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|
# -*- python -*- or near enough
import sys
import zlib
from cpython cimport PyBytes_FromStringAndSize, \
PyBytes_AS_STRING, PyBytes_Size
from pyalloc cimport pyalloc_v
from libc.stdio cimport fread, fseek, ftell
from libc.string cimport memcpy
cdef extern from "Python.h":
void *PyCObject_Import(char *, char *) except NULL
ctypedef struct PyTypeObject:
pass
ctypedef struct PyObject:
pass
ctypedef struct FILE
cdef extern from "py3k.h":
# From:
# http://svn.pyamf.org/pyamf/tags/release-0.4rc2/cpyamf/util.pyx
# (MIT license) - with thanks
void PycString_IMPORT()
int StringIO_cread "PycStringIO->cread" (object, char **, Py_ssize_t)
int StringIO_creadline "PycStringIO->creadline" (object, char **)
int StringIO_cwrite "PycStringIO->cwrite" (object, char *, Py_ssize_t)
object StringIO_cgetvalue "PycStringIO->cgetvalue" (obj)
bint PycStringIO_InputCheck(object O)
bint PycStringIO_OutputCheck(object O)
FILE* npy_PyFile_Dup(object file, char *mode) except NULL
int npy_PyFile_DupClose(object file, FILE *handle) except -1
int npy_PyFile_Check(object file)
# initialize cStringIO
PycString_IMPORT
DEF BLOCK_SIZE = 131072
cdef class GenericStream:
def __init__(self, fobj):
self.fobj = fobj
cpdef int seek(self, long int offset, int whence=0) except -1:
self.fobj.seek(offset, whence)
return 0
cpdef long int tell(self) except -1:
return self.fobj.tell()
def read(self, n_bytes):
return self.fobj.read(n_bytes)
cdef int read_into(self, void *buf, size_t n) except -1:
""" Read n bytes from stream into pre-allocated buffer `buf`
"""
cdef char *p
cdef size_t read_size, count
# Read data to buf in BLOCK_SIZE blocks
count = 0
p = <char*>buf
while count < n:
read_size = min(n - count, BLOCK_SIZE)
data = self.fobj.read(read_size)
read_size = len(data)
if read_size == 0:
break
memcpy(p, <const char*>data, read_size)
p += read_size
count += read_size
if count != n:
raise IOError('could not read bytes')
return 0
cdef object read_string(self, size_t n, void **pp, int copy=True):
"""Make new memory, wrap with object"""
if copy != True:
data = self.fobj.read(n)
if PyBytes_Size(data) != n:
raise IOError('could not read bytes')
pp[0] = <void*>PyBytes_AS_STRING(data)
return data
cdef object d_copy = pyalloc_v(n, pp)
self.read_into(pp[0], n)
return d_copy
cdef class ZlibInputStream(GenericStream):
"""
File-like object uncompressing bytes from a zlib compressed stream.
Parameters
----------
stream : file-like
Stream to read compressed data from.
max_length : int
Maximum number of bytes to read from the stream.
Notes
-----
Some matlab files contain zlib streams without valid Z_STREAM_END
termination. To get round this, we use the decompressobj object, that
allows you to decode an incomplete stream. See discussion at
http://bugs.python.org/issue8672
"""
cdef ssize_t _max_length
cdef object _decompressor
cdef bytes _buffer
cdef size_t _buffer_size
cdef size_t _buffer_position
cdef size_t _total_position
cdef size_t _read_bytes
def __init__(self, fobj, ssize_t max_length):
self.fobj = fobj
self._max_length = max_length
self._decompressor = zlib.decompressobj()
self._buffer = b''
self._buffer_size = 0
self._buffer_position = 0
self._total_position = 0
self._read_bytes = 0
cdef inline void _fill_buffer(self) except *:
cdef size_t read_size
cdef bytes block
if self._buffer_position < self._buffer_size:
return
read_size = min(BLOCK_SIZE, self._max_length - self._read_bytes)
block = self.fobj.read(read_size)
self._read_bytes += len(block)
self._buffer_position = 0
if not block:
self._buffer = self._decompressor.flush()
else:
self._buffer = self._decompressor.decompress(block)
self._buffer_size = len(self._buffer)
cdef int read_into(self, void *buf, size_t n) except -1:
"""Read n bytes from stream into pre-allocated buffer `buf`
"""
cdef char *dstp
cdef char *srcp
cdef size_t read_size, count, size
dstp = <char*>buf
count = 0
while count < n:
self._fill_buffer()
if self._buffer_size == 0:
break
srcp = <char*>self._buffer
srcp += self._buffer_position
size = min(n - count, self._buffer_size - self._buffer_position)
memcpy(dstp, srcp, size)
count += size
dstp += size
self._buffer_position += size
self._total_position += count
if count != n:
raise IOError('could not read bytes')
return 0
cdef object read_string(self, size_t n, void **pp, int copy=True):
"""Make new memory, wrap with object"""
cdef object d_copy = pyalloc_v(n, pp)
self.read_into(pp[0], n)
return d_copy
def read(self, n_bytes):
cdef void *p
return self.read_string(n_bytes, &p)
cpdef int all_data_read(self):
return (self._max_length == self._read_bytes) and \
(self._buffer_size == self._buffer_position)
cpdef long int tell(self) except -1:
if self._total_position == -1:
raise IOError("Invalid file position.")
