def write(self, writer, base_address):
pos = writer.tell()
writer.seek(0, io.SEEK_END)
end_position = writer.tell()
if self.is_leaf:
# Write the offset back at this nodes address.
writer.seek(pos)
writer.write_uint32((end_position - base_address - 2) | 0x80000000)
writer.seek(end_position + 4)
# Write the triangle indices and terminate the list with 0xFFFF.
writer.write_uint16s(self.indices)
writer.write_uint16(0xFFFF)
else:
writer.seek(pos)
writer.write_uint32(end_position - base_address)
writer.seek(end_position + 4)
base = writer.tell()
writer.write_uint32s([0x00000000] * 8)
writer.seek(base)
for node in self.branches:
node.write(writer, base)
writer.seek(pos + 4)
python类SEEK_END的实例源码
def refresh_contents(self):
log_file = open(self.log_path)
log_file.seek(0, io.SEEK_END)
end_pos = log_file.tell()
if end_pos > 20000:
log_file.seek(end_pos - 20000, io.SEEK_SET)
else:
log_file.seek(0, io.SEEK_SET)
contents = log_file.read().split("\n", 1)[-1]
if contents != self.contents:
self.contents = contents
self.textBrowser_LogContent.clear()
self.textBrowser_LogContent.setPlainText(contents)
# Scrolling to bottom
cursor = self.textBrowser_LogContent.textCursor()
cursor.movePosition(QTextCursor.End)
self.textBrowser_LogContent.setTextCursor(cursor)
self.textBrowser_LogContent.ensureCursorVisible()
log_file.close()
def _downstream_thread(self, stream, downstream_boundary):
data_buff = io.BytesIO()
multipart_parser = MultipartParser(data_buff, downstream_boundary)
while not self._stop_threads_event.is_set():
if stream.data:
current_buffer_pos = data_buff.tell()
data_buff.seek(0, io.SEEK_END)
data_buff.write(b''.join(stream.data))
data_buff.seek(current_buffer_pos)
stream.data = []
message_part = multipart_parser.get_next_part()
if not message_part:
time.sleep(0.5)
continue
self._process_message_parts([message_part])
def __init__(self, file_object, start, size):
"""
Build an object that will act like a BufferedReader object,
but constrained to a predetermined part of the file_object.
:param file_object: A file opened for reading in binary mode.
:param start: Start of the part within the file_object
:param size: Ideal size of the part. This will be set
to the number of bytes remaining in the
file if there aren't enough bytes remaining.
"""
self.file = file_object
self.bytes_read = 0
self.start = start
# Seek to the end of the file to see how many bytes remain
# from the start of the part.
self.file.seek(0, io.SEEK_END)
self.size = min(self.file.tell() - self.start, size)
# Reset the pointer to the start of the part.
self.file.seek(start, io.SEEK_SET)
def seek(self, offset, whence=io.SEEK_SET):
self.__raiseIfClosed()
if not self.__seekable:
raise OSError("Seek not enabled for this stream")
if whence == io.SEEK_SET:
if offset < 0:
raise ValueError("Cannot have a negative absolute seek")
newStreamPosition = offset
elif whence == io.SEEK_CUR:
newStreamPosition = self.__streamPosition + whence
elif whence == io.SEEK_END:
if not self.__buffers:
newStreamPosition = 0
else:
newStreamPosition = self.__streamEnd + offset
self.__streamPosition = newStreamPosition
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def get_media_size(media_io):
if hasattr(media_io, "getvalue"):
size = len(media_io.getvalue())
elif hasattr(media_io, "seekable") and media_io.seekable():
media_io.seek(0, SEEK_END)
size = media_io.tell()
media_io.seek(SEEK_SET)
else:
raise DontwiMediaError
return size
def _reset_frame(self):
self._iobuf = io.BytesIO(self._iobuf.read())
self._iobuf.seek(0, 2) # io.SEEK_END == 2 (constant not present in 2.6)
self._current_frame = None
def get_cell_log_pos(self):
"""Returns the current position of the last byte in the Tor cell log."""
