X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decode.c;h=76f6317eb51227761e30687ac0e73422f3f66f41;hp=da8624a4a40f125784398c64da9ca7a9f1dd45b0;hb=f7313eeaf3b64fafa792a225a2b70c745e8d5cc6;hpb=104260684195431f4023acad96ba37787a14a6ab diff --git a/decode.c b/decode.c index da8624a..76f6317 100644 --- a/decode.c +++ b/decode.c @@ -22,6 +22,7 @@ #include #include #include +#include /* Re-define some string functions for Python >= 3.0. */ #if PY_VERSION_HEX >= 0x03000000 @@ -33,6 +34,19 @@ /* The list of protocol decoders. */ GSList *list_pds = NULL; +/* + * Here's a quick overview of Python/C API reference counting. + * + * Check the Python/C API docs for what type of reference a function returns. + * + * - If it returns a "new reference", you're responsible to Py_XDECREF() it. + * + * - If it returns a "borrowed reference", you MUST NOT Py_XDECREF() it. + * + * - If a function "steals" a reference, you no longer are responsible for + * Py_XDECREF()ing it (someone else will do it for you at some point). + */ + /** * Initialize libsigrokdecode. * @@ -85,7 +99,7 @@ GSList *sigrokdecode_list_decoders(void) * * TODO: @param entries. * - * @return LIBSIGROKDECODE_OK upon success, a (negative) error code otherwise. + * @return SIGROKDECODE_OK upon success, a (negative) error code otherwise. * The 'outstr' argument points to a malloc()ed string upon success. */ static int h_str(PyObject *py_res, PyObject *py_func, PyObject *py_mod, @@ -93,37 +107,44 @@ static int h_str(PyObject *py_res, PyObject *py_func, PyObject *py_mod, { PyObject *py_str; char *str; + int ret; py_str = PyMapping_GetItemString(py_res, (char *)key); if (!py_str || !PyString_Check(py_str)) { - if (PyErr_Occurred()) - PyErr_Print(); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + goto err_h_decref_func; } + /* + * PyString_AsString()'s returned string refers to an internal buffer + * (not a copy), i.e. the data must not be modified, and the memory + * must not be free()'d. + */ if (!(str = PyString_AsString(py_str))) { - if (PyErr_Occurred()) - PyErr_Print(); - Py_DECREF(py_str); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + goto err_h_decref_str; } if (!(*outstr = strdup(str))) { - if (PyErr_Occurred()) - PyErr_Print(); - Py_DECREF(py_str); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_MALLOC; + ret = SIGROKDECODE_ERR_MALLOC; + goto err_h_decref_str; } - Py_DECREF(py_str); + Py_XDECREF(py_str); return SIGROKDECODE_OK; + +err_h_decref_str: + Py_XDECREF(py_str); +err_h_decref_func: + Py_XDECREF(py_func); +err_h_decref_mod: + Py_XDECREF(py_mod); + + if (PyErr_Occurred()) + PyErr_Print(); /* Returns void. */ + + return ret; } /** @@ -131,7 +152,7 @@ static int h_str(PyObject *py_res, PyObject *py_func, PyObject *py_mod, * * @param name TODO * - * @return LIBSIGROKDECODE_OK upon success, a (negative) error code otherwise. + * @return SIGROKDECODE_OK upon success, a (negative) error code otherwise. */ int sigrokdecode_load_decoder(const char *name, struct sigrokdecode_decoder **dec) @@ -141,33 +162,33 @@ int sigrokdecode_load_decoder(const char *name, int r; /* Get the name of the decoder module as Python string. */ - if (!(py_name = PyString_FromString(name))) { - PyErr_Print(); + if (!(py_name = PyString_FromString(name))) { /* NEWREF */ + PyErr_Print(); /* Returns void. */ return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ } /* "Import" the Python module. */ - if (!(py_mod = PyImport_Import(py_name))) { - PyErr_Print(); - Py_DECREF(py_name); + if (!(py_mod = PyImport_Import(py_name))) { /* NEWREF */ + PyErr_Print(); /* Returns void. */ + Py_XDECREF(py_name); return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ } - Py_DECREF(py_name); + Py_XDECREF(py_name); /* Get the 'register' function name as Python callable object. */ - py_func = PyObject_GetAttrString(py_mod, "register"); + py_func = PyObject_GetAttrString(py_mod, "register"); /* NEWREF */ if (!py_func || !PyCallable_Check(py_func)) { if (PyErr_Occurred()) - PyErr_Print(); - Py_DECREF(py_mod); + PyErr_Print(); /* Returns void. */ + Py_XDECREF(py_mod); return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ } /* Call the 'register' function without arguments, get the result. */ - if (!(py_res = PyObject_CallFunction(py_func, NULL))) { - PyErr_Print(); - Py_DECREF(py_func); - Py_DECREF(py_mod); + if (!