def _seek_to_next_range(self):
# We will cross range boundaries
if self._boundary is None:
# If we don't have a boundary, we can't find another range
raise errors.InvalidRange(
self._path, self._pos,
"Range (%s, %s) exhausted" % (self._start, self._size))
self.read_boundary()
self.read_range_definition()
def read(self, size=-1):
"""Read size bytes from the current position in the file.
Reading across ranges is not supported. We rely on the underlying http
client to clean the socket if we leave bytes unread. This may occur for
the final boundary line of a multipart response or for any range
request not entirely consumed by the client (due to offset coalescing)
:param size: The number of bytes to read. Leave unspecified or pass
-1 to read to EOF.
"""
if (self._size > 0 and self._pos == self._start + self._size):
if size == 0:
return ''
else:
self._seek_to_next_range()
elif self._pos < self._start:
raise errors.InvalidRange(
self._path, self._pos,
"Can't read %s bytes before range (%s, %s)" %
(size, self._start, self._size))
if self._size > 0:
if size > 0 and self._pos + size > self._start + self._size:
raise errors.InvalidRange(
self._path, self._pos,
"Can't read %s bytes across range (%s, %s)" %
(size, self._start, self._size))
# read data from file
buf = StringIO()
limited = size
if self._size > 0:
# Don't read past the range definition
limited = self._start + self._size - self._pos
if size >= 0:
limited = min(limited, size)
osutils.pumpfile(self._file, buf, limited, self._max_read_size)
data = buf.getvalue()
# Update _pos respecting the data effectively read
self._pos += len(data)
return data
def seek(self, offset, whence=0):
start_pos = self._pos
if whence == 0:
final_pos = offset
elif whence == 1:
final_pos = start_pos + offset
elif whence == 2:
if self._size > 0:
final_pos = self._start + self._size + offset # offset < 0
else:
raise errors.InvalidRange(
self._path, self._pos,
"RangeFile: can't seek from end while size is unknown")
else:
raise ValueError("Invalid value %s for whence." % whence)
if final_pos < self._pos:
# Can't seek backwards
raise errors.InvalidRange(
self._path, self._pos,
'RangeFile: trying to seek backwards to %s' % final_pos)
if self._size > 0:
cur_limit = self._start + self._size
while final_pos > cur_limit:
# We will cross range boundaries
remain = cur_limit - self._pos
if remain > 0:
# Finish reading the current range
self._checked_read(remain)
self._seek_to_next_range()
cur_limit = self._start + self._size
size = final_pos - self._pos
if size > 0: # size can be < 0 if we crossed a range boundary
# We don't need the data, just read it and throw it away
self._checked_read(size)
def test_invalid_range(self):
error = errors.InvalidRange('path', 12, 'bad range')
self.assertEquals("Invalid range access in path at 12: bad range",
str(error))