Package: xgammon
Version: 0.99.1128-3
Severity: important
Tags: patch
-- System Information:
Debian Release: squeeze/sid
APT prefers karmic-updates
APT policy: (500, 'karmic-updates'), (500, 'karmic-security'), (500, 'karmic')
Architecture: i386 (i686)
Kernel: Linux 2.6.31-17-generic (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages xgammon depends on:
ii libc6 2.10.1-0ubuntu15 GNU C Library: Shared libraries
ii libice6 2:1.0.5-1 X11 Inter-Client Exchange library
ii libsm6 2:1.1.0-2 X11 Session Management library
ii libx11-6 2:1.2.2-1ubuntu1 X11 client-side library
ii libxaw7 2:1.0.6-1 X11 Athena Widget library
ii libxext6 2:1.0.99.1-0ubuntu4 X11 miscellaneous extension librar
ii libxt6 1:1.0.5-3ubuntu1 X11 toolkit intrinsics library
xgammon recommends no packages.
xgammon suggests no packages.
-- no debconf information
It takes a while to get this SIGSEGV to occur. On my machine,
running a computer-vs-computer game it takes about 30 minutes.
The failure is due to an overflow of the DialogText string
in diawin.c. I recompiled the source with debugging turned on
and found the following:
Failing source line: 165 while (DialogText[i] != '\n') i++;
Variable: i = 38080
lastPos = 59986
After inserting some debug printf statements in the code, I
determined that with XtNeditType = XawtextAppend, the call
to XawTextReplace is failing with a non-zero return code.
The Athena Documentation says that XawTextReplace on an
XawtextAppend object can only replace the text at the end
of the buffer. Since this XawTextReplace is trying to
delete data at the beginning of the buffer, it fails.
To fix the problem, I put the object into XawtextEdit while
doing the XawTextReplace and then set it back to XawtextAppend.
This fixes the problem. I also found another problem with
the line: while (DialogText[i] != '\n') i++;
This line assumes that we are referencing DialogText. But
this is only true if where == LOWER. I also fixed that bug.
Here is the complete AppendDialogText that works.
void AppendDialogText (int where, char *s)
{
XawTextPosition i, lastPos;
XawTextBlock textblock, nullblock;
Widget w;
char *text_buffer;
XawTextEditType type;
if (where == UPPER) {
w = Player[0].X11Set.tournament_display;
text_buffer = TournamentText;
} else if (where == LOWER) {
w = Player[0].X11Set.text_display;
text_buffer = DialogText;
} else {
fprintf (stderr, "unkown widget for AppendDialogText ()\n");
return;
}
if (!s || !strcmp(s, "")) return;
textblock.firstPos = 0;
textblock.length = strlen(s);
textblock.ptr = s;
lastPos = TextGetLastPos (w);
if (textblock.length > DIALOGSIZE) {
fprintf (stderr, "xgammon error: cannot display string in
dialogue window\n\
string has %d bytes; dialogue window size limit is %d
bytes\n",
textblock.length, DIALOGSIZE);
return;
}
if (lastPos + textblock.length > DIALOGSIZE) {
nullblock.firstPos = 0;
nullblock.length = 0;
nullblock.ptr = "";
i = textblock.length - (DIALOGSIZE - lastPos);
if (i < 0.9*DIALOGSIZE) i += 0.1*DIALOGSIZE;
while (text_buffer[i] != '\n') i++;
XtVaGetValues(w, XtNeditType, (XtArgVal) &type, NULL);
XtVaSetValues(w, XtNeditType, XawtextEdit, NULL);
XawTextReplace (w, 0, i, &nullblock);
XtVaSetValues(w, XtNeditType, (XtArgVal) type, NULL);
lastPos = TextGetLastPos (w);
}
XawTextReplace (w, lastPos, lastPos, &textblock);
InputPos = TextGetLastPos (w);
if (where == UPPER) lt = InputPos;
XawTextSetInsertionPoint (w, InputPos);
if (gammon_resource.protokol) fprintf(protokol_file, "%s", s);
if (gammon_resource.other_display) {
if (where == UPPER) {
w = Player[1].X11Set.tournament_display;
text_buffer = TournamentText;
} else if (where == LOWER) {
w = Player[1].X11Set.text_display;
text_buffer = DialogText;
} else {
fprintf (stderr, "unkown widget for AppendDialogText ()\n");
return;
}
if (!s || !strcmp(s, "")) return;
textblock.firstPos = 0;
textblock.length = strlen(s);
textblock.ptr = s;
lastPos = TextGetLastPos (w);
if (textblock.length > DIALOGSIZE) {
fprintf (stderr, "xgammon error: cannot display string in
dialogue window\n\
string has %d bytes; dialogue window size limit is %d
bytes\n",
textblock.length, DIALOGSIZE);
return;
}
if (lastPos + textblock.length > DIALOGSIZE) {
nullblock.firstPos = 0;
nullblock.length = 0;
nullblock.ptr = "";
i = textblock.length - (DIALOGSIZE - lastPos);
if (i < 0.9*DIALOGSIZE) i += 0.1*DIALOGSIZE;
while (text_buffer[i] != '\n') i++;
XtVaGetValues(w, XtNeditType, (XtArgVal) &type, NULL);
XtVaSetValues(w, XtNeditType, XawtextEdit, NULL);
XawTextReplace (w, 0, i, &nullblock);
XtVaSetValues(w, XtNeditType, (XtArgVal) type, NULL);
lastPos = TextGetLastPos (w);
}
XawTextReplace (w, lastPos, lastPos, &textblock);
InputPos = TextGetLastPos (w);
if (where == UPPER) lt = InputPos;
XawTextSetInsertionPoint (w, InputPos);
}
}
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