srd_decoder_doc_get(): Add an additional sanity check.

Author: uwehermann

decoder.c

@@ -869,7 +869,7 @@ SRD_API int srd_decoder_load(const char *module_name)
 /**
  * Return a protocol decoder's docstring.
  *
- * @param dec The loaded protocol decoder.
+ * @param dec The loaded protocol decoder. Must not be NULL.
  *
  * @return A newly allocated buffer containing the protocol decoder's
  *         documentation. The caller is responsible for free'ing the buffer.
@@ -885,7 +885,7 @@ SRD_API char *srd_decoder_doc_get(const struct srd_decoder *dec)
 	if (!srd_check_init())
 		return NULL;
 
-	if (!dec)
+	if (!dec || !dec->py_mod)
 		return NULL;
 
 	gstate = PyGILState_Ensure();

tests/decoder.c

@@ -404,11 +404,19 @@ END_TEST
  * Check whether srd_decoder_doc_get() fails with NULL as argument.
  * If it returns a value != NULL (or segfaults) this test will fail.
  * See also: http://sigrok.org/bugzilla/show_bug.cgi?id=179
+ * Check whether srd_decoder_doc_get() fails with dec->py_mod == NULL.
+ * If it returns a value != NULL (or segfaults) this test will fail.
+ * See also: http://sigrok.org/bugzilla/show_bug.cgi?id=180
  */
 START_TEST(test_doc_get_null)
 {
+	struct srd_decoder dec;
+
+	dec.py_mod = NULL;
+
 	srd_init(DECODERS_TESTDIR);
 	fail_unless(srd_decoder_doc_get(NULL) == NULL);
+	fail_unless(srd_decoder_doc_get(&dec) == NULL);
 	srd_exit();
 }
 END_TEST