view contrib/python-zstandard/c-ext/decompressor.c @ 36747:4c71a26a4009

sslutil: some more forcebytes() on some exception messages

At this point, test-https.t no longer dumps tracebacks
everywhere. Instead, we get some results that look like we're not
adequately finding things in hg's configuration, which should be
manageable (if somewhat annoying to find and fix.)

Differential Revision: https://phab.mercurial-scm.org/D2690

/**
* 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"
#include "pool.h"

extern PyObject* ZstdError;

/**
  * Ensure the ZSTD_DStream on a ZstdDecompressor is initialized and reset.
  *
  * This should be called before starting a decompression operation with a
  * ZSTD_DStream on a ZstdDecompressor.
  */
int init_dstream(ZstdDecompressor* decompressor) {
	void* dictData = NULL;
	size_t dictSize = 0;
	size_t zresult;

	/* Simple case of dstream already exists. Just reset it. */
	if (decompressor->dstream) {
		zresult = ZSTD_resetDStream(decompressor->dstream);
		if (ZSTD_isError(zresult)) {
			PyErr_Format(ZstdError, "could not reset DStream: %s",
				ZSTD_getErrorName(zresult));
			return -1;
		}

		return 0;
	}

	decompressor->dstream = ZSTD_createDStream();
	if (!decompressor->dstream) {
		PyErr_SetString(ZstdError, "could not create DStream");
		return -1;
	}

	if (decompressor->dict) {
		dictData = decompressor->dict->dictData;
		dictSize = decompressor->dict->dictSize;
	}

	if (dictData) {
		zresult = ZSTD_initDStream_usingDict(decompressor->dstream, dictData, dictSize);
	}
	else {
		zresult = ZSTD_initDStream(decompressor->dstream);
	}

	if (ZSTD_isError(zresult)) {
		/* Don't leave a reference to an invalid object. */
		ZSTD_freeDStream(decompressor->dstream);
		decompressor->dstream = NULL;

		PyErr_Format(ZstdError, "could not initialize DStream: %s",
			ZSTD_getErrorName(zresult));
		return -1;
	}

	return 0;
}

PyDoc_STRVAR(Decompressor__doc__,
"ZstdDecompressor(dict_data=None)\n"
"\n"
"Create an object used to perform Zstandard decompression.\n"
"\n"
"An instance can perform multiple decompression operations."
);

static int Decompressor_init(ZstdDecompressor* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"dict_data",
		NULL
	};

	ZstdCompressionDict* dict = NULL;

	self->dctx = NULL;
	self->dict = NULL;
	self->ddict = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|O!:ZstdDecompressor", kwlist,
		&ZstdCompressionDictType, &dict)) {
		return -1;
	}

	/* TODO lazily initialize the reference ZSTD_DCtx on first use since
	   not instances of ZstdDecompressor will use a ZSTD_DCtx. */
	self->dctx = ZSTD_createDCtx();
	if (!self->dctx) {
		PyErr_NoMemory();
		goto except;
	}

	if (dict) {
		self->dict = dict;
		Py_INCREF(dict);
	}

	return 0;

except:
	if (self->dctx) {
		ZSTD_freeDCtx(self->dctx);
		self->dctx = NULL;
	}

	return -1;
}

static void Decompressor_dealloc(ZstdDecompressor* self) {
	Py_CLEAR(self->dict);

	if (self->ddict) {
		ZSTD_freeDDict(self->ddict);
		self->ddict = NULL;
	}

	if (self->dstream) {
		ZSTD_freeDStream(self->dstream);
		self->dstream = NULL;
	}

	if (self->dctx) {
		ZSTD_freeDCtx(self->dctx);
		self->dctx = NULL;
	}

	PyObject_Del(self);
}

PyDoc_STRVAR(Decompressor_copy_stream__doc__,
	"copy_stream(ifh, ofh[, read_size=default, write_size=default]) -- decompress data between streams\n"
	"\n"
	"Compressed data will be read from ``ifh``, decompressed, and written to\n"
	"``ofh``. ``ifh`` must have a ``read(size)`` method. ``ofh`` must have a\n"
	"``write(data)`` method.\n"
	"\n"
	"The optional ``read_size`` and ``write_size`` arguments control the chunk\n"
	"size of data that is ``read()`` and ``write()`` between streams. They default\n"
	"to the default input and output sizes of zstd decompressor streams.\n"
);

static PyObject* Decompressor_copy_stream(ZstdDecompressor* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"ifh",
		"ofh",
		"read_size",
		"write_size",
		NULL
	};

	PyObject* source;
	PyObject* dest;
	size_t inSize = ZSTD_DStreamInSize();
	size_t outSize = ZSTD_DStreamOutSize();
	ZSTD_inBuffer input;
	ZSTD_outBuffer output;
	Py_ssize_t totalRead = 0;
	Py_ssize_t totalWrite = 0;
	char* readBuffer;
	Py_ssize_t readSize;
	PyObject* readResult;
	PyObject* res = NULL;
	size_t zresult = 0;
	PyObject* writeResult;
	PyObject* totalReadPy;
	PyObject* totalWritePy;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OO|kk:copy_stream", kwlist,
		&source, &dest, &inSize, &outSize)) {
		return NULL;
	}

	if (!PyObject_HasAttrString(source, "read")) {
		PyErr_SetString(PyExc_ValueError, "first argument must have a read() method");
		return NULL;
	}

	if (!PyObject_HasAttrString(dest, "write")) {
		PyErr_SetString(PyExc_ValueError, "second argument must have a write() method");
		return NULL;
	}

	/* Prevent free on uninitialized memory in finally. */
	output.dst = NULL;

	if (0 != init_dstream(self)) {
		res = NULL;
		goto finally;
	}

	output.dst = PyMem_Malloc(outSize);
	if (!output.dst) {
		PyErr_NoMemory();
		res = NULL;
		goto finally;
	}
	output.size = outSize;
	output.pos = 0;

	/* Read source stream until EOF */
	while (1) {
		readResult = PyObject_CallMethod(source, "read", "n", inSize);
		if (!readResult) {
			PyErr_SetString(ZstdError, "could not read() from source");
			goto finally;
		}

		PyBytes_AsStringAndSize(readResult, &readBuffer, &readSize);

