| <!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/base64-0.13.1/src/decode.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>decode.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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| <span id="523">523</span> |
| <span id="524">524</span> |
| <span id="525">525</span> |
| <span id="526">526</span> |
| <span id="527">527</span> |
| <span id="528">528</span> |
| <span id="529">529</span> |
| <span id="530">530</span> |
| <span id="531">531</span> |
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| <span id="611">611</span> |
| <span id="612">612</span> |
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| <span id="617">617</span> |
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| <span id="619">619</span> |
| <span id="620">620</span> |
| <span id="621">621</span> |
| <span id="622">622</span> |
| <span id="623">623</span> |
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| <span id="626">626</span> |
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| <span id="628">628</span> |
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| <span id="630">630</span> |
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| <span id="643">643</span> |
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| <span id="648">648</span> |
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| <span id="654">654</span> |
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| <span id="657">657</span> |
| <span id="658">658</span> |
| <span id="659">659</span> |
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| <span id="662">662</span> |
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| <span id="669">669</span> |
| <span id="670">670</span> |
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| <span id="672">672</span> |
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| <span id="729">729</span> |
| <span id="730">730</span> |
| <span id="731">731</span> |
| <span id="732">732</span> |
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| <span id="734">734</span> |
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| <span id="737">737</span> |
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| <span id="744">744</span> |
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| <span id="748">748</span> |
| <span id="749">749</span> |
| <span id="750">750</span> |
| <span id="751">751</span> |
| <span id="752">752</span> |
| <span id="753">753</span> |
| <span id="754">754</span> |
| <span id="755">755</span> |
| <span id="756">756</span> |
| <span id="757">757</span> |
| <span id="758">758</span> |
| <span id="759">759</span> |
| <span id="760">760</span> |
| <span id="761">761</span> |
| <span id="762">762</span> |
| <span id="763">763</span> |
| <span id="764">764</span> |
| <span id="765">765</span> |
| <span id="766">766</span> |
| <span id="767">767</span> |
| <span id="768">768</span> |
| <span id="769">769</span> |
| <span id="770">770</span> |
| <span id="771">771</span> |
| <span id="772">772</span> |
| <span id="773">773</span> |
| <span id="774">774</span> |
| <span id="775">775</span> |
| <span id="776">776</span> |
| <span id="777">777</span> |
| <span id="778">778</span> |
| <span id="779">779</span> |
| <span id="780">780</span> |
| <span id="781">781</span> |
| <span id="782">782</span> |
| <span id="783">783</span> |
| <span id="784">784</span> |
| <span id="785">785</span> |
| <span id="786">786</span> |
| <span id="787">787</span> |
| <span id="788">788</span> |
| <span id="789">789</span> |
| <span id="790">790</span> |
| <span id="791">791</span> |
| <span id="792">792</span> |
| <span id="793">793</span> |
| <span id="794">794</span> |
| <span id="795">795</span> |
| <span id="796">796</span> |
| <span id="797">797</span> |
| <span id="798">798</span> |
| <span id="799">799</span> |
| <span id="800">800</span> |
| <span id="801">801</span> |
| <span id="802">802</span> |
| <span id="803">803</span> |
| <span id="804">804</span> |
| <span id="805">805</span> |
| <span id="806">806</span> |
| <span id="807">807</span> |
| <span id="808">808</span> |
| <span id="809">809</span> |
| <span id="810">810</span> |
| <span id="811">811</span> |
| <span id="812">812</span> |
| <span id="813">813</span> |
| <span id="814">814</span> |
| <span id="815">815</span> |
| <span id="816">816</span> |
| <span id="817">817</span> |
| <span id="818">818</span> |
| <span id="819">819</span> |
| <span id="820">820</span> |
| <span id="821">821</span> |
| <span id="822">822</span> |
| <span id="823">823</span> |
| <span id="824">824</span> |
| <span id="825">825</span> |
| <span id="826">826</span> |
| <span id="827">827</span> |
| <span id="828">828</span> |
| <span id="829">829</span> |
