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

cext: add Python 3.10 support

* Replace "Py_TYPE(obj) = type;" with "Py_SET_TYPE(obj, type);"
* Add pythoncapi_compat.h header file to get Py_SET_TYPE() on Python
  2.7-3.8. Header file added to mercurial/ and
  contrib/python-zstandard/zstd/common/.

In Python 3.10, Py_TYPE(obj) must not longer be used as an l-value.

pythoncapi_compat.h comes from:
https://github.com/pythoncapi/pythoncapi_compat

Differential Revision: https://phab.mercurial-scm.org/D9825

/**
* Copyright (c) 2016-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(ZstdDecompressionWriter__doc,
"""A context manager used for writing decompressed output.\n"
);

static void ZstdDecompressionWriter_dealloc(ZstdDecompressionWriter* self) {
	Py_XDECREF(self->decompressor);
	Py_XDECREF(self->writer);

	PyObject_Del(self);
}

static PyObject* ZstdDecompressionWriter_enter(ZstdDecompressionWriter* self) {
	if (self->closed) {
		PyErr_SetString(PyExc_ValueError, "stream is closed");
		return NULL;
	}

	if (self->entered) {
		PyErr_SetString(ZstdError, "cannot __enter__ multiple times");
		return NULL;
	}

	self->entered = 1;

	Py_INCREF(self);
	return (PyObject*)self;
}

static PyObject* ZstdDecompressionWriter_exit(ZstdDecompressionWriter* self, PyObject* args) {
	self->entered = 0;

	if (NULL == PyObject_CallMethod((PyObject*)self, "close", NULL)) {
		return NULL;
	}

	Py_RETURN_FALSE;
}

static PyObject* ZstdDecompressionWriter_memory_size(ZstdDecompressionWriter* self) {
	return PyLong_FromSize_t(ZSTD_sizeof_DCtx(self->decompressor->dctx));
}

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

	PyObject* result = NULL;
	Py_buffer source;
	size_t zresult = 0;
	ZSTD_inBuffer input;
	ZSTD_outBuffer output;
	PyObject* res;
	Py_ssize_t totalWrite = 0;

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*:write",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*:write",
#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;
	}

	if (self->closed) {
		PyErr_SetString(PyExc_ValueError, "stream is closed");
		return NULL;
	}

	output.dst = PyMem_Malloc(self->outSize);
	if (!output.dst) {
		PyErr_NoMemory();
		goto finally;
	}
	output.size = self->outSize;
	output.pos = 0;

	input.src = source.buf;
	input.size = source.len;
	input.pos = 0;

	while (input.pos < (size_t)source.len) {
		Py_BEGIN_ALLOW_THREADS
		zresult = ZSTD_decompressStream(self->decompressor->dctx, &output, &input);
		Py_END_ALLOW_THREADS

		if (ZSTD_isError(zresult)) {
			PyMem_Free(output.dst);
			PyErr_Format(ZstdError, "zstd decompress error: %s",
				ZSTD_getErrorName(zresult));
			goto finally;
		}

		if (output.pos) {
#if PY_MAJOR_VERSION >= 3
			res = PyObject_CallMethod(self->writer, "write", "y#",
#else
			res = PyObject_CallMethod(self->writer, "write", "s#",
#endif
				output.dst, output.pos);
			Py_XDECREF(res);
			totalWrite += output.pos;
			output.pos = 0;
		}
	}

	PyMem_Free(output.dst);

	if (self->writeReturnRead) {
		result = PyLong_FromSize_t(input.pos);
	}
	else {
		result = PyLong_FromSsize_t(totalWrite);
	}

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

static PyObject* ZstdDecompressionWriter_close(ZstdDecompressionWriter* self) {
	PyObject* result;

	if (self->closed) {
		Py_RETURN_NONE;
	}

	result = PyObject_CallMethod((PyObject*)self, "flush", NULL);
	self->closed = 1;

	if (NULL == result) {
		return NULL;
	}

	/* Call close on underlying stream as well. */
	if (PyObject_HasAttrString(self->writer, "close")) {
		return PyObject_CallMethod(self->writer, "close", NULL);
	}

