An updated FeedParser that should be RFC complaint, passes all existing
(standard) tests, and doesn't throw parse errors. I still need throw
Anthony's torture test at it, but I wanted to get this checked in and off my
disk.
diff --git a/Lib/email/FeedParser.py b/Lib/email/FeedParser.py
index a82d305..0bb9271 100644
--- a/Lib/email/FeedParser.py
+++ b/Lib/email/FeedParser.py
@@ -1,146 +1,144 @@
-# A new Feed-style Parser
+# Copyright (C) 2004 Python Software Foundation
+# Authors: Baxter, Wouters and Warsaw
-from email import Errors, Message
+"""FeedParser - An email feed parser.
+
+The feed parser implements an interface for incrementally parsing an email
+message, line by line. This has advantages for certain applications, such as
+those reading email messages off a socket.
+
+FeedParser.feed() is the primary interface for pushing new data into the
+parser. It returns when there's nothing more it can do with the available
+data. When you have no more data to push into the parser, call .close().
+This completes the parsing and returns the root message object.
+
+The other advantage of this parser is that it will never throw a parsing
+exception. Instead, when it finds something unexpected, it adds a 'defect' to
+the current message. Defects are just instances that live on the message
+object's .defect attribute.
+"""
+
import re
+from email import Errors
+from email import Message
NLCRE = re.compile('\r\n|\r|\n')
-
+NLCRE_bol = re.compile('(\r\n|\r|\n)')
+NLCRE_eol = re.compile('(\r\n|\r|\n)$')
+NLCRE_crack = re.compile('(\r\n|\r|\n)')
+headerRE = re.compile(r'^(From |[-\w]{2,}:|[\t ])')
EMPTYSTRING = ''
NL = '\n'
NeedMoreData = object()
-class FeedableLumpOfText:
- "A file-like object that can have new data loaded into it"
+
+class BufferedSubFile(object):
+ """A file-ish object that can have new data loaded into it.
+
+ You can also push and pop line-matching predicates onto a stack. When the
+ current predicate matches the current line, a false EOF response
+ (i.e. empty string) is returned instead. This lets the parser adhere to a
+ simple abstraction -- it parses until EOF closes the current message.
+ """
def __init__(self):
+ # The last partial line pushed into this object.
self._partial = ''
- self._done = False
- # _pending is a list of lines, in reverse order
- self._pending = []
+ # The list of full, pushed lines, in reverse order
+ self._lines = []
+ # The stack of false-EOF checking predicates.
+ self._eofstack = []
+ # A flag indicating whether the file has been closed or not.
+ self._closed = False
+
+ def push_eof_matcher(self, pred):
+ self._eofstack.append(pred)
+
+ def pop_eof_matcher(self):
+ return self._eofstack.pop()
+
+ def close(self):
+ # Don't forget any trailing partial line.
+ self._lines.append(self._partial)
+ self._closed = True
def readline(self):
- """ Return a line of data.
-
- If data has been pushed back with unreadline(), the most recently
- returned unreadline()d data will be returned.
- """
- if not self._pending:
- if self._done:
+ if not self._lines:
+ if self._closed:
return ''
return NeedMoreData
- return self._pending.pop()
+ # Pop the line off the stack and see if it matches the current
+ # false-EOF predicate.
+ line = self._lines.pop()
+ if self._eofstack:
+ matches = self._eofstack[-1]
+ if matches(line):
+ # We're at the false EOF. But push the last line back first.
+ self._lines.append(line)
+ return ''
+ return line
def unreadline(self, line):
- """ Push a line back into the object.
- """
- self._pending.append(line)
-
- def peekline(self):
- """ Non-destructively look at the next line """
- if not self._pending:
- if self._done:
- return ''
- return NeedMoreData
- return self._pending[-1]
-
-
- # for r in self._input.readuntil(regexp):
- # if r is NeedMoreData:
- # yield NeedMoreData
- # preamble, matchobj = r
- def readuntil(self, matchre, afterblank=False, includematch=False):
- """ Read a line at a time until we get the specified RE.
-
- Returns the text up to (and including, if includematch is true) the
- matched text, and the RE match object. If afterblank is true,
- there must be a blank line before the matched text. Moves current
- filepointer to the line following the matched line. If we reach
- end-of-file, return what we've got so far, and return None as the
- RE match object.
