diff -r 2e484bdea8c4 -r b86a448a2965 contrib/python-zstandard/c-ext/compressionwriter.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/python-zstandard/c-ext/compressionwriter.c	Thu Nov 10 22:15:58 2016 -0800
@@ -0,0 +1,235 @@
+/**
+* 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(ZstdCompresssionWriter__doc__,
+"""A context manager used for writing compressed output to a writer.\n"
+);
+
+static void ZstdCompressionWriter_dealloc(ZstdCompressionWriter* self) {
+	Py_XDECREF(self->compressor);
+	Py_XDECREF(self->writer);
+
+	if (self->cstream) {
+		ZSTD_freeCStream(self->cstream);
+		self->cstream = NULL;
+	}
+
+	PyObject_Del(self);
+}
+
+static PyObject* ZstdCompressionWriter_enter(ZstdCompressionWriter* self) {
+	if (self->entered) {
+		PyErr_SetString(ZstdError, "cannot __enter__ multiple times");
+		return NULL;
+	}
+
+	self->cstream = CStream_from_ZstdCompressor(self->compressor, self->sourceSize);
+	if (!self->cstream) {
+		return NULL;
+	}
+
+	self->entered = 1;
+
+	Py_INCREF(self);
+	return (PyObject*)self;
+}
+
+static PyObject* ZstdCompressionWriter_exit(ZstdCompressionWriter* self, PyObject* args) {
+	PyObject* exc_type;
+	PyObject* exc_value;
+	PyObject* exc_tb;
+	size_t zresult;
+
+	ZSTD_outBuffer output;
+	PyObject* res;
+
+	if (!PyArg_ParseTuple(args, "OOO", &exc_type, &exc_value, &exc_tb)) {
+		return NULL;
+	}
+
+	self->entered = 0;
+
+	if (self->cstream && exc_type == Py_None && exc_value == Py_None &&
+		exc_tb == Py_None) {
+
+		output.dst = malloc(self->outSize);
+		if (!output.dst) {
+			return PyErr_NoMemory();
+		}
+		output.size = self->outSize;
+		output.pos = 0;
+
+		while (1) {
+			zresult = ZSTD_endStream(self->cstream, &output);
+			if (ZSTD_isError(zresult)) {
+				PyErr_Format(ZstdError, "error ending compression stream: %s",
+					ZSTD_getErrorName(zresult));
+				free(output.dst);
+				return NULL;
+			}
+
+			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);
+			}
+
+			if (!zresult) {
+				break;
+			}
+
+			output.pos = 0;
+		}
+
+		free(output.dst);
+		ZSTD_freeCStream(self->cstream);
+		self->cstream = NULL;
+	}
+
+	Py_RETURN_FALSE;
+}
+
+static PyObject* ZstdCompressionWriter_memory_size(ZstdCompressionWriter* self) {
+	if (!self->cstream) {
+		PyErr_SetString(ZstdError, "cannot determine size of an inactive compressor; "
+			"call when a context manager is active");
+		return NULL;
+	}
+
+	return PyLong_FromSize_t(ZSTD_sizeof_CStream(self->cstream));
+}
+
+static PyObject* ZstdCompressionWriter_write(ZstdCompressionWriter* self, PyObject* args) {
+	const char* source;
+	Py_ssize_t sourceSize;
+	size_t zresult;
+	ZSTD_inBuffer input;
+	ZSTD_outBuffer output;
+	PyObject* res;
+
+#if PY_MAJOR_VERSION >= 3
+	if (!PyArg_ParseTuple(args, "y#", &source, &sourceSize)) {
+#else
+	if (!PyArg_ParseTuple(args, "s#", &source, &sourceSize)) {
+#endif
+		return NULL;
+	}
+
+	if (!self->entered) {
+		PyErr_SetString(ZstdError, "compress must be called from an active context manager");
+		return NULL;
+	}
+
+	output.dst = malloc(self->outSize);
+	if (!output.dst) {
+		return PyErr_NoMemory();
+	}
+	output.size = self->outSize;
+	output.pos = 0;
+
+	input.src = source;
+	input.size = sourceSize;
+	input.pos = 0;
+
+	while ((ssize_t)input.pos < sourceSize) {
+		Py_BEGIN_ALLOW_THREADS
+		zresult = ZSTD_compressStream(self->cstream, &output, &input);
+		Py_END_ALLOW_THREADS
+
+		if (ZSTD_isError(zresult)) {
+			free(output.dst);
+			PyErr_Format(ZstdError, "zstd compress error: %s", ZSTD_getErrorName(zresult));
+			return NULL;
+		}
+
+		/* Copy data from output buffer to writer. */
+		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);
+		}
+		output.pos = 0;
+	}
+
+	free(output.dst);
+
+	/* TODO return bytes written */
+	Py_RETURN_NONE;
+	}
+
+static PyMethodDef ZstdCompressionWriter_methods[] = {
+	{ "__enter__", (PyCFunction)ZstdCompressionWriter_enter, METH_NOARGS,
+	PyDoc_STR("Enter a compression context.") },
+	{ "__exit__", (PyCFunction)ZstdCompressionWriter_exit, METH_VARARGS,
+	PyDoc_STR("Exit a compression context.") },
+	{ "memory_size", (PyCFunction)ZstdCompressionWriter_memory_size, METH_NOARGS,
+	PyDoc_STR("Obtain the memory size of the underlying compressor") },
+	{ "write", (PyCFunction)ZstdCompressionWriter_write, METH_VARARGS,
+	PyDoc_STR("Compress data") },
+	{ NULL, NULL }
+};
+
+PyTypeObject ZstdCompressionWriterType = {
+	PyVarObject_HEAD_INIT(NULL, 0)
+	"zstd.ZstdCompressionWriter",  /* tp_name */
+	sizeof(ZstdCompressionWriter),  /* tp_basicsize */
+	0,                              /* tp_itemsize */
+	(destructor)ZstdCompressionWriter_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 */
+	ZstdCompresssionWriter__doc__,  /* tp_doc */
+	0,                              /* tp_traverse */
+	0,                              /* tp_clear */
+	0,                              /* tp_richcompare */
+	0,                              /* tp_weaklistoffset */
+	0,                              /* tp_iter */
+	0,                              /* tp_iternext */
+	ZstdCompressionWriter_methods,  /* tp_methods */
+	0,                              /* 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 compressionwriter_module_init(PyObject* mod) {
+	Py_TYPE(&ZstdCompressionWriterType) = &PyType_Type;
+	if (PyType_Ready(&ZstdCompressionWriterType) < 0) {
+		return;
+	}
+}