/*

python-bz2 - python bz2 library interface

Copyright (c) 2002 Gustavo Niemeyer <[email protected]>

Copyright (c) 2002 Python Software Foundation; All Rights Reserved

*/

#include "Python.h"

#include <stdio.h>

#include <bzlib.h>

#include "structmember.h"

#ifdef WITH_THREAD

#include "pythread.h"

#endif

static char __author__[] =

"The bz2 python module was written by:\n\

\n\

Gustavo Niemeyer <[email protected]>\n\

";

/* Our very own off_t-like type, 64-bit if possible */

/* copied from Objects/fileobject.c */

#if !defined(HAVE_LARGEFILE_SUPPORT)

typedef off_t Py_off_t;

#elif SIZEOF_OFF_T >= 8

typedef off_t Py_off_t;

#elif SIZEOF_FPOS_T >= 8

typedef fpos_t Py_off_t;

#else

#error "Large file support, but neither off_t nor fpos_t is large enough."

#endif

#define BUF(v) PyBytes_AS_STRING(v)

#define MODE_CLOSED 0

#define MODE_READ 1

#define MODE_READ_EOF 2

#define MODE_WRITE 3

#define BZ2FileObject_Check(v) (Py_TYPE(v) == &BZ2File_Type)

#ifdef BZ_CONFIG_ERROR

#if SIZEOF_LONG >= 8

#define BZS_TOTAL_OUT(bzs) \

(((long)bzs->total_out_hi32 << 32) + bzs->total_out_lo32)

#elif SIZEOF_LONG_LONG >= 8

#define BZS_TOTAL_OUT(bzs) \

(((PY_LONG_LONG)bzs->total_out_hi32 << 32) + bzs->total_out_lo32)

#else

#define BZS_TOTAL_OUT(bzs) \

bzs->total_out_lo32

#endif

#else /* ! BZ_CONFIG_ERROR */

#define BZ2_bzRead bzRead

#define BZ2_bzReadOpen bzReadOpen

#define BZ2_bzReadClose bzReadClose

#define BZ2_bzWrite bzWrite

#define BZ2_bzWriteOpen bzWriteOpen

#define BZ2_bzWriteClose bzWriteClose

#define BZ2_bzCompress bzCompress

#define BZ2_bzCompressInit bzCompressInit

#define BZ2_bzCompressEnd bzCompressEnd

#define BZ2_bzDecompress bzDecompress

#define BZ2_bzDecompressInit bzDecompressInit

#define BZ2_bzDecompressEnd bzDecompressEnd

#define BZS_TOTAL_OUT(bzs) bzs->total_out

#endif /* ! BZ_CONFIG_ERROR */

#ifdef WITH_THREAD

#define ACQUIRE_LOCK(obj) PyThread_acquire_lock(obj->lock, 1)

#define RELEASE_LOCK(obj) PyThread_release_lock(obj->lock)

#else

#define ACQUIRE_LOCK(obj)

#define RELEASE_LOCK(obj)

#endif

/* Bits in f_newlinetypes */

#define NEWLINE_UNKNOWN 0 /* No newline seen, yet */

#define NEWLINE_CR 1 /* \r newline seen */

#define NEWLINE_LF 2 /* \n newline seen */

#define NEWLINE_CRLF 4 /* \r\n newline seen */

/* ===================================================================== */

/* Structure definitions. */

typedef struct {

PyObject_HEAD

FILE *rawfp;

char* f_buf; /* Allocated readahead buffer */

char* f_bufend; /* Points after last occupied position */

char* f_bufptr; /* Current buffer position */

BZFILE *fp;

int mode;

Py_off_t pos;

Py_off_t size;

#ifdef WITH_THREAD

PyThread_type_lock lock;

#endif

} BZ2FileObject;

typedef struct {

PyObject_HEAD

bz_stream bzs;

int running;

#ifdef WITH_THREAD

PyThread_type_lock lock;

