Axel Rose has noted (SourceForge) that MacPerl crashes under certain
conditions if the script is stopped by Menu->StopScript or the
key-board equivalent. I can confirm this behaviour.
The condition is hard to define but involves a script of the general form:
$d = HTTP::Daemon();
while (1) {
$connection = $d->accept;
if ($connection) {
....
do stuff
....
}
$connection->close;
}
I have not been able to contrive a simple script which demonstrates
the problem. However with the complex and length script concerned
(not mine I hasten to add) MacPerl crashes every time on closing with
'StopScript'.
The MacsBugs report is attached, and again is exactly the same for
every crash. So the culprit without question is GUSITimer::Kill().
What is far from clear to me is how or why GUSITime::Kill() gets
involved, or, for that matter, what actually happens when
Menu->StopScript is hit.
This much is clear: fmStopScrip sets gAborting to 'true'. OK, that
sounds reasonable.
Now the fun starts: gAborting occurs seven times in 'macperl' as follows.
1) MPAppleEvents.c"; Line 264: gAborting = true;
2) MPConsole.cp"; Line 625: if (gAborting && gRunningPerl) {
3) MPConsole.cp"; Line 630: gAborting = false;
4) MPFile.c"; Line 193: gAborting = true;
5) MPGlobals.h"; Line 300: EXTERN Boolean gAborting;
6) MPMain.c"; Line 648: gAborting = true;
7) MPScript.c"; Line 647: gAborting = false;
Number 1 occurs in 'DoStopScript()' which is called by AppleEvents. OK.
Number 2 is more complicated and occurs in MPConsoleSpin() which is
the procedure for:
GUSISetHook(Gusi_SpinHook, (GUSIHook)MPConsoleSpin);
So far as I can determine GUSISetHook is called only once in
'InitConsole' -- all other instances have been commented out. I can
find no reason to suppose it (or MPConsoleSpin() for that matter)
gets called in response to a 'Menu->StopScript' hit. Does anybody
agree or disagree?
Number 3 occurs also in MPConsoleSpin(), the first few lines of which read:
if (gAborting && gRunningPerl) {
ResetConsole();
raise(SIGINT);
// don't raise SIGINT again
gAborting = false;
}
So -- let us suppose by some mechanism yet to be explained
MPConsoleSpin() DOES get called. What happens in ResetConsole()?
Well, it is:
for (DPtr doc = gConsoleList; doc; doc = doc->u.cons.next)
if (doc->u.cons.selected)
doc->u.cons.selected = false;
gWantConsoleInput = false;
ShowWindowStatus();
all of which looks reasonable but none of which seems to be involved
in any way with the SpinCursor.
Number 4 occurs in DoQuit() and as such sheds no further light on the matter.
Number 5 is in the header file which we can ignore here.
Number 6 is where gAborting is set by fmStopScript (i.e. where we started).
Number 7 occurs in CleanUpPerl(), which sheds no light on the proceedings.
So the questions that occurs to me are firstly: 'How is StopScript
supposed to work?' and secondly 'How or why does GUSITime::Kill() get
called?'
The matter is of this importance. The script which causes the crash
works fine on Windows and Linux and (I believe) on Mac OSX. On those
three platforms it also enjoys nice GUIs. On the Classic Mac it just
crashes and no-one can get a GUI to work with it anyway.
That's rather a pity, and I would like to try to help 'mend the
nuisance' (as Peyps put it in his diary when his neighbour
inadvertently filled up his cellar with sewage). I believe Axel feels
much the same way.
Alan Fry
--------
Disassembling PowerPC code from 168CCD38
GUSITimer::Kill()
+00024 168CCD38 bl RmvTime ;
0x168FE048 | 48031311
+00028 168CCD3C lwz RTOC,0x0014(SP)
| 80410014
+0002C 168CCD40 lwz r4,0x001A(r31)
| 809F001A
+00030 168CCD44 b GUSITimer::Kill()+0004C ;
0x168CCD60 | 4800001C
+00034 168CCD48 cmplw r3,r31
| 7C03F840
+00038 168CCD4C bne GUSITimer::Kill()+00048 ;
0x168CCD5C | 40820010
+0003C 168CCD50 lwz r0,0x001E(r31)
| 801F001E
+00040 168CCD54 stw r0,0x0000(r4)
| 90040000
+00044 168CCD58 b GUSITimer::Kill()+00058 ;
0x168CCD6C | 48000014
+00048 168CCD5C addi r4,r3,0x001E
| 3883001E
+0004C 168CCD60 *lwz r3,0x0000(r4)
| 80640000
+00050 168CCD64 cmplwi r3,0x0000
| 28030000
+00054 168CCD68 bne GUSITimer::Kill()+00034 ;
0x168CCD48 | 4082FFE0
+00058 168CCD6C li r0,0x0000
| 38000000
+0005C 168CCD70 stw r0,0x001E(r31)
| 901F001E
+00060 168CCD74 stw r0,0x001A(r31)
| 901F001A
+00064 168CCD78 lwz r0,0x0048(SP)
| 80010048
+00068 168CCD7C addi SP,SP,0x0040
| 38210040
+0006C 168CCD80 lwz r31,-0x0004(SP)
| 83E1FFFC
+00070 168CCD84 mtlr r0 ; LR =
0x0008 | 7C0803A6
