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</pre><pre class="rust"><code><span class="doccomment">//! Provides the [GeneralPurpose] engine and associated config types.
</span><span class="kw">use crate</span>::{
alphabet,
alphabet::Alphabet,
engine::{Config, DecodeMetadata, DecodePaddingMode},
DecodeError,
};
<span class="kw">use </span>core::convert::TryInto;
<span class="kw">mod </span>decode;
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">mod </span>decode_suffix;
<span class="kw">pub use </span>decode::GeneralPurposeEstimate;
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const </span>INVALID_VALUE: u8 = <span class="number">255</span>;
<span class="doccomment">/// A general-purpose base64 engine.
///
/// - It uses no vector CPU instructions, so it will work on any system.
/// - It is reasonably fast (~2-3GiB/s).
/// - It is not constant-time, though, so it is vulnerable to timing side-channel attacks. For loading cryptographic keys, etc, it is suggested to use the forthcoming constant-time implementation.
</span><span class="kw">pub struct </span>GeneralPurpose {
encode_table: [u8; <span class="number">64</span>],
decode_table: [u8; <span class="number">256</span>],
config: GeneralPurposeConfig,
}
<span class="kw">impl </span>GeneralPurpose {
<span class="doccomment">/// Create a `GeneralPurpose` engine from an [Alphabet].
///
/// While not very expensive to initialize, ideally these should be cached
/// if the engine will be used repeatedly.
</span><span class="kw">pub const fn </span>new(alphabet: <span class="kw-2">&amp;</span>Alphabet, config: GeneralPurposeConfig) -&gt; <span class="self">Self </span>{
<span class="self">Self </span>{
encode_table: encode_table(alphabet),
decode_table: decode_table(alphabet),
config,
}
}
}
<span class="kw">impl </span><span class="kw">super</span>::Engine <span class="kw">for </span>GeneralPurpose {
<span class="kw">type </span>Config = GeneralPurposeConfig;
<span class="kw">type </span>DecodeEstimate = GeneralPurposeEstimate;
<span class="kw">fn </span>internal_encode(<span class="kw-2">&amp;</span><span class="self">self</span>, input: <span class="kw-2">&amp;</span>[u8], output: <span class="kw-2">&amp;mut </span>[u8]) -&gt; usize {
<span class="kw">let </span><span class="kw-2">mut </span>input_index: usize = <span class="number">0</span>;
<span class="kw">const </span>BLOCKS_PER_FAST_LOOP: usize = <span class="number">4</span>;
<span class="kw">const </span>LOW_SIX_BITS: u64 = <span class="number">0x3F</span>;
<span class="comment">// we read 8 bytes at a time (u64) but only actually consume 6 of those bytes. Thus, we need
// 2 trailing bytes to be available to read..
</span><span class="kw">let </span>last_fast_index = input.len().saturating_sub(BLOCKS_PER_FAST_LOOP * <span class="number">6 </span>+ <span class="number">2</span>);
<span class="kw">let </span><span class="kw-2">mut </span>output_index = <span class="number">0</span>;
<span class="kw">if </span>last_fast_index &gt; <span class="number">0 </span>{
<span class="kw">while </span>input_index &lt;= last_fast_index {
<span class="comment">// Major performance wins from letting the optimizer do the bounds check once, mostly
// on the output side
</span><span class="kw">let </span>input_chunk =
<span class="kw-2">&amp;</span>input[input_index..(input_index + (BLOCKS_PER_FAST_LOOP * <span class="number">6 </span>+ <span class="number">2</span>))];
<span class="kw">let </span>output_chunk =
<span class="kw-2">&amp;mut </span>output[output_index..(output_index + BLOCKS_PER_FAST_LOOP * <span class="number">8</span>)];
<span class="comment">// Hand-unrolling for 32 vs 16 or 8 bytes produces yields performance about equivalent
// to unsafe pointer code on a Xeon E5-1650v3. 64 byte unrolling was slightly better for
// large inputs but significantly worse for 50-byte input, unsurprisingly. I suspect
// that it&#39;s a not uncommon use case to encode smallish chunks of data (e.g. a 64-byte
// SHA-512 digest), so it would be nice if that fit in the unrolled loop at least once.
// Plus, single-digit percentage performance differences might well be quite different
// on different hardware.
