resized vertically so that the text will just fit.
Recent input:
M-x s e t - v a r <return> s c r o l l - c o n s <return>
1 0 0 0 <return> M-x s e t - v a r <return> s c r o
l l - m a r <return> 1 <return> M-x t e m p - b <return>
C-h f m w h e e l - i n <tab> <return> C-x o M-: (
s c r o l l - u p SPC 3 ) <return> M-x r e p o r t
<tab> <return>
Recent messages:
Loading tooltip...done
For information about the GNU Project and its goals, type C-h C-p.
Temp-Buffer-Resize mode enabled
Loading view...done
Type C-x 1 to remove help window. C-M-v to scroll the help.
eval:
Loading debug...done
Entering debugger...
[2 times]
Loading emacsbug...done
==================== begin gdb output ====================
0x0807c935 in window_scroll_pixel_based (window=13, n=3, whole=0, noerror=0)
at window.c:4127
4127 move_it_by_lines (&it, 1, 1);
(gdb) l
4122 {
4123 /* We moved the window start towards ZV, so PT may be now
4124 in the scroll margin at the top. */
4125 move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
4126 while (it.current_y < this_scroll_margin)
4127 move_it_by_lines (&it, 1, 1);
4128 SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
4129 }
4130 else if (n < 0)
4131 {
(gdb) info locals
it = {
window = 1213260232,
w = 0x850e1c8,
f = 0x8495428,
method = 0x8061ea0 <next_element_from_buffer>,
stop_charpos = 150,
end_charpos = 150,
s = 0x0,
string_nchars = 0,
region_beg_charpos = -1,
region_end_charpos = -1,
redisplay_end_trigger_charpos = 0,
multibyte_p = 1,
header_line_p = 0,
string_from_display_prop_p = 0,
dp = 0x8492e80,
dpvec = 0x0,
dpend = 0x0,
dpvec_char_len = 0,
saved_face_id = 0,
ctl_chars = {0 <repeats 16 times>},
current = {
pos = {
charpos = 150,
bytepos = 150
},
overlay_string_index = -1,
string_pos = {
charpos = -1,
bytepos = -1
},
dpvec_index = -1
},
overlay_strings = {0, 0, 0},
n_overlay_strings = 0,
string = 405269724,
stack = {{
stop_charpos = 0,
face_id = 0,
---Type <return> to continue, or q <return> to quit---
string = 0,
pos = {
pos = {
charpos = 0,
bytepos = 0
},
overlay_string_index = 0,
string_pos = {
charpos = 0,
bytepos = 0
},
dpvec_index = 0
},
end_charpos = 0,
string_nchars = 0,
area = LEFT_MARGIN_AREA,
multibyte_p = 0,
string_from_display_prop_p = 0,
display_ellipsis_p = 0,
space_width = 0,
voffset = 0,
font_height = 0
}, {
stop_charpos = 0,
face_id = 0,
string = 0,
pos = {
pos = {
charpos = 0,
bytepos = 0
},
overlay_string_index = 0,
string_pos = {
charpos = 0,
bytepos = 0
},
dpvec_index = 0
},
end_charpos = 0,
---Type <return> to continue, or q <return> to quit---
string_nchars = 0,
area = LEFT_MARGIN_AREA,
multibyte_p = 0,
string_from_display_prop_p = 0,
display_ellipsis_p = 0,
space_width = 0,
voffset = 0,
font_height = 0
}},
sp = 0,
selective_display_ellipsis_p = 1,
ctl_arrow_p = 1,
selective = 0,
what = IT_EOB,
face_id = 0,
face_box_p = 0,
start_of_box_run_p = 0,
end_of_box_run_p = 0,
overlay_strings_at_end_processed_p = 1,
glyph_not_available_p = 0,
starts_in_middle_of_char_p = 0,
face_before_selective_p = 0,
base_face_id = 0,
c = 46,
len = 1,
cmp_id = 0,
cmp_len = 0,
char_to_display = 46,
image_id = 0,
space_width = 405269724,
voffset = 0,
font_height = 405269724,
object = 1211261376,
position = {
charpos = 150,
bytepos = 150
},
truncate_lines_p = 0,
tab_width = 8,
---Type <return> to continue, or q <return> to quit---
truncation_pixel_width = 0,
continuation_pixel_width = 0,
first_visible_x = 0,
last_visible_x = 560,
last_visible_y = 52,
extra_line_spacing = 0,
glyph_row = 0x85ba0f8,
area = TEXT_AREA,
nglyphs = 1,
pixel_width = 7,
ascent = 10,
descent = 3,
max_ascent = 10,
max_descent = 3,
phys_ascent = 1,
phys_descent = 0,
max_phys_ascent = 10,
max_phys_descent = 3,
current_x = 189,
continuation_lines_width = 0,
current_y = 0,
vpos = 0,
hpos = 27
}
w = (struct window *) 0x850e1c8
start = {
charpos = 674853048,
bytepos = 1
}
tem = 1
this_scroll_margin = 13
preserve_y = 13
vscrolled = 0
==================== end gdb output ====================
--
Sergey Vlasov
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2003-03-21 16:48 infinite loop in scroll-up Sergey Vlasov
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