From 8b4bbd2a0bcfdc2e186b345de087f23b9c904080 Mon Sep 17 00:00:00 2001
From: Bert Vermeulen <bert@biot.com>
Date: Wed, 28 Dec 2011 13:40:23 +0100
Subject: [PATCH] better python memory management

---
 decoder.c      | 16 +++++++--------
 sigrokdecode.h |  3 +--
 util.c         | 53 ++++++++++++++++++++++++++------------------------
 3 files changed, 37 insertions(+), 35 deletions(-)

diff --git a/decoder.c b/decoder.c
index 5d719d3..9f951c1 100644
--- a/decoder.c
+++ b/decoder.c
@@ -96,30 +96,30 @@ int srd_load_decoder(const char *name, struct srd_decoder **dec)
 	if (!(d = malloc(sizeof(struct srd_decoder))))
 		return SRD_ERR_MALLOC;
 
-	if ((r = h_str(py_res, py_mod, "id", &(d->id))) < 0)
+	if ((r = h_str(py_res, "id", &(d->id))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "name", &(d->name))) < 0)
+	if ((r = h_str(py_res, "name", &(d->name))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "longname",
+	if ((r = h_str(py_res, "longname",
 		       &(d->longname))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "desc", &(d->desc))) < 0)
+	if ((r = h_str(py_res, "desc", &(d->desc))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "longdesc",
+	if ((r = h_str(py_res, "longdesc",
 		       &(d->longdesc))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "author", &(d->author))) < 0)
+	if ((r = h_str(py_res, "author", &(d->author))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "email", &(d->email))) < 0)
+	if ((r = h_str(py_res, "email", &(d->email))) < 0)
 		return r;
 
-	if ((r = h_str(py_res, py_mod, "license", &(d->license))) < 0)
+	if ((r = h_str(py_res, "license", &(d->license))) < 0)
 		return r;
 
 	d->py_mod = py_mod;
diff --git a/sigrokdecode.h b/sigrokdecode.h
index 6005ad9..8266fb5 100644
--- a/sigrokdecode.h
+++ b/sigrokdecode.h
@@ -151,8 +151,7 @@ int srd_load_all_decoders(void);
 int srd_unload_all_decoders(void);
 
 /*--- util.c ----------------------------------------------------------------*/
-
-int h_str(PyObject *py_res, PyObject *py_mod, const char *key, char **outstr);
+int h_str(PyObject *py_res, const char *key, char **outstr);
 
 /*--- log.c -----------------------------------------------------------------*/
 
diff --git a/util.c b/util.c
index b6de2fb..0885626 100644
--- a/util.c
+++ b/util.c
@@ -23,54 +23,57 @@
 
 
 /**
- * Helper function to handle Python strings.
+ * Helper function to get the value of a python object's attribute,
+ * returned as a newly allocated char *.
  *
- * TODO: @param entries.
+ * @param py_obj The object to probe.
+ * @param key 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_res, PyObject *py_mod, const char *key, char **outstr)
+int h_str(PyObject *py_obj, const char *key, char **outstr)
 {
 	PyObject *py_str, *py_encstr;
 	char *str;
 	int ret;
 
-	if (!(py_str = PyObject_GetAttrString(py_res, (char *)key))) {
-		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
-		goto err_h_decref_mod;
+	py_str = py_encstr = NULL;
+	str = NULL;
+	ret = SRD_OK;
+
+	if (!(py_str = PyObject_GetAttrString(py_obj, (char *)key))) {
+		/* TODO: log level 4 debug message */
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
 	}
 
-	/*
-	 * PyBytes_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 (!(py_encstr = PyUnicode_AsEncodedString(py_str, "utf-8", NULL))) {
-		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
-		goto err_h_decref_str;
+		/* TODO: log level 4 debug message */
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
 	}
 	if (!(str = PyBytes_AS_STRING(py_encstr))) {
-		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
-		goto err_h_decref_str;
+		/* TODO: log level 4 debug message */
+		ret = SRD_ERR_PYTHON;
+		goto err_out;
 	}
 
 	if (!(*outstr = g_strdup(str))) {
+		/* TODO: log level 4 debug message */
 		ret = SRD_ERR_MALLOC;
-		goto err_h_decref_str;
+		goto err_out;
 	}
 
-	Py_XDECREF(py_str);
-
-	return SRD_OK;
-
-err_h_decref_str:
-	Py_XDECREF(py_str);
-err_h_decref_mod:
-	Py_XDECREF(py_mod);
+err_out:
+	if (py_str)
+		Py_XDECREF(py_str);
+	if (py_encstr)
+		Py_XDECREF(py_encstr);
 
 	if (PyErr_Occurred())
-		PyErr_Print(); /* Returns void. */
+		PyErr_Print();
 
 	return ret;
 }
-- 
2.30.2