[M3devel] cm3 is broken: More info

[Rodney M. Bates]

There are at least two problems.  The runaway recursion happens in RTExFrame.m3:175

   PROCEDURE InvokeHandler (f: Frame;  READONLY a: RT0.RaiseActivation) RAISES ANY =
     VAR p := LOOPHOLE (f, PF1);
     BEGIN
       IF DEBUG THEN
         PutExcept ("INVOKE HANDLER", a);
         RTIO.PutText ("  frame=");  RTIO.PutAddr (f);
         RTIO.PutText ("  class=");  RTIO.PutInt (f.class);
         RTIO.PutText ("\n");
         RTIO.Flush ();
       END;
       RTThread.SetCurrentHandlers (f.next); (* cut to the new handler *)
       p.info := a;                         (* copy the exception to the new frame *)
       <* ASSERT p.jmpbuf # NIL *>
------^^^^^^^^^^^^^^^^^^^^^^^^^^^ This assertion fails and tries to raise another fault.
       Csetjmp.ulongjmp (p.jmpbuf, 1);      (* and jump... *)
       RAISE OUCH;
     END InvokeHandler;

   (m3gdb) frame 0
   #0  InvokeHandler (f=16_00007fff509f4af0, a=
       RECORD exception = 16_00007ff696883aa0; arg = 16_00000000013e4ae8; module = 16_00007ff6968a3060; line = 50; pc = NIL; info0 = NIL; info1 = NIL; un_except = NIL; un_arg = NIL;  END) at ../src/runtime/ex_frame/RTExFrame.m3:175
   175	    <* ASSERT p.jmpbuf # NIL *>
   (m3gdb) p p.jmpbuf
   $31 = NIL
--------^^^
   (m3gdb)


The original problem starts in FSPosix.m3:328, when cm3.cfg is not found:

   PROCEDURE Status(pn: Pathname.T): File.Status RAISES {OSError.E} =
     VAR status: File.Status;  fname := M3toC.SharedTtoS(pn);
     BEGIN
       IF CStatus(fname, status) < 0 THEN Fail(pn, fname); END;
---------^^^^^^^^^^^^^^^^^^^^^^
       M3toC.FreeSharedS(pn, fname);
       RETURN status
     END Status;

   (m3gdb)
   #6  0x00007ff696593c14 in Status (pn=16_00000000013e4ac0, _result=RECORD type = 16_0000000000000001; modificationTime = ; size = 1;  END)
       at ../src/os/POSIX/FSPosix.m3:328
   328	    IF CStatus(fname, status) < 0 THEN Fail(pn, fname); END;
   (m3gdb) p pn
   $30 = (*16_00000000013e4ac0*) "./cm3.cfg"
--------------------------------^^^^^^^^^^^
   (m3gdb)

I have a cm3.cfg beside cm3, where it should be.  Could the current directory be wrong?

Also, I notice one other thing, that probably isn't part of this problem, but maybe needs
to be fixed.  Fail, when called from Status, uses Cerrno.GetErrno in a separate call,
after the failing CStatus above.  Obviously not thread safe.  Does it matter here?
As I recall from many years ago, there was a change in C library that provided a thread
safe alternative to this, and I even think I had to change something in pm3 or SRC to
adapt to it.  Do we care?

   PROCEDURE Fail(p: Pathname.T;  f: Ctypes.char_star) RAISES {OSError.E} =
     VAR err := Cerrno.GetErrno();
---------------^^^^^^^^^^^^^^^^^
     BEGIN
       M3toC.FreeSharedS(p, f);
       OSErrorPosix.Raise0(err);
     END Fail;



On 08/19/2015 05:20 PM, Rodney M. Bates wrote:
> As of a recent pull from modula3-cm3, done around 16:00 CDT, cm3 is going into
> runaway recursion trying to report a fault.  This happens immediately upon
> running it, before it produces any output.
>
> Here is one cycle of the backtrace:
>
> #1745 0x00007fd9b0b0d935 in _m3_fault (arg=5600) from /usr/local/cm3-uniboot/bin/../lib/libm3core.so.5
> #1746 0x00007fd9b0b0d05d in InvokeHandler (f=16_00007fff488bcc20, a=
>      RECORD exception = 16_00007fd9b0d4b780; arg = 16_000000000000001d; module = 16_00007fd9b0d62d40; line = 14; pc = NIL; info0 = NIL; info1 = NIL; un_except = NIL; un_arg = NIL;  END) at ../src/runtime/ex_frame/RTExFrame.m3:175
> #1747 0x00007fd9b0b0cef1 in ResumeRaise (a=
>      RECORD exception = 16_00007fd9b0d4b780; arg = 16_000000000000001d; module = 16_00007fd9b0d62d40; line = 14; pc = NIL; info0 = NIL; info1 = NIL; un_except = NIL; un_arg = NIL;  END) at ../src/runtime/ex_frame/RTExFrame.m3:145
> #1748 0x00007fd9b0b0ccfe in Raise (act=
>      RECORD exception = 16_00007fd9b0d4b780; arg = 16_000000000000001d; module = 16_00007fd9b0d62d40; line = 14; pc = NIL; info0 = NIL; info1 = NIL; un_except = NIL; un_arg = NIL;  END) at ../src/runtime/ex_frame/RTExFrame.m3:91
> #1749 0x00007fd9b0ae9693 in Raise (ex=16_00007fd9b0d4b780, arg=16_000000000000001d, module=16_00007fd9b0d62d40, line=14)
>      at ../src/runtime/common/RTHooks.m3:79
> #1750 0x00007fd9b0ae9951 in Self () at ../src/runtime/common/RuntimeError.m3:14
> #1751 0x00007fd9b0ae96ef in ReportFault (module=16_00007fd9b0d6a520, info=5600) at ../src/runtime/common/RTHooks.m3:98
> #1752 0x00007fd9b0b0d935 in _m3_fault (arg=5600) from /usr/local/cm3-uniboot/bin/../lib/libm3core.so.5
>
> So far, I haven't had the patience to keep hitting return until I get to the bottom of it.
>

-- 
Rodney Bates
rodney.m.bates at acm.org