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# Copyright (C) 2007 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Container format for Bazaar data.
"Containers" and "records" are described in doc/developers/container-format.txt.
"""
from bzrlib import errors
FORMAT_ONE = "bzr pack format 1"
class ContainerWriter(object):
"""A class for writing containers."""
def __init__(self, write_func):
"""Constructor.
:param write_func: a callable that will be called when this
ContainerWriter needs to write some bytes.
"""
self.write_func = write_func
def begin(self):
"""Begin writing a container."""
self.write_func(FORMAT_ONE + "\n")
def end(self):
"""Finish writing a container."""
self.write_func("E")
def add_bytes_record(self, bytes, names):
"""Add a Bytes record with the given names."""
# Kind marker
self.write_func("B")
# Length
self.write_func(str(len(bytes)) + "\n")
# Names
for name in names:
self.write_func(name + "\n")
# End of headers
self.write_func("\n")
# Finally, the contents.
self.write_func(bytes)
class BaseReader(object):
def __init__(self, reader_func):
"""Constructor.
:param reader_func: a callable that takes one optional argument,
``size``, and returns at most that many bytes. When the callable
returns less than the requested number of bytes, then the end of the
file/stream has been reached.
"""
self.reader_func = reader_func
def _read_line(self):
"""Read a line from the input stream.
This is a simple but inefficient implementation that just reads one byte
at a time. Lines should not be very long, so this is probably
tolerable.
:returns: a line, without the trailing newline
"""
# XXX: Have a maximum line length, to prevent malicious input from
# consuming an unreasonable amount of resources?
# -- Andrew Bennetts, 2007-05-07.
line = ''
while not line.endswith('\n'):
byte = self.reader_func(1)
if byte == '':
raise errors.UnexpectedEndOfContainerError()
line += byte
return line[:-1]
class ContainerReader(BaseReader):
"""A class for reading Bazaar's container format."""
def iter_records(self):
"""Iterate over the container, yielding each record as it is read.
Each yielded record will be a 2-tuple of (names, bytes), where names is
a ``list`` and bytes is a ``str`.
:raises UnknownContainerFormatError: if the format of the container is
unrecognised.
"""
format = self._read_line()
if format != FORMAT_ONE:
raise errors.UnknownContainerFormatError(format)
return self._iter_records()
def _iter_records(self):
while True:
record_kind = self.reader_func(1)
if record_kind == 'B':
# Bytes record.
reader = BytesRecordReader(self.reader_func)
yield reader.read()
elif record_kind == 'E':
# End marker. There are no more records.
return
elif record_kind == '':
# End of stream encountered, but no End Marker record seen, so
# this container is incomplete.
raise errors.UnexpectedEndOfContainerError()
else:
# Unknown record type.
raise errors.UnknownRecordTypeError(record_kind)
class ContainerWriter(object):
"""A class for writing containers."""
def __init__(self, write_func):
"""Constructor.
:param write_func: a callable that will be called when this
ContainerWriter needs to write some bytes.
"""
self.write_func = write_func
def begin(self):
"""Begin writing a container."""
self.write_func(FORMAT_ONE + "\n")
def end(self):
"""Finish writing a container."""
self.write_func("E")
def add_bytes_record(self, bytes, names):
"""Add a Bytes record with the given names."""
# Kind marker
self.write_func("B")
# Length
self.write_func(str(len(bytes)) + "\n")
# Names
for name in names:
self.write_func(name + "\n")
# End of headers
self.write_func("\n")
# Finally, the contents.
self.write_func(bytes)
class BytesRecordReader(BaseReader):
def read(self):
# Read the content length.
length_line = self._read_line()
try:
length = int(length_line)
except ValueError:
raise errors.InvalidRecordError(
"%r is not a valid length." % (length_line,))
# Read the list of names.
names = []
while True:
name = self._read_line()
if name == '':
break
names.append(name)
bytes = self.reader_func(length)
if len(bytes) != length:
raise errors.UnexpectedEndOfContainerError()
return names, bytes
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