#endif

} BZ2CompObject;

typedef struct {

PyObject_HEAD

bz_stream bzs;

int running;

PyObject *unused_data;

#ifdef WITH_THREAD

PyThread_type_lock lock;

#endif

} BZ2DecompObject;

/* ===================================================================== */

/* Utility functions. */

static int

Util_CatchBZ2Error(int bzerror)

{

int ret = 0;

switch(bzerror) {

case BZ_OK:

case BZ_STREAM_END:

break;

#ifdef BZ_CONFIG_ERROR

case BZ_CONFIG_ERROR:

PyErr_SetString(PyExc_SystemError,

"the bz2 library was not compiled "

"correctly");

ret = 1;

break;

#endif

case BZ_PARAM_ERROR:

PyErr_SetString(PyExc_ValueError,

"the bz2 library has received wrong "

"parameters");

ret = 1;

break;

case BZ_MEM_ERROR:

PyErr_NoMemory();

ret = 1;

break;

case BZ_DATA_ERROR:

case BZ_DATA_ERROR_MAGIC:

PyErr_SetString(PyExc_IOError, "invalid data stream");

ret = 1;

break;

case BZ_IO_ERROR:

PyErr_SetString(PyExc_IOError, "unknown IO error");

ret = 1;

break;

case BZ_UNEXPECTED_EOF:

PyErr_SetString(PyExc_EOFError,

"compressed file ended before the "

"logical end-of-stream was detected");

ret = 1;

break;

case BZ_SEQUENCE_ERROR:

PyErr_SetString(PyExc_RuntimeError,

"wrong sequence of bz2 library "

"commands used");

ret = 1;

break;

}

return ret;

}

#if BUFSIZ < 8192

#define SMALLCHUNK 8192

#else

#define SMALLCHUNK BUFSIZ

#endif

#if SIZEOF_INT < 4

#define BIGCHUNK (512 * 32)

#else

#define BIGCHUNK (512 * 1024)

#endif

/* This is a hacked version of Python's fileobject.c:new_buffersize(). */

static size_t

Util_NewBufferSize(size_t currentsize)

{

if (currentsize > SMALLCHUNK) {

/* Keep doubling until we reach BIGCHUNK;

then keep adding BIGCHUNK. */

if (currentsize <= BIGCHUNK)

return currentsize + currentsize;

else

return currentsize + BIGCHUNK;

}

return currentsize + SMALLCHUNK;

}

/* This is a hacked version of Python's fileobject.c:get_line(). */

static PyObject *

Util_GetLine(BZ2FileObject *f, int n)

{

char c;

char *buf, *end;

size_t total_v_size; /* total # of slots in buffer */

size_t used_v_size; /* # used slots in buffer */

size_t increment; /* amount to increment the buffer */

PyObject *v;

int bzerror;

int bytes_read;

total_v_size = n > 0 ? n : 100;

v = PyBytes_FromStringAndSize((char *)NULL, total_v_size);

if (v == NULL)

return NULL;

buf = BUF(v);

end = buf + total_v_size;

for (;;) {

Py_BEGIN_ALLOW_THREADS

do {

bytes_read = BZ2_bzRead(&bzerror, f->fp, &c, 1);

f->pos++;

if (bytes_read == 0)

break;

*buf++ = c;

} while (bzerror == BZ_OK && c != '\n' && buf != end);

Py_END_ALLOW_THREADS

if (bzerror == BZ_STREAM_END) {

f->size = f->pos;

f->mode = MODE_READ_EOF;

break;

} else if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

Py_DECREF(v);

return NULL;

}

if (c == '\n')

break;

/* Must be because buf == end */

if (n > 0)

break;

used_v_size = total_v_size;

increment = total_v_size >> 2; /* mild exponential growth */

total_v_size += increment;

if (total_v_size > INT_MAX) {

PyErr_SetString(PyExc_OverflowError,

"line is longer than a Python string can hold");