	Py_RETURN_NONE;
}

static PyObject* ZstdDecompressionWriter_fileno(ZstdDecompressionWriter* self) {
	if (PyObject_HasAttrString(self->writer, "fileno")) {
		return PyObject_CallMethod(self->writer, "fileno", NULL);
	}
	else {
		PyErr_SetString(PyExc_OSError, "fileno not available on underlying writer");
		return NULL;
	}
}

static PyObject* ZstdDecompressionWriter_flush(ZstdDecompressionWriter* self) {
	if (self->closed) {
		PyErr_SetString(PyExc_ValueError, "stream is closed");
		return NULL;
	}

	if (PyObject_HasAttrString(self->writer, "flush")) {
		return PyObject_CallMethod(self->writer, "flush", NULL);
	}
	else {
		Py_RETURN_NONE;
	}
}

static PyObject* ZstdDecompressionWriter_false(PyObject* self, PyObject* args) {
	Py_RETURN_FALSE;
}

static PyObject* ZstdDecompressionWriter_true(PyObject* self, PyObject* args) {
	Py_RETURN_TRUE;
}

static PyObject* ZstdDecompressionWriter_unsupported(PyObject* self, PyObject* args, PyObject* kwargs) {
	PyObject* iomod;
	PyObject* exc;

	iomod = PyImport_ImportModule("io");
	if (NULL == iomod) {
		return NULL;
	}

	exc = PyObject_GetAttrString(iomod, "UnsupportedOperation");
	if (NULL == exc) {
		Py_DECREF(iomod);
		return NULL;
	}

	PyErr_SetNone(exc);
	Py_DECREF(exc);
	Py_DECREF(iomod);

	return NULL;
}

static PyMethodDef ZstdDecompressionWriter_methods[] = {
	{ "__enter__", (PyCFunction)ZstdDecompressionWriter_enter, METH_NOARGS,
	PyDoc_STR("Enter a decompression context.") },
	{ "__exit__", (PyCFunction)ZstdDecompressionWriter_exit, METH_VARARGS,
	PyDoc_STR("Exit a decompression context.") },
	{ "memory_size", (PyCFunction)ZstdDecompressionWriter_memory_size, METH_NOARGS,
	PyDoc_STR("Obtain the memory size in bytes of the underlying decompressor.") },
	{ "close", (PyCFunction)ZstdDecompressionWriter_close, METH_NOARGS, NULL },
	{ "fileno", (PyCFunction)ZstdDecompressionWriter_fileno, METH_NOARGS, NULL },
	{ "flush", (PyCFunction)ZstdDecompressionWriter_flush, METH_NOARGS, NULL },
	{ "isatty", ZstdDecompressionWriter_false, METH_NOARGS, NULL },
	{ "readable", ZstdDecompressionWriter_false, METH_NOARGS, NULL },
	{ "readline", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "readlines", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "seek", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "seekable", ZstdDecompressionWriter_false, METH_NOARGS, NULL },
	{ "tell", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "truncate", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "writable", ZstdDecompressionWriter_true, METH_NOARGS, NULL },
	{ "writelines" , (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "read", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "readall", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "readinto", (PyCFunction)ZstdDecompressionWriter_unsupported, METH_VARARGS | METH_KEYWORDS, NULL },
	{ "write", (PyCFunction)ZstdDecompressionWriter_write, METH_VARARGS | METH_KEYWORDS,
	PyDoc_STR("Compress data") },
	{ NULL, NULL }
};

static PyMemberDef ZstdDecompressionWriter_members[] = {
	{ "closed", T_BOOL, offsetof(ZstdDecompressionWriter, closed), READONLY, NULL },
	{ NULL }
};

PyTypeObject ZstdDecompressionWriterType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdDecompressionWriter", /* tp_name */
	sizeof(ZstdDecompressionWriter),/* tp_basicsize */
	0,                              /* tp_itemsize */
	(destructor)ZstdDecompressionWriter_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 | Py_TPFLAGS_BASETYPE, /* tp_flags */
	ZstdDecompressionWriter__doc,   /* tp_doc */
	0,                              /* tp_traverse */
	0,                              /* tp_clear */
	0,                              /* tp_richcompare */
	0,                              /* tp_weaklistoffset */
	0,                              /* tp_iter */
	0,                              /* tp_iternext */
	ZstdDecompressionWriter_methods,/* tp_methods */
	ZstdDecompressionWriter_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 */
	PyType_GenericNew,              /* tp_new */
};

void decompressionwriter_module_init(PyObject* mod) {
	Py_SET_TYPE(&ZstdDecompressionWriterType, &PyType_Type);
	if (PyType_Ready(&ZstdDecompressionWriterType) < 0) {
		return;
	}
}