Re: [PATCH] Add isys.traceback(), which generates a traceback with no exception.

[David Cantrell <dcantrell redhat com>]

pjones wrote:
> Chris asked for this to help with his traceback handling fixups.  It
> generates a traceback object at the current location, but doesn't raise
> an exception.
> ---
>  isys/isys.c  |   39 +++++++++++++++++++++++++++++++++++++++
>  isys/isys.py |   18 ++++++++++++++++++
>  2 files changed, 57 insertions(+), 0 deletions(-)
> 
> diff --git a/isys/isys.c b/isys/isys.c
> index b3466ab..3b17b6f 100644
> --- a/isys/isys.c
> +++ b/isys/isys.c
> @@ -132,6 +132,7 @@ static PyObject * doGetBlkidData(PyObject * s, PyObject * args);
>  static PyObject * doGetDeviceByToken(PyObject *s, PyObject *args);
>  static PyObject * doIsCapsLockEnabled(PyObject * s, PyObject * args);
>  static PyObject * doGetLinkStatus(PyObject * s, PyObject * args);
> +static PyObject * doTraceback(PyObject *self, PyObject *args, PyObject *kwds);
>  
>  static PyMethodDef isysModuleMethods[] = {
>      { "ejectcdrom", (PyCFunction) doEjectCdrom, METH_VARARGS, NULL },
> @@ -179,6 +180,7 @@ static PyMethodDef isysModuleMethods[] = {
>      { "getdevicebytoken", (PyCFunction) doGetDeviceByToken, METH_VARARGS, NULL },
>      { "isCapsLockEnabled", (PyCFunction) doIsCapsLockEnabled, METH_VARARGS, NULL },
>      { "getLinkStatus", (PyCFunction) doGetLinkStatus, METH_VARARGS, NULL },
> +    { "traceback", (PyCFunction) doTraceback, METH_VARARGS|METH_KEYWORDS, NULL },
>      { NULL, NULL, 0, NULL }
>  } ;
>  
> @@ -932,4 +934,41 @@ static PyObject * doGetLinkStatus(PyObject * s, PyObject * args) {
>      return PyBool_FromLong(0);
>  }
>  
> +#include "frameobject.h"
> +
> +static PyObject *
> +doTraceback(PyObject *self, PyObject *args, PyObject *kwds)
> +{
> +	char *kwlist[] = {"frame", "previous", NULL};
> +	PyFrameObject *frame = NULL;
> +	PyThreadState *tstate;
> +	PyTracebackObject *intb = NULL;
> +	PyTracebackObject *oldtb = NULL;
> +	PyTracebackObject *tb;
> +
> +	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:traceback",
> +			kwlist, &frame, &intb))
> +		return NULL;
> +
> +	tstate = PyThreadState_GET();
> +	oldtb = (PyTracebackObject *)tstate->curexc_traceback;
> +
> +	/* this has side effects we have to undo afterwards. */
> +	if (PyTraceBack_Here(frame) < 0)
> +		return NULL;
> +
> +	tb = (PyTracebackObject *)tstate->curexc_traceback;
> +
> +	/* PyTraceBack_Here makes the new traceback be the "current"
> +	 * traceback, which isn't really desired */
> +	tstate->curexc_traceback = (PyObject *)oldtb;
> +
> +	/* PyTraceBack_Here adds the "current" traceback as this traceback's
> +	 * "next" traceback, which we really don't want. */
> +	Py_XINCREF(intb);
> +	tb->tb_next = intb;
> +
> +	return (PyObject *)tb;
> +}
> +
>  /* vim:set shiftwidth=4 softtabstop=4: */
> diff --git a/isys/isys.py b/isys/isys.py
> index 05e0806..db2aa4e 100755
> --- a/isys/isys.py
> +++ b/isys/isys.py
> @@ -946,6 +946,24 @@ def getMacAddress(dev):
>      device_macaddr = device_props_iface.Get(NM_MANAGER_IFACE, "HwAddress")
>      return device_macaddr.upper()
>  
> +def traceback(skipframes=0):
> +    frames = []
> +    n = skipframes + 1
> +    while True:
> +        try:
> +            frames.append(sys._getframe(n))
> +            n += 1
> +        except ValueError:
> +            break
> +
> +    tb = None
> +    for frame in frames:
> +        if tb is None:
> +            tb = _isys.traceback(frame)
> +        else:
> +            tb = _isys.traceback(frame, tb)
> +    return tb
> +
>  # Determine if a network device is a wireless device.
>  def isWireless(dev):
>      if dev == '' or dev is None:

I prefer dlehman's Python implementation over this new isys code.

-- 
David Cantrell <dcantrell redhat com>
Red Hat / Honolulu, HI