		/* If no data was read, we're at EOF. */
		if (0 == readSize) {
			break;
		}

		totalRead += readSize;

		/* Send data to decompressor */
		input.src = readBuffer;
		input.size = readSize;
		input.pos = 0;

		while (input.pos < input.size) {
			Py_BEGIN_ALLOW_THREADS
			zresult = ZSTD_decompressStream(self->dstream, &output, &input);
			Py_END_ALLOW_THREADS

			if (ZSTD_isError(zresult)) {
				PyErr_Format(ZstdError, "zstd decompressor error: %s",
					ZSTD_getErrorName(zresult));
				res = NULL;
				goto finally;
			}

			if (output.pos) {
#if PY_MAJOR_VERSION >= 3
				writeResult = PyObject_CallMethod(dest, "write", "y#",
#else
				writeResult = PyObject_CallMethod(dest, "write", "s#",
#endif
					output.dst, output.pos);

				Py_XDECREF(writeResult);
				totalWrite += output.pos;
				output.pos = 0;
			}
		}
	}

	/* Source stream is exhausted. Finish up. */

	totalReadPy = PyLong_FromSsize_t(totalRead);
	totalWritePy = PyLong_FromSsize_t(totalWrite);
	res = PyTuple_Pack(2, totalReadPy, totalWritePy);
	Py_DECREF(totalReadPy);
	Py_DECREF(totalWritePy);

finally:
	if (output.dst) {
		PyMem_Free(output.dst);
	}

	return res;
}

PyDoc_STRVAR(Decompressor_decompress__doc__,
"decompress(data[, max_output_size=None]) -- Decompress data in its entirety\n"
"\n"
"This method will decompress the entirety of the argument and return the\n"
"result.\n"
"\n"
"The input bytes are expected to contain a full Zstandard frame (something\n"
"compressed with ``ZstdCompressor.compress()`` or similar). If the input does\n"
"not contain a full frame, an exception will be raised.\n"
"\n"
"If the frame header of the compressed data does not contain the content size\n"
"``max_output_size`` must be specified or ``ZstdError`` will be raised. An\n"
"allocation of size ``max_output_size`` will be performed and an attempt will\n"
"be made to perform decompression into that buffer. If the buffer is too\n"
"small or cannot be allocated, ``ZstdError`` will be raised. The buffer will\n"
"be resized if it is too large.\n"
"\n"
"Uncompressed data could be much larger than compressed data. As a result,\n"
"calling this function could result in a very large memory allocation being\n"
"performed to hold the uncompressed data. Therefore it is **highly**\n"
"recommended to use a streaming decompression method instead of this one.\n"
);

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

	const char* source;
	Py_ssize_t sourceSize;
	Py_ssize_t maxOutputSize = 0;
	unsigned long long decompressedSize;
	size_t destCapacity;
	PyObject* result = NULL;
	void* dictData = NULL;
	size_t dictSize = 0;
	size_t zresult;

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y#|n:decompress",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s#|n:decompress",
#endif
		kwlist, &source, &sourceSize, &maxOutputSize)) {
		return NULL;
	}

	if (self->dict) {
		dictData = self->dict->dictData;
		dictSize = self->dict->dictSize;
	}

	if (dictData && !self->ddict) {
		Py_BEGIN_ALLOW_THREADS
		self->ddict = ZSTD_createDDict_byReference(dictData, dictSize);
		Py_END_ALLOW_THREADS

		if (!self->ddict) {
			PyErr_SetString(ZstdError, "could not create decompression dict");
			return NULL;
		}
	}

	decompressedSize = ZSTD_getDecompressedSize(source, sourceSize);
	/* 0 returned if content size not in the zstd frame header */
	if (0 == decompressedSize) {
		if (0 == maxOutputSize) {
			PyErr_SetString(ZstdError, "input data invalid or missing content size "
				"in frame header");
			return NULL;
		}
		else {
			result = PyBytes_FromStringAndSize(NULL, maxOutputSize);
			destCapacity = maxOutputSize;
		}
	}
	else {
		result = PyBytes_FromStringAndSize(NULL, decompressedSize);
		destCapacity = decompressedSize;
	}

	if (!result) {
		return NULL;
	}

	Py_BEGIN_ALLOW_THREADS
	if (self->ddict) {
		zresult = ZSTD_decompress_usingDDict(self->dctx,
			PyBytes_AsString(result), destCapacity,
			source, sourceSize, self->ddict);
	}
	else {
		zresult = ZSTD_decompressDCtx(self->dctx,
			PyBytes_AsString(result), destCapacity, source, sourceSize);
	}
	Py_END_ALLOW_THREADS

	if (ZSTD_isError(zresult)) {
		PyErr_Format(ZstdError, "decompression error: %s", ZSTD_getErrorName(zresult));
		Py_DECREF(result);
		return NULL;
	}
	else if (decompressedSize && zresult != decompressedSize) {
		PyErr_Format(ZstdError, "decompression error: decompressed %zu bytes; expected %llu",
			zresult, decompressedSize);
		Py_DECREF(result);
		return NULL;
	}
	else if (zresult < destCapacity) {
		if (_PyBytes_Resize(&result, zresult)) {
			Py_DECREF(result);
			return NULL;
		}
	}

	return result;
}

PyDoc_STRVAR(Decompressor_decompressobj__doc__,
"decompressobj()\n"
"\n"
"Incrementally feed data into a decompressor.\n"
"\n"
"The returned object exposes a ``decompress(data)`` method. This makes it\n"
"compatible with ``zlib.decompressobj`` and ``bz2.BZ2Decompressor`` so that\n"
"callers can swap in the zstd decompressor while using the same API.\n"
);

static ZstdDecompressionObj* Decompressor_decompressobj(ZstdDecompressor* self) {
	ZstdDecompressionObj* result = (ZstdDecompressionObj*)PyObject_CallObject((PyObject*)&ZstdDecompressionObjType, NULL);
	if (!result) {
		return NULL;
	}

	if (0 != init_dstream(self)) {
		Py_DECREF(result);
		return NULL;
	}

	result->decompressor = self;
	Py_INCREF(result->decompressor);

	return result;
}

PyDoc_STRVAR(Decompressor_read_from__doc__,
"read_from(reader[, read_size=default, write_size=default, skip_bytes=0])\n"
"Read compressed data and return an iterator\n"
"\n"
"Returns an iterator of decompressed data chunks produced from reading from\n"
"the ``reader``.\n"
"\n"
"Compressed data will be obtained from ``reader`` by calling the\n"
"``read(size)`` method of it. The source data will be streamed into a\n"
"decompressor. As decompressed data is available, it will be exposed to the\n"
"returned iterator.\n"
"\n"
"Data is ``read()`` in chunks of size ``read_size`` and exposed to the\n"
"iterator in chunks of size ``write_size``. The default values are the input\n"
"and output sizes for a zstd streaming decompressor.\n"
"\n"
"There is also support for skipping the first ``skip_bytes`` of data from\n"
"the source.\n"
);

static ZstdDecompressorIterator* Decompressor_read_from(ZstdDecompressor* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"reader",
		"read_size",
		"write_size",
		"skip_bytes",
		NULL
	};

