/* zlibmodule.c -- gzip-compatible data compression */

/* See http://www.gzip.org/zlib/ */

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

#include "Python.h"

#include "zlib.h"

#ifdef WITH_THREAD

#include "pythread.h"

/* #defs ripped off from _tkinter.c, even though the situation here is much

   simpler, because we don't have to worry about waiting for Tcl

   events!  And, since zlib itself is threadsafe, we don't need to worry

   about re-entering zlib functions.

   N.B.

   Since ENTER_ZLIB and LEAVE_ZLIB only need to be called on functions

   that modify the components of preexisting de/compress objects, it

   could prove to be a performance gain on multiprocessor machines if

   there was an de/compress object-specific lock.  However, for the

   moment the ENTER_ZLIB and LEAVE_ZLIB calls are global for ALL

   de/compress objects.

 */

static PyThread_type_lock zlib_lock = NULL; /* initialized on module load */

#define ENTER_ZLIB \

	Py_BEGIN_ALLOW_THREADS \

	PyThread_acquire_lock(zlib_lock, 1); \

	Py_END_ALLOW_THREADS

#define LEAVE_ZLIB \

	PyThread_release_lock(zlib_lock);

#else

#define ENTER_ZLIB

#define LEAVE_ZLIB

#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

#define DEF_WBITS MAX_WBITS

/* The output buffer will be increased in chunks of DEFAULTALLOC bytes. */

#define DEFAULTALLOC (16*1024)

#define PyInit_zlib initzlib

static PyTypeObject Comptype;

static PyTypeObject Decomptype;

static PyObject *ZlibError;

typedef struct

{

    PyObject_HEAD

    z_stream zst;

    PyObject *unused_data;

    PyObject *unconsumed_tail;

    int is_initialised;

} compobject;

static void

zlib_error(z_stream zst, int err, char *msg)

{

    if (zst.msg == Z_NULL)

	PyErr_Format(ZlibError, "Error %d %s", err, msg);

    else

	PyErr_Format(ZlibError, "Error %d %s: %.200s", err, msg, zst.msg);

}

PyDoc_STRVAR(compressobj__doc__,

"compressobj([level]) -- Return a compressor object.\n"

"\n"

"Optional arg level is the compression level, in 1-9.");

PyDoc_STRVAR(decompressobj__doc__,

"decompressobj([wbits]) -- Return a decompressor object.\n"

"\n"

"Optional arg wbits is the window buffer size.");

static compobject *

newcompobject(PyTypeObject *type)

{

    compobject *self;

    self = PyObject_New(compobject, type);

    if (self == NULL)

	return NULL;

    self->is_initialised = 0;

    self->unused_data = PyString_FromString("");

    if (self->unused_data == NULL) {

	Py_DECREF(self);

	return NULL;

    }

    self->unconsumed_tail = PyString_FromString("");

    if (self->unconsumed_tail == NULL) {

	Py_DECREF(self);

	return NULL;

    }

    return self;

}

PyDoc_STRVAR(compress__doc__,

"compress(string[, level]) -- Returned compressed string.\n"

"\n"

"Optional arg level is the compression level, in 1-9.");

static PyObject *

PyZlib_compress(PyObject *self, PyObject *args)

{

    PyObject *ReturnVal = NULL;

    Byte *input, *output;

    int length, level=Z_DEFAULT_COMPRESSION, err;

    z_stream zst;

    /* require Python string object, optional 'level' arg */

    if (!PyArg_ParseTuple(args, "s#|i:compress", &input, &length, &level))

	return NULL;

    zst.avail_out = length + length/1000 + 12 + 1;

    output = (Byte*)malloc(zst.avail_out);

    if (output == NULL) {

	PyErr_SetString(PyExc_MemoryError,

			"Can't allocate memory to compress data");

	return NULL;

    }

    /* Past the point of no return.  From here on out, we need to make sure

       we clean up mallocs & INCREFs. */

    zst.zalloc = (alloc_func)NULL;

    zst.zfree = (free_func)Z_NULL;

    zst.next_out = (Byte *)output;

    zst.next_in = (Byte *)input;

    zst.avail_in = length;

    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(ZlibError,

			"Bad compression level");

	goto error;

    default:

        deflateEnd(&zst);

	zlib_error(zst, err, "while compressing data");

	goto error;

    }

    Py_BEGIN_ALLOW_THREADS;

    err = deflate(&zst, Z_FINISH);

    Py_END_ALLOW_THREADS;

    if (err != Z_STREAM_END) {

	zlib_error(zst, err, "while compressing data");

	deflateEnd(&zst);

	goto error;

    }

    err=deflateEnd(&zst);

    if (err == Z_OK)