return self.cell_log.seek(0, SEEK_END)
def dump():
parser = argparse.ArgumentParser(description='Dump all the boxes from an MP4 file')
parser.add_argument("input_file", type=argparse.FileType("rb"), metavar="FILE", help="Path to the MP4 file to open")
args = parser.parse_args()
fd = args.input_file
fd.seek(0, io.SEEK_END)
eof = fd.tell()
fd.seek(0)
while fd.tell() < eof:
box = Box.parse_stream(fd)
print(box)
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def sendall(self, data):
self._buffer.seek(0, io.SEEK_END)
self._buffer.write(data)
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, offset, whence):
if (whence == io.SEEK_SET):
self._pos = offset
elif (whence == io.SEEK_CUR):
self._pos += offset
elif (whence == io.SEEK_END):
self._pos = self._file._filesize + offset
return self._pos
def test_small_file_seek_and_read(self):
with self.fs.open(self.KEY_LOGO_PNG, "rb") as f:
self.assertEqual(64, f.seek(64, io.SEEK_CUR))
self.assertEqual(128, f.seek(64, io.SEEK_CUR))
self.assertEqual(256, f.seek(256, io.SEEK_SET))
self.assertEqual(24610, f.seek(-256, io.SEEK_END))
self.assertEqual(
b'\x04$\x00_\x85$\xfb^\xf8\xe8]\x7f;}\xa8\xb7',
f.read(16))
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def testTruncate(self):
f = _FileIO(TESTFN, 'w')
f.write(bytes(bytearray(range(10))))
self.assertEqual(f.tell(), 10)
f.truncate(5)
self.assertEqual(f.tell(), 10)
self.assertEqual(f.seek(0, io.SEEK_END), 5)
f.truncate(15)
self.assertEqual(f.tell(), 5)
self.assertEqual(f.seek(0, io.SEEK_END), 15)
f.close()
def seek(self, offset, whence=io.SEEK_SET):
"""
Change the stream position to the given byte *offset*. *offset* is
interpreted relative to the position indicated by *whence*. Values for
*whence* are:
* ``SEEK_SET`` or ``0`` – start of the stream (the default); *offset*
should be zero or positive
* ``SEEK_CUR`` or ``1`` – current stream position; *offset* may be
negative
* ``SEEK_END`` or ``2`` – end of the stream; *offset* is usually
negative
Return the new absolute position.
"""
with self.lock:
if whence == io.SEEK_CUR:
offset = self._pos + offset
elif whence == io.SEEK_END:
offset = self._length + offset
if offset < 0:
raise ValueError(
'New position is before the start of the stream')
self._set_pos(offset)
return self._pos
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def test_seeking_from_end(self):
with EncodedFile(io.BytesIO(COMPRESSED)) as fp:
self.assertEqual(fp.read(100), TEXT[:100])
seeked_pos = fp.seek(-100, io.SEEK_END)
self.assertEqual(seeked_pos, len(TEXT) - 100)
self.assertEqual(fp.read(100), TEXT[-100:])
def test_seeking_from_end_beyond_beginning(self):
with EncodedFile(io.BytesIO(COMPRESSED)) as fp:
# Go to end to get size
size = fp.seek(0, io.SEEK_END)
# Go to beginning
self.assertNotRaises(fp.seek, -size, io.SEEK_END)
# One before beginning
self.assertRaises(IOError, fp.seek, -size - 1, io.SEEK_END)
def seek(self, offset, whence=io.SEEK_SET):
# Recalculate offset as an absolute file position.
if whence == io.SEEK_SET:
pass
elif whence == io.SEEK_CUR:
offset += self._pos
elif whence == io.SEEK_END:
if self._size < 0:
# Finish reading the file
while self.read(io.DEFAULT_BUFFER_SIZE):
pass
offset += self._size
else:
raise ValueError('Invalid value for whence: {}'.format(whence))
if offset < 0:
msg = '[Error {code}] {msg}'
raise IOError(msg.format(code=errno.EINVAL,
msg=os.strerror(errno.EINVAL)))
# Make it so that offset is the number of bytes to skip forward.
if offset < self._pos:
self._rewind()
else:
offset -= self._pos
# Read and discard data until we reach the desired position
while offset > 0:
data = self.read(min(io.DEFAULT_BUFFER_SIZE, offset))
if not data:
break
offset -= len(data)
return self._pos
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def testTruncate(self):
f = _FileIO(TESTFN, 'w')
f.write(bytes(bytearray(range(10))))
self.assertEqual(f.tell(), 10)
f.truncate(5)
self.assertEqual(f.tell(), 10)
self.assertEqual(f.seek(0, io.SEEK_END), 5)
f.truncate(15)
self.assertEqual(f.tell(), 5)
self.assertEqual(f.seek(0, io.SEEK_END), 15)
f.close()
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
def seek(self, position, whence=io.SEEK_SET):
"""Seek to a position in the file.
"""
if whence == io.SEEK_SET:
self.position = min(max(position, 0), self.size)
elif whence == io.SEEK_CUR:
if position < 0:
self.position = max(self.position + position, 0)
else:
self.position = min(self.position + position, self.size)
elif whence == io.SEEK_END:
self.position = max(min(self.size + position, self.size), 0)
else:
raise ValueError("Invalid argument")
return self.position
