On Thu Feb 05 2015 at 4:36:30 PM Francis Giraldeau < francis.girald...@gmail.com> wrote:
> I need to access frame members from within a signal handler for tracing > purpose. My first attempt to access co_filename was like this (omitting > error checking): > > PyFrameObject *frame = PyEval_GetFrame(); > PyObject *ob = PyUnicode_AsUTF8String(frame->f_code->co_filename) > char *str = PyBytes_AsString(ob) > > However, the function PyUnicode_AsUTF8String() calls PyObject_Malloc(), > which is not reentrant. If the signal handler nest over PyObject_Malloc(), > it causes a segfault, and it could also deadlock. > > Instead, I access members directly: > char *str = PyUnicode_DATA(frame->f_code->co_filename); > size_t len = PyUnicode_GET_DATA_SIZE(frame->f_code->co_filename); > > Is it safe to assume that unicode objects co_filename and co_name are > always UTF-8 data for loaded code? I looked at the PyTokenizer_FromString() > and it seems to convert everything to UTF-8 upfront, and I would like to > make sure this assumption is valid. > The faulthandler module calls into Python/traceback.c in signal context which has some low level code for extracting something useful from PyUnicode objects without triggering a conversion: https://hg.python.org/cpython/file/f1a82e949fb8/Python/traceback.c#l531 That code is written to write output to a fd. It's much more useful for signal handler tracing data collection from a signal handler if you refactor it to dump its output into a preallocated char* buffer. -gps > > Thanks! > > Francis > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > greg%40krypto.org >
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