srd: clean up module loading/unloading, and the decoder struct

PDs are now checked for a proper Decoder object, with at least the
required attributes.

The author, long_desc and func attributes in the decoder object are gone.

5 files changed, 171 insertions, 81 deletions

diff --git a/controller.c b/controller.c
index 07bf6f2..963345c 100644
--- a/controller.c
+++ b/controller.c
@@ -168,7 +168,7 @@ struct srd_decoder_instance *srd_instance_new(const char *id,
 	}
 
 	/* Create an instance of the 'Decoder' class. */
-	di->py_instance = PyObject_Call(dec->py_decobj, py_args, NULL);
+	di->py_instance = PyObject_Call(dec->py_dec, py_args, NULL);
 	if (!di->py_instance) {
 		if (PyErr_Occurred())
 			PyErr_Print();
@@ -230,6 +230,7 @@ int srd_instance_set_probe(struct srd_decoder_instance *di,
 	return SRD_OK;
 }
 
+/* TODO: this should go into the PD stack */
 struct srd_decoder_instance *srd_instance_find(char *instance_id)
 {
 	GSList *l;
diff --git a/decoder.c b/decoder.c
index e25e4e0..6b5fc95 100644
--- a/decoder.c
+++ b/decoder.c
@@ -26,6 +26,9 @@
 /* The list of protocol decoders. */
 GSList *pd_list = NULL;
 
+/* lives in module_sigrokdecode.c */
+extern PyObject *mod_sigrokdecode;
+
 
 /**
  * Returns the list of supported/loaded protocol decoders.
@@ -72,67 +75,89 @@ struct srd_decoder *srd_get_decoder_by_id(const char *id)
  */
 int srd_load_decoder(const char *name, struct srd_decoder **dec)
 {
-	PyObject *py_mod, *py_res, *py_annlist, *py_ann;
+	PyObject *py_basedec, *py_annlist, *py_ann;
 	struct srd_decoder *d;
-	int alen, r, i;
+	int alen, ret, i;
 	char **ann;
 
-	/* "Import" the Python module. */
-	if (!(py_mod = PyImport_ImportModule(name))) { /* NEWREF */
-		PyErr_Print(); /* Returns void. */
-		return SRD_ERR_PYTHON; /* TODO: More specific error? */
-	}
+	py_basedec = NULL;
+	ret = SRD_ERR;
+	srd_dbg("loading module %s", name);
 
-	/* Get the 'Decoder' class as Python object. */
-	py_res = PyObject_GetAttrString(py_mod, "Decoder"); /* NEWREF */
-	if (!py_res) {
-		if (PyErr_Occurred())
-			PyErr_Print(); /* Returns void. */
-		Py_XDECREF(py_mod);
-		srd_err("Decoder class not found in PD module %s", name);
-		return SRD_ERR_PYTHON; /* TODO: More specific error? */
+	if (!(d = g_try_malloc0(sizeof(struct srd_decoder)))) {
+		ret = SRD_ERR_MALLOC;
+		goto err_out;
 	}
 
-	if (!(d = malloc(sizeof(struct srd_decoder))))
-		return SRD_ERR_MALLOC;
+	/* Import the Python module. */
+	if (!(d->py_mod = PyImport_ImportModule(name))) {
+		/* TODO: report exception message/traceback to err/dbg */
+		srd_dbg("import failed");
+		PyErr_Clear();
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "id", &(d->id))) < 0)
-		return r;
+	/* Get the 'Decoder' class as Python object. */
+	if (!(d->py_dec = PyObject_GetAttrString(d->py_mod, "Decoder"))) {
+		/* This generated an AttributeError exception. */
+		PyErr_Clear();
+		srd_err("Decoder class not found in protocol decoder module %s", name);
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "name", &(d->name))) < 0)
-		return r;
+	if (!(py_basedec = PyObject_GetAttrString(mod_sigrokdecode, "Decoder"))) {
+		srd_dbg("sigrokdecode module not loaded");
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "longname", &(d->longname))) < 0)
-		return r;
+	if (!PyObject_IsSubclass(d->py_dec, py_basedec)) {
+		srd_err("Decoder class in protocol decoder module %s is not "
+				"a subclass of sigrokdecode.Decoder", name);
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
+	}
+	Py_DecRef(py_basedec);
 
