зеркало из https://github.com/github/ruby.git
364 строки
13 KiB
Ruby
364 строки
13 KiB
Ruby
# frozen_string_literal: true
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#
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# \Module \Base64 provides methods for:
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#
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# - Encoding a binary string (containing non-ASCII characters)
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# as a string of printable ASCII characters.
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# - Decoding such an encoded string.
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#
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# \Base64 is commonly used in contexts where binary data
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# is not allowed or supported:
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#
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# - Images in HTML or CSS files, or in URLs.
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# - Email attachments.
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#
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# A \Base64-encoded string is about one-third larger that its source.
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# See the {Wikipedia article}[https://en.wikipedia.org/wiki/Base64]
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# for more information.
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#
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# This module provides three pairs of encode/decode methods.
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# Your choices among these methods should depend on:
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#
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# - Which character set is to be used for encoding and decoding.
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# - Whether "padding" is to be used.
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# - Whether encoded strings are to contain newlines.
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#
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# Note: Examples on this page assume that the including program has executed:
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#
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# require 'base64'
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#
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# == Encoding Character Sets
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#
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# A \Base64-encoded string consists only of characters from a 64-character set:
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#
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# - <tt>('A'..'Z')</tt>.
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# - <tt>('a'..'z')</tt>.
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# - <tt>('0'..'9')</tt>.
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# - <tt>=</tt>, the 'padding' character.
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# - Either:
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# - <tt>%w[+ /]</tt>:
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# {RFC-2045-compliant}[https://datatracker.ietf.org/doc/html/rfc2045];
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# _not_ safe for URLs.
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# - <tt>%w[- _]</tt>:
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# {RFC-4648-compliant}[https://datatracker.ietf.org/doc/html/rfc4648];
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# safe for URLs.
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#
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# If you are working with \Base64-encoded strings that will come from
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# or be put into URLs, you should choose this encoder-decoder pair
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# of RFC-4648-compliant methods:
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#
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# - Base64.urlsafe_encode64 and Base64.urlsafe_decode64.
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#
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# Otherwise, you may choose any of the pairs in this module,
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# including the pair above, or the RFC-2045-compliant pairs:
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#
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# - Base64.encode64 and Base64.decode64.
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# - Base64.strict_encode64 and Base64.strict_decode64.
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#
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# == Padding
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#
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# \Base64-encoding changes a triplet of input bytes
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# into a quartet of output characters.
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#
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# <b>Padding in Encode Methods</b>
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#
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# Padding -- extending an encoded string with zero, one, or two trailing
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# <tt>=</tt> characters -- is performed by methods Base64.encode64,
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# Base64.strict_encode64, and, by default, Base64.urlsafe_encode64:
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#
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# Base64.encode64('s') # => "cw==\n"
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# Base64.strict_encode64('s') # => "cw=="
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# Base64.urlsafe_encode64('s') # => "cw=="
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# Base64.urlsafe_encode64('s', padding: false) # => "cw"
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#
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# When padding is performed, the encoded string is always of length <em>4n</em>,
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# where +n+ is a non-negative integer:
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#
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# - Input bytes of length <em>3n</em> generate unpadded output characters
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# of length <em>4n</em>:
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#
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# # n = 1: 3 bytes => 4 characters.
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# Base64.strict_encode64('123') # => "MDEy"
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# # n = 2: 6 bytes => 8 characters.
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# Base64.strict_encode64('123456') # => "MDEyMzQ1"
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#
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# - Input bytes of length <em>3n+1</em> generate padded output characters
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# of length <em>4(n+1)</em>, with two padding characters at the end:
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#
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# # n = 1: 4 bytes => 8 characters.
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# Base64.strict_encode64('1234') # => "MDEyMw=="
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# # n = 2: 7 bytes => 12 characters.
