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DinoV bpo-38074 : Make zlib extension module PEP-384 compatible (GH-15792 ) a1ffad0

Sep 10, 2019

33 contributors

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1475 lines (1256 sloc) 40.8 KB

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	/* zlibmodule.c -- gzip-compatible data compression */
	/* See http://zlib.net/ */

	/* Windows users: read Python's PCbuild\readme.txt */

	#define PY_SSIZE_T_CLEAN

	#include "Python.h"
	#include "structmember.h"
	#include "zlib.h"


	#include "pythread.h"
	#define ENTER_ZLIB(obj) \
	Py_BEGIN_ALLOW_THREADS; \
	PyThread_acquire_lock((obj)->lock, 1); \
	Py_END_ALLOW_THREADS;
	#define LEAVE_ZLIB(obj) PyThread_release_lock((obj)->lock);

	#if defined(ZLIB_VERNUM) && ZLIB_VERNUM >= 0x1221
	# define AT_LEAST_ZLIB_1_2_2_1
	#endif

	/* The following parameters are copied from zutil.h, version 0.95 */
	#define DEFLATED 8
	#if MAX_MEM_LEVEL >= 8
	# define DEF_MEM_LEVEL 8
	#else
	# define DEF_MEM_LEVEL MAX_MEM_LEVEL
	#endif

	/* Initial buffer size. */
	#define DEF_BUF_SIZE (16*1024)

	static PyModuleDef zlibmodule;

	typedef struct {
	PyTypeObject *Comptype;
	PyTypeObject *Decomptype;
	PyObject *ZlibError;
	} _zlibstate;

	#define _zlibstate(o) ((_zlibstate *)PyModule_GetState(o))
	#define _zlibstate_global ((_zlibstate *)PyModule_GetState(PyState_FindModule(&zlibmodule)))

	typedef struct
	{
	PyObject_HEAD
	z_stream zst;
	PyObject *unused_data;
	PyObject *unconsumed_tail;
	char eof;
	int is_initialised;
	PyObject *zdict;
	PyThread_type_lock lock;
	} compobject;

	static void
	zlib_error(z_stream zst, int err, const char *msg)
	{
	const char *zmsg = Z_NULL;
	/* In case of a version mismatch, zst.msg won't be initialized.
	Check for this case first, before looking at zst.msg. */
	if (err == Z_VERSION_ERROR)
	zmsg = "library version mismatch";
	if (zmsg == Z_NULL)
	zmsg = zst.msg;
	if (zmsg == Z_NULL) {
	switch (err) {
	case Z_BUF_ERROR:
	zmsg = "incomplete or truncated stream";
	break;
	case Z_STREAM_ERROR:
	zmsg = "inconsistent stream state";
	break;
	case Z_DATA_ERROR:
	zmsg = "invalid input data";
	break;
	}
	}
	if (zmsg == Z_NULL)
	PyErr_Format(_zlibstate_global->ZlibError, "Error %d %s", err, msg);
	else
	PyErr_Format(_zlibstate_global->ZlibError, "Error %d %s: %.200s", err, msg, zmsg);
	}

	/*[clinic input]
	module zlib
	class zlib.Compress "compobject *" "&Comptype"
	class zlib.Decompress "compobject *" "&Decomptype"
	[clinic start generated code]*/
	/[clinic end generated code: output=da39a3ee5e6b4b0d input=093935115c3e3158]/

	static compobject *
	newcompobject(PyTypeObject *type)
	{
	compobject *self;
	self = PyObject_New(compobject, type);
	if (self == NULL)
	return NULL;
	self->eof = 0;
	self->is_initialised = 0;
	self->zdict = NULL;
	self->unused_data = PyBytes_FromStringAndSize("", 0);
	if (self->unused_data == NULL) {
	Py_DECREF(self);
	return NULL;
	}
	self->unconsumed_tail = PyBytes_FromStringAndSize("", 0);
	if (self->unconsumed_tail == NULL) {
	Py_DECREF(self);
	return NULL;
	}
	self->lock = PyThread_allocate_lock();
	if (self->lock == NULL) {
	Py_DECREF(self);
	PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
	return NULL;
	}
	return self;
	}

	static void*
	PyZlib_Malloc(voidpf ctx, uInt items, uInt size)
	{
	if (size != 0 && items > (size_t)PY_SSIZE_T_MAX / size)
	return NULL;
	/* PyMem_Malloc() cannot be used: the GIL is not held when
	inflate() and deflate() are called */
	return PyMem_RawMalloc((size_t)items * (size_t)size);
	}

	static void
	PyZlib_Free(voidpf ctx, void *ptr)
	{
	PyMem_RawFree(ptr);
	}

	static void
	arrange_input_buffer(z_stream zst, Py_ssize_t remains)
	{
	zst->avail_in = (uInt)Py_MIN((size_t)*remains, UINT_MAX);
	*remains -= zst->avail_in;
	}

	static Py_ssize_t
	arrange_output_buffer_with_maximum(z_stream zst, PyObject *buffer,
	Py_ssize_t length,
	Py_ssize_t max_length)
	{
	Py_ssize_t occupied;

	if (*buffer == NULL) {
	if (!(*buffer = PyBytes_FromStringAndSize(NULL, length)))
	return -1;
	occupied = 0;
	}
	else {
	occupied = zst->next_out - (Byte )PyBytes_AS_STRING(buffer);

	if (length == occupied) {
	Py_ssize_t new_length;
	assert(length <= max_length);
	/* can not scale the buffer over max_length */
	if (length == max_length)
	return -2;
	if (length <= (max_length >> 1))
	new_length = length << 1;
	else
	new_length = max_length;
	if (_PyBytes_Resize(buffer, new_length) < 0)
	return -1;
	length = new_length;
	}
	}

	zst->avail_out = (uInt)Py_MIN((size_t)(length - occupied), UINT_MAX);
	zst->next_out = (Byte )PyBytes_AS_STRING(buffer) + occupied;

	return length;
	}

	static Py_ssize_t
	arrange_output_buffer(z_stream zst, PyObject *buffer, Py_ssize_t length)
	{
	Py_ssize_t ret;

	ret = arrange_output_buffer_with_maximum(zst, buffer, length,
	PY_SSIZE_T_MAX);
	if (ret == -2)
	PyErr_NoMemory();

	return ret;
	}

	/*[clinic input]
	zlib.compress

	data: Py_buffer
	Binary data to be compressed.
	/
	level: int(c_default="Z_DEFAULT_COMPRESSION") = Z_DEFAULT_COMPRESSION
	Compression level, in 0-9 or -1.

