Merge #11606: improved body_encode algorithm, no longer produces overlong lines
This commit is contained in:
R David Murray
commit
73bd0448b9
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@ -40,6 +40,7 @@ __all__ = [
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]
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import re
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import io
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from string import ascii_letters, digits, hexdigits
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@ -147,6 +148,59 @@ def header_encode(header_bytes, charset='iso-8859-1'):
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return '=?%s?q?%s?=' % (charset, EMPTYSTRING.join(encoded))
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class _body_accumulator(io.StringIO):
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def __init__(self, maxlinelen, eol, *args, **kw):
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super().__init__(*args, **kw)
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self.eol = eol
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self.maxlinelen = self.room = maxlinelen
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def write_str(self, s):
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"""Add string s to the accumulated body."""
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self.write(s)
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self.room -= len(s)
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def newline(self):
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"""Write eol, then start new line."""
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self.write_str(self.eol)
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self.room = self.maxlinelen
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def write_soft_break(self):
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"""Write a soft break, then start a new line."""
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self.write_str('=')
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self.newline()
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def write_wrapped(self, s, extra_room=0):
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"""Add a soft line break if needed, then write s."""
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if self.room < len(s) + extra_room:
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self.write_soft_break()
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self.write_str(s)
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def write_char(self, c, is_last_char):
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if not is_last_char:
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# Another character follows on this line, so we must leave
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# extra room, either for it or a soft break, and whitespace
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# need not be quoted.
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self.write_wrapped(c, extra_room=1)
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elif c not in ' \t':
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# For this and remaining cases, no more characters follow,
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# so there is no need to reserve extra room (since a hard
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# break will immediately follow).
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self.write_wrapped(c)
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elif self.room >= 3:
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# It's a whitespace character at end-of-line, and we have room
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# for the three-character quoted encoding.
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self.write(quote(c))
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elif self.room == 2:
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# There's room for the whitespace character and a soft break.
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self.write(c)
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self.write_soft_break()
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else:
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# There's room only for a soft break. The quoted whitespace
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# will be the only content on the subsequent line.
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self.write_soft_break()
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self.write(quote(c))
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def body_encode(body, maxlinelen=76, eol=NL):
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"""Encode with quoted-printable, wrapping at maxlinelen characters.
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@ -155,72 +209,43 @@ def body_encode(body, maxlinelen=76, eol=NL):
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this to "\\r\\n" if you will be using the result of this function directly
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in an email.
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Each line will be wrapped at, at most, maxlinelen characters (defaults to
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76 characters). Long lines will have the `soft linefeed' quoted-printable
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character "=" appended to them, so the decoded text will be identical to
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the original text.
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Each line will be wrapped at, at most, maxlinelen characters before the
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eol string (maxlinelen defaults to 76 characters, the maximum value
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permitted by RFC 2045). Long lines will have the 'soft line break'
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quoted-printable character "=" appended to them, so the decoded text will
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be identical to the original text.
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The minimum maxlinelen is 4 to have room for a quoted character ("=XX")
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followed by a soft line break. Smaller values will generate a
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ValueError.
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"""
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if maxlinelen < 4:
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raise ValueError("maxlinelen must be at least 4")
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if not body:
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return body
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# BAW: We're accumulating the body text by string concatenation. That
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# can't be very efficient, but I don't have time now to rewrite it. It
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# just feels like this algorithm could be more efficient.
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encoded_body = ''
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lineno = -1
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# Preserve line endings here so we can check later to see an eol needs to
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# be added to the output later.
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lines = body.splitlines(1)
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for line in lines:
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# But strip off line-endings for processing this line.
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if line.endswith(CRLF):
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line = line[:-2]
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elif line[-1] in CRLF:
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line = line[:-1]
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# The last line may or may not end in eol, but all other lines do.
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last_has_eol = (body[-1] in '\r\n')
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lineno += 1
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encoded_line = ''
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prev = None
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linelen = len(line)
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# Now we need to examine every character to see if it needs to be
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# quopri encoded. BAW: again, string concatenation is inefficient.