Py_DECREF(v);

return NULL;

}

if (_PyBytes_Resize(&v, total_v_size) < 0) {

return NULL;

}

buf = BUF(v) + used_v_size;

end = BUF(v) + total_v_size;

}

used_v_size = buf - BUF(v);

if (used_v_size != total_v_size) {

if (_PyBytes_Resize(&v, used_v_size) < 0) {

v = NULL;

}

}

return v;

}

/* This is a hacked version of Python's fileobject.c:drop_readahead(). */

static void

Util_DropReadAhead(BZ2FileObject *f)

{

if (f->f_buf != NULL) {

PyMem_Free(f->f_buf);

f->f_buf = NULL;

}

}

/* This is a hacked version of Python's fileobject.c:readahead(). */

static int

Util_ReadAhead(BZ2FileObject *f, int bufsize)

{

int chunksize;

int bzerror;

if (f->f_buf != NULL) {

if((f->f_bufend - f->f_bufptr) >= 1)

return 0;

else

Util_DropReadAhead(f);

}

if (f->mode == MODE_READ_EOF) {

f->f_bufptr = f->f_buf;

f->f_bufend = f->f_buf;

return 0;

}

if ((f->f_buf = PyMem_Malloc(bufsize)) == NULL) {

PyErr_NoMemory();

return -1;

}

Py_BEGIN_ALLOW_THREADS

chunksize = BZ2_bzRead(&bzerror, f->fp, f->f_buf, bufsize);

Py_END_ALLOW_THREADS

f->pos += chunksize;

if (bzerror == BZ_STREAM_END) {

f->size = f->pos;

f->mode = MODE_READ_EOF;

} else if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

Util_DropReadAhead(f);

return -1;

}

f->f_bufptr = f->f_buf;

f->f_bufend = f->f_buf + chunksize;

return 0;

}

/* This is a hacked version of Python's

* fileobject.c:readahead_get_line_skip(). */

static PyBytesObject *

Util_ReadAheadGetLineSkip(BZ2FileObject *f, int skip, int bufsize)

{

PyBytesObject* s;

char *bufptr;

char *buf;

int len;

if (f->f_buf == NULL)

if (Util_ReadAhead(f, bufsize) < 0)

return NULL;

len = f->f_bufend - f->f_bufptr;

if (len == 0)

return (PyBytesObject *)

PyBytes_FromStringAndSize(NULL, skip);

bufptr = memchr(f->f_bufptr, '\n', len);

if (bufptr != NULL) {

bufptr++; /* Count the '\n' */

len = bufptr - f->f_bufptr;

s = (PyBytesObject *)

PyBytes_FromStringAndSize(NULL, skip+len);

if (s == NULL)

return NULL;

memcpy(PyBytes_AS_STRING(s)+skip, f->f_bufptr, len);

f->f_bufptr = bufptr;

if (bufptr == f->f_bufend)

Util_DropReadAhead(f);

} else {

bufptr = f->f_bufptr;

buf = f->f_buf;

f->f_buf = NULL; /* Force new readahead buffer */

s = Util_ReadAheadGetLineSkip(f, skip+len,

bufsize + (bufsize>>2));

if (s == NULL) {

PyMem_Free(buf);

return NULL;

}

memcpy(PyBytes_AS_STRING(s)+skip, bufptr, len);

PyMem_Free(buf);

}

return s;

}

/* ===================================================================== */

/* Methods of BZ2File. */

PyDoc_STRVAR(BZ2File_read__doc__,

"read([size]) -> string\n\

\n\

Read at most size uncompressed bytes, returned as a string. If the size\n\

argument is negative or omitted, read until EOF is reached.\n\

");

/* This is a hacked version of Python's fileobject.c:file_read(). */

static PyObject *

BZ2File_read(BZ2FileObject *self, PyObject *args)

{

long bytesrequested = -1;

size_t bytesread, buffersize, chunksize;

int bzerror;