	Returns a bytes object containing compressed data.
	[clinic start generated code]*/

	static PyObject *
	zlib_compress_impl(PyObject module, Py_buffer data, int level)
	/[clinic end generated code: output=d80906d73f6294c8 input=638d54b6315dbed3]/
	{
	PyObject *RetVal = NULL;
	Byte *ibuf;
	Py_ssize_t ibuflen, obuflen = DEF_BUF_SIZE;
	int err, flush;
	z_stream zst;

	ibuf = data->buf;
	ibuflen = data->len;

	zst.opaque = NULL;
	zst.zalloc = PyZlib_Malloc;
	zst.zfree = PyZlib_Free;
	zst.next_in = ibuf;
	err = deflateInit(&zst, level);

	switch (err) {
	case Z_OK:
	break;
	case Z_MEM_ERROR:
	PyErr_SetString(PyExc_MemoryError,
	"Out of memory while compressing data");
	goto error;
	case Z_STREAM_ERROR:
	PyErr_SetString(_zlibstate_global->ZlibError, "Bad compression level");
	goto error;
	default:
	deflateEnd(&zst);
	zlib_error(zst, err, "while compressing data");
	goto error;
	}

	do {
	arrange_input_buffer(&zst, &ibuflen);
	flush = ibuflen == 0 ? Z_FINISH : Z_NO_FLUSH;

	do {
	obuflen = arrange_output_buffer(&zst, &RetVal, obuflen);
	if (obuflen < 0) {
	deflateEnd(&zst);
	goto error;
	}

	Py_BEGIN_ALLOW_THREADS
	err = deflate(&zst, flush);
	Py_END_ALLOW_THREADS

	if (err == Z_STREAM_ERROR) {
	deflateEnd(&zst);
	zlib_error(zst, err, "while compressing data");
	goto error;
	}

	} while (zst.avail_out == 0);
	assert(zst.avail_in == 0);

	} while (flush != Z_FINISH);
	assert(err == Z_STREAM_END);

	err = deflateEnd(&zst);
	if (err == Z_OK) {
	if (_PyBytes_Resize(&RetVal, zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) < 0)
	goto error;
	return RetVal;
	}
	else
	zlib_error(zst, err, "while finishing compression");
	error:
	Py_XDECREF(RetVal);
	return NULL;
	}

	/*[python input]

	class ssize_t_converter(CConverter):
	type = 'Py_ssize_t'
	converter = 'ssize_t_converter'
	c_ignored_default = "0"

	[python start generated code]*/
	/[python end generated code: output=da39a3ee5e6b4b0d input=5f34ba1b394cb8e7]/

	static int
	ssize_t_converter(PyObject obj, void ptr)
	{
	PyObject *long_obj;
	Py_ssize_t val;

	/* XXX Should be replaced with PyNumber_AsSsize_t after the end of the
	deprecation period. */
	long_obj = _PyLong_FromNbIndexOrNbInt(obj);
	if (long_obj == NULL) {
	return 0;
	}
	val = PyLong_AsSsize_t(long_obj);
	Py_DECREF(long_obj);
	if (val == -1 && PyErr_Occurred()) {
	return 0;
	}
	(Py_ssize_t )ptr = val;
	return 1;
	}

	/*[clinic input]
	zlib.decompress

	data: Py_buffer
	Compressed data.
	/
	wbits: int(c_default="MAX_WBITS") = MAX_WBITS
	The window buffer size and container format.
	bufsize: ssize_t(c_default="DEF_BUF_SIZE") = DEF_BUF_SIZE
	The initial output buffer size.

	Returns a bytes object containing the uncompressed data.
	[clinic start generated code]*/

	static PyObject *
	zlib_decompress_impl(PyObject module, Py_buffer data, int wbits,
	Py_ssize_t bufsize)
	/[clinic end generated code: output=77c7e35111dc8c42 input=21960936208e9a5b]/
	{
	PyObject *RetVal = NULL;
	Byte *ibuf;
	Py_ssize_t ibuflen;
	int err, flush;
	z_stream zst;

	if (bufsize < 0) {
	PyErr_SetString(PyExc_ValueError, "bufsize must be non-negative");
	return NULL;
	} else if (bufsize == 0) {
	bufsize = 1;
	}

	ibuf = data->buf;
	ibuflen = data->len;

	zst.opaque = NULL;
	zst.zalloc = PyZlib_Malloc;
	zst.zfree = PyZlib_Free;
	zst.avail_in = 0;
	zst.next_in = ibuf;
	err = inflateInit2(&zst, wbits);

	switch (err) {
	case Z_OK:
	break;
	case Z_MEM_ERROR:
	PyErr_SetString(PyExc_MemoryError,
	"Out of memory while decompressing data");
	goto error;
	default:
	inflateEnd(&zst);
	zlib_error(zst, err, "while preparing to decompress data");
	goto error;
	}

	do {
	arrange_input_buffer(&zst, &ibuflen);
	flush = ibuflen == 0 ? Z_FINISH : Z_NO_FLUSH;

	do {
	bufsize = arrange_output_buffer(&zst, &RetVal, bufsize);
	if (bufsize < 0) {
	inflateEnd(&zst);
	goto error;
	}

