Copying the email package back, despite its failings.

1 files changed, 307 insertions, 0 deletions

diff --git a/Lib/email/quoprimime.py b/Lib/email/quoprimime.py
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+# Copyright (C) 2001-2006 Python Software Foundation
+# Author: Ben Gertzfield
+# Contact: email-sig@python.org
+
+"""Quoted-printable content transfer encoding per RFCs 2045-2047.
+
+This module handles the content transfer encoding method defined in RFC 2045
+to encode US ASCII-like 8-bit data called `quoted-printable'.  It is used to
+safely encode text that is in a character set similar to the 7-bit US ASCII
+character set, but that includes some 8-bit characters that are normally not
+allowed in email bodies or headers.
+
+Quoted-printable is very space-inefficient for encoding binary files; use the
+email.base64MIME module for that instead.
+
+This module provides an interface to encode and decode both headers and bodies
+with quoted-printable encoding.
+
+RFC 2045 defines a method for including character set information in an
+`encoded-word' in a header.  This method is commonly used for 8-bit real names
+in To:/From:/Cc: etc. fields, as well as Subject: lines.
+
+This module does not do the line wrapping or end-of-line character
+conversion necessary for proper internationalized headers; it only
+does dumb encoding and decoding.  To deal with the various line
+wrapping issues, use the email.Header module.
+"""
+
+__all__ = [
+    'body_decode',
+    'body_encode',
+    'body_quopri_check',
+    'body_quopri_len',
+    'decode',
+    'decodestring',
+    'encode',
+    'encodestring',
+    'header_decode',
+    'header_encode',
+    'header_quopri_check',
+    'header_quopri_len',
+    'quote',
+    'unquote',
+    ]
+
+import re
+
+from string import ascii_letters, digits, hexdigits
+from email.utils import fix_eols
+
+CRLF = '\r\n'
+NL = '\n'
+EMPTYSTRING = ''
+
+# See also Charset.py
+MISC_LEN = 7
+
+HEADER_SAFE_BYTES = b'-!*+/ ' + bytes(ascii_letters) + bytes(digits)
+BODY_SAFE_BYTES   = (b' !"#$%&\'()*+,-./0123456789:;<>'
+                     b'?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`'
+                     b'abcdefghijklmnopqrstuvwxyz{|}~\t')
+
+
+
+# Helpers
+def header_quopri_check(c):
+    """Return True if the character should be escaped with header quopri."""
+    return c not in HEADER_SAFE_BYTES
+
+
+def body_quopri_check(c):
+    """Return True if the character should be escaped with body quopri."""
+    return c not in BODY_SAFE_BYTES
+
+
+def header_quopri_len(bytearray):
+    """Return the length of bytearray when it is encoded with header quopri.
+
+    Note that this does not include any RFC 2047 chrome added by
+    `header_encode()`.
+    """
+    count = 0
+    for c in bytearray:
+        count += (3 if header_quopri_check(c) else 1)
+    return count
+
+
+def body_quopri_len(bytearray):
+    """Return the length of bytearray when it is encoded with body quopri."""
+    count = 0
+    for c in bytearray:
+        count += (3 if body_quopri_check(c) else 1)
+    return count
+
+
+def _max_append(L, s, maxlen, extra=''):
+    if not isinstance(s, str):
+        s = chr(s)
+    if not L:
+        L.append(s.lstrip())
+    elif len(L[-1]) + len(s) <= maxlen:
+        L[-1] += extra + s
+    else:
+        L.append(s.lstrip())
+
+
+def unquote(s):
+    """Turn a string in the form =AB to the ASCII character with value 0xab"""
+    return chr(int(s[1:3], 16))
+
+
+def quote(c):
+    return '=%02X' % ord(c)
+
+
+
+def header_encode(header_bytes, charset='iso-8859-1'):
+    """Encode a single header line with quoted-printable (like) encoding.
+
+    Defined in RFC 2045, this `Q' encoding is similar to quoted-printable, but
+    used specifically for email header fields to allow charsets with mostly 7
+    bit characters (and some 8 bit) to remain more or less readable in non-RFC
+    2045 aware mail clients.
+
+    charset names the character set to use in the RFC 2046 header.  It
+    defaults to iso-8859-1.
+    """
+    # Return empty headers unchanged
+    if not header_bytes:
+        return str(header_bytes)
+    # Iterate over every byte, encoding if necessary.
+    encoded = []
+    for character in header_bytes:
+        # Space may be represented as _ instead of =20 for readability
+        if character == ord(' '):
+            encoded.append('_')
+        # These characters can be included verbatim.
+        elif not header_quopri_check(character):
+            encoded.append(chr(character))
+        # Otherwise, replace with hex value like =E2
+        else:
+            encoded.append('=%02X' % character)
+    # Now add the RFC chrome to each encoded chunk and glue the chunks
+    # together.
+    return '=?%s?q?%s?=' % (charset, EMPTYSTRING.join(encoded))
+
+
+
+def encode(body, binary=False, maxlinelen=76, eol=NL):
+    """Encode with quoted-printable, wrapping at maxlinelen characters.