-	if ((r = h_str(py_res, "desc", &(d->desc))) < 0)
-		return r;
+	if (py_attr_as_str(d->py_dec, "id", &(d->id)) != SRD_OK) {
+		return SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "longdesc", &(d->longdesc))) < 0)
-		return r;
+	if (py_attr_as_str(d->py_dec, "name", &(d->name)) != SRD_OK) {
+		return SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "author", &(d->author))) < 0)
-		return r;
+	if (py_attr_as_str(d->py_dec, "longname", &(d->longname)) != SRD_OK) {
+		return SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	if ((r = h_str(py_res, "license", &(d->license))) < 0)
-		return r;
+	if (py_attr_as_str(d->py_dec, "desc", &(d->desc)) != SRD_OK) {
+		return SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	d->py_mod = py_mod;
-	d->py_decobj = py_res;
+	if (py_attr_as_str(d->py_dec, "license", &(d->license)) != SRD_OK) {
+		return SRD_ERR_PYTHON;
+		goto err_out;
+	}
 
-	/* TODO: Handle func, inputformats, outputformats. */
-	/* Note: They must at least be set to NULL, will segfault otherwise. */
-	d->func = NULL;
+	/* TODO: Handle inputformats, outputformats. */
 	d->inputformats = NULL;
 	d->outputformats = NULL;
 
 	/* Convert class annotation attribute to GSList of **char */
 	d->annotations = NULL;
-	if (PyObject_HasAttrString(py_res, "annotations")) {
-		py_annlist = PyObject_GetAttrString(py_res, "annotations");
+	if (PyObject_HasAttrString(d->py_dec, "annotations")) {
+		py_annlist = PyObject_GetAttrString(d->py_dec, "annotations");
 		if (!PyList_Check(py_annlist)) {
 			srd_err("Protocol decoder module %s annotations should be a list", name);
-			return SRD_ERR_PYTHON;
+			ret = SRD_ERR_PYTHON;
+			goto err_out;
 		}
 		alen = PyList_Size(py_annlist);
 		for (i = 0; i < alen; i++) {
@@ -140,43 +165,66 @@ int srd_load_decoder(const char *name, struct srd_decoder **dec)
 			if (!PyList_Check(py_ann) || PyList_Size(py_ann) != 2) {
 				srd_err("Protocol decoder module %s annotation %d should be a list with two elements",
 						name, i+1);
-				return SRD_ERR_PYTHON;
+				ret = SRD_ERR_PYTHON;
+				goto err_out;
 			}
 
-			if (py_strlist_to_char(py_ann, &ann) != SRD_OK)
-				return SRD_ERR_PYTHON;
+			if (py_strlist_to_char(py_ann, &ann) != SRD_OK) {
+				ret = SRD_ERR_PYTHON;
+				goto err_out;
+			}
 			d->annotations = g_slist_append(d->annotations, ann);
 		}
 	}
 
 	*dec = d;
+	ret = SRD_OK;
+
+err_out:
+	if (ret != SRD_OK) {
+		Py_XDECREF(py_basedec);
+		Py_XDECREF(d->py_dec);
+		Py_XDECREF(d->py_mod);
+		g_free(d);
+	}
 
-	return SRD_OK;
+	return ret;
+}
+
+char *srd_decoder_doc(struct srd_decoder *dec)
+{
+	char *doc;
+
+	doc = NULL;
+	py_attr_as_str(dec->py_mod, "__doc__", &doc);
+
+	return doc;
 }
 
 
 /**
- * TODO
+ * Unload decoder module.
+ *
+ * @param dec The decoder struct to be unloaded.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
  */
 int srd_unload_decoder(struct srd_decoder *dec)
 {
+
 	g_free(dec->id);
 	g_free(dec->name);
 	g_free(dec->longname);
 	g_free(dec->desc);
-	g_free(dec->longdesc);
-	g_free(dec->author);
 	g_free(dec->license);
-	g_free(dec->func);
 
