Hi.
I've since reported the error to the maintainer of Ncurses and to the
slackware community, but it seems the general understanding of ncurses
packaging is low when I ask around.
Anyway. Here is an excerpt from parts of the dialog with the maintainer.
Might be useful for someone for reference.
<quote>
I've rebuilt with a 20201219 snapshot.
It does not fix the issue. Problem remains.
But a bit clearer.
Investigated the win->line allocation.
After initscr the value seems ok.
(gdb) print stdscr->_line[0]
$14 = {text = 0xce2a10, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print stdscr->_line[1]
$15 = {text = 0xce2ed0, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print stdscr->_line[2]
$16 = {text = 0xce3390, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print stdscr->_line[3]
$17 = {text = 0xce3850, firstchar = 0, lastchar = 301, oldindex = 0}
Breakpoint 1, main (ac=2, av=0x7ffffffefb28) at mconf.c:1000
1000 signal(SIGINT, sig_handler);
(gdb) c
Continuing.
Breakpoint 3, init_dialog (backtitle=backtitle@entry=0x0) at
lxdialog/util.c:319
319 initscr(); /* Init curses */
(gdb) c
Continuing.
Breakpoint 4, initscr () at ../ncurses/./base/lib_initscr.c:56
56 START_TRACE();
(gdb) c
Continuing.
Hardware watchpoint 5: stdscr->_line[1]->text
Old value = <unreadable>
New value = (chtype *) 0xce2ed0
_nc_setupscreen_sp (spp=0x7ffffffef938, slines=49, scolumns=302,
output=0x7ffff7f236a0 <_IO_2_1_stdout_>, filtered=0, slk_format=0) at
../ncurses/./base/lib_set_term.c:744
744 sp->_prescreen = FALSE;
(gdb) c
Continuing.
Hardware watchpoint 5: stdscr->_line[1]->text
Old value = (chtype *) 0xce2ed0
New value = (chtype *) 0x100ce2ed0
0x0000000000415c3f in attr_clear (win=0xce2690, height=49,
width=width@entry=302, attr=2097408) at lxdialog/util.c:247
247 for (i = 0; i < height; i++) {
(gdb) n
248 wmove(win, i, 0);
(gdb) n
249 for (j = 0; j < width; j++)
(gdb) n
250 waddch(win, ' ');
(gdb) print i
$28 = 0
(gdb) print j
$29 = 0
And at the segfault...
(gdb) print win->_line[0]
$9 = {text = 0xce2a10, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print win->_line[1]
$10 = {text = 0x100ce2ed0, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print win->_line[2]
$11 = {text = 0xce3390, firstchar = 0, lastchar = 301, oldindex = 0}
(gdb) print win->_line[3]
$12 = {text = 0xce3850, firstchar = 0, lastchar = 301, oldindex = 0}
Seems the line text pointer is botched by something.
</quote>
So in summary a pointer gets corrupted with the same operand value with
what seems to be a bitwise "or" macro operation.
On 1/8/21 9:46 AM, Michael Olbrich wrote:
On Fri, Dec 25, 2020 at 09:08:14PM +0100, Christian Melki wrote:
Ptxdist seems to assume things about the ncurses local build that doesn't
always turn up to be usable.
I use a ncurses-6.2 build in Slackware. Pretty normal build.
mconf headers point to the ncurses library, not ncursesw.
mconf gets built with:
-O2 -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600
and is linked with:
linux-vdso.so.1 (0x00007ffcd5f30000)
libncurses.so.6 => /lib64/libncurses.so.6 (0x00007f6914c68000)
libtinfo.so.6 => /lib64/libtinfo.so.6 (0x00007f6914c37000)
libc.so.6 => /lib64/libc.so.6 (0x00007f6914a52000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f6914a4d000)
/lib64/ld-linux-x86-64.so.2 (0x00007f6914cbd000)
And mconf segfaults with:
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7f84b9a in waddch () from /lib64/libncurses.so.6
(gdb) bt
#0 0x00007ffff7f84b9a in waddch () from /lib64/libncurses.so.6
#1 0x0000000000415c78 in attr_clear (win=0xcdf820, height=49, width=299,
attr=<optimized out>) at lxdialog/util.c:250
#2 0x0000000000415cfc in dialog_clear () at lxdialog/util.c:262
#3 0x0000000000416274 in init_dialog (backtitle=backtitle@entry=0x0) at
lxdialog/util.c:336
#4 0x000000000040272c in main (ac=2, av=0x7ffffffefd78) at mconf.c:1017
... second loop pass. Height = 0 passes the width loop. Height = 1, Width =
0 segfaults.
(gdb) print j
$8 = 298
(gdb) n
250 waddch(win, ' ');
(gdb) n
249 for (j = 0; j < width; j++)
(gdb) n
247 for (i = 0; i < height; i++) {
(gdb) n
248 wmove(win, i, 0);
(gdb) print i
$9 = 1
(gdb) n
249 for (j = 0; j < width; j++)
(gdb) n
250 waddch(win, ' ');
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
I am not sure what to blame here or if I understand things.
Or if it's resonable that ncurses should explode like this.
Seems pkg-config cflags answers:
pkg-config --cflags ncurses -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600
But if I understand things >= 600 = wide char header?
the pkg-config answers the same for ncursesw.
I see the same pkg-config results here on Debian.
I have no idea how this is supposed to work.
So the program will compile and link just fine.
If I use xterm and rxvt as $TERM the mconf program crashes, but is fine with
vt100.
Is this related to ext-colors support somehow?
If I force the program to link with ncursesw, then all is fine.
Hmmm, what happens if you add -DNCURSES_WIDECHAR=0 to the cflags and link
with ncurses? Does it work correctly now?
I think this is controlled through the headers with the XOPEN_SOURCE
level unless specified otherwise (ifndef)?
In curses.h:
#ifndef NCURSES_WIDECHAR
#if defined(_XOPEN_SOURCE_EXTENDED) || (defined(_XOPEN_SOURCE) &&
(_XOPEN_SOURCE - 0 >= 500))
#define NCURSES_WIDECHAR 1
#else
#define NCURSES_WIDECHAR 0
#endif
#endif /* NCURSES_WIDECHAR */
But yes. Your suggestion works.
I have never needed widechar for ptxdist.
Anyway.
This is what you meant?
Could be useful for forcibly disable wide char extensions if you're
linking with ncurses only.
--- configure.ac~ 2020-12-16 16:42:25.000000000 +0100
+++ configure.ac 2021-01-08 16:50:08.440868020 +0100
@@ -68,7 +68,7 @@
[AC_MSG_ERROR([ncurses headers not found])])
AC_SUBST(CURSES_LOC)
-CPPFLAGS="${NCURSES_CFLAGS}"
+CPPFLAGS="${NCURSES_CFLAGS} -DNCURSES_WIDECHAR=0"
AC_ARG_WITH(ncurses, AS_HELP_STRING([--with-ncurses],[Include path to
the ncurses headers]),
[
if test "x$withval" != "xyes"; then
My best guess is that the terminal is ext-color, program gets built with
wchar-support but linked with ncurses.
This probably shouldn't explode in ncurses, but I think it's also a
misconfiguration build.
I would suggest that ptxdist uses ncursesw + headers if found and ncurses
without wchar if not found.
Kernel seems to prefer something similar?
https://elixir.bootlin.com/linux/v5.10.2/source/scripts/kconfig/mconf-cfg.sh
The whole ncurses handling in configure.ac should probably cleaned up and
simplified.
Michael
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