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for j in range(linelen):
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c = line[j]
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prev = c
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# This accumulator will make it easier to build the encoded body.
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encoded_body = _body_accumulator(maxlinelen, eol)
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lines = body.splitlines()
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last_line_no = len(lines) - 1
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for line_no, line in enumerate(lines):
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last_char_index = len(line) - 1
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for i, c in enumerate(line):
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if body_check(ord(c)):
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c = quote(c)
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elif j+1 == linelen:
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# Check for whitespace at end of line; special case
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if c not in ' \t':
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encoded_line += c
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prev = c
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continue
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# Check to see to see if the line has reached its maximum length
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if len(encoded_line) + len(c) >= maxlinelen:
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encoded_body += encoded_line + '=' + eol
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encoded_line = ''
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encoded_line += c
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# Now at end of line..
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if prev and prev in ' \t':
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# Special case for whitespace at end of file
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if lineno + 1 == len(lines):
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prev = quote(prev)
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if len(encoded_line) + len(prev) > maxlinelen:
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encoded_body += encoded_line + '=' + eol + prev
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else:
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encoded_body += encoded_line + prev
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# Just normal whitespace at end of line
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else:
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encoded_body += encoded_line + prev + '=' + eol
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encoded_line = ''
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# Now look at the line we just finished and it has a line ending, we
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# need to add eol to the end of the line.
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if lines[lineno].endswith(CRLF) or lines[lineno][-1] in CRLF:
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encoded_body += encoded_line + eol
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else:
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encoded_body += encoded_line
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encoded_line = ''
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return encoded_body
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encoded_body.write_char(c, i==last_char_index)
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# Add an eol if input line had eol. All input lines have eol except
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# possibly the last one.
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if line_no < last_line_no or last_has_eol:
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encoded_body.newline()
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return encoded_body.getvalue()
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@ -3502,6 +3502,14 @@ class TestQuopri(unittest.TestCase):
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def test_encode_one_line_one_space(self):
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self._test_encode(' \n', '=20\n')
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# XXX: body_encode() expect strings, but uses ord(char) from these strings
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# to index into a 256-entry list. For code points above 255, this will fail.
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# Should there be a check for 8-bit only ord() values in body, or at least
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# a comment about the expected input?
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def test_encode_two_lines_one_space(self):
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self._test_encode(' \n \n', '=20\n=20\n')
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def test_encode_one_word_trailing_spaces(self):
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self._test_encode('hello ', 'hello =20')
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@ -3517,8 +3525,14 @@ class TestQuopri(unittest.TestCase):
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def test_encode_trailing_space_before_maxlinelen(self):
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self._test_encode('abcd \n1234', 'abcd =\n\n1234', maxlinelen=6)
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def test_encode_trailing_space_at_maxlinelen(self):
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self._test_encode('abcd \n1234', 'abcd=\n=20\n1234', maxlinelen=5)
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def test_encode_trailing_space_beyond_maxlinelen(self):
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self._test_encode('abcd \n1234', 'abc=\nd =\n\n1234', maxlinelen=4)
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self._test_encode('abcd \n1234', 'abc=\nd=20\n1234', maxlinelen=4)
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def test_encode_whitespace_lines(self):
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self._test_encode(' \n' * 5, '=20\n' * 5)
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def test_encode_quoted_equals(self):
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self._test_encode('a = b', 'a =3D b')
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@ -3539,6 +3553,9 @@ class TestQuopri(unittest.TestCase):
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def test_encode_shortest_maxlinelen(self):
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self._test_encode('=' * 5, '=3D=\n' * 4 + '=3D', maxlinelen=4)
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def test_encode_maxlinelen_too_small(self):
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self.assertRaises(ValueError, self._test_encode, '', '', maxlinelen=3)
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def test_encode(self):
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eq = self.assertEqual
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eq(quoprimime.body_encode(''), '')
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