contrib/python-zstandard/c-ext/frameparams.c

wireproto: support for pullbundles

Pullbundles are similar to clonebundles, but served as normal inline
bundle streams. They are almost transparent to the client -- the only
visible effect is that the client might get less changes than what it
asked for, i.e. not all requested head revisions are provided.

The client announces support for the necessary retries with the
partial-pull capability. After receiving a partial bundle, it updates
the set of revisions shared with the server and drops all now-known
heads from the request list. It will then rerun getbundle until
no changes are received or all remote heads are present.

Extend badserverext to support per-socket limit, i.e. don't assume that
the same limits should be applied to all sockets.

Differential Revision: https://phab.mercurial-scm.org/D1856

/**
* Copyright (c) 2017-present, Gregory Szorc
* All rights reserved.
*
* This software may be modified and distributed under the terms
* of the BSD license. See the LICENSE file for details.
*/

#include "python-zstandard.h"

extern PyObject* ZstdError;

PyDoc_STRVAR(FrameParameters__doc__,
	"FrameParameters: information about a zstd frame");

FrameParametersObject* get_frame_parameters(PyObject* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"data",
		NULL
	};

	Py_buffer source;
	ZSTD_frameHeader header;
	FrameParametersObject* result = NULL;
	size_t zresult;

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*:get_frame_parameters",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*:get_frame_parameters",
#endif
		kwlist, &source)) {
		return NULL;
	}

	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
		PyErr_SetString(PyExc_ValueError,
			"data buffer should be contiguous and have at most one dimension");
		goto finally;
	}

	zresult = ZSTD_getFrameHeader(&header, source.buf, source.len);

	if (ZSTD_isError(zresult)) {
		PyErr_Format(ZstdError, "cannot get frame parameters: %s", ZSTD_getErrorName(zresult));
		goto finally;
	}

	if (zresult) {
		PyErr_Format(ZstdError, "not enough data for frame parameters; need %zu bytes", zresult);
		goto finally;
	}

	result = PyObject_New(FrameParametersObject, &FrameParametersType);
	if (!result) {
		goto finally;
	}

	result->frameContentSize = header.frameContentSize;
	result->windowSize = header.windowSize;
	result->dictID = header.dictID;
	result->checksumFlag = header.checksumFlag ? 1 : 0;

finally:
	PyBuffer_Release(&source);
	return result;
}

static void FrameParameters_dealloc(PyObject* self) {
	PyObject_Del(self);
}

static PyMemberDef FrameParameters_members[] = {
	{ "content_size", T_ULONGLONG,
	  offsetof(FrameParametersObject, frameContentSize), READONLY,
	  "frame content size" },
	{ "window_size", T_ULONGLONG,
	  offsetof(FrameParametersObject, windowSize), READONLY,
	  "window size" },
	{ "dict_id", T_UINT,
	  offsetof(FrameParametersObject, dictID), READONLY,
	  "dictionary ID" },
	{ "has_checksum", T_BOOL,
	  offsetof(FrameParametersObject, checksumFlag), READONLY,
	  "checksum flag" },
	{ NULL }
};

PyTypeObject FrameParametersType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"FrameParameters",          /* tp_name */
	sizeof(FrameParametersObject), /* tp_basicsize */
	0,                         /* tp_itemsize */
	(destructor)FrameParameters_dealloc, /* tp_dealloc */
	0,                         /* tp_print */
	0,                         /* tp_getattr */
	0,                         /* tp_setattr */
	0,                         /* tp_compare */
	0,                         /* tp_repr */
	0,                         /* tp_as_number */
	0,                         /* tp_as_sequence */
	0,                         /* tp_as_mapping */
	0,                         /* tp_hash  */
	0,                         /* tp_call */
	0,                         /* tp_str */
	0,                         /* tp_getattro */
	0,                         /* tp_setattro */
	0,                         /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT,        /* tp_flags */
	FrameParameters__doc__,    /* tp_doc */
	0,                         /* tp_traverse */
	0,                         /* tp_clear */
	0,                         /* tp_richcompare */
	0,                         /* tp_weaklistoffset */
	0,                         /* tp_iter */
	0,                         /* tp_iternext */
	0,                         /* tp_methods */
	FrameParameters_members,   /* tp_members */
	0,                         /* tp_getset */
	0,                         /* tp_base */
	0,                         /* tp_dict */
	0,                         /* tp_descr_get */
	0,                         /* tp_descr_set */
	0,                         /* tp_dictoffset */
	0,                         /* tp_init */
	0,                         /* tp_alloc */
	0,                         /* tp_new */
};

void frameparams_module_init(PyObject* mod) {
	Py_TYPE(&FrameParametersType) = &PyType_Type;
	if (PyType_Ready(&FrameParametersType) < 0) {
		return;
	}

	Py_INCREF(&FrameParametersType);
	PyModule_AddObject(mod, "FrameParameters", (PyObject*)&FrameParametersType);
}