	ReturnVal = PyString_FromStringAndSize((char *)output,

					       zst.total_out);

    else

	zlib_error(zst, err, "while finishing compression");

 error:

    free(output);

    return ReturnVal;

}

PyDoc_STRVAR(decompress__doc__,

"decompress(string[, wbits[, bufsize]]) -- Return decompressed string.\n"

"\n"

"Optional arg wbits is the window buffer size.  Optional arg bufsize is\n"

"the initial output buffer size.");

static PyObject *

PyZlib_decompress(PyObject *self, PyObject *args)

{

    PyObject *result_str;

    Byte *input;

    int length, err;

    int wsize=DEF_WBITS;

    Py_ssize_t r_strlen=DEFAULTALLOC;

    z_stream zst;

    if (!PyArg_ParseTuple(args, "s#|in:decompress",

			  &input, &length, &wsize, &r_strlen))

	return NULL;

    if (r_strlen <= 0)

	r_strlen = 1;

    zst.avail_in = length;

    zst.avail_out = r_strlen;

    if (!(result_str = PyString_FromStringAndSize(NULL, r_strlen)))

	return NULL;

    zst.zalloc = (alloc_func)NULL;

    zst.zfree = (free_func)Z_NULL;

    zst.next_out = (Byte *)PyString_AS_STRING(result_str);

    zst.next_in = (Byte *)input;

    err = inflateInit2(&zst, wsize);

    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 {

	Py_BEGIN_ALLOW_THREADS

	err=inflate(&zst, Z_FINISH);

	Py_END_ALLOW_THREADS

	switch(err) {

	case(Z_STREAM_END):

	    break;

	case(Z_BUF_ERROR):

	    /*

	     * If there is at least 1 byte of room according to zst.avail_out

	     * and we get this error, assume that it means zlib cannot

	     * process the inflate call() due to an error in the data.

	     */

	    if (zst.avail_out > 0) {

		PyErr_Format(ZlibError, "Error %i while decompressing data",

			     err);

		inflateEnd(&zst);

		goto error;

	    }

	    /* fall through */

	case(Z_OK):

	    /* need more memory */

	    if (_PyString_Resize(&result_str, r_strlen << 1) < 0) {

		inflateEnd(&zst);

		goto error;

	    }

	    zst.next_out = (unsigned char *)PyString_AS_STRING(result_str) \

		+ r_strlen;

	    zst.avail_out = r_strlen;

	    r_strlen = r_strlen << 1;

	    break;

	default:

	    inflateEnd(&zst);

	    zlib_error(zst, err, "while decompressing data");

	    goto error;

	}

    } while (err != Z_STREAM_END);

    err = inflateEnd(&zst);

    if (err != Z_OK) {

	zlib_error(zst, err, "while finishing data decompression");

	goto error;

    }

    _PyString_Resize(&result_str, zst.total_out);

    return result_str;

 error:

    Py_XDECREF(result_str);

    return NULL;

}

static PyObject *

PyZlib_compressobj(PyObject *selfptr, PyObject *args)

{

    compobject *self;

    int level=Z_DEFAULT_COMPRESSION, method=DEFLATED;

    int wbits=MAX_WBITS, memLevel=DEF_MEM_LEVEL, strategy=0, err;

    if (!PyArg_ParseTuple(args, "|iiiii:compressobj", &level, &method, &wbits,

			  &memLevel, &strategy))

	return NULL;

    self = newcompobject(&Comptype);

    if (self==NULL)

	return(NULL);

    self->zst.zalloc = (alloc_func)NULL;

    self->zst.zfree = (free_func)Z_NULL;

    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;

	return (PyObject*)self;

    case (Z_MEM_ERROR):

	Py_DECREF(self);

	PyErr_SetString(PyExc_MemoryError,

			"Can't allocate memory for compression object");

	return NULL;

    case(Z_STREAM_ERROR):

	Py_DECREF(self);

	PyErr_SetString(PyExc_ValueError, "Invalid initialization option");

	return NULL;

    default:

	zlib_error(self->zst, err, "while creating compression object");

        Py_DECREF(self);

	return NULL;

    }

}

static PyObject *

PyZlib_decompressobj(PyObject *selfptr, PyObject *args)

{

    int wbits=DEF_WBITS, err;

    compobject *self;

    if (!PyArg_ParseTuple(args, "|i:decompressobj", &wbits))

	return NULL;

    self = newcompobject(&Decomptype);

    if (self == NULL)

	return(NULL);

    self->zst.zalloc = (alloc_func)NULL;

    self->zst.zfree = (free_func)Z_NULL;

    self->zst.next_in = NULL;

    self->zst.avail_in = 0;

    err = inflateInit2(&self->zst, wbits);

    switch(err) {

    case (Z_OK):

	self->is_initialised = 1;

	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

Comp_dealloc(compobject *self)