PyObject *ret = NULL;

if (!PyArg_ParseTuple(args, "|l:read", &bytesrequested))

return NULL;

ACQUIRE_LOCK(self);

switch (self->mode) {

case MODE_READ:

break;

case MODE_READ_EOF:

ret = PyBytes_FromStringAndSize("", 0);

goto cleanup;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto cleanup;

default:

PyErr_SetString(PyExc_IOError,

"file is not ready for reading");

goto cleanup;

}

if (bytesrequested < 0)

buffersize = Util_NewBufferSize((size_t)0);

else

buffersize = bytesrequested;

if (buffersize > INT_MAX) {

PyErr_SetString(PyExc_OverflowError,

"requested number of bytes is "

"more than a Python string can hold");

goto cleanup;

}

ret = PyBytes_FromStringAndSize((char *)NULL, buffersize);

if (ret == NULL || buffersize == 0)

goto cleanup;

bytesread = 0;

for (;;) {

Py_BEGIN_ALLOW_THREADS

chunksize = BZ2_bzRead(&bzerror, self->fp,

BUF(ret)+bytesread,

buffersize-bytesread);

self->pos += chunksize;

Py_END_ALLOW_THREADS

bytesread += chunksize;

if (bzerror == BZ_STREAM_END) {

self->size = self->pos;

self->mode = MODE_READ_EOF;

break;

} else if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

Py_DECREF(ret);

ret = NULL;

goto cleanup;

}

if (bytesrequested < 0) {

buffersize = Util_NewBufferSize(buffersize);

if (_PyBytes_Resize(&ret, buffersize) < 0) {

ret = NULL;

goto cleanup;

}

} else {

break;

}

}

if (bytesread != buffersize) {

if (_PyBytes_Resize(&ret, bytesread) < 0) {

ret = NULL;

}

}

cleanup:

RELEASE_LOCK(self);

return ret;

}

PyDoc_STRVAR(BZ2File_readline__doc__,

"readline([size]) -> string\n\

\n\

Return the next line from the file, as a string, retaining newline.\n\

A non-negative size argument will limit the maximum number of bytes to\n\

return (an incomplete line may be returned then). Return an empty\n\

string at EOF.\n\

");

static PyObject *

BZ2File_readline(BZ2FileObject *self, PyObject *args)

{

PyObject *ret = NULL;

int sizehint = -1;

if (!PyArg_ParseTuple(args, "|i:readline", &sizehint))

return NULL;

ACQUIRE_LOCK(self);

switch (self->mode) {

case MODE_READ:

break;

case MODE_READ_EOF:

ret = PyBytes_FromStringAndSize("", 0);

goto cleanup;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto cleanup;

default:

PyErr_SetString(PyExc_IOError,

"file is not ready for reading");

goto cleanup;

}

if (sizehint == 0)

ret = PyBytes_FromStringAndSize("", 0);

else

ret = Util_GetLine(self, (sizehint < 0) ? 0 : sizehint);

cleanup:

RELEASE_LOCK(self);

return ret;

}

PyDoc_STRVAR(BZ2File_readlines__doc__,

"readlines([size]) -> list\n\

\n\

Call readline() repeatedly and return a list of lines read.\n\

The optional size argument, if given, is an approximate bound on the\n\

total number of bytes in the lines returned.\n\

");

/* This is a hacked version of Python's fileobject.c:file_readlines(). */

static PyObject *

BZ2File_readlines(BZ2FileObject *self, PyObject *args)

{

long sizehint = 0;

PyObject *list = NULL;

PyObject *line;

char small_buffer[SMALLCHUNK];

char *buffer = small_buffer;

size_t buffersize = SMALLCHUNK;

PyObject *big_buffer = NULL;

size_t nfilled = 0;

size_t nread;

size_t totalread = 0;

char *p, *q, *end;

int err;

int shortread = 0;

int bzerror;

if (!PyArg_ParseTuple(args, "|l:readlines", &sizehint))

return NULL;

