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Aug 15, 2017
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Move base64 algorithms to Infra #2920

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198 changes: 11 additions & 187 deletions source
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Original file line number Diff line number Diff line change
Expand Up @@ -143,24 +143,6 @@

.parse-error-table td > p:first-child { margin-top: 0; }

#base64-table {
white-space: nowrap;
font-size: 0.6em;
column-width: 6em;
column-count: 5;
column-gap: 1em;
-moz-column-width: 6em;
-moz-column-count: 5;
-moz-column-gap: 1em;
-webkit-column-width: 6em;
-webkit-column-count: 5;
-webkit-column-gap: 1em;
}
#base64-table thead { display: none; }
#base64-table * { border: none; }
#base64-table tbody td:first-child:after { content: ':'; }
#base64-table tbody td:last-child { text-align: right; }

#named-character-references-table {
white-space: nowrap;
font-size: 0.6em;
Expand Down Expand Up @@ -2450,6 +2432,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
<dfn data-x="set append" data-x-href="https://infra.spec.whatwg.org/#set-append">append</dfn></li>
<li>The <dfn data-x-href="https://infra.spec.whatwg.org/#struct">struct</dfn> specification type and the associated definition for
<dfn data-x="struct item" data-x-href="https://infra.spec.whatwg.org/#struct-item">item</dfn></li>
<li>The <dfn data-x-href="https://infra.spec.whatwg.org/#forgiving-base64-encode">forgiving-base64 encode</dfn> and
<dfn data-x-href="https://infra.spec.whatwg.org/#forgiving-base64-decode">forgiving-base64 decode</dfn> algorithms</li>
<li><dfn data-x-href="https://infra.spec.whatwg.org/#html-namespace">HTML namespace</dfn></li>
<li><dfn data-x-href="https://infra.spec.whatwg.org/#mathml-namespace">MathML namespace</dfn></li>
<li><dfn data-x-href="https://infra.spec.whatwg.org/#svg-namespace">SVG namespace</dfn></li>
Expand Down Expand Up @@ -90025,7 +90009,7 @@ interface <dfn>WindowOrWorkerGlobalScope</dfn> {

// base64 utility methods
DOMString <span data-x="dom-btoa">btoa</span>(DOMString data);
DOMString <span data-x="dom-atob">atob</span>(DOMString data);
ByteString <span data-x="dom-atob">atob</span>(DOMString data);

// timers
long <span data-x="dom-setTimeout">setTimeout</span>(<span>TimerHandler</span> handler, optional long timeout = 0, any... arguments);
Expand Down Expand Up @@ -90114,180 +90098,23 @@ document.body.appendChild(frame)</pre>
<p>The <dfn data-x="dom-btoa"><code id="dom-windowbase64-btoa">btoa(<var>data</var>)</code></dfn>
method must throw an <span>"<code>InvalidCharacterError</code>"</span> <code>DOMException</code>
if <var>data</var> contains any character whose code point is greater than U+00FF. Otherwise, the
user agent must convert <var>data</var> to a sequence of octets whose <var>n</var>th octet is the
eight-bit representation of the code point of the <var>n</var>th character of <var>data</var>, and
then must apply the base64 algorithm to that sequence of octets, and return the result. <ref
spec=RFC4648><!--base64--></p>
<!-- Aryeh says: This seems to be what all browsers do as of January 2011 (except IE, which
doesn't support these functions at all). -->

user agent must convert <var>data</var> to a byte sequence whose <var>n</var>th byte is the
eight-bit representation of the <var>n</var>th code point of <var>data</var>, and then must apply
<span>forgiving-base64 encode</span> to that byte sequence and return the result.</p>

<p>The <dfn data-x="dom-atob"><code id="dom-windowbase64-atob">atob(<var>data</var>)</code></dfn>
method, when invoked, must run the following steps:</p>

<ol>
<li><p>Let <var>decodedData</var> be the result of running <span>forgiving-base64 decode</span>
on <var>data</var>.</p></li>

<!-- Aryeh says: Copies Firefox behavior as of January 2011 (4.0b8). WebKit is somewhat laxer,
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Should we preserve this info, at least as comments, in the Infra copy? The mailing list link seems especially interesting.

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The reason I didn't is that all browsers pass the atob() tests, which tests all of this. So it would only be useful if we expect someone to try to remove that later on, but I guess it doesn't hurt either. I'll add that link back.

and Opera throws no exceptions at all. gsnedders reports Opera's behavior causes site-compat
problems, and I figure most sites depend on Firefox if on anything, so go with that. -->

<!-- Since updated to drop whitespace, based on the arguments here:
https://lists.w3.org/Archives/Public/public-whatwg-archive/2011May/0207.html
-->

<li><p>Let <var>position</var> be a pointer into <var>data</var>, initially
pointing at the start of the string.</p></li>

<li><p>Remove all <span>ASCII whitespace</span> from <var>data</var>.</p></li>

<li><p>If the length of <var>data</var> divides by 4 leaving no remainder, then: if
<var>data</var> ends with one or two U+003D EQUALS SIGN (=) characters, remove them from
<var>data</var>.</p></li>

<li><p>If the length of <var>data</var> divides by 4 leaving a remainder of 1, throw an
<span>"<code>InvalidCharacterError</code>"</span> <code>DOMException</code> and abort these
steps.</p>