	Py_BEGIN_ALLOW_THREADS
	err = inflate(&zst, flush);
	Py_END_ALLOW_THREADS

	switch (err) {
	case Z_OK: /* fall through */
	case Z_BUF_ERROR: /* fall through */
	case Z_STREAM_END:
	break;
	case Z_MEM_ERROR:
	inflateEnd(&zst);
	PyErr_SetString(PyExc_MemoryError,
	"Out of memory while decompressing data");
	goto error;
	default:
	inflateEnd(&zst);
	zlib_error(zst, err, "while decompressing data");
	goto error;
	}

	} while (zst.avail_out == 0);

	} while (err != Z_STREAM_END && ibuflen != 0);


	if (err != Z_STREAM_END) {
	inflateEnd(&zst);
	zlib_error(zst, err, "while decompressing data");
	goto error;
	}

	err = inflateEnd(&zst);
	if (err != Z_OK) {
	zlib_error(zst, err, "while finishing decompression");
	goto error;
	}

	if (_PyBytes_Resize(&RetVal, zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) < 0)
	goto error;

	return RetVal;

	error:
	Py_XDECREF(RetVal);
	return NULL;
	}

	/*[clinic input]
	zlib.compressobj

	level: int(c_default="Z_DEFAULT_COMPRESSION") = Z_DEFAULT_COMPRESSION
	The compression level (an integer in the range 0-9 or -1; default is
	currently equivalent to 6). Higher compression levels are slower,
	but produce smaller results.
	method: int(c_default="DEFLATED") = DEFLATED
	The compression algorithm. If given, this must be DEFLATED.
	wbits: int(c_default="MAX_WBITS") = MAX_WBITS
	+9 to +15: The base-two logarithm of the window size. Include a zlib
	container.
	-9 to -15: Generate a raw stream.
	+25 to +31: Include a gzip container.
	memLevel: int(c_default="DEF_MEM_LEVEL") = DEF_MEM_LEVEL
	Controls the amount of memory used for internal compression state.
	Valid values range from 1 to 9. Higher values result in higher memory
	usage, faster compression, and smaller output.
	strategy: int(c_default="Z_DEFAULT_STRATEGY") = Z_DEFAULT_STRATEGY
	Used to tune the compression algorithm. Possible values are
	Z_DEFAULT_STRATEGY, Z_FILTERED, and Z_HUFFMAN_ONLY.
	zdict: Py_buffer = None
	The predefined compression dictionary - a sequence of bytes
	containing subsequences that are likely to occur in the input data.

	Return a compressor object.
	[clinic start generated code]*/

	static PyObject *
	zlib_compressobj_impl(PyObject *module, int level, int method, int wbits,
	int memLevel, int strategy, Py_buffer *zdict)
	/[clinic end generated code: output=8b5bed9c8fc3814d input=2fa3d026f90ab8d5]/
	{
	compobject *self = NULL;
	int err;

	if (zdict->buf != NULL && (size_t)zdict->len > UINT_MAX) {
	PyErr_SetString(PyExc_OverflowError,
	"zdict length does not fit in an unsigned int");
	goto error;
	}

	self = newcompobject(_zlibstate_global->Comptype);
	if (self == NULL)
	goto error;
	self->zst.opaque = NULL;
	self->zst.zalloc = PyZlib_Malloc;
	self->zst.zfree = PyZlib_Free;
	self->zst.next_in = NULL;
	self->zst.avail_in = 0;
	err = deflateInit2(&self->zst, level, method, wbits, memLevel, strategy);
	switch (err) {
	case Z_OK:
	self->is_initialised = 1;
	if (zdict->buf == NULL) {
	goto success;
	} else {
	err = deflateSetDictionary(&self->zst,
	zdict->buf, (unsigned int)zdict->len);
	switch (err) {
	case Z_OK:
	goto success;
	case Z_STREAM_ERROR:
	PyErr_SetString(PyExc_ValueError, "Invalid dictionary");
	goto error;
	default:
	PyErr_SetString(PyExc_ValueError, "deflateSetDictionary()");
	goto error;
	}
	}
	case Z_MEM_ERROR:
	PyErr_SetString(PyExc_MemoryError,
	"Can't allocate memory for compression object");
	goto error;
	case Z_STREAM_ERROR:
	PyErr_SetString(PyExc_ValueError, "Invalid initialization option");
	goto error;
	default:
	zlib_error(self->zst, err, "while creating compression object");
	goto error;
	}

	error:
	Py_CLEAR(self);
	success:
	return (PyObject *)self;
	}

	static int
	set_inflate_zdict(compobject *self)
	{
	Py_buffer zdict_buf;
	int err;

	if (PyObject_GetBuffer(self->zdict, &zdict_buf, PyBUF_SIMPLE) == -1) {
	return -1;
	}
	if ((size_t)zdict_buf.len > UINT_MAX) {
	PyErr_SetString(PyExc_OverflowError,
	"zdict length does not fit in an unsigned int");
	PyBuffer_Release(&zdict_buf);
	return -1;
	}
	err = inflateSetDictionary(&self->zst,
	zdict_buf.buf, (unsigned int)zdict_buf.len);
	PyBuffer_Release(&zdict_buf);
	if (err != Z_OK) {
	zlib_error(self->zst, err, "while setting zdict");
	return -1;
	}
	return 0;
	}

	/*[clinic input]
	zlib.decompressobj

	wbits: int(c_default="MAX_WBITS") = MAX_WBITS
	The window buffer size and container format.
	zdict: object(c_default="NULL") = b''
	The predefined compression dictionary. This must be the same
	dictionary as used by the compressor that produced the input data.