(py_res = PyObject_CallFunction(py_func, NULL))) { /* NEWREF */ + PyErr_Print(); /* Returns void. */ + Py_XDECREF(py_func); + Py_XDECREF(py_mod); return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ } @@ -185,15 +206,15 @@ int sigrokdecode_load_decoder(const char *name, d->py_mod = py_mod; - Py_DECREF(py_res); - Py_DECREF(py_func); + Py_XDECREF(py_res); + Py_XDECREF(py_func); /* Get the 'decode' function name as Python callable object. */ - py_func = PyObject_GetAttrString(py_mod, "decode"); + py_func = PyObject_GetAttrString(py_mod, "decode"); /* NEWREF */ if (!py_func || !PyCallable_Check(py_func)) { if (PyErr_Occurred()) - PyErr_Print(); - Py_DECREF(py_mod); + PyErr_Print(); /* Returns void. */ + Py_XDECREF(py_mod); return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ } @@ -215,14 +236,14 @@ int sigrokdecode_load_decoder(const char *name, * @param outbuf TODO * @param outbuflen TODO * - * @return LIBSIGROKDECODE_OK upon success, a (negative) error code otherwise. + * @return SIGROKDECODE_OK upon success, a (negative) error code otherwise. */ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec, uint8_t *inbuf, uint64_t inbuflen, uint8_t **outbuf, uint64_t *outbuflen) { PyObject *py_mod, *py_func, *py_args, *py_value, *py_res; - int ret; + int r, ret; /* TODO: Use #defines for the return codes. */ @@ -240,70 +261,67 @@ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec, /* TODO: Error handling. */ py_mod = dec->py_mod; + Py_XINCREF(py_mod); py_func = dec->py_func; - - /* TODO: Really run Py_DECREF on py_mod/py_func? */ + Py_XINCREF(py_func); /* Create a Python tuple of size 1. */ - if (!(py_args = PyTuple_New(1))) { - PyErr_Print(); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + if (!(py_args = PyTuple_New(1))) { /* NEWREF */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + goto err_run_decref_func; } /* Get the input buffer as Python "string" (byte array). */ /* TODO: int vs. uint64_t for 'inbuflen'? */ - if (!(py_value = Py_BuildValue("s#", inbuf, inbuflen))) { - PyErr_Print(); - Py_DECREF(py_args); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + if (!(py_value = Py_BuildValue("s#", inbuf, inbuflen))) { /* NEWREF */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + goto err_run_decref_args; } - if (PyTuple_SetItem(py_args, 0, py_value) != 0) { - PyErr_Print(); - Py_DECREF(py_value); - Py_DECREF(py_args); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + /* + * IMPORTANT: PyTuple_SetItem() "steals" a reference to py_value! + * That means we are no longer responsible for Py_XDECREF()'ing it. + * It will automatically be free'd when the 'py_args' tuple is free'd. + */ + if (PyTuple_SetItem(py_args, 0, py_value) != 0) { /* STEAL */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + Py_XDECREF(py_value); /* TODO: Ref. stolen upon error? */ + goto err_run_decref_args; } - if (!(py_res = PyObject_CallObject(py_func, py_args))) { - PyErr_Print(); - Py_DECREF(py_value); - Py_DECREF(py_args); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + if (!(py_res = PyObject_CallObject(py_func, py_args))) { /* NEWREF */ + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + goto err_run_decref_args; } - if ((ret = PyObject_AsCharBuffer(py_res, (const char **)outbuf, - (Py_ssize_t *)outbuflen))) { - PyErr_Print(); - Py_DECREF(py_res); - Py_DECREF(py_value); - Py_DECREF(py_args); - Py_DECREF(py_func); - Py_DECREF(py_mod); - return SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + if ((r = PyObject_AsCharBuffer(py_res, (const char **)outbuf, + (Py_ssize_t *)outbuflen))) { + ret = SIGROKDECODE_ERR_PYTHON; /* TODO: More specific error? */ + Py_XDECREF(py_res); + goto err_run_decref_args; } - Py_DECREF(py_res); - // Py_DECREF(py_value); - Py_DECREF(py_args); - Py_DECREF(py_func); - Py_DECREF(py_mod); + ret = SIGROKDECODE_OK; - return SIGROKDECODE_OK; + Py_XDECREF(py_res); + +err_run_decref_args: + Py_XDECREF(py_args); +err_run_decref_func: + Py_XDECREF(py_func); +err_run_decref_mod: + Py_XDECREF(py_mod); + + if (PyErr_Occurred()) + PyErr_Print(); /* Returns void. */ + + return ret; } /** * Shutdown libsigrokdecode. * - * @return LIBSIGROKDECODE_OK upon success, a (negative) error code otherwise. + * @return SIGROKDECODE_OK upon success, a (negative) error code otherwise. */ int sigrokdecode_shutdown(void) {