	PyObject* reader;
	size_t inSize = ZSTD_DStreamInSize();
	size_t outSize = ZSTD_DStreamOutSize();
	ZstdDecompressorIterator* result;
	size_t skipBytes = 0;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|kkk:read_from", kwlist,
		&reader, &inSize, &outSize, &skipBytes)) {
		return NULL;
	}

	if (skipBytes >= inSize) {
		PyErr_SetString(PyExc_ValueError,
			"skip_bytes must be smaller than read_size");
		return NULL;
	}

	result = (ZstdDecompressorIterator*)PyObject_CallObject((PyObject*)&ZstdDecompressorIteratorType, NULL);
	if (!result) {
		return NULL;
	}

	if (PyObject_HasAttrString(reader, "read")) {
		result->reader = reader;
		Py_INCREF(result->reader);
	}
	else if (1 == PyObject_CheckBuffer(reader)) {
		/* Object claims it is a buffer. Try to get a handle to it. */
		result->buffer = PyMem_Malloc(sizeof(Py_buffer));
		if (!result->buffer) {
			goto except;
		}

		memset(result->buffer, 0, sizeof(Py_buffer));

		if (0 != PyObject_GetBuffer(reader, result->buffer, PyBUF_CONTIG_RO)) {
			goto except;
		}
	}
	else {
		PyErr_SetString(PyExc_ValueError,
			"must pass an object with a read() method or conforms to buffer protocol");
		goto except;
	}

	result->decompressor = self;
	Py_INCREF(result->decompressor);

	result->inSize = inSize;
	result->outSize = outSize;
	result->skipBytes = skipBytes;

	if (0 != init_dstream(self)) {
		goto except;
	}

	result->input.src = PyMem_Malloc(inSize);
	if (!result->input.src) {
		PyErr_NoMemory();
		goto except;
	}

	goto finally;

except:
	Py_CLEAR(result->reader);

	if (result->buffer) {
		PyBuffer_Release(result->buffer);
		Py_CLEAR(result->buffer);
	}

	Py_CLEAR(result);

finally:

	return result;
}

PyDoc_STRVAR(Decompressor_write_to__doc__,
"Create a context manager to write decompressed data to an object.\n"
"\n"
"The passed object must have a ``write()`` method.\n"
"\n"
"The caller feeds intput data to the object by calling ``write(data)``.\n"
"Decompressed data is written to the argument given as it is decompressed.\n"
"\n"
"An optional ``write_size`` argument defines the size of chunks to\n"
"``write()`` to the writer. It defaults to the default output size for a zstd\n"
"streaming decompressor.\n"
);

static ZstdDecompressionWriter* Decompressor_write_to(ZstdDecompressor* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"writer",
		"write_size",
		NULL
	};

	PyObject* writer;
	size_t outSize = ZSTD_DStreamOutSize();
	ZstdDecompressionWriter* result;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|k:write_to", kwlist,
		&writer, &outSize)) {
		return NULL;
	}

	if (!PyObject_HasAttrString(writer, "write")) {
		PyErr_SetString(PyExc_ValueError, "must pass an object with a write() method");
		return NULL;
	}

	result = (ZstdDecompressionWriter*)PyObject_CallObject((PyObject*)&ZstdDecompressionWriterType, NULL);
	if (!result) {
		return NULL;
	}

	result->decompressor = self;
	Py_INCREF(result->decompressor);

	result->writer = writer;
	Py_INCREF(result->writer);

	result->outSize = outSize;

	return result;
}

PyDoc_STRVAR(Decompressor_decompress_content_dict_chain__doc__,
"Decompress a series of chunks using the content dictionary chaining technique\n"
);

static PyObject* Decompressor_decompress_content_dict_chain(PyObject* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"frames",
		NULL
	};

	PyObject* chunks;
	Py_ssize_t chunksLen;
	Py_ssize_t chunkIndex;
	char parity = 0;
	PyObject* chunk;
	char* chunkData;
	Py_ssize_t chunkSize;
	ZSTD_DCtx* dctx = NULL;
	size_t zresult;
	ZSTD_frameParams frameParams;
	void* buffer1 = NULL;
	size_t buffer1Size = 0;
	size_t buffer1ContentSize = 0;
	void* buffer2 = NULL;
	size_t buffer2Size = 0;
	size_t buffer2ContentSize = 0;
	void* destBuffer = NULL;
	PyObject* result = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O!:decompress_content_dict_chain",
		kwlist, &PyList_Type, &chunks)) {
		return NULL;
	}

	chunksLen = PyList_Size(chunks);
	if (!chunksLen) {
		PyErr_SetString(PyExc_ValueError, "empty input chain");
		return NULL;
	}

	/* The first chunk should not be using a dictionary. We handle it specially. */
	chunk = PyList_GetItem(chunks, 0);
	if (!PyBytes_Check(chunk)) {
		PyErr_SetString(PyExc_ValueError, "chunk 0 must be bytes");
		return NULL;
	}

