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comparison CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/lib/python3.8/email/base64mime.py @ 68:5028fdace37b

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planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 16:23:26 -0400
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67:0e9998148a16 68:5028fdace37b
1 # Copyright (C) 2002-2007 Python Software Foundation
2 # Author: Ben Gertzfield
3 # Contact: email-sig@python.org
4
5 """Base64 content transfer encoding per RFCs 2045-2047.
6
7 This module handles the content transfer encoding method defined in RFC 2045
8 to encode arbitrary 8-bit data using the three 8-bit bytes in four 7-bit
9 characters encoding known as Base64.
10
11 It is used in the MIME standards for email to attach images, audio, and text
12 using some 8-bit character sets to messages.
13
14 This module provides an interface to encode and decode both headers and bodies
15 with Base64 encoding.
16
17 RFC 2045 defines a method for including character set information in an
18 `encoded-word' in a header. This method is commonly used for 8-bit real names
19 in To:, From:, Cc:, etc. fields, as well as Subject: lines.
20
21 This module does not do the line wrapping or end-of-line character conversion
22 necessary for proper internationalized headers; it only does dumb encoding and
23 decoding. To deal with the various line wrapping issues, use the email.header
24 module.
25 """
26
27 __all__ = [
28 'body_decode',
29 'body_encode',
30 'decode',
31 'decodestring',
32 'header_encode',
33 'header_length',
34 ]
35
36
37 from base64 import b64encode
38 from binascii import b2a_base64, a2b_base64
39
40 CRLF = '\r\n'
41 NL = '\n'
42 EMPTYSTRING = ''
43
44 # See also Charset.py
45 MISC_LEN = 7
46
47
48
49 # Helpers
50 def header_length(bytearray):
51 """Return the length of s when it is encoded with base64."""
52 groups_of_3, leftover = divmod(len(bytearray), 3)
53 # 4 bytes out for each 3 bytes (or nonzero fraction thereof) in.
54 n = groups_of_3 * 4
55 if leftover:
56 n += 4
57 return n
58
59
60
61 def header_encode(header_bytes, charset='iso-8859-1'):
62 """Encode a single header line with Base64 encoding in a given charset.
63
64 charset names the character set to use to encode the header. It defaults
65 to iso-8859-1. Base64 encoding is defined in RFC 2045.
66 """
67 if not header_bytes:
68 return ""
69 if isinstance(header_bytes, str):
70 header_bytes = header_bytes.encode(charset)
71 encoded = b64encode(header_bytes).decode("ascii")
72 return '=?%s?b?%s?=' % (charset, encoded)
73
74
75
76 def body_encode(s, maxlinelen=76, eol=NL):
77 r"""Encode a string with base64.
78
79 Each line will be wrapped at, at most, maxlinelen characters (defaults to
80 76 characters).
81
82 Each line of encoded text will end with eol, which defaults to "\n". Set
83 this to "\r\n" if you will be using the result of this function directly
84 in an email.
85 """
86 if not s:
87 return s
88
89 encvec = []
90 max_unencoded = maxlinelen * 3 // 4
91 for i in range(0, len(s), max_unencoded):
92 # BAW: should encode() inherit b2a_base64()'s dubious behavior in
93 # adding a newline to the encoded string?
94 enc = b2a_base64(s[i:i + max_unencoded]).decode("ascii")
95 if enc.endswith(NL) and eol != NL:
96 enc = enc[:-1] + eol
97 encvec.append(enc)
98 return EMPTYSTRING.join(encvec)
99
100
101
102 def decode(string):
103 """Decode a raw base64 string, returning a bytes object.
104
105 This function does not parse a full MIME header value encoded with
106 base64 (like =?iso-8859-1?b?bmloISBuaWgh?=) -- please use the high
107 level email.header class for that functionality.
108 """
109 if not string:
110 return bytes()
111 elif isinstance(string, str):
112 return a2b_base64(string.encode('raw-unicode-escape'))
113 else:
114 return a2b_base64(string)
115
116
117 # For convenience and backwards compatibility w/ standard base64 module
118 body_decode = decode
119 decodestring = decode