	Return a decompressor object.
	[clinic start generated code]*/

	static PyObject *
	zlib_decompressobj_impl(PyObject module, int wbits, PyObject zdict)
	/[clinic end generated code: output=3069b99994f36906 input=d3832b8511fc977b]/
	{
	int err;
	compobject *self;

	if (zdict != NULL && !PyObject_CheckBuffer(zdict)) {
	PyErr_SetString(PyExc_TypeError,
	"zdict argument must support the buffer protocol");
	return NULL;
	}

	self = newcompobject(_zlibstate_global->Decomptype);
	if (self == NULL)
	return NULL;
	self->zst.opaque = NULL;
	self->zst.zalloc = PyZlib_Malloc;
	self->zst.zfree = PyZlib_Free;
	self->zst.next_in = NULL;
	self->zst.avail_in = 0;
	if (zdict != NULL) {
	Py_INCREF(zdict);
	self->zdict = zdict;
	}
	err = inflateInit2(&self->zst, wbits);
	switch (err) {
	case Z_OK:
	self->is_initialised = 1;
	if (self->zdict != NULL && wbits < 0) {
	#ifdef AT_LEAST_ZLIB_1_2_2_1
	if (set_inflate_zdict(self) < 0) {
	Py_DECREF(self);
	return NULL;
	}
	#else
	PyErr_Format(_zlibstate_global->ZlibError,
	"zlib version %s does not allow raw inflate with dictionary",
	ZLIB_VERSION);
	Py_DECREF(self);
	return NULL;
	#endif
	}
	return (PyObject *)self;
	case Z_STREAM_ERROR:
	Py_DECREF(self);
	PyErr_SetString(PyExc_ValueError, "Invalid initialization option");
	return NULL;
	case Z_MEM_ERROR:
	Py_DECREF(self);
	PyErr_SetString(PyExc_MemoryError,
	"Can't allocate memory for decompression object");
	return NULL;
	default:
	zlib_error(self->zst, err, "while creating decompression object");
	Py_DECREF(self);
	return NULL;
	}
	}

	static void
	Dealloc(compobject *self)
	{
	PyObject type = (PyObject )Py_TYPE(self);
	PyThread_free_lock(self->lock);
	Py_XDECREF(self->unused_data);
	Py_XDECREF(self->unconsumed_tail);
	Py_XDECREF(self->zdict);
	PyObject_Del(self);
	Py_DECREF(type);
	}

	static void
	Comp_dealloc(compobject *self)
	{
	if (self->is_initialised)
	deflateEnd(&self->zst);
	Dealloc(self);
	}

	static void
	Decomp_dealloc(compobject *self)
	{
	if (self->is_initialised)
	inflateEnd(&self->zst);
	Dealloc(self);
	}

	/*[clinic input]
	zlib.Compress.compress

	data: Py_buffer
	Binary data to be compressed.
	/

	Returns a bytes object containing compressed data.

	After calling this function, some of the input data may still
	be stored in internal buffers for later processing.
	Call the flush() method to clear these buffers.
	[clinic start generated code]*/

	static PyObject *
	zlib_Compress_compress_impl(compobject self, Py_buffer data)
	/[clinic end generated code: output=5d5cd791cbc6a7f4 input=0d95908d6e64fab8]/
	{
	PyObject *RetVal = NULL;
	Py_ssize_t ibuflen, obuflen = DEF_BUF_SIZE;
	int err;

	self->zst.next_in = data->buf;
	ibuflen = data->len;

	ENTER_ZLIB(self);

	do {
	arrange_input_buffer(&self->zst, &ibuflen);

	do {
	obuflen = arrange_output_buffer(&self->zst, &RetVal, obuflen);
	if (obuflen < 0)
	goto error;

	Py_BEGIN_ALLOW_THREADS
	err = deflate(&self->zst, Z_NO_FLUSH);
	Py_END_ALLOW_THREADS

	if (err == Z_STREAM_ERROR) {
	zlib_error(self->zst, err, "while compressing data");
	goto error;
	}

	} while (self->zst.avail_out == 0);
	assert(self->zst.avail_in == 0);

	} while (ibuflen != 0);

	if (_PyBytes_Resize(&RetVal, self->zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) == 0)
	goto success;

	error:
	Py_CLEAR(RetVal);
	success:
	LEAVE_ZLIB(self);
	return RetVal;
	}

	/* Helper for objdecompress() and flush(). Saves any unconsumed input data in
	self->unused_data or self->unconsumed_tail, as appropriate. */
	static int
	save_unconsumed_input(compobject self, Py_buffer data, int err)
	{
	if (err == Z_STREAM_END) {
	/* The end of the compressed data has been reached. Store the leftover
	input data in self->unused_data. */
	if (self->zst.avail_in > 0) {
	Py_ssize_t old_size = PyBytes_GET_SIZE(self->unused_data);
	Py_ssize_t new_size, left_size;
	PyObject *new_data;
	left_size = (Byte *)data->buf + data->len - self->zst.next_in;
	if (left_size > (PY_SSIZE_T_MAX - old_size)) {
	PyErr_NoMemory();
	return -1;
	}
	new_size = old_size + left_size;
	new_data = PyBytes_FromStringAndSize(NULL, new_size);
	if (new_data == NULL)
	return -1;
	memcpy(PyBytes_AS_STRING(new_data),
	PyBytes_AS_STRING(self->unused_data), old_size);
	memcpy(PyBytes_AS_STRING(new_data) + old_size,
	self->zst.next_in, left_size);
	Py_SETREF(self->unused_data, new_data);
	self->zst.avail_in = 0;
	}
	}

	if (self->zst.avail_in > 0 \|\| PyBytes_GET_SIZE(self->unconsumed_tail)) {
	/* This code handles two distinct cases:
	1. Output limit was reached. Save leftover input in unconsumed_tail.
	2. All input data was consumed. Clear unconsumed_tail. */
	Py_ssize_t left_size = (Byte *)data->buf + data->len - self->zst.next_in;
	PyObject *new_data = PyBytes_FromStringAndSize(
	(char *)self->zst.next_in, left_size);
	if (new_data == NULL)
	return -1;
	Py_SETREF(self->unconsumed_tail, new_data);
	}

	return 0;
	}

	/*[clinic input]
	zlib.Decompress.decompress

	data: Py_buffer
	The binary data to decompress.
	/
	max_length: ssize_t = 0
	The maximum allowable length of the decompressed data.
	Unconsumed input data will be stored in
	the unconsumed_tail attribute.