<li>

<p>If <var>data</var> contains a character that is not in the following list of
characters and character ranges, throw an <span>"<code>InvalidCharacterError</code>"</span>
<code>DOMException</code> and abort these steps:</p>

<ul class="brief">
<li>U+002B PLUS SIGN (+)
<li>U+002F SOLIDUS (/)
<li><span>ASCII alphanumeric</span>
</ul>

</li>

<li><p>Let <var>output</var> be a string, initially empty.</p></li>

<li><p>Let <var>buffer</var> be a buffer that can have bits appended to it, initially
empty.</p></li>

<li>

<p>While <var>position</var> does not point past the end of <var>data</var>, run these
substeps:</p>

<ol>

<li>

<p>Find the character pointed to by <var>position</var> in the first column of the
following table. Let <var>n</var> be the number given in the second cell of the same
row.</p>

<div id="base64-table">
<table>
<thead>
<tr>
<th>Character
<th>Number
<tbody>
<tr><td>A<td>0
<tr><td>B<td>1
<tr><td>C<td>2
<tr><td>D<td>3
<tr><td>E<td>4
<tr><td>F<td>5
<tr><td>G<td>6
<tr><td>H<td>7
<tr><td>I<td>8
<tr><td>J<td>9
<tr><td>K<td>10
<tr><td>L<td>11
<tr><td>M<td>12
<tr><td>N<td>13
<tr><td>O<td>14
<tr><td>P<td>15
<tr><td>Q<td>16
<tr><td>R<td>17
<tr><td>S<td>18
<tr><td>T<td>19
<tr><td>U<td>20
<tr><td>V<td>21
<tr><td>W<td>22
<tr><td>X<td>23
<tr><td>Y<td>24
<tr><td>Z<td>25
<tr><td>a<td>26
<tr><td>b<td>27
<tr><td>c<td>28
<tr><td>d<td>29
<tr><td>e<td>30
<tr><td>f<td>31
<tr><td>g<td>32
<tr><td>h<td>33
<tr><td>i<td>34
<tr><td>j<td>35
<tr><td>k<td>36
<tr><td>l<td>37
<tr><td>m<td>38
<tr><td>n<td>39
<tr><td>o<td>40
<tr><td>p<td>41
<tr><td>q<td>42
<tr><td>r<td>43
<tr><td>s<td>44
<tr><td>t<td>45
<tr><td>u<td>46
<tr><td>v<td>47
<tr><td>w<td>48
<tr><td>x<td>49
<tr><td>y<td>50
<tr><td>z<td>51
<tr><td>0<td>52
<tr><td>1<td>53
<tr><td>2<td>54
<tr><td>3<td>55
<tr><td>4<td>56
<tr><td>5<td>57
<tr><td>6<td>58
<tr><td>7<td>59
<tr><td>8<td>60
<tr><td>9<td>61
<tr><td>+<td>62
<tr><td>/<td>63
</table>
</div>

</li>

<li><p>Append to <var>buffer</var> the six bits corresponding to <var>number</var>, most significant bit first.</p></li>

<li><p>If <var>buffer</var> has accumulated 24 bits, interpret them as three 8-bit
big-endian numbers. Append the three characters with code points equal to those numbers to <var>output</var>, in the same order, and then empty <var>buffer</var>.</p></li>

<li><p>Advance <var>position</var> by one character.</p></li>

</ol>

</li>

<li>

<p>If <var>buffer</var> is not empty, it contains either 12 or 18 bits. If it contains
12 bits, discard the last four and interpret the remaining eight as an 8-bit big-endian number.
If it contains 18 bits, discard the last two and interpret the remaining 16 as two 8-bit
big-endian numbers. Append the one or two characters with code points equal to those one or two
numbers to <var>output</var>, in the same order.</p>

<p class="note">The discarded bits mean that, for instance, <code data-x="">atob("YQ")</code> and
<code data-x="">atob("YR")</code> both return "<code data-x="">a</code>".</p>

</li>

<li><p>Return <var>output</var>.</p></li>
<li><p>If <var>decodedData</var> is failure, then throw an
<span>"<code>InvalidCharacterError</code>"</span> <code>DOMException</code>.</p></li>

<li><p>Return <var>decodedData</var>.</p></li>
</ol>

<!-- Note: this function is defined explicitly here because RFC4648 does not specify how to handle
erroneous input, and no preexisting browser implementation simply throws an exception on all
erroneous input. -->

</div>


Expand Down Expand Up @@ -120244,9 +120071,6 @@ INSERT INTERFACES HERE
<dt id="refsRFC7595">[RFC7595]</dt>
<dd><cite><a href="https://tools.ietf.org/html/rfc7595">Guidelines and Registration Procedures for URI Schemes</a></cite>, D. Thaler, T. Hansen, T. Hardie. IETF.</dd>

<dt id="refsRFC4648">[RFC4648]</dt>
<dd><cite><a href="https://tools.ietf.org/html/rfc4648">The Base16, Base32, and Base64 Data Encodings</a></cite>, S. Josefsson. IETF.</dd>

<dt id="refsRFC5322">[RFC5322]</dt>
<dd><cite><a href="https://tools.ietf.org/html/rfc5322">Internet Message Format</a></cite>, P. Resnick. IETF.</dd>

Expand Down