ACQUIRE_LOCK(self);

switch (self->mode) {

case MODE_READ:

break;

case MODE_READ_EOF:

list = PyList_New(0);

goto cleanup;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto cleanup;

default:

PyErr_SetString(PyExc_IOError,

"file is not ready for reading");

goto cleanup;

}

if ((list = PyList_New(0)) == NULL)

goto cleanup;

for (;;) {

Py_BEGIN_ALLOW_THREADS

nread = BZ2_bzRead(&bzerror, self->fp,

buffer+nfilled, buffersize-nfilled);

self->pos += nread;

Py_END_ALLOW_THREADS

if (bzerror == BZ_STREAM_END) {

self->size = self->pos;

self->mode = MODE_READ_EOF;

if (nread == 0) {

sizehint = 0;

break;

}

shortread = 1;

} else if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

error:

Py_DECREF(list);

list = NULL;

goto cleanup;

}

totalread += nread;

p = memchr(buffer+nfilled, '\n', nread);

if (!shortread && p == NULL) {

/* Need a larger buffer to fit this line */

nfilled += nread;

buffersize *= 2;

if (buffersize > INT_MAX) {

PyErr_SetString(PyExc_OverflowError,

"line is longer than a Python string can hold");

goto error;

}

if (big_buffer == NULL) {

/* Create the big buffer */

big_buffer = PyBytes_FromStringAndSize(

NULL, buffersize);

if (big_buffer == NULL)

goto error;

buffer = PyBytes_AS_STRING(big_buffer);

memcpy(buffer, small_buffer, nfilled);

}

else {

/* Grow the big buffer */

if (_PyBytes_Resize(&big_buffer, buffersize) < 0){

big_buffer = NULL;

goto error;

}

buffer = PyBytes_AS_STRING(big_buffer);

}

continue;

}

end = buffer+nfilled+nread;

q = buffer;

while (p != NULL) {

/* Process complete lines */

p++;

line = PyBytes_FromStringAndSize(q, p-q);

if (line == NULL)

goto error;

err = PyList_Append(list, line);

Py_DECREF(line);

if (err != 0)

goto error;

q = p;

p = memchr(q, '\n', end-q);

}

/* Move the remaining incomplete line to the start */

nfilled = end-q;

memmove(buffer, q, nfilled);

if (sizehint > 0)

if (totalread >= (size_t)sizehint)

break;

if (shortread) {

sizehint = 0;

break;

}

}

if (nfilled != 0) {

/* Partial last line */

line = PyBytes_FromStringAndSize(buffer, nfilled);

if (line == NULL)

goto error;

if (sizehint > 0) {

/* Need to complete the last line */

PyObject *rest = Util_GetLine(self, 0);

if (rest == NULL) {

Py_DECREF(line);

goto error;

}

PyBytes_Concat(&line, rest);

Py_DECREF(rest);

if (line == NULL)

goto error;

}

err = PyList_Append(list, line);

Py_DECREF(line);

if (err != 0)

goto error;

}

cleanup:

RELEASE_LOCK(self);

if (big_buffer) {

Py_DECREF(big_buffer);

}

return list;

}

PyDoc_STRVAR(BZ2File_write__doc__,

"write(data) -> None\n\

\n\

Write the 'data' string to file. Note that due to buffering, close() may\n\

be needed before the file on disk reflects the data written.\n\

");

/* This is a hacked version of Python's fileobject.c:file_write(). */

static PyObject *

BZ2File_write(BZ2FileObject *self, PyObject *args)

{

PyObject *ret = NULL;

Py_buffer pbuf;

char *buf;

int len;

int bzerror;

if (!PyArg_ParseTuple(args, "y*:write", &pbuf))

return NULL;

buf = pbuf.buf;

len = pbuf.len;

ACQUIRE_LOCK(self);

switch (self->mode) {

case MODE_WRITE:

break;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto cleanup;

default:

PyErr_SetString(PyExc_IOError,

"file is not ready for writing");

goto cleanup;

}

Py_BEGIN_ALLOW_THREADS

BZ2_bzWrite (&bzerror, self->fp, buf, len);

self->pos += len;

Py_END_ALLOW_THREADS

if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

goto cleanup;

}

Py_INCREF(Py_None);

ret = Py_None;

cleanup:

PyBuffer_Release(&pbuf);

RELEASE_LOCK(self);

return ret;

}

PyDoc_STRVAR(BZ2File_writelines__doc__,

"writelines(sequence_of_strings) -> None\n\

\n\

Write the sequence of strings to the file. Note that newlines are not\n\

added. The sequence can be any iterable object producing strings. This is\n\

equivalent to calling write() for each string.\n\

");

/* This is a hacked version of Python's fileobject.c:file_writelines(). */

static PyObject *

BZ2File_writelines(BZ2FileObject *self, PyObject *seq)

{

#define CHUNKSIZE 1000

PyObject *list = NULL;

PyObject *iter = NULL;

PyObject *ret = NULL;

PyObject *line;

int i, j, index, len, islist;

int bzerror;

ACQUIRE_LOCK(self);

switch (self->mode) {

case MODE_WRITE:

break;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto error;

default:

PyErr_SetString(PyExc_IOError,

"file is not ready for writing");

goto error;

}

islist = PyList_Check(seq);

if (!islist) {

iter = PyObject_GetIter(seq);

if (iter == NULL) {

PyErr_SetString(PyExc_TypeError,

"writelines() requires an iterable argument");

goto error;

}

list = PyList_New(CHUNKSIZE);

if (list == NULL)

goto error;

}

/* Strategy: slurp CHUNKSIZE lines into a private list,

checking that they are all strings, then write that list

without holding the interpreter lock, then come back for more. */

for (index = 0; ; index += CHUNKSIZE) {

if (islist) {

Py_XDECREF(list);

list = PyList_GetSlice(seq, index, index+CHUNKSIZE);

if (list == NULL)

goto error;

j = PyList_GET_SIZE(list);

}

else {

for (j = 0; j < CHUNKSIZE; j++) {

line = PyIter_Next(iter);

if (line == NULL) {

if (PyErr_Occurred())

goto error;

break;

}

PyList_SetItem(list, j, line);

}

}

if (j == 0)

break;

/* Check that all entries are indeed byte strings. If not,

apply the same rules as for file.write() and

convert the rets to strings. This is slow, but

seems to be the only way since all conversion APIs

could potentially execute Python code. */

for (i = 0; i < j; i++) {

PyObject *v = PyList_GET_ITEM(list, i);

if (!PyBytes_Check(v)) {

const char *buffer;

Py_ssize_t len;

if (PyObject_AsCharBuffer(v, &buffer, &len)) {

PyErr_SetString(PyExc_TypeError,

"writelines() "

"argument must be "

"a sequence of "

"bytes objects");

goto error;

}

line = PyBytes_FromStringAndSize(buffer,

len);

if (line == NULL)

goto error;

Py_DECREF(v);

PyList_SET_ITEM(list, i, line);

}

}

/* Since we are releasing the global lock, the

following code may *not* execute Python code. */

Py_BEGIN_ALLOW_THREADS

for (i = 0; i < j; i++) {

line = PyList_GET_ITEM(list, i);

len = PyBytes_GET_SIZE(line);

BZ2_bzWrite (&bzerror, self->fp,

PyBytes_AS_STRING(line), len);

if (bzerror != BZ_OK) {

Py_BLOCK_THREADS

Util_CatchBZ2Error(bzerror);

goto error;

}

}

Py_END_ALLOW_THREADS

if (j < CHUNKSIZE)

break;

}

Py_INCREF(Py_None);

ret = Py_None;

error:

RELEASE_LOCK(self);

Py_XDECREF(list);