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# Base64.strict_encode64('1234567') # => "MDEyMzQ1Ng=="
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#
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# - Input bytes of length <em>3n+2</em> generate padded output characters
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# of length <em>4(n+1)</em>, with one padding character at the end:
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#
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# # n = 1: 5 bytes => 8 characters.
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# Base64.strict_encode64('12345') # => "MDEyMzQ="
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# # n = 2: 8 bytes => 12 characters.
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# Base64.strict_encode64('12345678') # => "MDEyMzQ1Njc="
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#
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# When padding is suppressed, for a positive integer <em>n</em>:
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#
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# - Input bytes of length <em>3n</em> generate unpadded output characters
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# of length <em>4n</em>:
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#
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# # n = 1: 3 bytes => 4 characters.
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# Base64.urlsafe_encode64('123', padding: false) # => "MDEy"
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# # n = 2: 6 bytes => 8 characters.
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# Base64.urlsafe_encode64('123456', padding: false) # => "MDEyMzQ1"
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#
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# - Input bytes of length <em>3n+1</em> generate unpadded output characters
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# of length <em>4n+2</em>, with two padding characters at the end:
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#
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# # n = 1: 4 bytes => 6 characters.
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# Base64.urlsafe_encode64('1234', padding: false) # => "MDEyMw"
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# # n = 2: 7 bytes => 10 characters.
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# Base64.urlsafe_encode64('1234567', padding: false) # => "MDEyMzQ1Ng"
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#
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# - Input bytes of length <em>3n+2</em> generate unpadded output characters
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# of length <em>4n+3</em>, with one padding character at the end:
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#
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# # n = 1: 5 bytes => 7 characters.
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# Base64.urlsafe_encode64('12345', padding: false) # => "MDEyMzQ"
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# # m = 2: 8 bytes => 11 characters.
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# Base64.urlsafe_encode64('12345678', padding: false) # => "MDEyMzQ1Njc"
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#
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# <b>Padding in Decode Methods</b>
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#
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# All of the \Base64 decode methods support (but do not require) padding.
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#
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# \Method Base64.decode64 does not check the size of the padding:
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#
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# Base64.decode64("MDEyMzQ1Njc") # => "01234567"
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# Base64.decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.decode64("MDEyMzQ1Njc==") # => "01234567"
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#
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# \Method Base64.strict_decode64 strictly enforces padding size:
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#
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# Base64.strict_decode64("MDEyMzQ1Njc") # Raises ArgumentError
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# Base64.strict_decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.strict_decode64("MDEyMzQ1Njc==") # Raises ArgumentError
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#
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# \Method Base64.urlsafe_decode64 allows padding in +str+,
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# which if present, must be correct:
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# see {Padding}[Base64.html#module-Base64-label-Padding], above:
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#
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# Base64.urlsafe_decode64("MDEyMzQ1Njc") # => "01234567"
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# Base64.urlsafe_decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.urlsafe_decode64("MDEyMzQ1Njc==") # Raises ArgumentError.
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#
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# == Newlines
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#
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# An encoded string returned by Base64.encode64 or Base64.urlsafe_encode64
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# has an embedded newline character
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# after each 60-character sequence, and, if non-empty, at the end:
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#
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# # No newline if empty.
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# encoded = Base64.encode64("\x00" * 0)
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# encoded.index("\n") # => nil
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#
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# # Newline at end of short output.
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# encoded = Base64.encode64("\x00" * 1)
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# encoded.size # => 4
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# encoded.index("\n") # => 4
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#
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# # Newline at end of longer output.
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# encoded = Base64.encode64("\x00" * 45)
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# encoded.size # => 60
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# encoded.index("\n") # => 60
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#
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# # Newlines embedded and at end of still longer output.