</span><span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&amp;</span>input_chunk[<span class="number">0</span>..]);
output_chunk[<span class="number">0</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">58</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">1</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">52</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">2</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">46</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">3</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">40</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">4</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">34</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">5</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">28</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">6</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">22</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">7</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">16</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
<span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&amp;</span>input_chunk[<span class="number">6</span>..]);
output_chunk[<span class="number">8</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">58</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">9</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">52</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">10</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">46</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">11</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">40</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">12</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">34</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">13</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">28</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">14</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">22</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">15</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">16</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
<span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&amp;</span>input_chunk[<span class="number">12</span>..]);
output_chunk[<span class="number">16</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">58</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">17</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">52</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">18</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">46</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">19</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">40</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">20</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">34</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">21</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">28</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">22</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">22</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">23</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">16</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
<span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&amp;</span>input_chunk[<span class="number">18</span>..]);
output_chunk[<span class="number">24</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">58</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">25</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">52</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">26</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">46</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">27</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">40</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">28</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">34</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">29</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">28</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">30</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">22</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_chunk[<span class="number">31</span>] = <span class="self">self</span>.encode_table[((input_u64 &gt;&gt; <span class="number">16</span>) &amp; LOW_SIX_BITS) <span class="kw">as </span>usize];
output_index += BLOCKS_PER_FAST_LOOP * <span class="number">8</span>;
input_index += BLOCKS_PER_FAST_LOOP * <span class="number">6</span>;
}
}
<span class="comment">// Encode what&#39;s left after the fast loop.
</span><span class="kw">const </span>LOW_SIX_BITS_U8: u8 = <span class="number">0x3F</span>;
<span class="kw">let </span>rem = input.len() % <span class="number">3</span>;
<span class="kw">let </span>start_of_rem = input.len() - rem;
<span class="comment">// start at the first index not handled by fast loop, which may be 0.
</span><span class="kw">while </span>input_index &lt; start_of_rem {
<span class="kw">let </span>input_chunk = <span class="kw-2">&amp;</span>input[input_index..(input_index + <span class="number">3</span>)];
<span class="kw">let </span>output_chunk = <span class="kw-2">&amp;mut </span>output[output_index..(output_index + <span class="number">4</span>)];
output_chunk[<span class="number">0</span>] = <span class="self">self</span>.encode_table[(input_chunk[<span class="number">0</span>] &gt;&gt; <span class="number">2</span>) <span class="kw">as </span>usize];
output_chunk[<span class="number">1</span>] = <span class="self">self</span>.encode_table
[((input_chunk[<span class="number">0</span>] &lt;&lt; <span class="number">4 </span>| input_chunk[<span class="number">1</span>] &gt;&gt; <span class="number">4</span>) &amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
output_chunk[<span class="number">2</span>] = <span class="self">self</span>.encode_table
[((input_chunk[<span class="number">1</span>] &lt;&lt; <span class="number">2 </span>| input_chunk[<span class="number">2</span>] &gt;&gt; <span class="number">6</span>) &amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
output_chunk[<span class="number">3</span>] = <span class="self">self</span>.encode_table[(input_chunk[<span class="number">2</span>] &amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
input_index += <span class="number">3</span>;
output_index += <span class="number">4</span>;
}
<span class="kw">if </span>rem == <span class="number">2 </span>{
