Files
git/git_remote_helpers/fastimport/parser.py
2013-01-31 23:46:51 +00:00

622 lines
21 KiB
Python

# Copyright (C) 2008 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
import warnings
"""Parser of import data into command objects.
In order to reuse existing front-ends, the stream format is a subset of
the one used by git-fast-import (as of the 1.5.4 release of git at least).
The grammar is:
stream ::= cmd*;
cmd ::= new_blob
| new_commit
| new_tag
| reset_branch
| checkpoint
| progress
;
new_blob ::= 'blob' lf
mark?
file_content;
file_content ::= data;
new_commit ::= 'commit' sp ref_str lf
mark?
('author' sp name '<' email '>' when lf)?
'committer' sp name '<' email '>' when lf
commit_msg
('from' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf)?
('merge' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf)*
file_change*
lf?;
commit_msg ::= data;
file_change ::= file_clr
| file_del
| file_rnm
| file_cpy
| file_obm
| file_inm;
file_clr ::= 'deleteall' lf;
file_del ::= 'D' sp path_str lf;
file_rnm ::= 'R' sp path_str sp path_str lf;
file_cpy ::= 'C' sp path_str sp path_str lf;
file_obm ::= 'M' sp mode sp (hexsha1 | idnum) sp path_str lf;
file_inm ::= 'M' sp mode sp 'inline' sp path_str lf
data;
new_tag ::= 'tag' sp tag_str lf
'from' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf
'tagger' sp name '<' email '>' when lf
tag_msg;
tag_msg ::= data;
reset_branch ::= 'reset' sp ref_str lf
('from' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf)?
lf?;
checkpoint ::= 'checkpoint' lf
lf?;
progress ::= 'progress' sp not_lf* lf
lf?;
# note: the first idnum in a stream should be 1 and subsequent
# idnums should not have gaps between values as this will cause
# the stream parser to reserve space for the gapped values. An
# idnum can be updated in the future to a new object by issuing
# a new mark directive with the old idnum.
#
mark ::= 'mark' sp idnum lf;
data ::= (delimited_data | exact_data)
lf?;
# note: delim may be any string but must not contain lf.
# data_line may contain any data but must not be exactly
# delim. The lf after the final data_line is included in
# the data.
delimited_data ::= 'data' sp '<<' delim lf
(data_line lf)*
delim lf;
# note: declen indicates the length of binary_data in bytes.
# declen does not include the lf preceeding the binary data.
#
exact_data ::= 'data' sp declen lf
binary_data;
# note: quoted strings are C-style quoting supporting \c for
# common escapes of 'c' (e..g \n, \t, \\, \") or \nnn where nnn
# is the signed byte value in octal. Note that the only
# characters which must actually be escaped to protect the
# stream formatting is: \, \" and LF. Otherwise these values
# are UTF8.
#
ref_str ::= ref;
sha1exp_str ::= sha1exp;
tag_str ::= tag;
path_str ::= path | '"' quoted(path) '"' ;
mode ::= '100644' | '644'
| '100755' | '755'
| '120000'
;
declen ::= # unsigned 32 bit value, ascii base10 notation;
bigint ::= # unsigned integer value, ascii base10 notation;
binary_data ::= # file content, not interpreted;
when ::= raw_when | rfc2822_when;
raw_when ::= ts sp tz;
rfc2822_when ::= # Valid RFC 2822 date and time;
sp ::= # ASCII space character;
lf ::= # ASCII newline (LF) character;
# note: a colon (':') must precede the numerical value assigned to
# an idnum. This is to distinguish it from a ref or tag name as
# GIT does not permit ':' in ref or tag strings.
#
idnum ::= ':' bigint;
path ::= # GIT style file path, e.g. \"a/b/c\";
ref ::= # GIT ref name, e.g. \"refs/heads/MOZ_GECKO_EXPERIMENT\";
tag ::= # GIT tag name, e.g. \"FIREFOX_1_5\";
sha1exp ::= # Any valid GIT SHA1 expression;
hexsha1 ::= # SHA1 in hexadecimal format;