- """
- prematch = []
- blankseen = 0
- while 1:
- if not self._pending:
- if self._done:
- # end of file
- yield EMPTYSTRING.join(prematch), None
- else:
- yield NeedMoreData
- continue
- line = self._pending.pop()
- if afterblank:
- if NLCRE.match(line):
- blankseen = 1
- continue
- else:
- blankseen = 0
- m = matchre.match(line)
- if (m and not afterblank) or (m and afterblank and blankseen):
- if includematch:
- prematch.append(line)
- yield EMPTYSTRING.join(prematch), m
- prematch.append(line)
-
-
- NLatend = re.compile('(\r\n|\r|\n)$').match
- NLCRE_crack = re.compile('(\r\n|\r|\n)')
+ # Let the consumer push a line back into the buffer.
+ self._lines.append(line)
def push(self, data):
- """ Push some new data into this object """
+ """Push some new data into this object."""
# Handle any previous leftovers
- data, self._partial = self._partial+data, ''
- # Crack into lines, but leave the newlines on the end of each
- lines = self.NLCRE_crack.split(data)
- # The *ahem* interesting behaviour of re.split when supplied
- # groups means that the last element is the data after the
- # final RE. In the case of a NL/CR terminated string, this is
- # the empty string.
- self._partial = lines.pop()
- o = []
- for i in range(len(lines) / 2):
- o.append(EMPTYSTRING.join([lines[i*2], lines[i*2+1]]))
- self.pushlines(o)
-
+ data, self._partial = self._partial + data, ''
+ # Crack into lines, but preserve the newlines on the end of each
+ parts = NLCRE_crack.split(data)
+ # The *ahem* interesting behaviour of re.split when supplied grouping
+ # parentheses is that the last element of the resulting list is the
+ # data after the final RE. In the case of a NL/CR terminated string,
+ # this is the empty string.
+ self._partial = parts.pop()
+ # parts is a list of strings, alternating between the line contents
+ # and the eol character(s). Gather up a list of lines after
+ # re-attaching the newlines.
+ lines = []
+ for i in range(len(parts) / 2):
+ lines.append(parts[i*2] + parts[i*2+1])
+ self.pushlines(lines)
+
def pushlines(self, lines):
- """ Push a list of new lines into the object """
- # Reverse and insert at the front of _pending
- self._pending[:0] = lines[::-1]
+ # Reverse and insert at the front of the lines.
+ self._lines[:0] = lines[::-1]
- def end(self):
- """ There is no more data """
- self._done = True
-
- def is_done(self):
- return self._done
+ def is_closed(self):
+ return self._closed
def __iter__(self):
return self
def next(self):
- l = self.readline()
- if l == '':
+ line = self.readline()
+ if line == '':
raise StopIteration
- return l
+ return line
+
+
class FeedParser:
- "A feed-style parser of email. copy docstring here"
+ """A feed-style parser of email."""
- def __init__(self, _class=Message.Message):
- "fnord fnord fnord"
- self._class = _class
- self._input = FeedableLumpOfText()
- self._root = None
- self._objectstack = []
+ def __init__(self, _factory=Message.Message):
+ """_factory is called with no arguments to create a new message obj"""
+ self._factory = _factory
+ self._input = BufferedSubFile()
+ self._msgstack = []
self._parse = self._parsegen().next
+ self._cur = None
+ self._last = None
+ self._headersonly = False
- def end(self):
- self._input.end()
- self._call_parse()
- return self._root
+ # Non-public interface for supporting Parser's headersonly flag
+ def _set_headersonly(self):
+ self._headersonly = True
def feed(self, data):
+ """Push more data into the parser."""
self._input.push(data)
self._call_parse()
@@ -150,213 +148,285 @@
except StopIteration:
pass
- headerRE = re.compile(r'^(From |[-\w]{2,}:|[\t ])')
+ def close(self):
+ """Parse all remaining data and return the root message object."""
+ self._input.close()
+ self._call_parse()
+ root = self._pop_message()
+ assert not self._msgstack
+ return root
- def _parse_headers(self,headerlist):
- # Passed a list of strings that are the headers for the
- # current object
+ def _new_message(self):
+ msg = self._factory()
+ if self._cur and self._cur.get_content_type() == 'multipart/digest':
+ msg.set_default_type('message/rfc822')
+ if self._msgstack:
+ self._msgstack[-1].attach(msg)
+ self._msgstack.append(msg)
+ self._cur = msg
+ self._cur.defects = []
+ self._last = msg
+
+ def _pop_message(self):
+ retval = self._msgstack.pop()
+ if self._msgstack:
+ self._cur = self._msgstack[-1]
+ else:
+ self._cur = None
+ return retval
+
+ def _parsegen(self):
+ # Create a new message and start by parsing headers.