	/* We require that all chunks be zstd frames and that they have content size set. */
	PyBytes_AsStringAndSize(chunk, &chunkData, &chunkSize);
	zresult = ZSTD_getFrameParams(&frameParams, (void*)chunkData, chunkSize);
	if (ZSTD_isError(zresult)) {
		PyErr_SetString(PyExc_ValueError, "chunk 0 is not a valid zstd frame");
		return NULL;
	}
	else if (zresult) {
		PyErr_SetString(PyExc_ValueError, "chunk 0 is too small to contain a zstd frame");
		return NULL;
	}

	if (0 == frameParams.frameContentSize) {
		PyErr_SetString(PyExc_ValueError, "chunk 0 missing content size in frame");
		return NULL;
	}

	dctx = ZSTD_createDCtx();
	if (!dctx) {
		PyErr_NoMemory();
		goto finally;
	}

	buffer1Size = frameParams.frameContentSize;
	buffer1 = PyMem_Malloc(buffer1Size);
	if (!buffer1) {
		goto finally;
	}

	Py_BEGIN_ALLOW_THREADS
	zresult = ZSTD_decompressDCtx(dctx, buffer1, buffer1Size, chunkData, chunkSize);
	Py_END_ALLOW_THREADS
	if (ZSTD_isError(zresult)) {
		PyErr_Format(ZstdError, "could not decompress chunk 0: %s", ZSTD_getErrorName(zresult));
		goto finally;
	}

	buffer1ContentSize = zresult;

	/* Special case of a simple chain. */
	if (1 == chunksLen) {
		result = PyBytes_FromStringAndSize(buffer1, buffer1Size);
		goto finally;
	}

	/* This should ideally look at next chunk. But this is slightly simpler. */
	buffer2Size = frameParams.frameContentSize;
	buffer2 = PyMem_Malloc(buffer2Size);
	if (!buffer2) {
		goto finally;
	}

	/* For each subsequent chunk, use the previous fulltext as a content dictionary.
	   Our strategy is to have 2 buffers. One holds the previous fulltext (to be
	   used as a content dictionary) and the other holds the new fulltext. The
	   buffers grow when needed but never decrease in size. This limits the
	   memory allocator overhead.
	*/
	for (chunkIndex = 1; chunkIndex < chunksLen; chunkIndex++) {
		chunk = PyList_GetItem(chunks, chunkIndex);
		if (!PyBytes_Check(chunk)) {
			PyErr_Format(PyExc_ValueError, "chunk %zd must be bytes", chunkIndex);
			goto finally;
		}

		PyBytes_AsStringAndSize(chunk, &chunkData, &chunkSize);
		zresult = ZSTD_getFrameParams(&frameParams, (void*)chunkData, chunkSize);
		if (ZSTD_isError(zresult)) {
			PyErr_Format(PyExc_ValueError, "chunk %zd is not a valid zstd frame", chunkIndex);
			goto finally;
		}
		else if (zresult) {
			PyErr_Format(PyExc_ValueError, "chunk %zd is too small to contain a zstd frame", chunkIndex);
			goto finally;
		}

		if (0 == frameParams.frameContentSize) {
			PyErr_Format(PyExc_ValueError, "chunk %zd missing content size in frame", chunkIndex);
			goto finally;
		}

		parity = chunkIndex % 2;

		/* This could definitely be abstracted to reduce code duplication. */
		if (parity) {
			/* Resize destination buffer to hold larger content. */
			if (buffer2Size < frameParams.frameContentSize) {
				buffer2Size = frameParams.frameContentSize;
				destBuffer = PyMem_Realloc(buffer2, buffer2Size);
				if (!destBuffer) {
					goto finally;
				}
				buffer2 = destBuffer;
			}

			Py_BEGIN_ALLOW_THREADS
			zresult = ZSTD_decompress_usingDict(dctx, buffer2, buffer2Size,
				chunkData, chunkSize, buffer1, buffer1ContentSize);
			Py_END_ALLOW_THREADS
			if (ZSTD_isError(zresult)) {
				PyErr_Format(ZstdError, "could not decompress chunk %zd: %s",
					chunkIndex, ZSTD_getErrorName(zresult));
				goto finally;
			}
			buffer2ContentSize = zresult;
		}
		else {
			if (buffer1Size < frameParams.frameContentSize) {
				buffer1Size = frameParams.frameContentSize;
				destBuffer = PyMem_Realloc(buffer1, buffer1Size);
				if (!destBuffer) {
					goto finally;
				}
				buffer1 = destBuffer;
			}

			Py_BEGIN_ALLOW_THREADS
			zresult = ZSTD_decompress_usingDict(dctx, buffer1, buffer1Size,
				chunkData, chunkSize, buffer2, buffer2ContentSize);
			Py_END_ALLOW_THREADS
			if (ZSTD_isError(zresult)) {
				PyErr_Format(ZstdError, "could not decompress chunk %zd: %s",
					chunkIndex, ZSTD_getErrorName(zresult));
				goto finally;
			}
			buffer1ContentSize = zresult;
		}
	}

	result = PyBytes_FromStringAndSize(parity ? buffer2 : buffer1,
		parity ? buffer2ContentSize : buffer1ContentSize);

finally:
	if (buffer2) {
		PyMem_Free(buffer2);
	}
	if (buffer1) {
		PyMem_Free(buffer1);
	}

	if (dctx) {
		ZSTD_freeDCtx(dctx);
	}

	return result;
}

typedef struct {
	void* sourceData;
	size_t sourceSize;
	unsigned long long destSize;
} FramePointer;

typedef struct {
	FramePointer* frames;
	Py_ssize_t framesSize;
	unsigned long long compressedSize;
} FrameSources;

typedef struct {
	void* dest;
	Py_ssize_t destSize;
	BufferSegment* segments;
	Py_ssize_t segmentsSize;
} DestBuffer;

typedef enum {
	WorkerError_none = 0,
	WorkerError_zstd = 1,
	WorkerError_memory = 2,
	WorkerError_sizeMismatch = 3,
	WorkerError_unknownSize = 4,
} WorkerError;

typedef struct {
	/* Source records and length */
	FramePointer* framePointers;
	/* Which records to process. */
	Py_ssize_t startOffset;
	Py_ssize_t endOffset;
	unsigned long long totalSourceSize;

	/* Compression state and settings. */
	ZSTD_DCtx* dctx;
	ZSTD_DDict* ddict;
	int requireOutputSizes;

	/* Output storage. */
	DestBuffer* destBuffers;
	Py_ssize_t destCount;

