[M3devel] cm3 is broken: More info

[Rodney M. Bates]

On 08/22/2015 11:33 AM, Rodney M. Bates wrote:
> 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?

A bit more info:

   (m3gdb) down
   #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 Process.GetWorkingDirectory()
   $32 = (*16_0000000001420170*) "/home/rodney/proj/m3/exp/trytemp/src"
--------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   (m3gdb)

This is where I ran cm3 from.


>
> 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