[Libguestfs] [nbdkit PATCH 2/2] python: Simplify calling into plugin

PyObject_CallObject is powerful, but awkward - we have to wrap all arguments into a temporary tuple before using it. Let python do more of the work by using PyObject_CallFunction anywhere that all arguments can be described by a Py_BuildValue() format string, instead of creating one-shot arguments ourselves. In fact, for our py_config(), this makes it easier to not worry about python 2 String vs. python 3 Unicode. Similarly, PyObject_CallFunctionObjArgs is nicer when we already have PyObjects for all parameters (including in py_open(), where we can't use a Py_BuildValue() string for converting a C int into Py_True or Py_False, but can easily avoid the tuple wrapper). py_zero() is not converted, as it will be changed differently to make 'may_trim' an optional callback parameter. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- plugins/python/python.c | 97 ++++++++----------------------------------------- 1 file changed, 15 insertions(+), 82 deletions(-) diff --git a/plugins/python/python.c b/plugins/python/python.c index c5cc4bd..5ece97a 100644 --- a/plugins/python/python.c +++ b/plugins/python/python.c @@ -209,7 +209,6 @@ py_config (const char *key, const char *value) FILE *fp; PyObject *modname; PyObject *fn; - PyObject *args; PyObject *r; if (!script) { @@ -258,17 +257,8 @@ py_config (const char *key, const char *value) /* Other parameters are passed to the Python .config callback. */ PyErr_Clear (); - args = PyTuple_New (2); -#ifdef HAVE_PYSTRING_FROMSTRING - PyTuple_SetItem (args, 0, PyString_FromString (key)); - PyTuple_SetItem (args, 1, PyString_FromString (value)); -#else - PyTuple_SetItem (args, 0, PyUnicode_FromString (key)); - PyTuple_SetItem (args, 1, PyUnicode_FromString (value)); -#endif - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunction (fn, "ss", key, value); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("config") == -1) return -1; Py_DECREF (r); @@ -306,7 +296,6 @@ static void * py_open (int readonly) { PyObject *fn; - PyObject *args; PyObject *handle; if (!callback_defined ("open", &fn)) { @@ -316,11 +305,9 @@ py_open (int readonly) PyErr_Clear (); - args = PyTuple_New (1); - PyTuple_SetItem (args, 0, PyBool_FromLong (readonly)); - handle = PyObject_CallObject (fn, args); + handle = PyObject_CallFunctionObjArgs (fn, readonly ? Py_True : Py_False, + NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("open") == -1) return NULL; @@ -332,18 +319,13 @@ py_close (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (callback_defined ("close", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); check_python_failure ("close"); Py_XDECREF (r); } @@ -356,7 +338,6 @@ py_get_size (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; int64_t ret; @@ -367,12 +348,8 @@ py_get_size (void *handle) PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("get_size") == -1) return -1; @@ -390,7 +367,6 @@ py_pread (void *handle, void *buf, { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (!callback_defined ("pread", &fn)) { @@ -400,14 +376,8 @@ py_pread (void *handle, void *buf, PyErr_Clear (); - args = PyTuple_New (3); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - PyTuple_SetItem (args, 1, PyLong_FromLong (count)); - PyTuple_SetItem (args, 2, PyLong_FromUnsignedLongLong (offset)); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunction (fn, "OiL", obj, count, offset, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("pread") == -1) return -1; @@ -436,20 +406,15 @@ py_pwrite (void *handle, const void *buf, { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (callback_defined ("pwrite", &fn)) { PyErr_Clear (); - args = PyTuple_New (3); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - PyTuple_SetItem (args, 1, PyByteArray_FromStringAndSize (buf, count)); - PyTuple_SetItem (args, 2, PyLong_FromUnsignedLongLong (offset)); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunction (fn, "OOL", obj, + PyByteArray_FromStringAndSize (buf, count), + offset, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("pwrite") == -1) return -1; Py_DECREF (r); @@ -467,18 +432,13 @@ py_flush (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (callback_defined ("flush", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("flush") == -1) return -1; Py_DECREF (r); @@ -496,20 +456,13 @@ py_trim (void *handle, uint32_t count, uint64_t offset) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (callback_defined ("trim", &fn)) { PyErr_Clear (); - args = PyTuple_New (3); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - PyTuple_SetItem (args, 1, PyLong_FromLong (count)); - PyTuple_SetItem (args, 2, PyLong_FromUnsignedLongLong (offset)); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunction (fn, "OiL", obj, count, offset, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("trim") == -1) return -1; Py_DECREF (r); @@ -568,19 +521,14 @@ py_can_write (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; int ret; if (callback_defined ("can_write", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("can_write") == -1) return -1; ret = r == Py_True; @@ -601,19 +549,14 @@ py_can_flush (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; int ret; if (callback_defined ("can_flush", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("can_flush") == -1) return -1; ret = r == Py_True; @@ -634,19 +577,14 @@ py_is_rotational (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; int ret; if (callback_defined ("is_rotational", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("is_rotational") == -1) return -1; ret = r == Py_True; @@ -662,19 +600,14 @@ py_can_trim (void *handle) { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; int ret; if (callback_defined ("can_trim", &fn)) { PyErr_Clear (); - args = PyTuple_New (1); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - Py_DECREF (args); if (check_python_failure ("can_trim") == -1) return -1; ret = r == Py_True; -- 2.14.3