	Return a bytes object containing the decompressed version of the data.

	After calling this function, some of the input data may still be stored in
	internal buffers for later processing.
	Call the flush() method to clear these buffers.
	[clinic start generated code]*/

	static PyObject *
	zlib_Decompress_decompress_impl(compobject self, Py_buffer data,
	Py_ssize_t max_length)
	/[clinic end generated code: output=6e5173c74e710352 input=b85a212a012b770a]/
	{
	int err = Z_OK;
	Py_ssize_t ibuflen, obuflen = DEF_BUF_SIZE, hard_limit;
	PyObject *RetVal = NULL;

	if (max_length < 0) {
	PyErr_SetString(PyExc_ValueError, "max_length must be non-negative");
	return NULL;
	} else if (max_length == 0)
	hard_limit = PY_SSIZE_T_MAX;
	else
	hard_limit = max_length;

	self->zst.next_in = data->buf;
	ibuflen = data->len;

	/* limit amount of data allocated to max_length */
	if (max_length && obuflen > max_length)
	obuflen = max_length;

	ENTER_ZLIB(self);

	do {
	arrange_input_buffer(&self->zst, &ibuflen);

	do {
	obuflen = arrange_output_buffer_with_maximum(&self->zst, &RetVal,
	obuflen, hard_limit);
	if (obuflen == -2) {
	if (max_length > 0) {
	goto save;
	}
	PyErr_NoMemory();
	}
	if (obuflen < 0) {
	goto abort;
	}

	Py_BEGIN_ALLOW_THREADS
	err = inflate(&self->zst, Z_SYNC_FLUSH);
	Py_END_ALLOW_THREADS

	switch (err) {
	case Z_OK: /* fall through */
	case Z_BUF_ERROR: /* fall through */
	case Z_STREAM_END:
	break;
	default:
	if (err == Z_NEED_DICT && self->zdict != NULL) {
	if (set_inflate_zdict(self) < 0)
	goto abort;
	else
	break;
	}
	goto save;
	}

	} while (self->zst.avail_out == 0 \|\| err == Z_NEED_DICT);

	} while (err != Z_STREAM_END && ibuflen != 0);

	save:
	if (save_unconsumed_input(self, data, err) < 0)
	goto abort;

	if (err == Z_STREAM_END) {
	/* This is the logical place to call inflateEnd, but the old behaviour
	of only calling it on flush() is preserved. */
	self->eof = 1;
	} else if (err != Z_OK && err != Z_BUF_ERROR) {
	/* We will only get Z_BUF_ERROR if the output buffer was full
	but there wasn't more output when we tried again, so it is
	not an error condition.
	*/
	zlib_error(self->zst, err, "while decompressing data");
	goto abort;
	}

	if (_PyBytes_Resize(&RetVal, self->zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) == 0)
	goto success;

	abort:
	Py_CLEAR(RetVal);
	success:
	LEAVE_ZLIB(self);
	return RetVal;
	}

	/*[clinic input]
	zlib.Compress.flush

	mode: int(c_default="Z_FINISH") = zlib.Z_FINISH
	One of the constants Z_SYNC_FLUSH, Z_FULL_FLUSH, Z_FINISH.
	If mode == Z_FINISH, the compressor object can no longer be
	used after calling the flush() method. Otherwise, more data
	can still be compressed.
	/

	Return a bytes object containing any remaining compressed data.
	[clinic start generated code]*/

	static PyObject *
	zlib_Compress_flush_impl(compobject *self, int mode)
	/[clinic end generated code: output=a203f4cefc9de727 input=73ed066794bd15bc]/
	{
	int err;
	Py_ssize_t length = DEF_BUF_SIZE;
	PyObject *RetVal = NULL;

	/* Flushing with Z_NO_FLUSH is a no-op, so there's no point in
	doing any work at all; just return an empty string. */
	if (mode == Z_NO_FLUSH) {
	return PyBytes_FromStringAndSize(NULL, 0);
	}

	ENTER_ZLIB(self);

	self->zst.avail_in = 0;

	do {
	length = arrange_output_buffer(&self->zst, &RetVal, length);
	if (length < 0) {
	Py_CLEAR(RetVal);
	goto error;
	}

	Py_BEGIN_ALLOW_THREADS
	err = deflate(&self->zst, mode);
	Py_END_ALLOW_THREADS

	if (err == Z_STREAM_ERROR) {
	zlib_error(self->zst, err, "while flushing");
	Py_CLEAR(RetVal);
	goto error;
	}
	} while (self->zst.avail_out == 0);
	assert(self->zst.avail_in == 0);

	/* If mode is Z_FINISH, we also have to call deflateEnd() to free
	various data structures. Note we should only get Z_STREAM_END when
	mode is Z_FINISH, but checking both for safety*/
	if (err == Z_STREAM_END && mode == Z_FINISH) {
	err = deflateEnd(&self->zst);
	if (err != Z_OK) {
	zlib_error(self->zst, err, "while finishing compression");
	Py_CLEAR(RetVal);
	goto error;
	}
	else
	self->is_initialised = 0;

	/* We will only get Z_BUF_ERROR if the output buffer was full
	but there wasn't more output when we tried again, so it is
	not an error condition.
	*/
	} else if (err != Z_OK && err != Z_BUF_ERROR) {
	zlib_error(self->zst, err, "while flushing");
	Py_CLEAR(RetVal);
	goto error;
	}

	if (_PyBytes_Resize(&RetVal, self->zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) < 0)
	Py_CLEAR(RetVal);

	error:
	LEAVE_ZLIB(self);
	return RetVal;
	}

	#ifdef HAVE_ZLIB_COPY

	/*[clinic input]
	zlib.Compress.copy

	Return a copy of the compression object.
	[clinic start generated code]*/

	static PyObject *
	zlib_Compress_copy_impl(compobject *self)
	/[clinic end generated code: output=5144aa153c21e805 input=c656351f94b82718]/
	{
	compobject *retval = NULL;
	int err;

	retval = newcompobject(_zlibstate_global->Comptype);
	if (!retval) return NULL;