| <span id="830">830</span> |
| <span id="831">831</span> |
| <span id="832">832</span> |
| <span id="833">833</span> |
| <span id="834">834</span> |
| <span id="835">835</span> |
| <span id="836">836</span> |
| <span id="837">837</span> |
| <span id="838">838</span> |
| <span id="839">839</span> |
| <span id="840">840</span> |
| <span id="841">841</span> |
| <span id="842">842</span> |
| <span id="843">843</span> |
| <span id="844">844</span> |
| <span id="845">845</span> |
| <span id="846">846</span> |
| <span id="847">847</span> |
| <span id="848">848</span> |
| <span id="849">849</span> |
| <span id="850">850</span> |
| <span id="851">851</span> |
| <span id="852">852</span> |
| <span id="853">853</span> |
| <span id="854">854</span> |
| <span id="855">855</span> |
| <span id="856">856</span> |
| <span id="857">857</span> |
| <span id="858">858</span> |
| <span id="859">859</span> |
| <span id="860">860</span> |
| <span id="861">861</span> |
| <span id="862">862</span> |
| <span id="863">863</span> |
| <span id="864">864</span> |
| <span id="865">865</span> |
| <span id="866">866</span> |
| <span id="867">867</span> |
| <span id="868">868</span> |
| <span id="869">869</span> |
| <span id="870">870</span> |
| <span id="871">871</span> |
| <span id="872">872</span> |
| <span id="873">873</span> |
| <span id="874">874</span> |
| <span id="875">875</span> |
| <span id="876">876</span> |
| <span id="877">877</span> |
| <span id="878">878</span> |
| <span id="879">879</span> |
| <span id="880">880</span> |
| <span id="881">881</span> |
| <span id="882">882</span> |
| <span id="883">883</span> |
| <span id="884">884</span> |
| <span id="885">885</span> |
| <span id="886">886</span> |
| <span id="887">887</span> |
| <span id="888">888</span> |
| <span id="889">889</span> |
| <span id="890">890</span> |
| <span id="891">891</span> |
| <span id="892">892</span> |
| <span id="893">893</span> |
| </pre><pre class="rust"><code><span class="kw">use crate</span>::{tables, Config, PAD_BYTE}; |
| |
| <span class="attribute">#[cfg(any(feature = <span class="string">"alloc"</span>, feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">use </span><span class="kw">crate</span>::STANDARD; |
| <span class="attribute">#[cfg(any(feature = <span class="string">"alloc"</span>, feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">use </span>alloc::vec::Vec; |
| <span class="kw">use </span>core::fmt; |
| <span class="attribute">#[cfg(any(feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">use </span>std::error; |
| |
| <span class="comment">// decode logic operates on chunks of 8 input bytes without padding |
| </span><span class="kw">const </span>INPUT_CHUNK_LEN: usize = <span class="number">8</span>; |
| <span class="kw">const </span>DECODED_CHUNK_LEN: usize = <span class="number">6</span>; |
| <span class="comment">// we read a u64 and write a u64, but a u64 of input only yields 6 bytes of output, so the last |
| // 2 bytes of any output u64 should not be counted as written to (but must be available in a |
| // slice). |
| </span><span class="kw">const </span>DECODED_CHUNK_SUFFIX: usize = <span class="number">2</span>; |
| |
| <span class="comment">// how many u64's of input to handle at a time |
| </span><span class="kw">const </span>CHUNKS_PER_FAST_LOOP_BLOCK: usize = <span class="number">4</span>; |
| <span class="kw">const </span>INPUT_BLOCK_LEN: usize = CHUNKS_PER_FAST_LOOP_BLOCK * INPUT_CHUNK_LEN; |
| <span class="comment">// includes the trailing 2 bytes for the final u64 write |
| </span><span class="kw">const </span>DECODED_BLOCK_LEN: usize = |
| CHUNKS_PER_FAST_LOOP_BLOCK * DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX; |
| |
| <span class="doccomment">/// Errors that can occur while decoding. |
| </span><span class="attribute">#[derive(Clone, Debug, PartialEq, Eq)] |
| </span><span class="kw">pub enum </span>DecodeError { |
| <span class="doccomment">/// An invalid byte was found in the input. The offset and offending byte are provided. |
| </span>InvalidByte(usize, u8), |
| <span class="doccomment">/// The length of the input is invalid. |
| /// A typical cause of this is stray trailing whitespace or other separator bytes. |
| /// In the case where excess trailing bytes have produced an invalid length *and* the last byte |
| /// is also an invalid base64 symbol (as would be the case for whitespace, etc), `InvalidByte` |
| /// will be emitted instead of `InvalidLength` to make the issue easier to debug. |
| </span>InvalidLength, |
| <span class="doccomment">/// The last non-padding input symbol's encoded 6 bits have nonzero bits that will be discarded. |
| /// This is indicative of corrupted or truncated Base64. |
| /// Unlike InvalidByte, which reports symbols that aren't in the alphabet, this error is for |