	/* Item that error occurred on. */
	Py_ssize_t errorOffset;
	/* If an error occurred. */
	WorkerError error;
	/* result from zstd decompression operation */
	size_t zresult;
} WorkerState;

static void decompress_worker(WorkerState* state) {
	size_t allocationSize;
	DestBuffer* destBuffer;
	Py_ssize_t frameIndex;
	Py_ssize_t localOffset = 0;
	Py_ssize_t currentBufferStartIndex = state->startOffset;
	Py_ssize_t remainingItems = state->endOffset - state->startOffset + 1;
	void* tmpBuf;
	Py_ssize_t destOffset = 0;
	FramePointer* framePointers = state->framePointers;
	size_t zresult;
	unsigned long long totalOutputSize = 0;

	assert(NULL == state->destBuffers);
	assert(0 == state->destCount);
	assert(state->endOffset - state->startOffset >= 0);

	/*
	 * We need to allocate a buffer to hold decompressed data. How we do this
	 * depends on what we know about the output. The following scenarios are
	 * possible:
	 *
	 * 1. All structs defining frames declare the output size.
	 * 2. The decompressed size is embedded within the zstd frame.
	 * 3. The decompressed size is not stored anywhere.
	 *
	 * For now, we only support #1 and #2.
	 */

	/* Resolve ouput segments. */
	for (frameIndex = state->startOffset; frameIndex <= state->endOffset; frameIndex++) {
		FramePointer* fp = &framePointers[frameIndex];

		if (0 == fp->destSize) {
			fp->destSize = ZSTD_getDecompressedSize(fp->sourceData, fp->sourceSize);
			if (0 == fp->destSize && state->requireOutputSizes) {
				state->error = WorkerError_unknownSize;
				state->errorOffset = frameIndex;
				return;
			}
		}

		totalOutputSize += fp->destSize;
	}

	state->destBuffers = calloc(1, sizeof(DestBuffer));
	if (NULL == state->destBuffers) {
		state->error = WorkerError_memory;
		return;
	}

	state->destCount = 1;

	destBuffer = &state->destBuffers[state->destCount - 1];

	assert(framePointers[state->startOffset].destSize > 0); /* For now. */

	allocationSize = roundpow2(state->totalSourceSize);

	if (framePointers[state->startOffset].destSize > allocationSize) {
		allocationSize = roundpow2(framePointers[state->startOffset].destSize);
	}

	destBuffer->dest = malloc(allocationSize);
	if (NULL == destBuffer->dest) {
		state->error = WorkerError_memory;
		return;
	}

	destBuffer->destSize = allocationSize;

	destBuffer->segments = calloc(remainingItems, sizeof(BufferSegment));
	if (NULL == destBuffer->segments) {
		/* Caller will free state->dest as part of cleanup. */
		state->error = WorkerError_memory;
		return;
	}

	destBuffer->segmentsSize = remainingItems;

	for (frameIndex = state->startOffset; frameIndex <= state->endOffset; frameIndex++) {
		const void* source = framePointers[frameIndex].sourceData;
		const size_t sourceSize = framePointers[frameIndex].sourceSize;
		void* dest;
		const size_t decompressedSize = framePointers[frameIndex].destSize;
		size_t destAvailable = destBuffer->destSize - destOffset;

		assert(decompressedSize > 0); /* For now. */

		/*
		 * Not enough space in current buffer. Finish current before and allocate and
		 * switch to a new one.
		 */
		if (decompressedSize > destAvailable) {
			/*
			 * Shrinking the destination buffer is optional. But it should be cheap,
			 * so we just do it.
			 */
			if (destAvailable) {
				tmpBuf = realloc(destBuffer->dest, destOffset);
				if (NULL == tmpBuf) {
					state->error = WorkerError_memory;
					return;
				}

				destBuffer->dest = tmpBuf;
				destBuffer->destSize = destOffset;
			}

			/* Truncate segments buffer. */
			tmpBuf = realloc(destBuffer->segments,
				(frameIndex - currentBufferStartIndex) * sizeof(BufferSegment));
			if (NULL == tmpBuf) {
				state->error = WorkerError_memory;
				return;
			}

			destBuffer->segments = tmpBuf;
			destBuffer->segmentsSize = frameIndex - currentBufferStartIndex;

			/* Grow space for new DestBuffer. */
			tmpBuf = realloc(state->destBuffers, (state->destCount + 1) * sizeof(DestBuffer));
			if (NULL == tmpBuf) {
				state->error = WorkerError_memory;
				return;
			}

			state->destBuffers = tmpBuf;
			state->destCount++;

			destBuffer = &state->destBuffers[state->destCount - 1];

			/* Don't take any chances will non-NULL pointers. */
			memset(destBuffer, 0, sizeof(DestBuffer));

			allocationSize = roundpow2(state->totalSourceSize);

			if (decompressedSize > allocationSize) {
				allocationSize = roundpow2(decompressedSize);
			}

			destBuffer->dest = malloc(allocationSize);
			if (NULL == destBuffer->dest) {
				state->error = WorkerError_memory;
				return;
			}

			destBuffer->destSize = allocationSize;
			destAvailable = allocationSize;
			destOffset = 0;
			localOffset = 0;

			destBuffer->segments = calloc(remainingItems, sizeof(BufferSegment));
			if (NULL == destBuffer->segments) {
				state->error = WorkerError_memory;
				return;
			}

			destBuffer->segmentsSize = remainingItems;
			currentBufferStartIndex = frameIndex;
		}

		dest = (char*)destBuffer->dest + destOffset;

		if (state->ddict) {
			zresult = ZSTD_decompress_usingDDict(state->dctx, dest, decompressedSize,
				source, sourceSize, state->ddict);
		}
		else {
			zresult = ZSTD_decompressDCtx(state->dctx, dest, decompressedSize,
				source, sourceSize);
		}

		if (ZSTD_isError(zresult)) {
			state->error = WorkerError_zstd;
			state->zresult = zresult;
			state->errorOffset = frameIndex;
			return;
		}
		else if (zresult != decompressedSize) {
			state->error = WorkerError_sizeMismatch;
			state->zresult = zresult;
			state->errorOffset = frameIndex;
			return;
		}

		destBuffer->segments[localOffset].offset = destOffset;
		destBuffer->segments[localOffset].length = decompressedSize;
		destOffset += zresult;
		localOffset++;
		remainingItems--;
	}