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# encoded = Base64.encode64("\x00" * 46)
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# encoded.size # => 65
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# encoded.rindex("\n") # => 65
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# encoded.split("\n").map {|s| s.size } # => [60, 4]
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#
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# The string to be encoded may itself contain newlines,
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# which are encoded as \Base64:
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#
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# # Base64.encode64("\n\n\n") # => "CgoK\n"
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# s = "This is line 1\nThis is line 2\n"
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# Base64.encode64(s) # => "VGhpcyBpcyBsaW5lIDEKVGhpcyBpcyBsaW5lIDIK\n"
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#
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module Base64
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VERSION = "0.2.0"
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module_function
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# Returns a string containing the RFC-2045-compliant \Base64-encoding of +bin+.
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#
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# Per RFC 2045, the returned string may contain the URL-unsafe characters
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# <tt>+</tt> or <tt>/</tt>;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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#
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# Base64.encode64("\xFB\xEF\xBE") # => "++++\n"
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# Base64.encode64("\xFF\xFF\xFF") # => "////\n"
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#
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# The returned string may include padding;
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# see {Padding}[Base64.html#module-Base64-label-Padding] above.
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#
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# Base64.encode64('*') # => "Kg==\n"
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#
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# The returned string ends with a newline character, and if sufficiently long
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# will have one or more embedded newline characters;
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# see {Newlines}[Base64.html#module-Base64-label-Newlines] above:
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#
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# Base64.encode64('*') # => "Kg==\n"
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# Base64.encode64('*' * 46)
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# # => "KioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioq\nKg==\n"
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#
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# The string to be encoded may itself contain newlines,
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# which will be encoded as ordinary \Base64:
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#
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# Base64.encode64("\n\n\n") # => "CgoK\n"
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# s = "This is line 1\nThis is line 2\n"
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# Base64.encode64(s) # => "VGhpcyBpcyBsaW5lIDEKVGhpcyBpcyBsaW5lIDIK\n"
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#
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def encode64(bin)
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[bin].pack("m")
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end
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# Returns a string containing the decoding of an RFC-2045-compliant
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# \Base64-encoded string +str+:
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#
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# s = "VGhpcyBpcyBsaW5lIDEKVGhpcyBpcyBsaW5lIDIK\n"
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# Base64.decode64(s) # => "This is line 1\nThis is line 2\n"
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#
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# Non-\Base64 characters in +str+ are ignored;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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# these include newline characters and characters <tt>-</tt> and <tt>/</tt>:
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#
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# Base64.decode64("\x00\n-_") # => ""
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#
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# Padding in +str+ (even if incorrect) is ignored:
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#
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# Base64.decode64("MDEyMzQ1Njc") # => "01234567"
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# Base64.decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.decode64("MDEyMzQ1Njc==") # => "01234567"
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#
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def decode64(str)
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str.unpack1("m")
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end
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# Returns a string containing the RFC-2045-compliant \Base64-encoding of +bin+.
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#
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# Per RFC 2045, the returned string may contain the URL-unsafe characters
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# <tt>+</tt> or <tt>/</tt>;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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#
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# Base64.strict_encode64("\xFB\xEF\xBE") # => "++++\n"
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# Base64.strict_encode64("\xFF\xFF\xFF") # => "////\n"
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#
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# The returned string may include padding;
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# see {Padding}[Base64.html#module-Base64-label-Padding] above.