 	/* TODO: Free everything in inputformats and outputformats. */
-
 	if (dec->inputformats != NULL)
 		g_slist_free(dec->inputformats);
 	if (dec->outputformats != NULL)
 		g_slist_free(dec->outputformats);
 
-	Py_XDECREF(dec->py_decobj);
+	Py_XDECREF(dec->py_dec);
 	Py_XDECREF(dec->py_mod);
 
 	/* TODO: (g_)free dec itself? */
diff --git a/module_sigrokdecode.c b/module_sigrokdecode.c
index a18583b..cb43372 100644
--- a/module_sigrokdecode.c
+++ b/module_sigrokdecode.c
@@ -21,6 +21,12 @@
 #include "sigrokdecode-internal.h"
 #include "config.h"
 
+
+/* When initialized, a reference to this module inside the python interpreter
+ * lives here.
+ */
+PyObject *mod_sigrokdecode = NULL;
+
 /* lives in type_logic.c */
 extern PyTypeObject srd_logic_type;
 
@@ -236,6 +242,8 @@ PyMODINIT_FUNC PyInit_sigrokdecode(void)
 			PyLong_FromLong(SRD_OUTPUT_BINARY)) == -1)
 		return NULL;
 
+	mod_sigrokdecode = mod;
+
 	return mod;
 }
 
diff --git a/sigrokdecode.h b/sigrokdecode.h
index 71d0ae4..863608b 100644
--- a/sigrokdecode.h
+++ b/sigrokdecode.h
@@ -90,19 +90,10 @@ struct srd_decoder {
 	/** A (short, one-line) description of the decoder. */
 	char *desc;
 
-	/** A (long, multi-line) description of the decoder. May be NULL. */
-	char *longdesc;
-
-	/** The author of the decoder. May be NULL. */
-	char *author;
-
 	/** The license of the decoder. Valid values: "gplv2+", "gplv3+". */
 	char *license;
 
 	/** TODO */
-	char *func;
-
-	/** TODO */
 	GSList *inputformats;
 
 	/** TODO */
@@ -113,11 +104,11 @@ struct srd_decoder {
 	 */
 	GSList *annotations;
 
-	/** TODO */
+	/** Python module */
 	PyObject *py_mod;
 
-	/** Python object that performs the decoding */
-	PyObject *py_decobj;
+	/** sigrokdecode.Decoder class */
+	PyObject *py_dec;
 };
 
 struct srd_decoder_instance {
@@ -191,20 +182,20 @@ int srd_register_callback(int output_type, void *cb);
 void *srd_find_callback(int output_type);
 
 /*--- decoder.c -------------------------------------------------------------*/
-
 GSList *srd_list_decoders(void);
 struct srd_decoder *srd_get_decoder_by_id(const char *id);
 int srd_load_decoder(const char *name, struct srd_decoder **dec);
 int srd_unload_decoder(struct srd_decoder *dec);
 int srd_load_all_decoders(void);
 int srd_unload_all_decoders(void);
+char *srd_decoder_doc(struct srd_decoder *dec);
 
 /*--- util.c ----------------------------------------------------------------*/
-int h_str(PyObject *py_res, const char *key, char **outstr);
+int py_attr_as_str(PyObject *py_obj, const char *attr, char **outstr);
+int py_str_as_str(PyObject *py_str, char **outstr);
 int py_strlist_to_char(PyObject *py_strlist, char ***outstr);
 
 /*--- log.c -----------------------------------------------------------------*/
-
 int srd_set_loglevel(int loglevel);
 int srd_get_loglevel(void);
 
diff --git a/util.c b/util.c
index df433d7..51b7cd6 100644
--- a/util.c
+++ b/util.c
@@ -19,49 +19,81 @@
  */
 
 #include "sigrokdecode.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
+#include "sigrokdecode-internal.h"
 #include "config.h"
 