output[output_index] = <span class="self">self</span>.encode_table[(input[start_of_rem] &gt;&gt; <span class="number">2</span>) <span class="kw">as </span>usize];
output[output_index + <span class="number">1</span>] =
<span class="self">self</span>.encode_table[((input[start_of_rem] &lt;&lt; <span class="number">4 </span>| input[start_of_rem + <span class="number">1</span>] &gt;&gt; <span class="number">4</span>)
&amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
output[output_index + <span class="number">2</span>] =
<span class="self">self</span>.encode_table[((input[start_of_rem + <span class="number">1</span>] &lt;&lt; <span class="number">2</span>) &amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
output_index += <span class="number">3</span>;
} <span class="kw">else if </span>rem == <span class="number">1 </span>{
output[output_index] = <span class="self">self</span>.encode_table[(input[start_of_rem] &gt;&gt; <span class="number">2</span>) <span class="kw">as </span>usize];
output[output_index + <span class="number">1</span>] =
<span class="self">self</span>.encode_table[((input[start_of_rem] &lt;&lt; <span class="number">4</span>) &amp; LOW_SIX_BITS_U8) <span class="kw">as </span>usize];
output_index += <span class="number">2</span>;
}
output_index
}
<span class="kw">fn </span>internal_decoded_len_estimate(<span class="kw-2">&amp;</span><span class="self">self</span>, input_len: usize) -&gt; <span class="self">Self</span>::DecodeEstimate {
GeneralPurposeEstimate::new(input_len)
}
<span class="kw">fn </span>internal_decode(
<span class="kw-2">&amp;</span><span class="self">self</span>,
input: <span class="kw-2">&amp;</span>[u8],
output: <span class="kw-2">&amp;mut </span>[u8],
estimate: <span class="self">Self</span>::DecodeEstimate,
) -&gt; <span class="prelude-ty">Result</span>&lt;DecodeMetadata, DecodeError&gt; {
decode::decode_helper(
input,
estimate,
output,
<span class="kw-2">&amp;</span><span class="self">self</span>.decode_table,
<span class="self">self</span>.config.decode_allow_trailing_bits,
<span class="self">self</span>.config.decode_padding_mode,
)
}
<span class="kw">fn </span>config(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span><span class="self">Self</span>::Config {
<span class="kw-2">&amp;</span><span class="self">self</span>.config
}
}
<span class="doccomment">/// Returns a table mapping a 6-bit index to the ASCII byte encoding of the index
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const fn </span>encode_table(alphabet: <span class="kw-2">&amp;</span>Alphabet) -&gt; [u8; <span class="number">64</span>] {
<span class="comment">// the encode table is just the alphabet:
// 6-bit index lookup -&gt; printable byte
</span><span class="kw">let </span><span class="kw-2">mut </span>encode_table = [<span class="number">0_u8</span>; <span class="number">64</span>];
{
<span class="kw">let </span><span class="kw-2">mut </span>index = <span class="number">0</span>;
<span class="kw">while </span>index &lt; <span class="number">64 </span>{
encode_table[index] = alphabet.symbols[index];
index += <span class="number">1</span>;
}
}
encode_table
}
<span class="doccomment">/// Returns a table mapping base64 bytes as the lookup index to either:
/// - [INVALID_VALUE] for bytes that aren&#39;t members of the alphabet
/// - a byte whose lower 6 bits are the value that was encoded into the index byte
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const fn </span>decode_table(alphabet: <span class="kw-2">&amp;</span>Alphabet) -&gt; [u8; <span class="number">256</span>] {
<span class="kw">let </span><span class="kw-2">mut </span>decode_table = [INVALID_VALUE; <span class="number">256</span>];
<span class="comment">// Since the table is full of `INVALID_VALUE` already, we only need to overwrite
// the parts that are valid.
</span><span class="kw">let </span><span class="kw-2">mut </span>index = <span class="number">0</span>;
<span class="kw">while </span>index &lt; <span class="number">64 </span>{
<span class="comment">// The index in the alphabet is the 6-bit value we care about.
// Since the index is in 0-63, it is safe to cast to u8.
</span>decode_table[alphabet.symbols[index] <span class="kw">as </span>usize] = index <span class="kw">as </span>u8;
index += <span class="number">1</span>;
}
decode_table
}
<span class="attribute">#[inline]
</span><span class="kw">fn </span>read_u64(s: <span class="kw-2">&amp;</span>[u8]) -&gt; u64 {
u64::from_be_bytes(s[..<span class="number">8</span>].try_into().unwrap())
}
<span class="doccomment">/// Contains configuration parameters for base64 encoding and decoding.
///
/// ```
/// # use base64::engine::GeneralPurposeConfig;
/// let config = GeneralPurposeConfig::new()
/// .with_encode_padding(false);
/// // further customize using `.with_*` methods as needed
/// ```
///
/// The constants [PAD] and [NO_PAD] cover most use cases.
///
/// To specify the characters used, see [Alphabet].
</span><span class="attribute">#[derive(Clone, Copy, Debug)]
</span><span class="kw">pub struct </span>GeneralPurposeConfig {
encode_padding: bool,
decode_allow_trailing_bits: bool,
decode_padding_mode: DecodePaddingMode,
}
<span class="kw">impl </span>GeneralPurposeConfig {
<span class="doccomment">/// Create a new config with `padding` = `true`, `decode_allow_trailing_bits` = `false`, and
/// `decode_padding_mode = DecodePaddingMode::RequireCanonicalPadding`.
///
/// This probably matches most people&#39;s expectations, but consider disabling padding to save
/// a few bytes unless you specifically need it for compatibility with some legacy system.
</span><span class="kw">pub const fn </span>new() -&gt; <span class="self">Self </span>{
<span class="self">Self </span>{
<span class="comment">// RFC states that padding must be applied by default
</span>encode_padding: <span class="bool-val">true</span>,
decode_allow_trailing_bits: <span class="bool-val">false</span>,
decode_padding_mode: DecodePaddingMode::RequireCanonical,
}
}
<span class="doccomment">/// Create a new config based on `self` with an updated `padding` setting.
///
/// If `padding` is `true`, encoding will append either 1 or 2 `=` padding characters as needed
/// to produce an output whose length is a multiple of 4.
///
/// Padding is not needed for correct decoding and only serves to waste bytes, but it&#39;s in the
/// [spec](https://datatracker.ietf.org/doc/html/rfc4648#section-3.2).
///
/// For new applications, consider not using padding if the decoders you&#39;re using don&#39;t require
/// padding to be present.