+ self._new_message()
+ headers = []
+ # Collect the headers, searching for a line that doesn't match the RFC
+ # 2822 header or continuation pattern (including an empty line).
+ for line in self._input:
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ if not headerRE.match(line):
+ # If we saw the RFC defined header/body separator
+ # (i.e. newline), just throw it away. Otherwise the line is
+ # part of the body so push it back.
+ if not NLCRE.match(line):
+ self._input.unreadline(line)
+ break
+ headers.append(line)
+ # Done with the headers, so parse them and figure out what we're
+ # supposed to see in the body of the message.
+ self._parse_headers(headers)
+ # Headers-only parsing is a backwards compatibility hack, which was
+ # necessary in the older parser, which could throw errors. All
+ # remaining lines in the input are thrown into the message body.
+ if self._headersonly:
+ lines = []
+ while True:
+ line = self._input.readline()
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ if line == '':
+ break
+ lines.append(line)
+ self._cur.set_payload(EMPTYSTRING.join(lines))
+ return
+ # So now the input is sitting at the first body line. If the message
+ # claims to be a message/rfc822 type, then what follows is another RFC
+ # 2822 message.
+ if self._cur.get_content_type() == 'message/rfc822':
+ for retval in self._parsegen():
+ if retval is NeedMoreData:
+ yield NeedMoreData
+ continue
+ break
+ self._pop_message()
+ return
+ if self._cur.get_content_type() == 'message/delivery-status':
+ # message/delivery-status contains blocks of headers separated by
+ # a blank line. We'll represent each header block as a separate
+ # nested message object. A blank line separates the subparts.
+ while True:
+ self._input.push_eof_matcher(NLCRE.match)
+ for retval in self._parsegen():
+ if retval is NeedMoreData:
+ yield NeedMoreData
+ continue
+ break
+ msg = self._pop_message()
+ # We need to pop the EOF matcher in order to tell if we're at
+ # the end of the current file, not the end of the last block
+ # of message headers.
+ self._input.pop_eof_matcher()
+ # The input stream must be sitting at the newline or at the
+ # EOF. We want to see if we're at the end of this subpart, so
+ # first consume the blank line, then test the next line to see
+ # if we're at this subpart's EOF.
+ line = self._input.readline()
+ line = self._input.readline()
+ if line == '':
+ break
+ # Not at EOF so this is a line we're going to need.
+ self._input.unreadline(line)
+ return
+ if self._cur.get_content_maintype() == 'multipart':
+ boundary = self._cur.get_boundary()
+ if boundary is None:
+ # The message /claims/ to be a multipart but it has not
+ # defined a boundary. That's a problem which we'll handle by
+ # reading everything until the EOF and marking the message as
+ # defective.
+ self._cur.defects.append(Errors.NoBoundaryInMultipart())
+ lines = []
+ for line in self._input:
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ lines.append(line)
+ self._cur.set_payload(EMPTYSTRING.join(lines))
+ return
+ # Create a line match predicate which matches the inter-part
+ # boundary as well as the end-of-multipart boundary. Don't push
+ # this onto the input stream until we've scanned past the
+ # preamble.
+ separator = '--' + boundary
+ boundaryre = re.compile(
+ '(?P<sep>' + re.escape(separator) +
+ r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)$')
+ capturing_preamble = True
+ preamble = []
+ linesep = False
+ while True:
+ line = self._input.readline()
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ if line == '':
+ break
+ mo = boundaryre.match(line)
+ if mo:
+ # If we're looking at the end boundary, we're done with
+ # this multipart. If there was a newline at the end of
+ # the closing boundary, then we need to initialize the
+ # epilogue with the empty string (see below).
+ if mo.group('end'):
+ linesep = mo.group('linesep')
+ break
+ # We saw an inter-part boundary. Were we in the preamble?
+ if capturing_preamble:
+ if preamble:
+ # According to RFC 2046, the last newline belongs
+ # to the boundary.
+ lastline = preamble[-1]
+ eolmo = NLCRE_eol.search(lastline)
+ if eolmo:
+ preamble[-1] = lastline[:-len(eolmo.group(0))]
+ self._cur.preamble = EMPTYSTRING.join(preamble)
+ capturing_preamble = False
+ self._input.unreadline(line)
+ continue
+ # We saw a boundary separating two parts. Recurse to
+ # parse this subpart; the input stream points at the
+ # subpart's first line.