	/* Copy the zstream state
	* We use ENTER_ZLIB / LEAVE_ZLIB to make this thread-safe
	*/
	ENTER_ZLIB(self);
	err = deflateCopy(&retval->zst, &self->zst);
	switch (err) {
	case Z_OK:
	break;
	case Z_STREAM_ERROR:
	PyErr_SetString(PyExc_ValueError, "Inconsistent stream state");
	goto error;
	case Z_MEM_ERROR:
	PyErr_SetString(PyExc_MemoryError,
	"Can't allocate memory for compression object");
	goto error;
	default:
	zlib_error(self->zst, err, "while copying compression object");
	goto error;
	}
	Py_INCREF(self->unused_data);
	Py_XSETREF(retval->unused_data, self->unused_data);
	Py_INCREF(self->unconsumed_tail);
	Py_XSETREF(retval->unconsumed_tail, self->unconsumed_tail);
	Py_XINCREF(self->zdict);
	Py_XSETREF(retval->zdict, self->zdict);
	retval->eof = self->eof;

	/* Mark it as being initialized */
	retval->is_initialised = 1;

	LEAVE_ZLIB(self);
	return (PyObject *)retval;

	error:
	LEAVE_ZLIB(self);
	Py_XDECREF(retval);
	return NULL;
	}

	/*[clinic input]
	zlib.Compress.__copy__
	[clinic start generated code]*/

	static PyObject *
	zlib_Compress___copy___impl(compobject *self)
	/[clinic end generated code: output=1875e6791975442e input=be97a05a788dfd83]/
	{
	return zlib_Compress_copy_impl(self);
	}

	/*[clinic input]
	zlib.Compress.__deepcopy__

	memo: object
	/

	[clinic start generated code]*/

	static PyObject *
	zlib_Compress___deepcopy__(compobject self, PyObject memo)
	/[clinic end generated code: output=f47a2213282c9eb0 input=a9a8b0b40d83388e]/
	{
	return zlib_Compress_copy_impl(self);
	}

	/*[clinic input]
	zlib.Decompress.copy

	Return a copy of the decompression object.
	[clinic start generated code]*/

	static PyObject *
	zlib_Decompress_copy_impl(compobject *self)
	/[clinic end generated code: output=02a883a2a510c8cc input=ba6c3e96712a596b]/
	{
	compobject *retval = NULL;
	int err;

	retval = newcompobject(_zlibstate_global->Decomptype);
	if (!retval) return NULL;

	/* Copy the zstream state
	* We use ENTER_ZLIB / LEAVE_ZLIB to make this thread-safe
	*/
	ENTER_ZLIB(self);
	err = inflateCopy(&retval->zst, &self->zst);
	switch (err) {
	case Z_OK:
	break;
	case Z_STREAM_ERROR:
	PyErr_SetString(PyExc_ValueError, "Inconsistent stream state");
	goto error;
	case Z_MEM_ERROR:
	PyErr_SetString(PyExc_MemoryError,
	"Can't allocate memory for decompression object");
	goto error;
	default:
	zlib_error(self->zst, err, "while copying decompression object");
	goto error;
	}

	Py_INCREF(self->unused_data);
	Py_XSETREF(retval->unused_data, self->unused_data);
	Py_INCREF(self->unconsumed_tail);
	Py_XSETREF(retval->unconsumed_tail, self->unconsumed_tail);
	Py_XINCREF(self->zdict);
	Py_XSETREF(retval->zdict, self->zdict);
	retval->eof = self->eof;

	/* Mark it as being initialized */
	retval->is_initialised = 1;

	LEAVE_ZLIB(self);
	return (PyObject *)retval;

	error:
	LEAVE_ZLIB(self);
	Py_XDECREF(retval);
	return NULL;
	}

	/*[clinic input]
	zlib.Decompress.__copy__
	[clinic start generated code]*/

	static PyObject *
	zlib_Decompress___copy___impl(compobject *self)
	/[clinic end generated code: output=80bae8bc43498ad4 input=efcb98b5472c13d2]/
	{
	return zlib_Decompress_copy_impl(self);
	}

	/*[clinic input]
	zlib.Decompress.__deepcopy__

	memo: object
	/

	[clinic start generated code]*/

	static PyObject *
	zlib_Decompress___deepcopy__(compobject self, PyObject memo)
	/[clinic end generated code: output=1f77286ab490124b input=6e99bd0ac4b9cd8b]/
	{
	return zlib_Decompress_copy_impl(self);
	}

	#endif

	/*[clinic input]
	zlib.Decompress.flush

	length: ssize_t(c_default="DEF_BUF_SIZE") = zlib.DEF_BUF_SIZE
	the initial size of the output buffer.
	/

	Return a bytes object containing any remaining decompressed data.
	[clinic start generated code]*/

	static PyObject *
	zlib_Decompress_flush_impl(compobject *self, Py_ssize_t length)
	/[clinic end generated code: output=68c75ea127cbe654 input=aa4ec37f3aef4da0]/
	{
	int err, flush;
	Py_buffer data;
	PyObject *RetVal = NULL;
	Py_ssize_t ibuflen;

	if (length <= 0) {
	PyErr_SetString(PyExc_ValueError, "length must be greater than zero");
	return NULL;
	}

	if (PyObject_GetBuffer(self->unconsumed_tail, &data, PyBUF_SIMPLE) == -1)
	return NULL;

	ENTER_ZLIB(self);

	self->zst.next_in = data.buf;
	ibuflen = data.len;

	do {
	arrange_input_buffer(&self->zst, &ibuflen);
	flush = ibuflen == 0 ? Z_FINISH : Z_NO_FLUSH;

	do {
	length = arrange_output_buffer(&self->zst, &RetVal, length);
	if (length < 0)
	goto abort;

