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from __future__ import unicode_literals
import os
from functools import wraps
import six
from psycopg2cffi._impl import exceptions
from psycopg2cffi._impl import consts
from psycopg2cffi._impl.libpq import libpq, ffi
INV_WRITE = 0x00020000
INV_READ = 0x00040000
def check_unmarked(func):
@wraps(func)
def check_unmarked_(self, *args, **kwargs):
if self._mark != self._conn._mark:
raise exceptions.ProgrammingError("lobject isn't valid anymore")
return func(self, *args, **kwargs)
return check_unmarked_
def check_closed(func):
@wraps(func)
def check_closed_(self, *args, **kwargs):
if self.closed:
raise exceptions.InterfaceError("lobject already closed")
return func(self, *args, **kwargs)
return check_closed_
class LargeObject(object):
def __init__(self, conn=None, oid=0, mode='', new_oid=0, new_file=None):
self._conn = conn
self._oid = oid
self._mode = self._parse_mode(mode)
self._smode = mode
self._new_oid = new_oid
self._new_file = new_file
self._fd = -1
self._mark = conn._mark
if conn.autocommit:
raise exceptions.ProgrammingError(
"can't use a lobject outside of transactions")
self._open()
@property
def oid(self):
return self._oid
@property
def mode(self):
return self._smode
@check_closed
@check_unmarked
def read(self, size=-1):
"""Read at most size bytes or to the end of the large object."""
if size < 0:
where = self.tell()
end = self.seek(0, os.SEEK_END)
self.seek(where, os.SEEK_SET)
size = end - where
binary_mode = self._mode & consts.LOBJECT_BINARY
if size == 0:
return b'' if binary_mode else ''
buf = ffi.new('char []', size)
length = libpq.lo_read(self._conn._pgconn, self._fd, buf, size)
if length < 0:
return
return ffi.buffer(buf, length)[:] if binary_mode else \
ffi.string(buf).decode(self._conn._py_enc)
@check_closed
@check_unmarked
def write(self, value):
"""Write a string to the large object."""
if isinstance(value, six.text_type):
value = value.encode(self._conn._py_enc)
length = libpq.lo_write(
self._conn._pgconn, self._fd, value, len(value))
if length < 0:
raise self._conn._create_exception()
return length
def export(self, file_name):
"""Export large object to given file."""
self._conn._begin_transaction()
if isinstance(file_name, six.text_type):
file_name = file_name.encode(self._conn._py_enc)
if libpq.lo_export(self._conn._pgconn, self._oid, file_name) < 0:
raise self._conn._create_exception()
@check_closed
@check_unmarked
def seek(self, offset, whence=0):
"""Set the lobject's current position."""
return libpq.lo_lseek(self._conn._pgconn, self._fd, offset, whence)
@check_closed
@check_unmarked
def tell(self):
"""Return the lobject's current position."""
return libpq.lo_tell(self._conn._pgconn, self._fd)
@check_closed
@check_unmarked
def truncate(self, length=0):
ret = libpq.lo_truncate(self._conn._pgconn, self._fd, length)
if ret < 0:
raise self._conn._create_exception()
return ret
def close(self):
"""Close and then remove the lobject."""
if self.closed:
return True
if self._conn.autocommit or self._conn._mark != self._mark:
return True
ret = libpq.lo_close(self._conn._pgconn, self._fd)
self._fd = -1
if ret < 0:
raise self._conn._create_exception()
else:
return True
@property
def closed(self):
return self._fd < 0 or not self._conn or self._conn.closed
def unlink(self):
self._conn._begin_transaction()
self.close()
libpq.lo_unlink(self._conn._pgconn, self._oid)
def _open(self):
conn = self._conn
conn._begin_transaction()
if self._oid == 0:
if self._new_file:
_new_file = self._new_file
if isinstance(self._new_file, six.text_type):
_new_file = self._new_file.encode(conn._py_enc)
self._oid = libpq.lo_import(conn._pgconn, _new_file)
else:
self._oid = libpq.lo_create(conn._pgconn, self._new_oid)
self._mode = \
(self._mode & ~consts.LOBJECT_READ) | consts.LOBJECT_WRITE
pgmode = 0
if self._mode & consts.LOBJECT_READ:
pgmode |= INV_READ
if self._mode & consts.LOBJECT_WRITE:
pgmode |= INV_WRITE
if pgmode:
self._fd = libpq.lo_open(conn._pgconn, self._oid, pgmode)
if self._fd < 0:
raise self._conn._create_exception()
self._smode = self._unparse_mode(self._mode)
def _parse_mode(self, smode):
"""Convert a mode string to a mode int"""
mode = 0
pos = 0
binary_default = consts.LOBJECT_TEXT if six.PY3 else \
consts.LOBJECT_BINARY
if not smode:
return consts.LOBJECT_READ | binary_default
if smode[0:2] == 'rw':
mode |= consts.LOBJECT_READ | consts.LOBJECT_WRITE
pos = 2
else:
if smode[0] == 'r':
mode |= consts.LOBJECT_READ
pos = 1
elif smode[0] == 'w':
mode |= consts.LOBJECT_WRITE
pos = 1
elif smode[0] == 'n':
pos = 1
else:
mode |= consts.LOBJECT_READ
if len(smode) > pos:
if smode[pos] == 't':
mode |= consts.LOBJECT_TEXT
pos += 1
elif smode[pos] == 'b':
mode |= consts.LOBJECT_BINARY
pos += 1
else:
mode |= binary_default
else:
mode |= binary_default
if len(smode) != pos:
raise ValueError("bad mode for lobject: '%s'", smode)
return mode
def _unparse_mode(self, mode):
"""Convert a mode int to a mode string"""
smode = ''
if mode & consts.LOBJECT_READ:
smode += 'r'
if mode & consts.LOBJECT_WRITE:
smode += 'w'
if not smode:
smode += 'n'
if mode & consts.LOBJECT_TEXT:
smode += 't'
else:
smode += 'b'
return smode
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