	if (destBuffer->destSize > destOffset) {
		tmpBuf = realloc(destBuffer->dest, destOffset);
		if (NULL == tmpBuf) {
			state->error = WorkerError_memory;
			return;
		}

		destBuffer->dest = tmpBuf;
		destBuffer->destSize = destOffset;
	}
}

ZstdBufferWithSegmentsCollection* decompress_from_framesources(ZstdDecompressor* decompressor, FrameSources* frames,
	unsigned int threadCount) {
	void* dictData = NULL;
	size_t dictSize = 0;
	Py_ssize_t i = 0;
	int errored = 0;
	Py_ssize_t segmentsCount;
	ZstdBufferWithSegments* bws = NULL;
	PyObject* resultArg = NULL;
	Py_ssize_t resultIndex;
	ZstdBufferWithSegmentsCollection* result = NULL;
	FramePointer* framePointers = frames->frames;
	unsigned long long workerBytes = 0;
	int currentThread = 0;
	Py_ssize_t workerStartOffset = 0;
	POOL_ctx* pool = NULL;
	WorkerState* workerStates = NULL;
	unsigned long long bytesPerWorker;

	/* Caller should normalize 0 and negative values to 1 or larger. */
	assert(threadCount >= 1);

	/* More threads than inputs makes no sense under any conditions. */
	threadCount = frames->framesSize < threadCount ? (unsigned int)frames->framesSize
												   : threadCount;

	/* TODO lower thread count if input size is too small and threads would just
	   add overhead. */

	if (decompressor->dict) {
		dictData = decompressor->dict->dictData;
		dictSize = decompressor->dict->dictSize;
	}

	if (dictData && !decompressor->ddict) {
		Py_BEGIN_ALLOW_THREADS
		decompressor->ddict = ZSTD_createDDict_byReference(dictData, dictSize);
		Py_END_ALLOW_THREADS

		if (!decompressor->ddict) {
			PyErr_SetString(ZstdError, "could not create decompression dict");
			return NULL;
		}
	}

	/* If threadCount==1, we don't start a thread pool. But we do leverage the
	   same API for dispatching work. */
	workerStates = PyMem_Malloc(threadCount * sizeof(WorkerState));
	if (NULL == workerStates) {
		PyErr_NoMemory();
		goto finally;
	}

	memset(workerStates, 0, threadCount * sizeof(WorkerState));

	if (threadCount > 1) {
		pool = POOL_create(threadCount, 1);
		if (NULL == pool) {
			PyErr_SetString(ZstdError, "could not initialize zstd thread pool");
			goto finally;
		}
	}

	bytesPerWorker = frames->compressedSize / threadCount;

	for (i = 0; i < threadCount; i++) {
		workerStates[i].dctx = ZSTD_createDCtx();
		if (NULL == workerStates[i].dctx) {
			PyErr_NoMemory();
			goto finally;
		}

		ZSTD_copyDCtx(workerStates[i].dctx, decompressor->dctx);

		workerStates[i].ddict = decompressor->ddict;
		workerStates[i].framePointers = framePointers;
		workerStates[i].requireOutputSizes = 1;
	}

	Py_BEGIN_ALLOW_THREADS
	/* There are many ways to split work among workers.

	   For now, we take a simple approach of splitting work so each worker
	   gets roughly the same number of input bytes. This will result in more
	   starvation than running N>threadCount jobs. But it avoids complications
	   around state tracking, which could involve extra locking.
	*/
	for (i = 0; i < frames->framesSize; i++) {
		workerBytes += frames->frames[i].sourceSize;

		/*
		 * The last worker/thread needs to handle all remaining work. Don't
		 * trigger it prematurely. Defer to the block outside of the loop.
		 * (But still process this loop so workerBytes is correct.
		 */
		if (currentThread == threadCount - 1) {
			continue;
		}

		if (workerBytes >= bytesPerWorker) {
			workerStates[currentThread].startOffset = workerStartOffset;
			workerStates[currentThread].endOffset = i;
			workerStates[currentThread].totalSourceSize = workerBytes;

			if (threadCount > 1) {
				POOL_add(pool, (POOL_function)decompress_worker, &workerStates[currentThread]);
			}
			else {
				decompress_worker(&workerStates[currentThread]);
			}
			currentThread++;
			workerStartOffset = i + 1;
			workerBytes = 0;
		}
	}

	if (workerBytes) {
		workerStates[currentThread].startOffset = workerStartOffset;
		workerStates[currentThread].endOffset = frames->framesSize - 1;
		workerStates[currentThread].totalSourceSize = workerBytes;

		if (threadCount > 1) {
			POOL_add(pool, (POOL_function)decompress_worker, &workerStates[currentThread]);
		}
		else {
			decompress_worker(&workerStates[currentThread]);
		}
	}

	if (threadCount > 1) {
		POOL_free(pool);
		pool = NULL;
	}
	Py_END_ALLOW_THREADS

	for (i = 0; i < threadCount; i++) {
		switch (workerStates[i].error) {
		case WorkerError_none:
			break;

		case WorkerError_zstd:
			PyErr_Format(ZstdError, "error decompressing item %zd: %s",
				workerStates[i].errorOffset, ZSTD_getErrorName(workerStates[i].zresult));
			errored = 1;
			break;

		case WorkerError_memory:
			PyErr_NoMemory();
			errored = 1;
			break;

		case WorkerError_sizeMismatch:
			PyErr_Format(ZstdError, "error decompressing item %zd: decompressed %zu bytes; expected %llu",
				workerStates[i].errorOffset, workerStates[i].zresult,
				framePointers[workerStates[i].errorOffset].destSize);
			errored = 1;
			break;

		case WorkerError_unknownSize:
			PyErr_Format(PyExc_ValueError, "could not determine decompressed size of item %zd",
				workerStates[i].errorOffset);
			errored = 1;
			break;

		default:
			PyErr_Format(ZstdError, "unhandled error type: %d; this is a bug",
				workerStates[i].error);
			errored = 1;
			break;
		}

		if (errored) {
			break;
		}
	}

	if (errored) {
		goto finally;
	}

	segmentsCount = 0;
	for (i = 0; i < threadCount; i++) {
		segmentsCount += workerStates[i].destCount;
	}

	resultArg = PyTuple_New(segmentsCount);
	if (NULL == resultArg) {
		goto finally;
	}

	resultIndex = 0;

	for (i = 0; i < threadCount; i++) {
		Py_ssize_t bufferIndex;
		WorkerState* state = &workerStates[i];

		for (bufferIndex = 0; bufferIndex < state->destCount; bufferIndex++) {
			DestBuffer* destBuffer = &state->destBuffers[bufferIndex];

			bws = BufferWithSegments_FromMemory(destBuffer->dest, destBuffer->destSize,
				destBuffer->segments, destBuffer->segmentsSize);
			if (NULL == bws) {
				goto finally;
			}