| /// symbols that are in the alphabet but represent nonsensical encodings. |
| </span>InvalidLastSymbol(usize, u8), |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>DecodeError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter) -> fmt::Result { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| DecodeError::InvalidByte(index, byte) => { |
| <span class="macro">write!</span>(f, <span class="string">"Invalid byte {}, offset {}."</span>, byte, index) |
| } |
| DecodeError::InvalidLength => <span class="macro">write!</span>(f, <span class="string">"Encoded text cannot have a 6-bit remainder."</span>), |
| DecodeError::InvalidLastSymbol(index, byte) => { |
| <span class="macro">write!</span>(f, <span class="string">"Invalid last symbol {}, offset {}."</span>, byte, index) |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(any(feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">impl </span>error::Error <span class="kw">for </span>DecodeError { |
| <span class="kw">fn </span>description(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str { |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| DecodeError::InvalidByte(<span class="kw">_</span>, <span class="kw">_</span>) => <span class="string">"invalid byte"</span>, |
| DecodeError::InvalidLength => <span class="string">"invalid length"</span>, |
| DecodeError::InvalidLastSymbol(<span class="kw">_</span>, <span class="kw">_</span>) => <span class="string">"invalid last symbol"</span>, |
| } |
| } |
| |
| <span class="kw">fn </span>cause(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="kw">dyn </span>error::Error> { |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="doccomment">///Decode from string reference as octets. |
| ///Returns a Result containing a Vec<u8>. |
| ///Convenience `decode_config(input, base64::STANDARD);`. |
| /// |
| ///# Example |
| /// |
| ///```rust |
| ///extern crate base64; |
| /// |
| ///fn main() { |
| /// let bytes = base64::decode("aGVsbG8gd29ybGQ=").unwrap(); |
| /// println!("{:?}", bytes); |
| ///} |
| ///``` |
| </span><span class="attribute">#[cfg(any(feature = <span class="string">"alloc"</span>, feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">pub fn </span>decode<T: AsRef<[u8]>>(input: T) -> <span class="prelude-ty">Result</span><Vec<u8>, DecodeError> { |
| decode_config(input, STANDARD) |
| } |
| |
| <span class="doccomment">///Decode from string reference as octets. |
| ///Returns a Result containing a Vec<u8>. |
| /// |
| ///# Example |
| /// |
| ///```rust |
| ///extern crate base64; |
| /// |
| ///fn main() { |
| /// let bytes = base64::decode_config("aGVsbG8gd29ybGR+Cg==", base64::STANDARD).unwrap(); |
| /// println!("{:?}", bytes); |
| /// |
| /// let bytes_url = base64::decode_config("aGVsbG8gaW50ZXJuZXR-Cg==", base64::URL_SAFE).unwrap(); |
| /// println!("{:?}", bytes_url); |
| ///} |
| ///``` |
| </span><span class="attribute">#[cfg(any(feature = <span class="string">"alloc"</span>, feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">pub fn </span>decode_config<T: AsRef<[u8]>>(input: T, config: Config) -> <span class="prelude-ty">Result</span><Vec<u8>, DecodeError> { |
| <span class="kw">let </span>decoded_length_estimate = (input |
| .as_ref() |
| .len() |
| .checked_add(<span class="number">3</span>) |
| .expect(<span class="string">"decoded length calculation overflow"</span>)) |
| / <span class="number">4 |
| </span>* <span class="number">3</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = Vec::<u8>::with_capacity(decoded_length_estimate); |
| |
| decode_config_buf(input, config, <span class="kw-2">&mut </span>buffer).map(|<span class="kw">_</span>| buffer) |
| } |
| |
| <span class="doccomment">///Decode from string reference as octets. |
| ///Writes into the supplied buffer to avoid allocation. |
| ///Returns a Result containing an empty tuple, aka (). |
| /// |
| ///# Example |
| /// |
| ///```rust |
| ///extern crate base64; |
| /// |
| ///fn main() { |
| /// let mut buffer = Vec::<u8>::new(); |
| /// base64::decode_config_buf("aGVsbG8gd29ybGR+Cg==", base64::STANDARD, &mut buffer).unwrap(); |
| /// println!("{:?}", buffer); |
| /// |
| /// buffer.clear(); |
| /// |
| /// base64::decode_config_buf("aGVsbG8gaW50ZXJuZXR-Cg==", base64::URL_SAFE, &mut buffer) |
| /// .unwrap(); |
| /// println!("{:?}", buffer); |
| ///} |
| ///``` |
| </span><span class="attribute">#[cfg(any(feature = <span class="string">"alloc"</span>, feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">pub fn </span>decode_config_buf<T: AsRef<[u8]>>( |
| input: T, |
| config: Config, |
| buffer: <span class="kw-2">&mut </span>Vec<u8>, |
| ) -> <span class="prelude-ty">Result</span><(), DecodeError> { |
