| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/base64-0.21.2/src/engine/general_purpose/mod.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mod.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../base64/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../base64/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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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">&</span>Alphabet, config: GeneralPurposeConfig) -> <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">&</span><span class="self">self</span>, input: <span class="kw-2">&</span>[u8], output: <span class="kw-2">&mut </span>[u8]) -> 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 > <span class="number">0 </span>{ |
| <span class="kw">while </span>input_index <= 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">&</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">&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'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">&</span>input_chunk[<span class="number">0</span>..]); |
| |
| output_chunk[<span class="number">0</span>] = <span class="self">self</span>.encode_table[((input_u64 >> <span class="number">58</span>) & 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 >> <span class="number">52</span>) & 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 >> <span class="number">46</span>) & 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 >> <span class="number">40</span>) & 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 >> <span class="number">34</span>) & 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 >> <span class="number">28</span>) & 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 >> <span class="number">22</span>) & 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 >> <span class="number">16</span>) & LOW_SIX_BITS) <span class="kw">as </span>usize]; |
| |
| <span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&</span>input_chunk[<span class="number">6</span>..]); |
| |
| output_chunk[<span class="number">8</span>] = <span class="self">self</span>.encode_table[((input_u64 >> <span class="number">58</span>) & 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 >> <span class="number">52</span>) & 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 >> <span class="number">46</span>) & 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 >> <span class="number">40</span>) & 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 >> <span class="number">34</span>) & 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 >> <span class="number">28</span>) & 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 >> <span class="number">22</span>) & 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 >> <span class="number">16</span>) & LOW_SIX_BITS) <span class="kw">as </span>usize]; |
| |
| <span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&</span>input_chunk[<span class="number">12</span>..]); |
| |
| output_chunk[<span class="number">16</span>] = <span class="self">self</span>.encode_table[((input_u64 >> <span class="number">58</span>) & 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 >> <span class="number">52</span>) & 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 >> <span class="number">46</span>) & 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 >> <span class="number">40</span>) & 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 >> <span class="number">34</span>) & 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 >> <span class="number">28</span>) & 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 >> <span class="number">22</span>) & 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 >> <span class="number">16</span>) & LOW_SIX_BITS) <span class="kw">as </span>usize]; |
| |
| <span class="kw">let </span>input_u64 = read_u64(<span class="kw-2">&</span>input_chunk[<span class="number">18</span>..]); |
| |
| output_chunk[<span class="number">24</span>] = <span class="self">self</span>.encode_table[((input_u64 >> <span class="number">58</span>) & 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 >> <span class="number">52</span>) & 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 >> <span class="number">46</span>) & 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 >> <span class="number">40</span>) & 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 >> <span class="number">34</span>) & 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 >> <span class="number">28</span>) & 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 >> <span class="number">22</span>) & 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 >> <span class="number">16</span>) & 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'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 < start_of_rem { |
| <span class="kw">let </span>input_chunk = <span class="kw-2">&</span>input[input_index..(input_index + <span class="number">3</span>)]; |
| <span class="kw">let </span>output_chunk = <span class="kw-2">&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>] >> <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>] << <span class="number">4 </span>| input_chunk[<span class="number">1</span>] >> <span class="number">4</span>) & 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>] << <span class="number">2 </span>| input_chunk[<span class="number">2</span>] >> <span class="number">6</span>) & 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>] & 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] >> <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] << <span class="number">4 </span>| input[start_of_rem + <span class="number">1</span>] >> <span class="number">4</span>) |
| & 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>] << <span class="number">2</span>) & 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] >> <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] << <span class="number">4</span>) & 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">&</span><span class="self">self</span>, input_len: usize) -> <span class="self">Self</span>::DecodeEstimate { |
| GeneralPurposeEstimate::new(input_len) |
| } |
| |
| <span class="kw">fn </span>internal_decode( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| input: <span class="kw-2">&</span>[u8], |
| output: <span class="kw-2">&mut </span>[u8], |
| estimate: <span class="self">Self</span>::DecodeEstimate, |
| ) -> <span class="prelude-ty">Result</span><DecodeMetadata, DecodeError> { |
| decode::decode_helper( |
| input, |
| estimate, |
| output, |
| <span class="kw-2">&</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">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="self">Self</span>::Config { |
| <span class="kw-2">&</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">&</span>Alphabet) -> [u8; <span class="number">64</span>] { |
| <span class="comment">// the encode table is just the alphabet: |
| // 6-bit index lookup -> 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 < <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'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">&</span>Alphabet) -> [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 < <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">&</span>[u8]) -> 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'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() -> <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'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're using don't require |
| /// padding to be present. |
| </span><span class="kw">pub const fn </span>with_encode_padding(<span class="self">self</span>, padding: bool) -> <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'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) -> <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 "canonical" in your circumstance means _no_ padding rather than padding to the |
| /// next multiple of four, there's `DecodePaddingMode::RequireNoPadding`. |
| </span><span class="kw">pub const fn </span>with_decode_padding_mode(<span class="self">self</span>, mode: DecodePaddingMode) -> <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() -> <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">&</span><span class="self">self</span>) -> 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">&</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">&</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">&</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">&</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'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> |