{

    if (self->is_initialised)

	deflateEnd(&self->zst);

    Py_XDECREF(self->unused_data);

    Py_XDECREF(self->unconsumed_tail);

    PyObject_Del(self);

}

static void

Decomp_dealloc(compobject *self)

{

    if (self->is_initialised)

	inflateEnd(&self->zst);

    Py_XDECREF(self->unused_data);

    Py_XDECREF(self->unconsumed_tail);

    PyObject_Del(self);

}

PyDoc_STRVAR(comp_compress__doc__,

"compress(data) -- Return a string containing data compressed.\n"

"\n"

"After calling this function, some of the input data may still\n"

"be stored in internal buffers for later processing.\n"

"Call the flush() method to clear these buffers.");

static PyObject *

PyZlib_objcompress(compobject *self, PyObject *args)

{

    int err, inplen, length = DEFAULTALLOC;

    PyObject *RetVal;

    Byte *input;

    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "s#:compress", &input, &inplen))

	return NULL;

    if (!(RetVal = PyString_FromStringAndSize(NULL, length)))

	return NULL;

    ENTER_ZLIB

    start_total_out = self->zst.total_out;

    self->zst.avail_in = inplen;

    self->zst.next_in = input;

    self->zst.avail_out = length;

    self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal);

    Py_BEGIN_ALLOW_THREADS

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

    Py_END_ALLOW_THREADS

    /* while Z_OK and the output buffer is full, there might be more output,

       so extend the output buffer and try again */

    while (err == Z_OK && self->zst.avail_out == 0) {

	if (_PyString_Resize(&RetVal, length << 1) < 0)

	    goto error;

	self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal) \

	    + length;

	self->zst.avail_out = length;

	length = length << 1;

	Py_BEGIN_ALLOW_THREADS

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

	Py_END_ALLOW_THREADS

    }

    /* 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.

    */

    if (err != Z_OK && err != Z_BUF_ERROR) {

	zlib_error(self->zst, err, "while compressing");

	Py_DECREF(RetVal);

	RetVal = NULL;

	goto error;

    }

    _PyString_Resize(&RetVal, self->zst.total_out - start_total_out);

 error:

    LEAVE_ZLIB

    return RetVal;

}

PyDoc_STRVAR(decomp_decompress__doc__,

"decompress(data, max_length) -- Return a string containing the decompressed\n"

"version of the data.\n"

"\n"

"After calling this function, some of the input data may still be stored in\n"

"internal buffers for later processing.\n"

"Call the flush() method to clear these buffers.\n"

"If the max_length parameter is specified then the return value will be\n"

"no longer than max_length.  Unconsumed input data will be stored in\n"

"the unconsumed_tail attribute.");

static PyObject *

PyZlib_objdecompress(compobject *self, PyObject *args)

{

    int err, inplen, old_length, length = DEFAULTALLOC;

    int max_length = 0;

    PyObject *RetVal;

    Byte *input;

    unsigned long start_total_out;

    if (!PyArg_ParseTuple(args, "s#|i:decompress", &input,

			  &inplen, &max_length))

	return NULL;

    if (max_length < 0) {

	PyErr_SetString(PyExc_ValueError,

			"max_length must be greater than zero");

	return NULL;

    }

    /* limit amount of data allocated to max_length */

    if (max_length && length > max_length)

	length = max_length;

    if (!(RetVal = PyString_FromStringAndSize(NULL, length)))

	return NULL;

    ENTER_ZLIB

    start_total_out = self->zst.total_out;

    self->zst.avail_in = inplen;

    self->zst.next_in = input;

    self->zst.avail_out = length;

    self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal);

    Py_BEGIN_ALLOW_THREADS

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

    Py_END_ALLOW_THREADS

    /* While Z_OK and the output buffer is full, there might be more output.

       So extend the output buffer and try again.

    */

    while (err == Z_OK && self->zst.avail_out == 0) {

	/* If max_length set, don't continue decompressing if we've already

	   reached the limit.

	*/

	if (max_length && length >= max_length)

	    break;

	/* otherwise, ... */

	old_length = length;

	length = length << 1;

	if (max_length && length > max_length)

	    length = max_length;

	if (_PyString_Resize(&RetVal, length) < 0)

	    goto error;

	self->zst.next_out = (unsigned char *)PyString_AS_STRING(RetVal) \

	    + old_length;

	self->zst.avail_out = length - old_length;

	Py_BEGIN_ALLOW_THREADS

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

	Py_END_ALLOW_THREADS

    }

    /* Not all of the compressed data could be accommodated in the output buffer

       of specified size. Return the unconsumed tail in an attribute.*/

    if(max_length) {

	Py_DECREF(self->unconsumed_tail);

	self->unconsumed_tail = PyString_FromStringAndSize((char *)self->zst.next_in,