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added _write_stream
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@decalage2
decalage2 committed Jan 2, 2024
1 parent a0a70a5 commit 3b9e8da
Showing 1 changed file with 82 additions and 35 deletions.
117 changes: 82 additions & 35 deletions olefile/olefile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -791,8 +791,8 @@ def __init__(self, entry, sid, ole_file):
self.used = False
# decode DirEntry
(
self.name_raw, # 64s: string containing entry name in unicode UTF-16 (max 31 chars) + null char = 64 bytes
self.namelength, # H: uint16, number of bytes used in name buffer, including null = (len+1)*2
self.name_raw, # 64s: string containing entry name in unicode UTF-16LE (max 31 chars) + null char = 64 bytes
self.namelength, # H: uint16, number of bytes used in name buffer, including null >= (len+1)*2
self.entry_type,
self.color,
self.sid_left,
Expand Down Expand Up @@ -2061,6 +2061,52 @@ def _write_mini_stream(self, entry, data_to_write):
data_per_sector = data_to_write[idx * self.mini_sector_size:]
self._write_mini_sect(fp_pos, data_per_sector)

def _write_stream(self, sect, data, is_minifat=None):
"""
Write any stream to disk, even if it is not in the directory (e.g. FAT, directory, etc).
For now, it is only possible to replace an existing stream by data of the same size.
:param sect: index of 1st sector of the stream
:param data: bytes, data to be written, must be the same size as the original stream.
:param is_minifat: bool, True if the stream is in the miniFAT, False otherwise.
if None, it will be determined from the data size.
:return: nothing
"""
size = len(data)
if is_minifat == None:
# determine if this stream is in the FAT or miniFAT, based on size:
if size < self.minisectorcutoff:
is_minifat = True
if is_minifat == True:
raise NotImplementedError("Writing to ministream not yet implemented")
# number of sectors to write
nb_sectors = (size + (self.sectorsize-1)) // self.sectorsize
log.debug('nb_sectors = %d' % nb_sectors)
for i in range(nb_sectors):
# extract one sector from data, the last one being smaller:
if i < (nb_sectors-1):
data_sector = data [i*self.sectorsize : (i+1)*self.sectorsize]
# TODO: comment this if it works
assert(len(data_sector)==self.sectorsize)
else:
# Last sector
data_sector = data [i*self.sectorsize:]
# TODO: comment this if it works
log.debug('write_stream: size=%d sectorsize=%d data_sector=%Xh size%%sectorsize=%d'
% (size, self.sectorsize, len(data_sector), size % self.sectorsize))
assert(len(data_sector) % self.sectorsize==size % self.sectorsize)
self.write_sect(sect, data_sector)
# jump to next sector in the FAT:
try:
sect = self.fat[sect]
except IndexError:
# if pointer is out of the FAT an exception is raised
raise IOError('incorrect OLE FAT, sector index out of range')
# Last sector should be an "end of chain" marker:
if sect != ENDOFCHAIN:
raise IOError('incorrect last sector index in OLE stream')

def write_stream(self, stream_name, data):
"""
Write a stream to disk. For now, it is only possible to replace an
Expand All @@ -2086,41 +2132,42 @@ def write_stream(self, stream_name, data):
if size != len(data):
raise ValueError("write_stream: data must be the same size as the existing stream")
if size < self.minisectorcutoff and entry.entry_type != STGTY_ROOT:
return self._write_mini_stream(entry = entry, data_to_write = data)
self._write_mini_stream(entry = entry, data_to_write = data)

sect = entry.isectStart
# number of sectors to write
nb_sectors = (size + (self.sectorsize-1)) // self.sectorsize
log.debug('nb_sectors = %d' % nb_sectors)
for i in range(nb_sectors):
# try:
# self.fp.seek(offset + self.sectorsize * sect)
# except Exception:
# log.debug('sect=%d, seek=%d' %
# (sect, offset+self.sectorsize*sect))
# raise IOError('OLE sector index out of range')
# extract one sector from data, the last one being smaller:
if i<(nb_sectors-1):
data_sector = data [i*self.sectorsize : (i+1)*self.sectorsize]
# TODO: comment this if it works
assert(len(data_sector)==self.sectorsize)
else:
data_sector = data [i*self.sectorsize:]
# TODO: comment this if it works
log.debug('write_stream: size=%d sectorsize=%d data_sector=%Xh size%%sectorsize=%d'
% (size, self.sectorsize, len(data_sector), size % self.sectorsize))
assert(len(data_sector) % self.sectorsize==size % self.sectorsize)
self.write_sect(sect, data_sector)
# self.fp.write(data_sector)
# jump to next sector in the FAT:
try:
sect = self.fat[sect]
except IndexError:
# [PL] if pointer is out of the FAT an exception is raised
raise IOError('incorrect OLE FAT, sector index out of range')
# [PL] Last sector should be a "end of chain" marker:
if sect != ENDOFCHAIN:
raise IOError('incorrect last sector index in OLE stream')
self._write_stream(sect, data, is_minifat=False)
# # number of sectors to write
# nb_sectors = (size + (self.sectorsize-1)) // self.sectorsize
# log.debug('nb_sectors = %d' % nb_sectors)
# for i in range(nb_sectors):
# # try:
# # self.fp.seek(offset + self.sectorsize * sect)
# # except Exception:
# # log.debug('sect=%d, seek=%d' %
# # (sect, offset+self.sectorsize*sect))
# # raise IOError('OLE sector index out of range')
# # extract one sector from data, the last one being smaller:
# if i<(nb_sectors-1):
# data_sector = data [i*self.sectorsize : (i+1)*self.sectorsize]
# # TODO: comment this if it works
# assert(len(data_sector)==self.sectorsize)
# else:
# data_sector = data [i*self.sectorsize:]
# # TODO: comment this if it works
# log.debug('write_stream: size=%d sectorsize=%d data_sector=%Xh size%%sectorsize=%d'
# % (size, self.sectorsize, len(data_sector), size % self.sectorsize))
# assert(len(data_sector) % self.sectorsize==size % self.sectorsize)
# self.write_sect(sect, data_sector)
# # self.fp.write(data_sector)
# # jump to next sector in the FAT:
# try:
# sect = self.fat[sect]
# except IndexError:
# # [PL] if pointer is out of the FAT an exception is raised
# raise IOError('incorrect OLE FAT, sector index out of range')
# # [PL] Last sector should be a "end of chain" marker:
# if sect != ENDOFCHAIN:
# raise IOError('incorrect last sector index in OLE stream')

def get_type(self, filename):
"""
Expand Down

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