Bugfix: PyTuple_SetItem() "steals" a reference.

[libsigrokdecode.git] / decode.c

diff --git a/decode.c b/decode.c
index 1b12c9ee33644f853712a333ff1185db1edf2969..c2beab29a6bc619fbb783aae3d2d14db2d3f8858 100644 (file)
--- a/decode.c
+++ b/decode.c
@@ -21,6 +21,31 @@
 #include <sigrokdecode.h> /* First, so we avoid a _POSIX_C_SOURCE warning. */
 #include <stdio.h>
 #include <string.h>
+#include <dirent.h>
+#include <config.h>
+
+/* Re-define some string functions for Python >= 3.0. */
+#if PY_VERSION_HEX >= 0x03000000
+#define PyString_AsString PyBytes_AsString
+#define PyString_FromString PyBytes_FromString
+#define PyString_Check PyBytes_Check
+#endif
+
+/* 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_DECREF() it.
+ *
+ *  - If it returns a "borrowed reference", you MUST NOT Py_DECREF() it.
+ *
+ *  - If a function "steals" a reference, you no longer are responsible for
+ *    Py_DECREF()ing it (someone else will do it for you at some point).
+ */
 
 /**
  * Initialize libsigrokdecode.
@@ -29,22 +54,46 @@
  */
 int sigrokdecode_init(void)
 {
+       DIR *dir;
+       struct dirent *dp;
+       char *tmp;
+
        /* Py_Initialize() returns void and usually cannot fail. */
        Py_Initialize();
 
-       /* Add some more search directories for convenience. */
+       /* Add search directory for the protocol decoders. */
        /* FIXME: Check error code. */
        /* FIXME: What happens if this function is called multiple times? */
-       PyRun_SimpleString(
-               "import sys;"
-               "sys.path.append('libsigrokdecode/scripts');"
-               "sys.path.append('../libsigrokdecode/scripts');"
-               "sys.path.append('/usr/local/share/sigrok');"
-               );
+       PyRun_SimpleString("import sys;"
+                          "sys.path.append(r'" DECODERS_DIR "');");
+
+       if (!(dir = opendir(DECODERS_DIR)))
+               return SIGROKDECODE_ERR_DECODERS_DIR;
+
+       while ((dp = readdir(dir)) != NULL) {
+               if (!g_str_has_suffix(dp->d_name, ".py"))
+                       continue;
+               /* For now use the filename (without .py) as decoder name. */
+               if ((tmp = g_strndup(dp->d_name, strlen(dp->d_name) - 3)))
+                       list_pds = g_slist_append(list_pds, tmp);
+       }
+       closedir(dir);
 
        return SIGROKDECODE_OK;
 }
 
+/**
+ * Returns the list of supported/loaded protocol decoders.
+ *
+ * This is a GSList containing the names of the decoders as strings.
+ *
+ * @return List of decoders, NULL if none are supported or loaded.
+ */
+GSList *sigrokdecode_list_decoders(void)
+{
+       return list_pds;
+}
+
 /**
  * Helper function to handle Python strings.
  *
@@ -227,9 +276,14 @@ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec,
                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_DECREF()'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) {
                PyErr_Print();
-               Py_DECREF(py_value);
+               Py_DECREF(py_value); /* TODO: Ref. stolen upon error? */
                Py_DECREF(py_args);
                Py_DECREF(py_func);
                Py_DECREF(py_mod);
@@ -238,7 +292,6 @@ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec,
 
        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);
@@ -249,7 +302,6 @@ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec,
                                         (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);
@@ -257,7 +309,6 @@ int sigrokdecode_run_decoder(struct sigrokdecode_decoder *dec,
        }
 
        Py_DECREF(py_res);
-       // Py_DECREF(py_value);
        Py_DECREF(py_args);
        Py_DECREF(py_func);
        Py_DECREF(py_mod);