return self._total_position
cpdef int seek(self, long int offset, int whence=0) except -1:
cdef ssize_t new_pos, size
if whence == 1:
new_pos = <ssize_t>self._total_position + offset
elif whence == 0:
new_pos = offset
elif whence == 2:
raise IOError("Zlib stream cannot seek from file end")
else:
raise ValueError("Invalid value for whence")
if new_pos < self._total_position:
raise IOError("Zlib stream cannot seek backwards")
while self._total_position < new_pos:
self._fill_buffer()
if self._buffer_size == 0:
break
size = min(new_pos - self._total_position,
self._buffer_size - self._buffer_position)
self._total_position += size
self._buffer_position += size
return 0
cdef class cStringStream(GenericStream):
cpdef int seek(self, long int offset, int whence=0) except -1:
cdef char *ptr
if whence == 1 and offset >=0: # forward, from here
StringIO_cread(self.fobj, &ptr, offset)
return 0
else: # use python interface
return GenericStream.seek(self, offset, whence)
cdef int read_into(self, void *buf, size_t n) except -1:
""" Read n bytes from stream into pre-allocated buffer `buf`
"""
cdef:
size_t n_red
char* d_ptr
n_red = StringIO_cread(self.fobj, &d_ptr, n)
if n_red != n:
raise IOError('could not read bytes')
memcpy(buf, <void *>d_ptr, n)
return 0
cdef object read_string(self, size_t n, void **pp, int copy=True):
""" Make new memory, wrap with object
It's not obvious to me how to avoid a copy
"""
cdef:
char *d_ptr
object obj
cdef size_t n_red = StringIO_cread(self.fobj, &d_ptr, n)
if n_red != n:
raise IOError('could not read bytes')
obj = pyalloc_v(n, pp)
memcpy(pp[0], d_ptr, n)
return obj
cdef class FileStream(GenericStream):
cdef FILE* file
def __init__(self, fobj):
self.fobj = fobj
self.file = npy_PyFile_Dup(fobj, "rb")
def __del__(self):
npy_PyFile_DupClose(self.fobj, self.file)
cpdef int seek(self, long int offset, int whence=0) except -1:
cdef int ret
""" move `offset` bytes in stream
Parameters
----------
offset : long int
number of bytes to move. Positive for forward in file,
negative for backward
whence : int
`whence` can be:
* 0 - from beginning of file (`offset` should be >=0)
* 1 - from current file position
* 2 - from end of file (`offset` nearly always <=0)
Returns
-------
ret : int
"""
ret = fseek(self.file, offset, whence)
if ret:
raise IOError('Failed seek')
return ret
cpdef long int tell(self) except -1:
cdef long int position = ftell(self.file)
if position == -1:
raise IOError("Invalid file position.")
return position
cdef int read_into(self, void *buf, size_t n) except -1:
""" Read n bytes from stream into pre-allocated buffer `buf`
"""
cdef:
size_t n_red
char* d_ptr
n_red = fread(buf, 1, n, self.file)
if n_red != n:
raise IOError('Could not read bytes')
return 0
cdef object read_string(self, size_t n, void **pp, int copy=True):
""" Make new memory, wrap with object """
cdef object obj = pyalloc_v(n, pp)
cdef size_t n_red = fread(pp[0], 1, n, self.file)
if n_red != n:
raise IOError('could not read bytes')
return obj
def _read_into(GenericStream st, size_t n):
# for testing only. Use st.read instead
cdef char * d_ptr
my_str = b' ' * n
d_ptr = my_str
st.read_into(d_ptr, n)
return my_str
def _read_string(GenericStream st, size_t n):
# for testing only. Use st.read instead
cdef void *d_ptr
cdef object obj = st.read_string(n, &d_ptr, True)
my_str = b'A' * n
cdef char *mys_ptr = my_str
memcpy(mys_ptr, d_ptr, n)
return my_str
cpdef GenericStream make_stream(object fobj):
""" Make stream of correct type for file-like `fobj`
"""
if npy_PyFile_Check(fobj):
if <int>sys.version_info[0] >= 3:
return GenericStream(fobj)
else:
return FileStream(fobj)
elif PycStringIO_InputCheck(fobj) or PycStringIO_OutputCheck(fobj):
return cStringStream(fobj)
elif isinstance(fobj, GenericStream):
return fobj
return GenericStream(fobj)
|
