/brz/remove-bazaar

# objects.py -- Acces to base git objects

# Copyright (C) 2007 James Westby <jw+debian@jameswestby.net>

# The header parsing code is based on that from git itself, which is

# Copyright (C) 2005 Linus Torvalds

# and licensed under v2 of the GPL.

# 

# 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; version 2

# of the License.

# 

# 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., 51 Franklin Street, Fifth Floor, Boston,

# MA  02110-1301, USA.

import mmap

import os

import sha

import zlib

from errors import (NotCommitError,

                    NotTreeError,

                    NotBlobError,

                    )

blob_id = "blob"

tree_id = "tree"

commit_id = "commit"

parent_id = "parent"

author_id = "author"

committer_id = "committer"

def _decompress(string):

    dcomp = zlib.decompressobj()

    dcomped = dcomp.decompress(string)

    dcomped += dcomp.flush()

    return dcomped

def sha_to_hex(sha):

  """Takes a string and returns the hex of the sha within"""

  hexsha = ''

  for c in sha:

    hexsha += "%02x" % ord(c)

  assert len(hexsha) == 40, "Incorrect length of sha1 string: %d" % \

         len(hexsha)

  return hexsha

class ShaFile(object):

  """A git SHA file."""

  def _update_contents(self):

    """Update the _contents from the _text"""

    self._contents = [ord(c) for c in self._text]

  @classmethod

  def _parse_legacy_object(cls, map):

    """Parse a legacy object, creating it and setting object._text"""

    text = _decompress(map)

    object = None

    for posstype in type_map.keys():

      if text.startswith(posstype):

        object = type_map[posstype]()

        text = text[len(posstype):]

        break

    assert object is not None, "%s is not a known object type" % text[:9]

    assert text[0] == ' ', "%s is not a space" % text[0]

    text = text[1:]

    size = 0

    i = 0

    while text[0] >= '0' and text[0] <= '9':

      if i > 0 and size == 0:

        assert False, "Size is not in canonical format"

      size = (size * 10) + int(text[0])

      text = text[1:]

      i += 1

    object._size = size

    assert text[0] == "\0", "Size not followed by null"

    text = text[1:]

    object._text = text

    object._update_contents()

    return object

  @classmethod

  def _parse_object(cls, map):

    """Parse a new style object , creating it and setting object._text"""

    used = 0

    byte = ord(map[used])

    used += 1

    num_type = (byte >> 4) & 7

    try:

      object = num_type_map[num_type]()

    except KeyError:

      assert False, "Not a known type: %d" % num_type

    while((byte & 0x80) != 0):

      byte = ord(map[used])

      used += 1

    raw = map[used:]

    object._text = _decompress(raw)

    object._update_contents()

    return object

  @classmethod

  def _parse_file(cls, map):

    word = (ord(map[0]) << 8) + ord(map[1])

    if ord(map[0]) == 0x78 and (word % 31) == 0:

      return cls._parse_legacy_object(map)

    else:

      return cls._parse_object(map)

  def __init__(self):

    """Don't call this directly"""

  def _parse_text(self):

    """For subclasses to do initialistion time parsing"""

  @classmethod

  def from_file(cls, filename):

    """Get the contents of a SHA file on disk"""

    size = os.path.getsize(filename)

    f = open(filename, 'rb')

    try:

      map = mmap.mmap(f.fileno(), size, access=mmap.ACCESS_READ)

      shafile = cls._parse_file(map)

      shafile._parse_text()

      return shafile

    finally:

      f.close()

  @classmethod

  def from_raw_string(cls, type, string):

    """Creates an object of the indicated type from the raw string given.

    Type is the numeric type of an object. String is the raw uncompressed

    contents.

    """

    real_class = num_type_map[type]

    obj = real_class()

    obj._text = string

    obj._update_contents()

    return obj

  def _header(self):

    return "%s %lu\0" % (self._type, len(self._contents))

  def contents(self):

    """The raw bytes of this object"""

    return self._contents

  def sha(self):

    """The SHA1 object that is the name of this object."""

    ressha = sha.new()

    ressha.update(self._header())

    ressha.update(self._text)

    return ressha

  def __eq__(self, other):

    """Return true id the sha of the two objects match.

    The __le__ etc methods aren't overriden as they make no sense,

    certainly at this level.

    """

    return self.sha().digest() == other.sha().digest()

class Blob(ShaFile):

  """A Git Blob object."""