	Py_BEGIN_ALLOW_THREADS
	err = inflate(&self->zst, flush);
	Py_END_ALLOW_THREADS

	switch (err) {
	case Z_OK: /* fall through */
	case Z_BUF_ERROR: /* fall through */
	case Z_STREAM_END:
	break;
	default:
	if (err == Z_NEED_DICT && self->zdict != NULL) {
	if (set_inflate_zdict(self) < 0)
	goto abort;
	else
	break;
	}
	goto save;
	}

	} while (self->zst.avail_out == 0 \|\| err == Z_NEED_DICT);

	} while (err != Z_STREAM_END && ibuflen != 0);

	save:
	if (save_unconsumed_input(self, &data, err) < 0)
	goto abort;

	/* If at end of stream, clean up any memory allocated by zlib. */
	if (err == Z_STREAM_END) {
	self->eof = 1;
	self->is_initialised = 0;
	err = inflateEnd(&self->zst);
	if (err != Z_OK) {
	zlib_error(self->zst, err, "while finishing decompression");
	goto abort;
	}
	}

	if (_PyBytes_Resize(&RetVal, self->zst.next_out -
	(Byte *)PyBytes_AS_STRING(RetVal)) == 0)
	goto success;

	abort:
	Py_CLEAR(RetVal);
	success:
	PyBuffer_Release(&data);
	LEAVE_ZLIB(self);
	return RetVal;
	}

	#include "clinic/zlibmodule.c.h"

	static PyMethodDef comp_methods[] =
	{
	ZLIB_COMPRESS_COMPRESS_METHODDEF
	ZLIB_COMPRESS_FLUSH_METHODDEF
	ZLIB_COMPRESS_COPY_METHODDEF
	ZLIB_COMPRESS___COPY___METHODDEF
	ZLIB_COMPRESS___DEEPCOPY___METHODDEF
	{NULL, NULL}
	};

	static PyMethodDef Decomp_methods[] =
	{
	ZLIB_DECOMPRESS_DECOMPRESS_METHODDEF
	ZLIB_DECOMPRESS_FLUSH_METHODDEF
	ZLIB_DECOMPRESS_COPY_METHODDEF
	ZLIB_DECOMPRESS___COPY___METHODDEF
	ZLIB_DECOMPRESS___DEEPCOPY___METHODDEF
	{NULL, NULL}
	};

	#define COMP_OFF(x) offsetof(compobject, x)
	static PyMemberDef Decomp_members[] = {
	{"unused_data", T_OBJECT, COMP_OFF(unused_data), READONLY},
	{"unconsumed_tail", T_OBJECT, COMP_OFF(unconsumed_tail), READONLY},
	{"eof", T_BOOL, COMP_OFF(eof), READONLY},
	{NULL},
	};

	/*[clinic input]
	zlib.adler32

	data: Py_buffer
	value: unsigned_int(bitwise=True) = 1
	Starting value of the checksum.
	/

	Compute an Adler-32 checksum of data.

	The returned checksum is an integer.
	[clinic start generated code]*/

	static PyObject *
	zlib_adler32_impl(PyObject module, Py_buffer data, unsigned int value)
	/[clinic end generated code: output=422106f5ca8c92c0 input=6ff4557872160e88]/
	{
	/* Releasing the GIL for very small buffers is inefficient
	and may lower performance */
	if (data->len > 1024*5) {
	unsigned char *buf = data->buf;
	Py_ssize_t len = data->len;

	Py_BEGIN_ALLOW_THREADS
	/* Avoid truncation of length for very large buffers. adler32() takes
	length as an unsigned int, which may be narrower than Py_ssize_t. */
	while ((size_t)len > UINT_MAX) {
	value = adler32(value, buf, UINT_MAX);
	buf += (size_t) UINT_MAX;
	len -= (size_t) UINT_MAX;
	}
	value = adler32(value, buf, (unsigned int)len);
	Py_END_ALLOW_THREADS
	} else {
	value = adler32(value, data->buf, (unsigned int)data->len);
	}
	return PyLong_FromUnsignedLong(value & 0xffffffffU);
	}

	/*[clinic input]
	zlib.crc32

	data: Py_buffer
	value: unsigned_int(bitwise=True) = 0
	Starting value of the checksum.
	/

	Compute a CRC-32 checksum of data.

	The returned checksum is an integer.
	[clinic start generated code]*/

	static PyObject *
	zlib_crc32_impl(PyObject module, Py_buffer data, unsigned int value)
	/[clinic end generated code: output=63499fa20af7ea25 input=26c3ed430fa00b4c]/
	{
	int signed_val;

	/* Releasing the GIL for very small buffers is inefficient
	and may lower performance */
	if (data->len > 1024*5) {
	unsigned char *buf = data->buf;
	Py_ssize_t len = data->len;

	Py_BEGIN_ALLOW_THREADS
	/* Avoid truncation of length for very large buffers. crc32() takes
	length as an unsigned int, which may be narrower than Py_ssize_t. */
	while ((size_t)len > UINT_MAX) {
	value = crc32(value, buf, UINT_MAX);
	buf += (size_t) UINT_MAX;
	len -= (size_t) UINT_MAX;
	}
	signed_val = crc32(value, buf, (unsigned int)len);
	Py_END_ALLOW_THREADS
	} else {
	signed_val = crc32(value, data->buf, (unsigned int)data->len);
	}
	return PyLong_FromUnsignedLong(signed_val & 0xffffffffU);
	}


	static PyMethodDef zlib_methods[] =
	{
	ZLIB_ADLER32_METHODDEF
	ZLIB_COMPRESS_METHODDEF
	ZLIB_COMPRESSOBJ_METHODDEF
	ZLIB_CRC32_METHODDEF
	ZLIB_DECOMPRESS_METHODDEF
	ZLIB_DECOMPRESSOBJ_METHODDEF
	{NULL, NULL}
	};

	static PyType_Slot Comptype_slots[] = {
	{Py_tp_dealloc, Comp_dealloc},
	{Py_tp_methods, comp_methods},
	{0, 0},
	};

	static PyType_Spec Comptype_spec = {
	"zlib.Compress",
	sizeof(compobject),
	0,
	Py_TPFLAGS_DEFAULT,
	Comptype_slots
	};

	static PyType_Slot Decomptype_slots[] = {
	{Py_tp_dealloc, Decomp_dealloc},
	{Py_tp_methods, Decomp_methods},
	{Py_tp_members, Decomp_members},
	{0, 0},
	};

	static PyType_Spec Decomptype_spec = {
	"zlib.Decompress",
	sizeof(compobject),
	0,
	Py_TPFLAGS_DEFAULT,
	Decomptype_slots
	};