# note: name and email are UTF8 strings, however name must not
# contain '<' or lf and email must not contain any of the
# following: '<', '>', lf.
#
name ::= # valid GIT author/committer name;
email ::= # valid GIT author/committer email;
ts ::= # time since the epoch in seconds, ascii base10 notation;
tz ::= # GIT style timezone;
# note: comments may appear anywhere in the input, except
# within a data command. Any form of the data command
# always escapes the related input from comment processing.
#
# In case it is not clear, the '#' that starts the comment
# must be the first character on that the line (an lf have
# preceeded it).
#
comment ::= '#' not_lf* lf;
not_lf ::= # Any byte that is not ASCII newline (LF);
"""
import re
import sys
from git_remote_helpers.fastimport import (
commands,
dates,
errors
)
## Stream parsing ##
class LineBasedParser(object):
def __init__(self, input, filename=None):
"""A Parser that keeps track of line numbers.
:param input: the file-like object to read from
"""
self.input = input
if filename is None:
try:
self.filename = input.name
except AttributeError:
self.filename = "(unknown)"
else:
self.filename = filename
self.lineno = 0
# Lines pushed back onto the input stream
self._buffer = []
def abort(self, exception, *args):
"""Raise an exception providing line number information."""
raise exception(self.filename, self.lineno, *args)
def readline(self):
"""Get the next line including the newline or '' on EOF."""
self.lineno += 1
if self._buffer:
return self._buffer.pop()
else:
return self.input.readline()
def next_line(self):
"""Get the next line without the newline or None on EOF."""
line = self.readline()
if line:
return line[:-1]
else:
return None
def push_line(self, line):
"""Push line back onto the line buffer.
:param line: the line with no trailing newline
"""
self.lineno -= 1
self._buffer.append(line + "\n")
def read_bytes(self, count):
"""Read a given number of bytes from the input stream.
Throws MissingBytes if the bytes are not found.
Note: This method does not read from the line buffer.
:return: a string
"""
result = self.input.read(count)
found = len(result)
self.lineno += result.count("\n")
if found != count:
self.abort(errors.MissingBytes, count, found)
return result
def read_until(self, terminator):
"""Read the input stream until the terminator is found.
Throws MissingTerminator if the terminator is not found.
Note: This method does not read from the line buffer.
:return: the bytes read up to but excluding the terminator.
"""
lines = []
term = terminator + '\n'
while True:
line = self.input.readline()
if line == term:
break
else:
lines.append(line)
return ''.join(lines)
# Regular expression used for parsing. (Note: The spec states that the name
# part should be non-empty but git-fast-export doesn't always do that so
# the first bit is \w*, not \w+.) Also git-fast-import code says the
# space before the email is optional.
_WHO_AND_WHEN_RE = re.compile(r'([^<]*)<(.*)> (.+)')
_WHO_RE = re.compile(r'([^<]*)<(.*)>')
class ImportParser(LineBasedParser):
def __init__(self, input, filename=None):
"""A Parser of import commands.
:param input: the file-like object to read from
:param verbose: display extra information of not
"""
LineBasedParser.__init__(self, input, filename)
# We auto-detect the date format when a date is first encountered
self.date_parser = None
def warning(self, msg):
sys.stderr.write("warning line %d: %s\n" % (self.lineno, msg))
def parse(self):
"""Parse the input stream, yielding a sequence of ImportCommand
objects. Iteration terminates on EOF. Raises InvalidCommand on
parse error."""
while True:
line = self.next_line()
if line is None:
break
elif len(line) == 0 or line.startswith('#'):
continue
# Search for commands in order of likelihood
elif line.startswith('commit '):
yield self._parse_commit(line[len('commit '):])
elif line.startswith('blob'):
yield self._parse_blob()
elif line.startswith('done'):
break
elif line.startswith('progress '):
yield commands.ProgressCommand(line[len('progress '):])
elif line.startswith('reset '):
yield self._parse_reset(line[len('reset '):])
elif line.startswith('tag '):
yield self._parse_tag(line[len('tag '):])
elif line.startswith('checkpoint'):
yield commands.CheckpointCommand()
elif line.startswith('feature'):
yield self._parse_feature(line[len('feature '):])
else:
self.abort(errors.InvalidCommand, line)
def iter_commands(self):
warnings.warn("iter_commands() deprecated: use parse()",
DeprecationWarning, stacklevel=2)
return self.parse()
def iter_file_commands(self):
"""Iterator returning FileCommand objects.