			/*
			* Memory for buffer and segments was allocated using malloc() in worker
			* and the memory is transferred to the BufferWithSegments instance. So
			* tell instance to use free() and NULL the reference in the state struct
			* so it isn't freed below.
			*/
			bws->useFree = 1;
			destBuffer->dest = NULL;
			destBuffer->segments = NULL;

			PyTuple_SET_ITEM(resultArg, resultIndex++, (PyObject*)bws);
		}
	}

	result = (ZstdBufferWithSegmentsCollection*)PyObject_CallObject(
		(PyObject*)&ZstdBufferWithSegmentsCollectionType, resultArg);

finally:
	Py_CLEAR(resultArg);

	if (workerStates) {
		for (i = 0; i < threadCount; i++) {
			Py_ssize_t bufferIndex;
			WorkerState* state = &workerStates[i];

			if (state->dctx) {
				ZSTD_freeDCtx(state->dctx);
			}

			for (bufferIndex = 0; bufferIndex < state->destCount; bufferIndex++) {
				if (state->destBuffers) {
					/*
					* Will be NULL if memory transfered to a BufferWithSegments.
					* Otherwise it is left over after an error occurred.
					*/
					free(state->destBuffers[bufferIndex].dest);
					free(state->destBuffers[bufferIndex].segments);
				}
			}

			free(state->destBuffers);
		}

		PyMem_Free(workerStates);
	}

	POOL_free(pool);

	return result;
}

PyDoc_STRVAR(Decompressor_multi_decompress_to_buffer__doc__,
"Decompress multiple frames to output buffers\n"
"\n"
"Receives a ``BufferWithSegments``, a ``BufferWithSegmentsCollection`` or a\n"
"list of bytes-like objects. Each item in the passed collection should be a\n"
"compressed zstd frame.\n"
"\n"
"Unless ``decompressed_sizes`` is specified, the content size *must* be\n"
"written into the zstd frame header. If ``decompressed_sizes`` is specified,\n"
"it is an object conforming to the buffer protocol that represents an array\n"
"of 64-bit unsigned integers in the machine's native format. Specifying\n"
"``decompressed_sizes`` avoids a pre-scan of each frame to determine its\n"
"output size.\n"
"\n"
"Returns a ``BufferWithSegmentsCollection`` containing the decompressed\n"
"data. All decompressed data is allocated in a single memory buffer. The\n"
"``BufferWithSegments`` instance tracks which objects are at which offsets\n"
"and their respective lengths.\n"
"\n"
"The ``threads`` argument controls how many threads to use for operations.\n"
"Negative values will use the same number of threads as logical CPUs on the\n"
"machine.\n"
);

static ZstdBufferWithSegmentsCollection* Decompressor_multi_decompress_to_buffer(ZstdDecompressor* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"frames",
		"decompressed_sizes",
		"threads",
		NULL
	};

	PyObject* frames;
	Py_buffer frameSizes;
	int threads = 0;
	Py_ssize_t frameCount;
	Py_buffer* frameBuffers = NULL;
	FramePointer* framePointers = NULL;
	unsigned long long* frameSizesP = NULL;
	unsigned long long totalInputSize = 0;
	FrameSources frameSources;
	ZstdBufferWithSegmentsCollection* result = NULL;
	Py_ssize_t i;

	memset(&frameSizes, 0, sizeof(frameSizes));

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|y*i:multi_decompress_to_buffer",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|s*i:multi_decompress_to_buffer",
#endif
		kwlist, &frames, &frameSizes, &threads)) {
		return NULL;
	}

	if (frameSizes.buf) {
		if (!PyBuffer_IsContiguous(&frameSizes, 'C') || frameSizes.ndim > 1) {
			PyErr_SetString(PyExc_ValueError, "decompressed_sizes buffer should be contiguous and have a single dimension");
			goto finally;
		}

		frameSizesP = (unsigned long long*)frameSizes.buf;
	}

	if (threads < 0) {
		threads = cpu_count();
	}

	if (threads < 2) {
		threads = 1;
	}

	if (PyObject_TypeCheck(frames, &ZstdBufferWithSegmentsType)) {
		ZstdBufferWithSegments* buffer = (ZstdBufferWithSegments*)frames;
		frameCount = buffer->segmentCount;

		if (frameSizes.buf && frameSizes.len != frameCount * (Py_ssize_t)sizeof(unsigned long long)) {
			PyErr_Format(PyExc_ValueError, "decompressed_sizes size mismatch; expected %zd, got %zd",
				frameCount * sizeof(unsigned long long), frameSizes.len);
			goto finally;
		}

		framePointers = PyMem_Malloc(frameCount * sizeof(FramePointer));
		if (!framePointers) {
			PyErr_NoMemory();
			goto finally;
		}

		for (i = 0; i < frameCount; i++) {
			void* sourceData;
			unsigned long long sourceSize;
			unsigned long long decompressedSize = 0;

			if (buffer->segments[i].offset + buffer->segments[i].length > buffer->dataSize) {
				PyErr_Format(PyExc_ValueError, "item %zd has offset outside memory area", i);
				goto finally;
			}

			sourceData = (char*)buffer->data + buffer->segments[i].offset;
			sourceSize = buffer->segments[i].length;
			totalInputSize += sourceSize;

			if (frameSizesP) {
				decompressedSize = frameSizesP[i];
			}

			framePointers[i].sourceData = sourceData;
			framePointers[i].sourceSize = sourceSize;
			framePointers[i].destSize = decompressedSize;
		}
	}
	else if (PyObject_TypeCheck(frames, &ZstdBufferWithSegmentsCollectionType)) {
		Py_ssize_t offset = 0;
		ZstdBufferWithSegments* buffer;
		ZstdBufferWithSegmentsCollection* collection = (ZstdBufferWithSegmentsCollection*)frames;

		frameCount = BufferWithSegmentsCollection_length(collection);

		if (frameSizes.buf && frameSizes.len != frameCount) {
			PyErr_Format(PyExc_ValueError,
				"decompressed_sizes size mismatch; expected %zd; got %zd",
				frameCount * sizeof(unsigned long long), frameSizes.len);
			goto finally;
		}

		framePointers = PyMem_Malloc(frameCount * sizeof(FramePointer));
		if (NULL == framePointers) {
			PyErr_NoMemory();
			goto finally;
		}