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#
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# Base64.strict_encode64('*') # => "Kg==\n"
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#
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# The returned string will have no newline characters, regardless of its length;
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# see {Newlines}[Base64.html#module-Base64-label-Newlines] above:
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#
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# Base64.strict_encode64('*') # => "Kg=="
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# Base64.strict_encode64('*' * 46)
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# # => "KioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKg=="
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#
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# The string to be encoded may itself contain newlines,
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# which will be encoded as ordinary \Base64:
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#
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# Base64.strict_encode64("\n\n\n") # => "CgoK"
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# s = "This is line 1\nThis is line 2\n"
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# Base64.strict_encode64(s) # => "VGhpcyBpcyBsaW5lIDEKVGhpcyBpcyBsaW5lIDIK"
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#
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def strict_encode64(bin)
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[bin].pack("m0")
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end
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# Returns a string containing the decoding of an RFC-2045-compliant
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# \Base64-encoded string +str+:
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#
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# s = "VGhpcyBpcyBsaW5lIDEKVGhpcyBpcyBsaW5lIDIK"
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# Base64.strict_decode64(s) # => "This is line 1\nThis is line 2\n"
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#
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# Non-\Base64 characters in +str+ not allowed;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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# these include newline characters and characters <tt>-</tt> and <tt>/</tt>:
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#
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# Base64.strict_decode64("\n") # Raises ArgumentError
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# Base64.strict_decode64('-') # Raises ArgumentError
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# Base64.strict_decode64('_') # Raises ArgumentError
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#
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# Padding in +str+, if present, must be correct:
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#
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# Base64.strict_decode64("MDEyMzQ1Njc") # Raises ArgumentError
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# Base64.strict_decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.strict_decode64("MDEyMzQ1Njc==") # Raises ArgumentError
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#
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def strict_decode64(str)
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str.unpack1("m0")
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end
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# Returns the RFC-4648-compliant \Base64-encoding of +bin+.
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#
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# Per RFC 4648, the returned string will not contain the URL-unsafe characters
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# <tt>+</tt> or <tt>/</tt>,
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# but instead may contain the URL-safe characters
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# <tt>-</tt> and <tt>_</tt>;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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#
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# Base64.urlsafe_encode64("\xFB\xEF\xBE") # => "----"
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# Base64.urlsafe_encode64("\xFF\xFF\xFF") # => "____"
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#
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# By default, the returned string may have padding;
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# see {Padding}[Base64.html#module-Base64-label-Padding], above:
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#
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# Base64.urlsafe_encode64('*') # => "Kg=="
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#
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# Optionally, you can suppress padding:
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#
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# Base64.urlsafe_encode64('*', padding: false) # => "Kg"
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#
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# The returned string will have no newline characters, regardless of its length;
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# see {Newlines}[Base64.html#module-Base64-label-Newlines] above:
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#
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# Base64.urlsafe_encode64('*') # => "Kg=="
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# Base64.urlsafe_encode64('*' * 46)
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# # => "KioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKg=="
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#
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def urlsafe_encode64(bin, padding: true)
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str = strict_encode64(bin)
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str.chomp!("==") or str.chomp!("=") unless padding
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str.tr!("+/", "-_")
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str
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end
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# Returns the decoding of an RFC-4648-compliant \Base64-encoded string +str+:
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#
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# +str+ may not contain non-Base64 characters;
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# see {Encoding Character Set}[Base64.html#module-Base64-label-Encoding+Character+Sets] above:
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#
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# Base64.urlsafe_decode64('+') # Raises ArgumentError.
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# Base64.urlsafe_decode64('/') # Raises ArgumentError.
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# Base64.urlsafe_decode64("\n") # Raises ArgumentError.
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#
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# Padding in +str+, if present, must be correct:
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# see {Padding}[Base64.html#module-Base64-label-Padding], above:
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#
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# Base64.urlsafe_decode64("MDEyMzQ1Njc") # => "01234567"
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# Base64.urlsafe_decode64("MDEyMzQ1Njc=") # => "01234567"
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# Base64.urlsafe_decode64("MDEyMzQ1Njc==") # Raises ArgumentError.
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#
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def urlsafe_decode64(str)
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# NOTE: RFC 4648 does say nothing about unpadded input, but says that
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# "the excess pad characters MAY also be ignored", so it is inferred that
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# unpadded input is also acceptable.
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if !str.end_with?("=") && str.length % 4 != 0
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str = str.ljust((str.length + 3) & ~3, "=")
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str.tr!("-_", "+/")
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else
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str = str.tr("-_", "+/")
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end
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strict_decode64(str)
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end
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end
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