If an invalid file command is found, the line is silently
pushed back and iteration ends.
"""
while True:
line = self.next_line()
if line is None:
break
elif len(line) == 0 or line.startswith('#'):
continue
# Search for file commands in order of likelihood
elif line.startswith('M '):
yield self._parse_file_modify(line[2:])
elif line.startswith('D '):
path = self._path(line[2:])
yield commands.FileDeleteCommand(path)
elif line.startswith('R '):
old, new = self._path_pair(line[2:])
yield commands.FileRenameCommand(old, new)
elif line.startswith('C '):
src, dest = self._path_pair(line[2:])
yield commands.FileCopyCommand(src, dest)
elif line.startswith('deleteall'):
yield commands.FileDeleteAllCommand()
else:
self.push_line(line)
break
def _parse_blob(self):
"""Parse a blob command."""
location = (self.filename, self.lineno)
mark = self._get_mark_if_any()
data = self._get_data('blob')
return commands.BlobCommand(mark, data, location)
def _parse_commit(self, ref):
"""Parse a commit command."""
location = (self.filename, self.lineno)
mark = self._get_mark_if_any()
author = self._get_user_info('commit', 'author', False)
more_authors = []
while True:
another_author = self._get_user_info('commit', 'author', False)
if another_author is not None:
more_authors.append(another_author)
else:
break
committer = self._get_user_info('commit', 'committer')
message = self._get_data('commit', 'message')
try:
message = message.decode('utf_8')
except UnicodeDecodeError:
self.warning(
"commit message not in utf8 - replacing unknown characters")
message = message.decode('utf_8', 'replace')
from_ = self._get_from()
merges = []
while True:
merge = self._get_merge()
if merge is not None:
# while the spec suggests it's illegal, git-fast-export
# outputs multiple merges on the one line, e.g.
# merge :x :y :z
these_merges = merge.split(" ")
merges.extend(these_merges)
else:
break
properties = {}
while True:
name_value = self._get_property()
if name_value is not None:
name, value = name_value
properties[name] = value
else:
break
file_cmds = list(self.iter_file_commands())
return commands.CommitCommand(ref, mark, author, committer, message,
from_, merges, file_cmds, location,
more_authors=more_authors, properties=properties)
def _parse_feature(self, info):
"""Parse a feature command."""
parts = info.split("=", 1)
name = parts[0]
if len(parts) > 1:
value = self._path(parts[1])
else:
value = None
location = (self.filename, self.lineno)
return commands.FeatureCommand(name, value, location=location)
def _parse_file_modify(self, info):
"""Parse a filemodify command within a commit.
:param info: a string in the format "mode dataref path"
(where dataref might be the hard-coded literal 'inline').
"""
params = info.split(' ', 2)
path = self._path(params[2])
mode = params[0]
if params[1] == 'inline':
dataref = None
data = self._get_data('filemodify')
else:
dataref = params[1]
data = None
return commands.FileModifyCommand(path, mode, dataref, data)
def _parse_reset(self, ref):
"""Parse a reset command."""
from_ = self._get_from()
return commands.ResetCommand(ref, from_)
def _parse_tag(self, name):
"""Parse a tag command."""
from_ = self._get_from('tag')
tagger = self._get_user_info('tag', 'tagger', accept_just_who=True)
message = self._get_data('tag', 'message').decode('utf_8')
return commands.TagCommand(name, from_, tagger, message)
def _get_mark_if_any(self):
"""Parse a mark section."""
line = self.next_line()
if line.startswith('mark :'):
return line[len('mark :'):]
else:
self.push_line(line)
return None
def _get_from(self, required_for=None):
"""Parse a from section."""
line = self.next_line()
if line is None:
return None
elif line.startswith('from '):
return line[len('from '):]
elif required_for:
self.abort(errors.MissingSection, required_for, 'from')
else:
self.push_line(line)
return None
def _get_merge(self):
"""Parse a merge section."""
line = self.next_line()
if line is None:
return None
elif line.startswith('merge '):
return line[len('merge '):]
else:
self.push_line(line)
return None
def _get_property(self):
"""Parse a property section."""