		/* Iterate the data structure directly because it is faster. */
		for (i = 0; i < collection->bufferCount; i++) {
			Py_ssize_t segmentIndex;
			buffer = collection->buffers[i];

			for (segmentIndex = 0; segmentIndex < buffer->segmentCount; segmentIndex++) {
				if (buffer->segments[segmentIndex].offset + buffer->segments[segmentIndex].length > buffer->dataSize) {
					PyErr_Format(PyExc_ValueError, "item %zd has offset outside memory area",
						offset);
					goto finally;
				}

				totalInputSize += buffer->segments[segmentIndex].length;

				framePointers[offset].sourceData = (char*)buffer->data + buffer->segments[segmentIndex].offset;
				framePointers[offset].sourceSize = buffer->segments[segmentIndex].length;
				framePointers[offset].destSize = frameSizesP ? frameSizesP[offset] : 0;

				offset++;
			}
		}
	}
	else if (PyList_Check(frames)) {
		frameCount = PyList_GET_SIZE(frames);

		if (frameSizes.buf && frameSizes.len != frameCount * (Py_ssize_t)sizeof(unsigned long long)) {
			PyErr_Format(PyExc_ValueError, "decompressed_sizes size mismatch; expected %zd, got %zd",
				frameCount * sizeof(unsigned long long), frameSizes.len);
			goto finally;
		}

		framePointers = PyMem_Malloc(frameCount * sizeof(FramePointer));
		if (!framePointers) {
			PyErr_NoMemory();
			goto finally;
		}

		/*
		 * It is not clear whether Py_buffer.buf is still valid after
		 * PyBuffer_Release. So, we hold a reference to all Py_buffer instances
		 * for the duration of the operation.
		 */
		frameBuffers = PyMem_Malloc(frameCount * sizeof(Py_buffer));
		if (NULL == frameBuffers) {
			PyErr_NoMemory();
			goto finally;
		}

		memset(frameBuffers, 0, frameCount * sizeof(Py_buffer));

		/* Do a pass to assemble info about our input buffers and output sizes. */
		for (i = 0; i < frameCount; i++) {
			if (0 != PyObject_GetBuffer(PyList_GET_ITEM(frames, i),
				&frameBuffers[i], PyBUF_CONTIG_RO)) {
				PyErr_Clear();
				PyErr_Format(PyExc_TypeError, "item %zd not a bytes like object", i);
				goto finally;
			}

			totalInputSize += frameBuffers[i].len;

			framePointers[i].sourceData = frameBuffers[i].buf;
			framePointers[i].sourceSize = frameBuffers[i].len;
			framePointers[i].destSize = frameSizesP ? frameSizesP[i] : 0;
		}
	}
	else {
		PyErr_SetString(PyExc_TypeError, "argument must be list or BufferWithSegments");
		goto finally;
	}

	/* We now have an array with info about our inputs and outputs. Feed it into
	   our generic decompression function. */
	frameSources.frames = framePointers;
	frameSources.framesSize = frameCount;
	frameSources.compressedSize = totalInputSize;

	result = decompress_from_framesources(self, &frameSources, threads);

finally:
	if (frameSizes.buf) {
		PyBuffer_Release(&frameSizes);
	}
	PyMem_Free(framePointers);

	if (frameBuffers) {
		for (i = 0; i < frameCount; i++) {
			PyBuffer_Release(&frameBuffers[i]);
		}

		PyMem_Free(frameBuffers);
	}

	return result;
}

static PyMethodDef Decompressor_methods[] = {
	{ "copy_stream", (PyCFunction)Decompressor_copy_stream, METH_VARARGS | METH_KEYWORDS,
	Decompressor_copy_stream__doc__ },
	{ "decompress", (PyCFunction)Decompressor_decompress, METH_VARARGS | METH_KEYWORDS,
	Decompressor_decompress__doc__ },
	{ "decompressobj", (PyCFunction)Decompressor_decompressobj, METH_NOARGS,
	Decompressor_decompressobj__doc__ },
	{ "read_from", (PyCFunction)Decompressor_read_from, METH_VARARGS | METH_KEYWORDS,
	Decompressor_read_from__doc__ },
	{ "write_to", (PyCFunction)Decompressor_write_to, METH_VARARGS | METH_KEYWORDS,
	Decompressor_write_to__doc__ },
	{ "decompress_content_dict_chain", (PyCFunction)Decompressor_decompress_content_dict_chain,
	  METH_VARARGS | METH_KEYWORDS, Decompressor_decompress_content_dict_chain__doc__ },
	{ "multi_decompress_to_buffer", (PyCFunction)Decompressor_multi_decompress_to_buffer,
	  METH_VARARGS | METH_KEYWORDS, Decompressor_multi_decompress_to_buffer__doc__ },
	{ NULL, NULL }
};

PyTypeObject ZstdDecompressorType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdDecompressor",        /* tp_name */
	sizeof(ZstdDecompressor),       /* tp_basicsize */
	0,                              /* tp_itemsize */
	(destructor)Decompressor_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 */
	Decompressor__doc__,            /* tp_doc */
	0,                              /* tp_traverse */
	0,                              /* tp_clear */
	0,                              /* tp_richcompare */
	0,                              /* tp_weaklistoffset */
	0,                              /* tp_iter */
	0,                              /* tp_iternext */
	Decompressor_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 */
	(initproc)Decompressor_init,    /* tp_init */
	0,                              /* tp_alloc */
	PyType_GenericNew,              /* tp_new */
};

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

	Py_INCREF((PyObject*)&ZstdDecompressorType);
	PyModule_AddObject(mod, "ZstdDecompressor",
		(PyObject*)&ZstdDecompressorType);
}