[LinuxCNC/linuxcnc Issue#116] loading a program changes optional stop setting

#1 – jepler 于 2016-07-22

I used gdb to find where optional stop is being set back to true. It happens while task is processing a message of type EMCTASKPLAN_INIT

Hardware watchpoint 3: *$1
Old value = false
New value = true
(gdb) where
#0  INIT_CANON () at emc/task/emccanon.cc:2474
#1  0x00007f712c3ee65a in Interp::init (this=0x11b8c50)
    at emc/rs274ngc/rs274ngc_pre.cc:814
#2  0x0000000000413bca in emcTaskPlanInit () at emc/task/emctask.cc:440
#3  0x000000000041e77f in emcTaskIssueCommand (cmd=0x118d7f0)
    at emc/task/emctaskmain.cc:2301
#4  0x0000000000411993 in emcTaskPlan () at emc/task/emctaskmain.cc:1228
#5  main (argc=, argv=)
    at emc/task/emctaskmain.cc:3309

All UIs using the Python linuxcnc module recently had their behavior change, by adding a call to resetinterpreter to programopen. At the time I made this change, I didn’t realize this consequence of it (see commit 27d3822f):

static PyObject reset_interpreter(pyCommandChannel s, PyObject *o) {
    EMCTASKPLAN_INIT m;
    emcSendCommand(s, m);
    PyINCREF(PyNone);
    return Py_None;
}
static PyObject program_open(pyCommandChannel s, PyObject *o) {
    if(!reset_interpreter(s, o))
        return NULL;
    EMCTASKPLAN_OPEN m;
    char *file;
    int len;
    if(!PyArg_ParseTuple(o, "s#", &file, &len)) return NULL;
    if(unsigned(len) > sizeof(m.file) - 1) {
        PyErrFormat(PyExcValueError, "File name limited to %zu characters", sizeof(m.file) - 1);
        return NULL;
    }
    strcpy(m.file, file);
    emcSendCommand(s, m);
    PyINCREF(PyNone);
    return Py_None;
}

#2 – pkmcnc 于 2016-07-25

https://github.com/LinuxCNC/linuxcnc/commit/92ca9a20cc2e19facfb31d7066340acc1120f3ae also fixed a dangerous bug with spontaneous TLO reset.