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"""
Contains standalone functions to accompany the index implementation and make it
more versatile
"""
from git.utils import (
IndexFileSHA1Writer,
)
from typ import (
IndexEntry,
CE_NAMEMASK
)
from util import (
pack,
unpack
)
from binascii import (
hexlify,
unhexlify
)
__all__ = ('write_cache', 'read_cache' )
def write_cache_entry(entry, stream):
"""Write the given entry to the stream"""
beginoffset = stream.tell()
write = stream.write
write(entry[4]) # ctime
write(entry[5]) # mtime
path = entry[3]
plen = len(path) & CE_NAMEMASK # path length
assert plen == len(path), "Path %s too long to fit into index" % entry[3]
flags = plen | entry[2]
write(pack(">LLLLLL20sH", entry[6], entry[7], entry[0],
entry[8], entry[9], entry[10], unhexlify(entry[1]), flags))
write(path)
real_size = ((stream.tell() - beginoffset + 8) & ~7)
write("\0" * ((beginoffset + real_size) - stream.tell()))
def write_cache(entries, stream, extension_data=None, ShaStreamCls=IndexFileSHA1Writer):
"""Write the cache represented by entries to a stream
:param entries: **sorted** list of entries
:param stream: stream to wrap into the AdapterStreamCls - it is used for
final output.
:param ShaStreamCls: Type to use when writing to the stream. It produces a sha
while writing to it, before the data is passed on to the wrapped stream
:param extension_data: any kind of data to write as a trailer, it must begin
a 4 byte identifier, followed by its size ( 4 bytes )"""
# wrap the stream into a compatible writer
stream = ShaStreamCls(stream)
# header
version = 2
stream.write("DIRC")
stream.write(pack(">LL", version, len(entries)))
# body
for entry in entries:
write_cache_entry(entry, stream)
# END for each entry
# write previously cached extensions data
if extension_data is not None:
stream.write(extension_data)
# write the sha over the content
stream.write_sha()
def read_entry(stream):
"""Return: One entry of the given stream"""
beginoffset = stream.tell()
ctime = unpack(">8s", stream.read(8))[0]
mtime = unpack(">8s", stream.read(8))[0]
(dev, ino, mode, uid, gid, size, sha, flags) = \
unpack(">LLLLLL20sH", stream.read(20 + 4 * 6 + 2))
path_size = flags & CE_NAMEMASK
path = stream.read(path_size)
real_size = ((stream.tell() - beginoffset + 8) & ~7)
data = stream.read((beginoffset + real_size) - stream.tell())
return IndexEntry((mode, hexlify(sha), flags, path, ctime, mtime, dev, ino, uid, gid, size))
def read_header(stream):
"""Return tuple(version_long, num_entries) from the given stream"""
type_id = stream.read(4)
if type_id != "DIRC":
raise AssertionError("Invalid index file header: %r" % type_id)
version, num_entries = unpack(">LL", stream.read(4 * 2))
# TODO: handle version 3: extended data, see read-cache.c
assert version in (1, 2)
return version, num_entries
def entry_key(*entry):
""":return: Key suitable to be used for the index.entries dictionary
:param *entry: One instance of type BaseIndexEntry or the path and the stage"""
if len(entry) == 1:
return (entry[0].path, entry[0].stage)
else:
return tuple(entry)
# END handle entry
def read_cache(stream):
"""Read a cache file from the given stream
:return: tuple(version, entries_dict, extension_data, content_sha)
* version is the integer version number
* entries dict is a dictionary which maps IndexEntry instances to a path
at a stage
* extension_data is '' or 4 bytes of type + 4 bytes of size + size bytes
* content_sha is a 20 byte sha on all cache file contents"""
version, num_entries = read_header(stream)
count = 0
entries = dict()
while count < num_entries:
entry = read_entry(stream)
# entry_key would be the method to use, but we safe the effort
entries[(entry.path, entry.stage)] = entry
count += 1
# END for each entry
# the footer contains extension data and a sha on the content so far
# Keep the extension footer,and verify we have a sha in the end
# Extension data format is:
# 4 bytes ID
# 4 bytes length of chunk
# repeated 0 - N times
extension_data = stream.read(~0)
assert len(extension_data) > 19, "Index Footer was not at least a sha on content as it was only %i bytes in size" % len(extension_data)
content_sha = extension_data[-20:]
# truncate the sha in the end as we will dynamically create it anyway
extension_data = extension_data[:-20]
return (version, entries, extension_data, content_sha)
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