EmbeddedPkg: Extend NvVarStoreFormattedLib LIBRARY_CLASS

[mirror_edk2.git] / AppPkg / Applications / Python / Python-2.7.2 / Lib / email / base64mime.py

# Copyright (C) 2002-2006 Python Software Foundation\r
# Author: Ben Gertzfield\r
# Contact: email-sig@python.org\r
\r
"""Base64 content transfer encoding per RFCs 2045-2047.\r
\r
This module handles the content transfer encoding method defined in RFC 2045\r
to encode arbitrary 8-bit data using the three 8-bit bytes in four 7-bit\r
characters encoding known as Base64.\r
\r
It is used in the MIME standards for email to attach images, audio, and text\r
using some 8-bit character sets to messages.\r
\r
This module provides an interface to encode and decode both headers and bodies\r
with Base64 encoding.\r
\r
RFC 2045 defines a method for including character set information in an\r
`encoded-word' in a header.  This method is commonly used for 8-bit real names\r
in To:, From:, Cc:, etc. fields, as well as Subject: lines.\r
\r
This module does not do the line wrapping or end-of-line character conversion\r
necessary for proper internationalized headers; it only does dumb encoding and\r
decoding.  To deal with the various line wrapping issues, use the email.header\r
module.\r
"""\r
\r
__all__ = [\r
    'base64_len',\r
    'body_decode',\r
    'body_encode',\r
    'decode',\r
    'decodestring',\r
    'encode',\r
    'encodestring',\r
    'header_encode',\r
    ]\r
\r
\r
from binascii import b2a_base64, a2b_base64\r
from email.utils import fix_eols\r
\r
CRLF = '\r\n'\r
NL = '\n'\r
EMPTYSTRING = ''\r
\r
# See also Charset.py\r
MISC_LEN = 7\r
\r
\r
\f\r
# Helpers\r
def base64_len(s):\r
    """Return the length of s when it is encoded with base64."""\r
    groups_of_3, leftover = divmod(len(s), 3)\r
    # 4 bytes out for each 3 bytes (or nonzero fraction thereof) in.\r
    # Thanks, Tim!\r
    n = groups_of_3 * 4\r
    if leftover:\r
        n += 4\r
    return n\r
\r
\r
\f\r
def header_encode(header, charset='iso-8859-1', keep_eols=False,\r
                  maxlinelen=76, eol=NL):\r
    """Encode a single header line with Base64 encoding in a given charset.\r
\r
    Defined in RFC 2045, this Base64 encoding is identical to normal Base64\r
    encoding, except that each line must be intelligently wrapped (respecting\r
    the Base64 encoding), and subsequent lines must start with a space.\r
\r
    charset names the character set to use to encode the header.  It defaults\r
    to iso-8859-1.\r
\r
    End-of-line characters (\\r, \\n, \\r\\n) will be automatically converted\r
    to the canonical email line separator \\r\\n unless the keep_eols\r
    parameter is True (the default is False).\r
\r
    Each line of the header will be terminated in the value of eol, which\r
    defaults to "\\n".  Set this to "\\r\\n" if you are using the result of\r
    this function directly in email.\r
\r
    The resulting string will be in the form:\r
\r
    "=?charset?b?WW/5ciBtYXp66XLrIHf8eiBhIGhhbXBzdGHuciBBIFlv+XIgbWF6euly?=\\n\r
      =?charset?b?6yB3/HogYSBoYW1wc3Rh7nIgQkMgWW/5ciBtYXp66XLrIHf8eiBhIGhh?="\r
\r
    with each line wrapped at, at most, maxlinelen characters (defaults to 76\r
    characters).\r
    """\r
    # Return empty headers unchanged\r
    if not header:\r
        return header\r
\r
    if not keep_eols:\r
        header = fix_eols(header)\r
\r
    # Base64 encode each line, in encoded chunks no greater than maxlinelen in\r
    # length, after the RFC chrome is added in.\r
    base64ed = []\r
    max_encoded = maxlinelen - len(charset) - MISC_LEN\r
    max_unencoded = max_encoded * 3 // 4\r
\r
    for i in range(0, len(header), max_unencoded):\r
        base64ed.append(b2a_base64(header[i:i+max_unencoded]))\r
\r
    # Now add the RFC chrome to each encoded chunk\r
    lines = []\r
    for line in base64ed:\r
        # Ignore the last character of each line if it is a newline\r
        if line.endswith(NL):\r
            line = line[:-1]\r
        # Add the chrome\r
        lines.append('=?%s?b?%s?=' % (charset, line))\r
    # Glue the lines together and return it.  BAW: should we be able to\r
    # specify the leading whitespace in the joiner?\r
    joiner = eol + ' '\r
    return joiner.join(lines)\r
\r
\r
\f\r
def encode(s, binary=True, maxlinelen=76, eol=NL):\r
    """Encode a string with base64.\r
\r
    Each line will be wrapped at, at most, maxlinelen characters (defaults to\r
    76 characters).\r
\r
    If binary is False, end-of-line characters will be converted to the\r
    canonical email end-of-line sequence \\r\\n.  Otherwise they will be left\r
    verbatim (this is the default).\r
\r
    Each line of encoded text will end with eol, which defaults to "\\n".  Set\r
    this to "\r\n" if you will be using the result of this function directly\r
    in an email.\r
    """\r
    if not s:\r
        return s\r
\r
    if not binary:\r
        s = fix_eols(s)\r
\r
    encvec = []\r
    max_unencoded = maxlinelen * 3 // 4\r
    for i in range(0, len(s), max_unencoded):\r
        # BAW: should encode() inherit b2a_base64()'s dubious behavior in\r
        # adding a newline to the encoded string?\r
        enc = b2a_base64(s[i:i + max_unencoded])\r
        if enc.endswith(NL) and eol != NL:\r
            enc = enc[:-1] + eol\r
        encvec.append(enc)\r
    return EMPTYSTRING.join(encvec)\r
\r
\r
# For convenience and backwards compatibility w/ standard base64 module\r
body_encode = encode\r
encodestring = encode\r
\r
\r
\f\r
def decode(s, convert_eols=None):\r
    """Decode a raw base64 string.\r
\r
    If convert_eols is set to a string value, all canonical email linefeeds,\r
    e.g. "\\r\\n", in the decoded text will be converted to the value of\r
    convert_eols.  os.linesep is a good choice for convert_eols if you are\r
    decoding a text attachment.\r
\r
    This function does not parse a full MIME header value encoded with\r
    base64 (like =?iso-8895-1?b?bmloISBuaWgh?=) -- please use the high\r
    level email.header class for that functionality.\r
    """\r
    if not s:\r
        return s\r
\r
    dec = a2b_base64(s)\r
    if convert_eols:\r
        return dec.replace(CRLF, convert_eols)\r
    return dec\r
\r
\r
# For convenience and backwards compatibility w/ standard base64 module\r
body_decode = decode\r
decodestring = decode\r