+
+    If binary is False (the default), end-of-line characters will be converted
+    to the canonical email end-of-line sequence \\r\\n.  Otherwise they will
+    be left verbatim.
+
+    Each line of encoded text will end with eol, which defaults to "\\n".  Set
+    this to "\\r\\n" if you will be using the result of this function directly
+    in an email.
+
+    Each line will be wrapped at, at most, maxlinelen characters (defaults to
+    76 characters).  Long lines will have the `soft linefeed' quoted-printable
+    character "=" appended to them, so the decoded text will be identical to
+    the original text.
+    """
+    if not body:
+        return body
+
+    if not binary:
+        body = fix_eols(body)
+
+    # BAW: We're accumulating the body text by string concatenation.  That
+    # can't be very efficient, but I don't have time now to rewrite it.  It
+    # just feels like this algorithm could be more efficient.
+    encoded_body = ''
+    lineno = -1
+    # Preserve line endings here so we can check later to see an eol needs to
+    # be added to the output later.
+    lines = body.splitlines(1)
+    for line in lines:
+        # But strip off line-endings for processing this line.
+        if line.endswith(CRLF):
+            line = line[:-2]
+        elif line[-1] in CRLF:
+            line = line[:-1]
+
+        lineno += 1
+        encoded_line = ''
+        prev = None
+        linelen = len(line)
+        # Now we need to examine every character to see if it needs to be
+        # quopri encoded.  BAW: again, string concatenation is inefficient.
+        for j in range(linelen):
+            c = line[j]
+            prev = c
+            if body_quopri_check(c):
+                c = quote(c)
+            elif j+1 == linelen:
+                # Check for whitespace at end of line; special case
+                if c not in ' \t':
+                    encoded_line += c
+                prev = c
+                continue
+            # Check to see to see if the line has reached its maximum length
+            if len(encoded_line) + len(c) >= maxlinelen:
+                encoded_body += encoded_line + '=' + eol
+                encoded_line = ''
+            encoded_line += c
+        # Now at end of line..
+        if prev and prev in ' \t':
+            # Special case for whitespace at end of file
+            if lineno + 1 == len(lines):
+                prev = quote(prev)
+                if len(encoded_line) + len(prev) > maxlinelen:
+                    encoded_body += encoded_line + '=' + eol + prev
+                else:
+                    encoded_body += encoded_line + prev
+            # Just normal whitespace at end of line
+            else:
+                encoded_body += encoded_line + prev + '=' + eol
+            encoded_line = ''
+        # Now look at the line we just finished and it has a line ending, we
+        # need to add eol to the end of the line.
+        if lines[lineno].endswith(CRLF) or lines[lineno][-1] in CRLF:
+            encoded_body += encoded_line + eol
+        else:
+            encoded_body += encoded_line
+        encoded_line = ''
+    return encoded_body
+
+
+# For convenience and backwards compatibility w/ standard base64 module
+body_encode = encode
+encodestring = encode
+
+
+
+# BAW: I'm not sure if the intent was for the signature of this function to be
+# the same as base64MIME.decode() or not...
+def decode(encoded, eol=NL):
+    """Decode a quoted-printable string.
+
+    Lines are separated with eol, which defaults to \\n.
+    """
+    if not encoded:
+        return encoded
+    # BAW: see comment in encode() above.  Again, we're building up the
+    # decoded string with string concatenation, which could be done much more
+    # efficiently.
+    decoded = ''
+
+    for line in encoded.splitlines():
+        line = line.rstrip()
+        if not line:
+            decoded += eol
+            continue
+
+        i = 0
+        n = len(line)
+        while i < n:
+            c = line[i]
+            if c != '=':
+                decoded += c
+                i += 1
+            # Otherwise, c == "=".  Are we at the end of the line?  If so, add
+            # a soft line break.
+            elif i+1 == n:
+                i += 1
+                continue
+            # Decode if in form =AB
+            elif i+2 < n and line[i+1] in hexdigits and line[i+2] in hexdigits:
+                decoded += unquote(line[i:i+3])
+                i += 3
+            # Otherwise, not in form =AB, pass literally
+            else:
+                decoded += c
+                i += 1
+
+            if i == n:
+                decoded += eol
+    # Special case if original string did not end with eol
+    if not encoded.endswith(eol) and decoded.endswith(eol):
+        decoded = decoded[:-1]
+    return decoded
+
+
+# For convenience and backwards compatibility w/ standard base64 module
+body_decode = decode
+decodestring = decode
+
+
+
+def _unquote_match(match):
+    """Turn a match in the form =AB to the ASCII character with value 0xab"""
+    s = match.group(0)
+    return unquote(s)
+
+
+# Header decoding is done a bit differently
+def header_decode(s):
+    """Decode a string encoded with RFC 2045 MIME header `Q' encoding.
+
+    This function does not parse a full MIME header value encoded with
+    quoted-printable (like =?iso-8895-1?q?Hello_World?=) -- please use
+    the high level email.Header class for that functionality.
+    """
+    s = s.replace('_', ' ')
+    return re.sub(r'=\w{2}', _unquote_match, s)