+ self._input.push_eof_matcher(boundaryre.match)
+ for retval in self._parsegen():
+ if retval is NeedMoreData:
+ yield NeedMoreData
+ continue
+ break
+ # Because of RFC 2046, the newline preceding the boundary
+ # separator actually belongs to the boundary, not the
+ # previous subpart's payload (or epilogue if the previous
+ # part is a multipart).
+ if self._last.get_content_maintype() == 'multipart':
+ epilogue = self._last.epilogue
+ if epilogue == '':
+ self._last.epilogue = None
+ elif epilogue is not None:
+ mo = NLCRE_eol.search(epilogue)
+ if mo:
+ end = len(mo.group(0))
+ self._last.epilogue = epilogue[:-end]
+ else:
+ payload = self._last.get_payload()
+ if isinstance(payload, basestring):
+ mo = NLCRE_eol.search(payload)
+ if mo:
+ payload = payload[:-len(mo.group(0))]
+ self._last.set_payload(payload)
+ self._input.pop_eof_matcher()
+ self._pop_message()
+ # Set the multipart up for newline cleansing, which will
+ # happen if we're in a nested multipart.
+ self._last = self._cur
+ else:
+ # I think we must be in the preamble
+ assert capturing_preamble
+ preamble.append(line)
+ # We've seen either the EOF or the end boundary. If we're still
+ # capturing the preamble, we never saw the start boundary. Note
+ # that as a defect and store the captured text as the payload.
+ # Otherwise everything from here to the EOF is epilogue.
+ if capturing_preamble:
+ self._cur.defects.append(Errors.StartBoundaryNotFound())
+ self._cur.set_payload(EMPTYSTRING.join(preamble))
+ return
+ # If the end boundary ended in a newline, we'll need to make sure
+ # the epilogue isn't None
+ if linesep:
+ epilogue = ['']
+ else:
+ epilogue = []
+ for line in self._input:
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ epilogue.append(line)
+ # Any CRLF at the front of the epilogue is not technically part of
+ # the epilogue. Also, watch out for an empty string epilogue,
+ # which means a single newline.
+ firstline = epilogue[0]
+ bolmo = NLCRE_bol.match(firstline)
+ if bolmo:
+ epilogue[0] = firstline[len(bolmo.group(0)):]
+ self._cur.epilogue = EMPTYSTRING.join(epilogue)
+ return
+ # Otherwise, it's some non-multipart type, so the entire rest of the
+ # file contents becomes the payload.
+ lines = []
+ for line in self._input:
+ if line is NeedMoreData:
+ yield NeedMoreData
+ continue
+ lines.append(line)
+ self._cur.set_payload(EMPTYSTRING.join(lines))
+
+ def _parse_headers(self, lines):
+ # Passed a list of lines that make up the headers for the current msg
lastheader = ''
lastvalue = []
-
-
- for lineno, line in enumerate(headerlist):
+ for lineno, line in enumerate(lines):
# Check for continuation
if line[0] in ' \t':
if not lastheader:
- raise Errors.HeaderParseError('First line must not be a continuation')
+ # The first line of the headers was a continuation. This
+ # is illegal, so let's note the defect, store the illegal
+ # line, and ignore it for purposes of headers.
+ defect = Errors.FirstHeaderLineIsContinuation(line)
+ self._cur.defects.append(defect)
+ continue
lastvalue.append(line)
continue
-
if lastheader:
# XXX reconsider the joining of folded lines
- self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip()
+ self._cur[lastheader] = EMPTYSTRING.join(lastvalue)[:-1]
lastheader, lastvalue = '', []
-
- # Check for Unix-From
+ # Check for envelope header, i.e. unix-from
if line.startswith('From '):
if lineno == 0:
self._cur.set_unixfrom(line)
continue
- elif lineno == len(headerlist) - 1:
+ elif lineno == len(lines) - 1:
# Something looking like a unix-from at the end - it's
- # probably the first line of the body
+ # probably the first line of the body, so push back the
+ # line and stop.
self._input.unreadline(line)
return
else:
- # Weirdly placed unix-from line. Ignore it.
+ # Weirdly placed unix-from line. Note this as a defect
+ # and ignore it.
+ defect = Errors.MisplacedEnvelopeHeader(line)
+ self._cur.defects.append(defect)
continue
-
+ # Split the line on the colon separating field name from value.
i = line.find(':')
if i < 0:
- # The older parser had various special-cases here. We've
- # already handled them
- raise Errors.HeaderParseError(
- "Not a header, not a continuation: ``%s''" % line)
+ defect = Errors.MalformedHeader(line)
+ self._cur.defects.append(defect)
+ continue
lastheader = line[:i]
lastvalue = [line[i+1:].lstrip()]
-
+ # Done with all the lines, so handle the last header.
if lastheader:
# XXX reconsider the joining of folded lines
self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip()
-
-
- def _parsegen(self):
- # Parse any currently available text
- self._new_sub_object()
- self._root = self._cur
- completing = False
- last = None
-
- for line in self._input:
- if line is NeedMoreData:
- yield None # Need More Data
- continue
- self._input.unreadline(line)
- if not completing:
- headers = []
- # Now collect all headers.
