# index.py # Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors # # This module is part of GitPython and is released under # the BSD License: http://www.opensource.org/licenses/bsd-license.php """ Module containing Index implementation, allowing to perform all kinds of index manipulations such as querying and merging. """ import struct import binascii import mmap import objects class IndexEntry(tuple): """ Allows convenient access to IndexEntry data without completely unpacking it. Attributes usully accessed often are cached in the tuple whereas others are unpacked on demand. See the properties for a mapping between names and tuple indices. """ @property def ctime(self): """ Returns Tuple(int_time_seconds_since_epoch, int_nano_seconds) of the file's creation time """ return struct.unpack(">LL", self[0]) @property def mtime(self): """ See ctime property, but returns modification time """ return struct.unpack(">LL", self[1]) @property def dev(self): """ Device ID """ return self[2] @property def inode(self): """ Inode ID """ return self[3] @property def mode(self): """ File Mode, compatible to stat module constants """ return self[4] @property def uid(self): """ User ID """ return self[5] @property def gid(self): """ Group ID """ return self[6] @property def size(self): """ Uncompressed size of the blob Note Will be 0 if the stage is not 0 ( hence it is an unmerged entry ) """ return self[7] @property def sha(self): """ hex sha of the blob """ return self[8] @property def stage(self): """ Stage of the entry, either: 0 = default stage 1 = stage before a merge or common ancestor entry in case of a 3 way merge 2 = stage of entries from the 'left' side of the merge 3 = stage of entries from the right side of the merge Note: For more information, see http://www.kernel.org/pub/software/scm/git/docs/git-read-tree.html """ return self[9] @property def path(self): return self[10] class Index(object): """ Implements an Index that can be manipulated using a native implementation in order to save git command function calls wherever possible. It provides custom merging facilities and to create custom commits. ``Entries`` The index contains an entries dict whose keys are tuples of """ __slots__ = ( "version", "entries", "_extension_data" ) _VERSION = 2 # latest version we support def __init__(self, stream = None): """ Initialize this Index instance, optionally from the given ``stream`` """ self.entries = dict() self.version = self._VERSION self._extension_data = '' if stream is not None: self._read_from_stream(stream) @classmethod def _read_entry(cls, stream): """Return: One entry of the given stream""" beginoffset = stream.tell() ctime = struct.unpack(">8s", stream.read(8))[0] mtime = struct.unpack(">8s", stream.read(8))[0] (dev, ino, mode, uid, gid, size, sha, flags) = \ struct.unpack(">LLLLLL20sH", stream.read(20 + 4 * 6 + 2)) path_size = flags & 0x0fff path = stream.read(path_size) real_size = ((stream.tell() - beginoffset + 8) & ~7) data = stream.read((beginoffset + real_size) - stream.tell()) return IndexEntry((ctime, mtime, dev, ino, mode, uid, gid, size, binascii.hexlify(sha), flags >> 12, path)) @classmethod def _read_header(cls, 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 = struct.unpack(">LL", stream.read(4 * 2)) assert version in (1, 2) return version, num_entries def _read_from_stream(self, stream): """ Initialize this instance with index values read from the given stream Note We explicitly do not clear the entries dict here to allow for reading multiple chunks from multiple streams into the same Index instance """ self.version, num_entries = self._read_header(stream) count = 0 while count < num_entries: entry = self._read_entry(stream) self.entries[(entry.path,entry.stage)] = entry count += 1 # END for each entry # this data chunk is the footer of the index, don't yet know what it is for self._extension_data = stream.read(~0) @classmethod def from_file(cls, file_path): """ Returns Index instance as recreated from the given stream. ``file_pa `` File path pointing to git index file Note Reading is based on the dulwich project. """ fp = open(file_path, "r") # try memory map for speed stream = fp try: stream = mmap.mmap(fp.fileno(), 0, access=mmap.ACCESS_READ) except Exception: pass # END memory mapping try: return cls(stream) finally: fp.close() @classmethod def to_file(cls, index, file_path): """ Write the index data to the given file path. ``index`` Index you wish to write. ``file_path`` Path at which to write the index data. Please note that missing directories will lead to an exception to be thrown. Raise IOError if the file could not be written """ fp = open(file_path, "w") try: return index.write(fp) finally: fp.close() # END exception handling @classmethod def _write_cache_entry(cls, stream, entry): """ Write an IndexEntry to a stream """ beginoffset = stream.tell() stream.write(entry[0]) # ctime stream.write(entry[1]) # mtime path = entry[10] plen = len(path) & 0x0fff # path length assert plen == len(path), "Path %s too long to fit into index" % entry[10] flags = plen | (entry[9] << 12)# stage and path length are 2 byte flags stream.write(struct.pack(">LLLLLL20sH", entry[2], entry[3], entry[4], entry[5], entry[6], entry[7], binascii.unhexlify(entry[8]), flags)) stream.write(path) real_size = ((stream.tell() - beginoffset + 8) & ~7) stream.write("\0" * ((beginoffset + real_size) - stream.tell())) def write(self, stream): """ Write the current state to the given stream ``stream`` File-like object Returns self Note Index writing based on the dulwich implementation """ # header stream.write("DIRC") stream.write(struct.pack(">LL", self.version, len(self.entries))) # body entries_sorted = self.entries.values() entries_sorted.sort(key=lambda e: (e[10], e[9])) # use path/stage as sort key for entry in entries_sorted: self._write_cache_entry(stream, entry) # END for each entry # write extension_data which we currently cannot interprete stream.write(self._extension_data)