  _type = blob_id

  def text(self):

    """The text contained within the blob object."""

    return self._text

  @classmethod

  def from_file(cls, filename):

    blob = ShaFile.from_file(filename)

    if blob._type != cls._type:

      raise NotBlobError(filename)

    return blob

  @classmethod

  def from_string(cls, string):

    """Create a blob from a string."""

    shafile = cls()

    shafile._text = string

    shafile._update_contents()

    return shafile

class Tree(ShaFile):

  """A Git tree object"""

  _type = tree_id

  @classmethod

  def from_file(cls, filename):

    tree = ShaFile.from_file(filename)

    if tree._type != cls._type:

      raise NotTreeError(filename)

    return tree

  def entries(self):

    """Reutrn a list of tuples describing the tree entries"""

    return self._entries

  def _parse_text(self):

    """Grab the entries in the tree"""

    self._entries = []

    count = 0

    while count < len(self._text):

      mode = 0

      chr = self._text[count]

      while chr != ' ':

        assert chr >= '0' and chr <= '7', "%s is not a valid mode char" % chr

        mode = (mode << 3) + (ord(chr) - ord('0'))

        count += 1

        chr = self._text[count]

      count += 1

      chr = self._text[count]

      name = ''

      while chr != '\0':

        name += chr

        count += 1

        chr = self._text[count]

      count += 1

      chr = self._text[count]

      sha = self._text[count:count+20]

      hexsha = sha_to_hex(sha)

      self._entries.append((mode, name, hexsha))

      count = count + 20

class Commit(ShaFile):

  """A git commit object"""

  _type = commit_id

  @classmethod

  def from_file(cls, filename):

    commit = ShaFile.from_file(filename)

    if commit._type != cls._type:

      raise NotCommitError(filename)

    return commit

  def _parse_text(self):

    text = self._text

    count = 0

    assert text.startswith(tree_id), "Invlid commit object, " \

         "must start with %s" % tree_id

    count += len(tree_id)

    assert text[count] == ' ', "Invalid commit object, " \

         "%s must be followed by space not %s" % (tree_id, text[count])

    count += 1

    self._tree = text[count:count+40]

    count = count + 40

    assert text[count] == "\n", "Invalid commit object, " \

         "tree sha must be followed by newline"

    count += 1

    self._parents = []

    while text[count:].startswith(parent_id):

      count += len(parent_id)

      assert text[count] == ' ', "Invalid commit object, " \

           "%s must be followed by space not %s" % (parent_id, text[count])

      count += 1

      self._parents.append(text[count:count+40])

      count += 40

      assert text[count] == "\n", "Invalid commit object, " \

           "parent sha must be followed by newline"

      count += 1

    self._author = None

    if text[count:].startswith(author_id):

      count += len(author_id)

      assert text[count] == ' ', "Invalid commit object, " \

           "%s must be followed by space not %s" % (author_id, text[count])

      count += 1

      self._author = ''

      while text[count] != '>':

        assert text[count] != '\n', "Malformed author information"

        self._author += text[count]

        count += 1

      self._author += text[count]

      count += 1

      while text[count] != '\n':

        count += 1

      count += 1

    self._committer = None

    if text[count:].startswith(committer_id):

      count += len(committer_id)

      assert text[count] == ' ', "Invalid commit object, " \

           "%s must be followed by space not %s" % (committer_id, text[count])

      count += 1

      self._committer = ''

      while text[count] != '>':

        assert text[count] != '\n', "Malformed committer information"

        self._committer += text[count]

        count += 1

      self._committer += text[count]

      count += 1

      assert text[count] == ' ', "Invalid commit object, " \

           "commiter information must be followed by space not %s" % text[count]

      count += 1

      self._commit_time = int(text[count:count+10])

      while text[count] != '\n':

        count += 1

      count += 1

    assert text[count] == '\n', "There must be a new line after the headers"

    count += 1

    # XXX: There can be an encoding field.

    self._message = text[count:]

  def tree(self):

    """Returns the tree that is the state of this commit"""

    return self._tree

  def parents(self):

    """Return a list of parents of this commit."""

    return self._parents

  def author(self):

    """Returns the name of the author of the commit"""

    return self._author

  def committer(self):

    """Returns the name of the committer of the commit"""

    return self._committer

  def message(self):

    """Returns the commit message"""

    return self._message

  def commit_time(self):

    """Returns the timestamp of the commit.

    Returns it as the number of seconds since the epoch.

    """

    return self._commit_time

type_map = {

  blob_id : Blob,

  tree_id : Tree,

  commit_id : Commit,

}

num_type_map = {

  1 : Commit,

  2 : Tree,

  3 : Blob,

}