 
 /**
- * Helper function to get the value of a python object's attribute,
- * returned as a newly allocated char *.
+ * Get the value of a python object's attribute, returned as a newly
+ * allocated char *.
  *
  * @param py_obj The object to probe.
- * @param key Name of the attribute to retrieve.
+ * @param attr Name of the attribute to retrieve.
  * @param outstr ptr to char * storage to be filled in.
  *
  * @return SRD_OK upon success, a (negative) error code otherwise.
  *         The 'outstr' argument points to a malloc()ed string upon success.
  */
-int h_str(PyObject *py_obj, const char *key, char **outstr)
+int py_attr_as_str(PyObject *py_obj, const char *attr, char **outstr)
 {
-	PyObject *py_str, *py_encstr;
-	char *str;
+	PyObject *py_str;
 	int ret;
 
-	py_str = py_encstr = NULL;
+	if (!PyObject_HasAttrString(py_obj, attr)) {
+		srd_dbg("object has no attribute '%s'", attr);
+		return SRD_ERR_PYTHON;
+	}
+
+	if (!(py_str = PyObject_GetAttrString(py_obj, attr))) {
+		/* TODO: report exception message/traceback to err/dbg */
+		PyErr_Clear();
+		return SRD_ERR_PYTHON;
+	}
+
+	ret = py_str_as_str(py_str, outstr);
+	Py_XDECREF(py_str);
+
+	return ret;
+}
+
+
+/**
+ * Get the value of a python unicode string object, returned as a newly
+ * allocated char *.
+ *
+ * @param py_str The unicode string object.
+ * @param outstr ptr to char * storage to be filled in.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ *         The 'outstr' argument points to a malloc()ed string upon success.
+ */
+int py_str_as_str(PyObject *py_str, char **outstr)
+{
+	PyObject *py_encstr;
+	int ret;
+	char *str;
+
+	py_encstr = NULL;
 	str = NULL;
 	ret = SRD_OK;
 
-	if (!(py_str = PyObject_GetAttrString(py_obj, (char *)key))) {
-		/* TODO: log level 4 debug message */
+	if (!PyUnicode_Check(py_str)) {
+		srd_dbg("not a string object");
 		ret = SRD_ERR_PYTHON;
 		goto err_out;
 	}
 
 	if (!(py_encstr = PyUnicode_AsEncodedString(py_str, "utf-8", NULL))) {
-		/* TODO: log level 4 debug message */
 		ret = SRD_ERR_PYTHON;
 		goto err_out;
 	}
 	if (!(str = PyBytes_AS_STRING(py_encstr))) {
-		/* TODO: log level 4 debug message */
 		ret = SRD_ERR_PYTHON;
 		goto err_out;
 	}
 
 	if (!(*outstr = g_strdup(str))) {
-		/* TODO: log level 4 debug message */
+		srd_dbg("malloc failed");
 		ret = SRD_ERR_MALLOC;
 		goto err_out;
 	}
@@ -72,16 +104,25 @@ err_out:
 	if (py_encstr)
 		Py_XDECREF(py_encstr);
 
-	if (PyErr_Occurred())
-		/* TODO: log level 4 debug message */
-		PyErr_Print();
+	if (PyErr_Occurred()) {
+		srd_dbg("string conversion failed");
+		/* TODO: dump exception to srd_dbg */
+		PyErr_Clear();
+	}
 
 	return ret;
 }
 
+
 /**
  * Convert a python list of unicode strings to a NULL-terminated UTF8-encoded
  * char * array. The caller must free each string when finished.
+ *
+ * @param py_strlist The list object.
+ * @param outstr ptr to char ** storage to be filled in.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ *         The 'outstr' argument points to a malloc()ed char ** upon success.
  */
 int py_strlist_to_char(PyObject *py_strlist, char ***outstr)
 {
@@ -93,7 +134,8 @@ int py_strlist_to_char(PyObject *py_strlist, char ***outstr)
 	if (!(out = g_try_malloc(sizeof(char *) * (list_len + 1))))
 		return SRD_ERR_MALLOC;
 	for (i = 0; i < list_len; i++) {
-		if (!(py_str = PyUnicode_AsEncodedString(PyList_GetItem(py_strlist, i), "utf-8", NULL)))
+		if (!(py_str = PyUnicode_AsEncodedString(
+				PyList_GetItem(py_strlist, i), "utf-8", NULL)))
 			return SRD_ERR_PYTHON;
 		if (!(str = PyBytes_AS_STRING(py_str)))
 			return SRD_ERR_PYTHON;