</span><span class="kw">pub const fn </span>with_encode_padding(<span class="self">self</span>, padding: bool) -&gt; <span class="self">Self </span>{
<span class="self">Self </span>{
encode_padding: padding,
..<span class="self">self
</span>}
}
<span class="doccomment">/// Create a new config based on `self` with an updated `decode_allow_trailing_bits` setting.
///
/// Most users will not need to configure this. It&#39;s useful if you need to decode base64
/// produced by a buggy encoder that has bits set in the unused space on the last base64
/// character as per [forgiving-base64 decode](https://infra.spec.whatwg.org/#forgiving-base64-decode).
/// If invalid trailing bits are present and this is `true`, those bits will
/// be silently ignored, else `DecodeError::InvalidLastSymbol` will be emitted.
</span><span class="kw">pub const fn </span>with_decode_allow_trailing_bits(<span class="self">self</span>, allow: bool) -&gt; <span class="self">Self </span>{
<span class="self">Self </span>{
decode_allow_trailing_bits: allow,
..<span class="self">self
</span>}
}
<span class="doccomment">/// Create a new config based on `self` with an updated `decode_padding_mode` setting.
///
/// Padding is not useful in terms of representing encoded data -- it makes no difference to
/// the decoder if padding is present or not, so if you have some un-padded input to decode, it
/// is perfectly fine to use `DecodePaddingMode::Indifferent` to prevent errors from being
/// emitted.
///
/// However, since in practice
/// [people who learned nothing from BER vs DER seem to expect base64 to have one canonical encoding](https://eprint.iacr.org/2022/361),
/// the default setting is the stricter `DecodePaddingMode::RequireCanonicalPadding`.
///
/// Or, if &quot;canonical&quot; in your circumstance means _no_ padding rather than padding to the
/// next multiple of four, there&#39;s `DecodePaddingMode::RequireNoPadding`.
</span><span class="kw">pub const fn </span>with_decode_padding_mode(<span class="self">self</span>, mode: DecodePaddingMode) -&gt; <span class="self">Self </span>{
<span class="self">Self </span>{
decode_padding_mode: mode,
..<span class="self">self
</span>}
}
}
<span class="kw">impl </span>Default <span class="kw">for </span>GeneralPurposeConfig {
<span class="doccomment">/// Delegates to [GeneralPurposeConfig::new].
</span><span class="kw">fn </span>default() -&gt; <span class="self">Self </span>{
<span class="self">Self</span>::new()
}
}
<span class="kw">impl </span>Config <span class="kw">for </span>GeneralPurposeConfig {
<span class="kw">fn </span>encode_padding(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; bool {
<span class="self">self</span>.encode_padding
}
}
<span class="doccomment">/// A [GeneralPurpose] engine using the [alphabet::STANDARD] base64 alphabet and [PAD] config.
</span><span class="kw">pub const </span>STANDARD: GeneralPurpose = GeneralPurpose::new(<span class="kw-2">&amp;</span>alphabet::STANDARD, PAD);
<span class="doccomment">/// A [GeneralPurpose] engine using the [alphabet::STANDARD] base64 alphabet and [NO_PAD] config.
</span><span class="kw">pub const </span>STANDARD_NO_PAD: GeneralPurpose = GeneralPurpose::new(<span class="kw-2">&amp;</span>alphabet::STANDARD, NO_PAD);
<span class="doccomment">/// A [GeneralPurpose] engine using the [alphabet::URL_SAFE] base64 alphabet and [PAD] config.
</span><span class="kw">pub const </span>URL_SAFE: GeneralPurpose = GeneralPurpose::new(<span class="kw-2">&amp;</span>alphabet::URL_SAFE, PAD);
<span class="doccomment">/// A [GeneralPurpose] engine using the [alphabet::URL_SAFE] base64 alphabet and [NO_PAD] config.
</span><span class="kw">pub const </span>URL_SAFE_NO_PAD: GeneralPurpose = GeneralPurpose::new(<span class="kw-2">&amp;</span>alphabet::URL_SAFE, NO_PAD);
<span class="doccomment">/// Include padding bytes when encoding, and require that they be present when decoding.
///
/// This is the standard per the base64 RFC, but consider using [NO_PAD] instead as padding serves
/// little purpose in practice.
</span><span class="kw">pub const </span>PAD: GeneralPurposeConfig = GeneralPurposeConfig::new();
<span class="doccomment">/// Don&#39;t add padding when encoding, and require no padding when decoding.
</span><span class="kw">pub const </span>NO_PAD: GeneralPurposeConfig = GeneralPurposeConfig::new()
.with_encode_padding(<span class="bool-val">false</span>)
.with_decode_padding_mode(DecodePaddingMode::RequireNone);
</code></pre></div>
</section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="base64" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html>