	PyDoc_STRVAR(zlib_module_documentation,
	"The functions in this module allow compression and decompression using the\n"
	"zlib library, which is based on GNU zip.\n"
	"\n"
	"adler32(string[, start]) -- Compute an Adler-32 checksum.\n"
	"compress(data[, level]) -- Compress data, with compression level 0-9 or -1.\n"
	"compressobj([level[, ...]]) -- Return a compressor object.\n"
	"crc32(string[, start]) -- Compute a CRC-32 checksum.\n"
	"decompress(string,[wbits],[bufsize]) -- Decompresses a compressed string.\n"
	"decompressobj([wbits[, zdict]]]) -- Return a decompressor object.\n"
	"\n"
	"'wbits' is window buffer size and container format.\n"
	"Compressor objects support compress() and flush() methods; decompressor\n"
	"objects support decompress() and flush().");

	static int
	zlib_clear(PyObject *m)
	{
	_zlibstate *state = _zlibstate(m);
	Py_CLEAR(state->Comptype);
	Py_CLEAR(state->Decomptype);
	Py_CLEAR(state->ZlibError);
	return 0;
	}

	static int
	zlib_traverse(PyObject m, visitproc visit, void arg)
	{
	_zlibstate *state = _zlibstate(m);
	Py_VISIT(state->Comptype);
	Py_VISIT(state->Decomptype);
	Py_VISIT(state->ZlibError);
	return 0;
	}

	static void
	zlib_free(void *m)
	{
	zlib_clear((PyObject *)m);
	}

	static struct PyModuleDef zlibmodule = {
	PyModuleDef_HEAD_INIT,
	"zlib",
	zlib_module_documentation,
	sizeof(_zlibstate),
	zlib_methods,
	NULL,
	zlib_traverse,
	zlib_clear,
	zlib_free,
	};

	PyMODINIT_FUNC
	PyInit_zlib(void)
	{
	PyObject m, ver;
	m = PyState_FindModule(&zlibmodule);
	if (m != NULL) {
	Py_INCREF(m);
	return m;
	}
	m = PyModule_Create(&zlibmodule);
	if (m == NULL)
	return NULL;

	PyTypeObject Comptype = (PyTypeObject )PyType_FromSpec(&Comptype_spec);
	if (Comptype == NULL)
	return NULL;
	_zlibstate(m)->Comptype = Comptype;

	PyTypeObject Decomptype = (PyTypeObject )PyType_FromSpec(&Decomptype_spec);
	if (Decomptype == NULL)
	return NULL;
	_zlibstate(m)->Decomptype = Decomptype;

	PyObject *ZlibError = PyErr_NewException("zlib.error", NULL, NULL);
	if (ZlibError != NULL) {
	Py_INCREF(ZlibError);
	PyModule_AddObject(m, "error", ZlibError);
	_zlibstate(m)->ZlibError = ZlibError;
	}
	PyModule_AddIntMacro(m, MAX_WBITS);
	PyModule_AddIntMacro(m, DEFLATED);
	PyModule_AddIntMacro(m, DEF_MEM_LEVEL);
	PyModule_AddIntMacro(m, DEF_BUF_SIZE);
	// compression levels
	PyModule_AddIntMacro(m, Z_NO_COMPRESSION);
	PyModule_AddIntMacro(m, Z_BEST_SPEED);
	PyModule_AddIntMacro(m, Z_BEST_COMPRESSION);
	PyModule_AddIntMacro(m, Z_DEFAULT_COMPRESSION);
	// compression strategies
	PyModule_AddIntMacro(m, Z_FILTERED);
	PyModule_AddIntMacro(m, Z_HUFFMAN_ONLY);
	#ifdef Z_RLE // 1.2.0.1
	PyModule_AddIntMacro(m, Z_RLE);
	#endif
	#ifdef Z_FIXED // 1.2.2.2
	PyModule_AddIntMacro(m, Z_FIXED);
	#endif
	PyModule_AddIntMacro(m, Z_DEFAULT_STRATEGY);
	// allowed flush values
	PyModule_AddIntMacro(m, Z_NO_FLUSH);
	PyModule_AddIntMacro(m, Z_PARTIAL_FLUSH);
	PyModule_AddIntMacro(m, Z_SYNC_FLUSH);
	PyModule_AddIntMacro(m, Z_FULL_FLUSH);
	PyModule_AddIntMacro(m, Z_FINISH);
	#ifdef Z_BLOCK // 1.2.0.5 for inflate, 1.2.3.4 for deflate
	PyModule_AddIntMacro(m, Z_BLOCK);
	#endif
	#ifdef Z_TREES // 1.2.3.4, only for inflate
	PyModule_AddIntMacro(m, Z_TREES);
	#endif
	ver = PyUnicode_FromString(ZLIB_VERSION);
	if (ver != NULL)
	PyModule_AddObject(m, "ZLIB_VERSION", ver);

	ver = PyUnicode_FromString(zlibVersion());
	if (ver != NULL)
	PyModule_AddObject(m, "ZLIB_RUNTIME_VERSION", ver);

	PyModule_AddStringConstant(m, "__version__", "1.0");

	PyState_AddModule(m, &zlibmodule);
	return m;
	}

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