line = self.next_line()
if line is None:
return None
elif line.startswith('property '):
return self._name_value(line[len('property '):])
else:
self.push_line(line)
return None
def _get_user_info(self, cmd, section, required=True,
accept_just_who=False):
"""Parse a user section."""
line = self.next_line()
if line.startswith(section + ' '):
return self._who_when(line[len(section + ' '):], cmd, section,
accept_just_who=accept_just_who)
elif required:
self.abort(errors.MissingSection, cmd, section)
else:
self.push_line(line)
return None
def _get_data(self, required_for, section='data'):
"""Parse a data section."""
line = self.next_line()
if line.startswith('data '):
rest = line[len('data '):]
if rest.startswith('<<'):
return self.read_until(rest[2:])
else:
size = int(rest)
read_bytes = self.read_bytes(size)
# optional LF after data.
next = self.input.readline()
self.lineno += 1
if len(next) > 1 or next != "\n":
self.push_line(next[:-1])
return read_bytes
else:
self.abort(errors.MissingSection, required_for, section)
def _who_when(self, s, cmd, section, accept_just_who=False):
"""Parse who and when information from a string.
:return: a tuple of (name,email,timestamp,timezone). name may be
the empty string if only an email address was given.
"""
match = _WHO_AND_WHEN_RE.search(s)
if match:
datestr = match.group(3)
if self.date_parser is None:
# auto-detect the date format
if len(datestr.split(' ')) == 2:
format = 'raw'
elif datestr == 'now':
format = 'now'
else:
format = 'rfc2822'
self.date_parser = dates.DATE_PARSERS_BY_NAME[format]
when = self.date_parser(datestr, self.lineno)
else:
match = _WHO_RE.search(s)
if accept_just_who and match:
# HACK around missing time
# TODO: output a warning here
when = dates.DATE_PARSERS_BY_NAME['now']('now')
else:
self.abort(errors.BadFormat, cmd, section, s)
# Do not attempt to decode name or email address; they are just
# bytes. (Everything will work out better if they are in UTF-8,
# but that's not guaranteed.)
name = match.group(1).rstrip()
email = match.group(2)
return (name, email, when[0], when[1])
def _name_value(self, s):
"""Parse a (name,value) tuple from 'name value-length value'."""
parts = s.split(' ', 2)
name = parts[0]
if len(parts) == 1:
value = None
else:
size = int(parts[1])
value = parts[2]
still_to_read = size - len(value)
if still_to_read == 1:
value += "\n"
elif still_to_read > 0:
read_bytes = self.read_bytes(still_to_read - 1)
value += "\n" + read_bytes
value = value.decode('utf8')
return (name, value)
def _path(self, s):
"""Parse a path."""
if s.startswith('"'):
if s[-1] != '"':
self.abort(errors.BadFormat, '?', '?', s)
else:
return _unquote_c_string(s[1:-1])
# Do *not* decode the path to a Unicode string: filenames on
# Unix are just bytes. Git and Mercurial, at least, inherit
# this stance. git-fast-import(1) merely says "It is
# recommended that <path> always be encoded using UTF-8.", which
# is good advice ... but not something we can count on here.
return s
def _path_pair(self, s):
"""Parse two paths separated by a space."""
# TODO: handle a space in the first path
if s.startswith('"'):
parts = s[1:].split('" ', 1)
else:
parts = s.split(' ', 1)
if len(parts) != 2:
self.abort(errors.BadFormat, '?', '?', s)
elif parts[1].startswith('"') and parts[1].endswith('"'):
parts[1] = parts[1][1:-1]
elif parts[1].startswith('"') or parts[1].endswith('"'):
self.abort(errors.BadFormat, '?', '?', s)
return map(_unquote_c_string, parts)
def _mode(self, s):
"""Parse a file mode into executable and symlink flags.
:return (is_executable, is_symlink)
"""
# Note: Output from git-fast-export slightly different to spec
if s in ['644', '100644', '0100644']:
return False, False
elif s in ['755', '100755', '0100755']:
return True, False
elif s in ['120000', '0120000']:
return False, True
else:
self.abort(errors.BadFormat, 'filemodify', 'mode', s)
def _unquote_c_string(s):
"""replace C-style escape sequences (\n, \", etc.) with real chars."""
# HACK: Python strings are close enough
return s.decode('string_escape', 'replace')