Py_XDECREF(iter);

return ret;

#undef CHUNKSIZE

}

PyDoc_STRVAR(BZ2File_seek__doc__,

"seek(offset [, whence]) -> None\n\

\n\

Move to new file position. Argument offset is a byte count. Optional\n\

argument whence defaults to 0 (offset from start of file, offset\n\

should be >= 0); other values are 1 (move relative to current position,\n\

positive or negative), and 2 (move relative to end of file, usually\n\

negative, although many platforms allow seeking beyond the end of a file).\n\

\n\

Note that seeking of bz2 files is emulated, and depending on the parameters\n\

the operation may be extremely slow.\n\

");

static PyObject *

BZ2File_seek(BZ2FileObject *self, PyObject *args)

{

int where = 0;

PyObject *offobj;

Py_off_t offset;

char small_buffer[SMALLCHUNK];

char *buffer = small_buffer;

size_t buffersize = SMALLCHUNK;

Py_off_t bytesread = 0;

size_t readsize;

int chunksize;

int bzerror;

PyObject *ret = NULL;

if (!PyArg_ParseTuple(args, "O|i:seek", &offobj, &where))

return NULL;

#if !defined(HAVE_LARGEFILE_SUPPORT)

offset = PyLong_AsLong(offobj);

#else

offset = PyLong_Check(offobj) ?

PyLong_AsLongLong(offobj) : PyLong_AsLong(offobj);

#endif

if (PyErr_Occurred())

return NULL;

ACQUIRE_LOCK(self);

Util_DropReadAhead(self);

switch (self->mode) {

case MODE_READ:

case MODE_READ_EOF:

break;

case MODE_CLOSED:

PyErr_SetString(PyExc_ValueError,

"I/O operation on closed file");

goto cleanup;

default:

PyErr_SetString(PyExc_IOError,

"seek works only while reading");

goto cleanup;

}

if (where == 2) {

if (self->size == -1) {

assert(self->mode != MODE_READ_EOF);

for (;;) {

Py_BEGIN_ALLOW_THREADS

chunksize = BZ2_bzRead(&bzerror, self->fp,

buffer, buffersize);

self->pos += chunksize;

Py_END_ALLOW_THREADS

bytesread += chunksize;

if (bzerror == BZ_STREAM_END) {

break;

} else if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

goto cleanup;

}

}

self->mode = MODE_READ_EOF;

self->size = self->pos;

bytesread = 0;

}

offset = self->size + offset;

} else if (where == 1) {

offset = self->pos + offset;

}

/* Before getting here, offset must be the absolute position the file

* pointer should be set to. */

if (offset >= self->pos) {

/* we can move forward */

offset -= self->pos;

} else {

/* we cannot move back, so rewind the stream */

BZ2_bzReadClose(&bzerror, self->fp);

if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

goto cleanup;

}

rewind(self->rawfp);

self->pos = 0;

self->fp = BZ2_bzReadOpen(&bzerror, self->rawfp,

0, 0, NULL, 0);

if (bzerror != BZ_OK) {

Util_CatchBZ2Error(bzerror);

goto cleanup;

}

self->mode = MODE_READ;

}

if (offset <= 0 || self->mode == MODE_READ_EOF)

goto exit;

/* Before getting here, offset must be set to the number of bytes

* to walk forward. */

for (;;) {

if (offset-bytesread > buffersize)

readsize = buffersize;

else

/* offset might be wider that readsize, but the result

* of the subtraction is bound by buffersize (see the

* condition above). buffersize is 8192. */

readsize = (size_t)(offset-bytesread);

Py_BEGIN_ALLOW_THREADS

chunksize = BZ2_bzRead(&bzerror, self->fp, buffer, readsize);

self->pos += chunksize;

Py_END_ALLOW_THREADS

bytesread += chunksize;

if (bzerror == BZ_STREAM_END) {

self->size = self->pos;

self->mode = MODE_READ_EOF;

break;