- for line in self._input:
- if line is NeedMoreData:
- yield None # Need More Data
- continue
- if not self.headerRE.match(line):
- self._parse_headers(headers)
- # A message/rfc822 has no body and no internal
- # boundary.
- if self._cur.get_content_maintype() == "message":
- self._new_sub_object()
- completing = False
- headers = []
- continue
- if line.strip():
- # No blank line between headers and body.
- # Push this line back, it's the first line of
- # the body.
- self._input.unreadline(line)
- break
- else:
- headers.append(line)
- else:
- # We're done with the data and are still inside the headers
- self._parse_headers(headers)
-
- # Now we're dealing with the body
- boundary = self._cur.get_boundary()
- isdigest = (self._cur.get_content_type() == 'multipart/digest')
- if boundary and not self._cur._finishing:
- separator = '--' + boundary
- self._cur._boundaryRE = re.compile(
- r'(?P<sep>' + re.escape(separator) +
- r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)$')
- for r in self._input.readuntil(self._cur._boundaryRE):
- if r is NeedMoreData:
- yield NeedMoreData
- else:
- preamble, matchobj = r
- break
- if not matchobj:
- # Broken - we hit the end of file. Just set the body
- # to the text.
- if completing:
- self._attach_trailer(last, preamble)
- else:
- self._attach_preamble(self._cur, preamble)
- # XXX move back to the parent container.
- self._pop_container()
- completing = True
- continue
- if preamble:
- if completing:
- preamble = preamble[:-len(matchobj.group('linesep'))]
- self._attach_trailer(last, preamble)
- else:
- self._attach_preamble(self._cur, preamble)
- elif not completing:
- # The module docs specify an empty preamble is None, not ''
- self._cur.preamble = None
- # If we _are_ completing, the last object gets no payload
-
- if matchobj.group('end'):
- # That was the end boundary tag. Bounce back to the
- # parent container
- last = self._pop_container()
- self._input.unreadline(matchobj.group('linesep'))
- completing = True
- continue
-
- # A number of MTAs produced by a nameless large company
- # we shall call "SicroMoft" produce repeated boundary
- # lines.
- while True:
- line = self._input.peekline()
- if line is NeedMoreData:
- yield None
- continue
- if self._cur._boundaryRE.match(line):
- self._input.readline()
- else:
- break
-
- self._new_sub_object()
-
- completing = False
- if isdigest:
- self._cur.set_default_type('message/rfc822')
- continue
- else:
- # non-multipart or after end-boundary
- if last is not self._root:
- last = self._pop_container()
- if self._cur.get_content_maintype() == "message":
- # We double-pop to leave the RFC822 object
- self._pop_container()
- completing = True
- elif self._cur._boundaryRE and last <> self._root:
- completing = True
- else:
- # Non-multipart top level, or in the trailer of the
- # top level multipart
- while not self._input.is_done():
- yield None
- data = list(self._input)
- body = EMPTYSTRING.join(data)
- self._attach_trailer(last, body)
-
-
- def _attach_trailer(self, obj, trailer):
- #import pdb ; pdb.set_trace()
- if obj.get_content_maintype() in ( "multipart", "message" ):
- obj.epilogue = trailer
- else:
- obj.set_payload(trailer)
-
- def _attach_preamble(self, obj, trailer):
- if obj.get_content_maintype() in ( "multipart", "message" ):
- obj.preamble = trailer
- else:
- obj.set_payload(trailer)
-
-
- def _new_sub_object(self):
- new = self._class()
- #print "pushing", self._objectstack, repr(new)
- if self._objectstack:
- self._objectstack[-1].attach(new)
- self._objectstack.append(new)
- new._boundaryRE = None
- new._finishing = False
- self._cur = new
-
- def _pop_container(self):
- # Move the pointer to the container of the current object.
- # Returns the (old) current object
- #import pdb ; pdb.set_trace()
- #print "popping", self._objectstack
- last = self._objectstack.pop()
- if self._objectstack:
- self._cur = self._objectstack[-1]
- else:
- self._cur._finishing = True
- return last
-
-