| <span class="kw">let </span>input_bytes = input.as_ref(); |
| |
| <span class="kw">let </span>starting_output_len = buffer.len(); |
| |
| <span class="kw">let </span>num_chunks = num_chunks(input_bytes); |
| <span class="kw">let </span>decoded_len_estimate = num_chunks |
| .checked_mul(DECODED_CHUNK_LEN) |
| .and_then(|p| p.checked_add(starting_output_len)) |
| .expect(<span class="string">"Overflow when calculating output buffer length"</span>); |
| buffer.resize(decoded_len_estimate, <span class="number">0</span>); |
| |
| <span class="kw">let </span>bytes_written; |
| { |
| <span class="kw">let </span>buffer_slice = <span class="kw-2">&mut </span>buffer.as_mut_slice()[starting_output_len..]; |
| bytes_written = decode_helper(input_bytes, num_chunks, config, buffer_slice)<span class="question-mark">?</span>; |
| } |
| |
| buffer.truncate(starting_output_len + bytes_written); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Decode the input into the provided output slice. |
| /// |
| /// This will not write any bytes past exactly what is decoded (no stray garbage bytes at the end). |
| /// |
| /// If you don't know ahead of time what the decoded length should be, size your buffer with a |
| /// conservative estimate for the decoded length of an input: 3 bytes of output for every 4 bytes of |
| /// input, rounded up, or in other words `(input_len + 3) / 4 * 3`. |
| /// |
| /// If the slice is not large enough, this will panic. |
| </span><span class="kw">pub fn </span>decode_config_slice<T: AsRef<[u8]>>( |
| input: T, |
| config: Config, |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><usize, DecodeError> { |
| <span class="kw">let </span>input_bytes = input.as_ref(); |
| |
| decode_helper(input_bytes, num_chunks(input_bytes), config, output) |
| } |
| |
| <span class="doccomment">/// Return the number of input chunks (including a possibly partial final chunk) in the input |
| </span><span class="kw">fn </span>num_chunks(input: <span class="kw-2">&</span>[u8]) -> usize { |
| input |
| .len() |
| .checked_add(INPUT_CHUNK_LEN - <span class="number">1</span>) |
| .expect(<span class="string">"Overflow when calculating number of chunks in input"</span>) |
| / INPUT_CHUNK_LEN |
| } |
| |
| <span class="doccomment">/// Helper to avoid duplicating num_chunks calculation, which is costly on short inputs. |
| /// Returns the number of bytes written, or an error. |
| </span><span class="comment">// We're on the fragile edge of compiler heuristics here. If this is not inlined, slow. If this is |
| // inlined(always), a different slow. plain ol' inline makes the benchmarks happiest at the moment, |
| // but this is fragile and the best setting changes with only minor code modifications. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">fn </span>decode_helper( |
| input: <span class="kw-2">&</span>[u8], |
| num_chunks: usize, |
| config: Config, |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><usize, DecodeError> { |
| <span class="kw">let </span>char_set = config.char_set; |
| <span class="kw">let </span>decode_table = char_set.decode_table(); |
| |
| <span class="kw">let </span>remainder_len = input.len() % INPUT_CHUNK_LEN; |
| |
| <span class="comment">// Because the fast decode loop writes in groups of 8 bytes (unrolled to |
| // CHUNKS_PER_FAST_LOOP_BLOCK times 8 bytes, where possible) and outputs 8 bytes at a time (of |
| // which only 6 are valid data), we need to be sure that we stop using the fast decode loop |
| // soon enough that there will always be 2 more bytes of valid data written after that loop. |
| </span><span class="kw">let </span>trailing_bytes_to_skip = <span class="kw">match </span>remainder_len { |
| <span class="comment">// if input is a multiple of the chunk size, ignore the last chunk as it may have padding, |
| // and the fast decode logic cannot handle padding |
| </span><span class="number">0 </span>=> INPUT_CHUNK_LEN, |
| <span class="comment">// 1 and 5 trailing bytes are illegal: can't decode 6 bits of input into a byte |
| </span><span class="number">1 </span>| <span class="number">5 </span>=> { |
| <span class="comment">// trailing whitespace is so common that it's worth it to check the last byte to |
| // possibly return a better error message |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(b) = input.last() { |
| <span class="kw">if </span><span class="kw-2">*</span>b != PAD_BYTE && decode_table[<span class="kw-2">*</span>b <span class="kw">as </span>usize] == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(input.len() - <span class="number">1</span>, <span class="kw-2">*</span>b)); |
| } |
| } |
| |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidLength); |
| } |
| <span class="comment">// This will decode to one output byte, which isn't enough to overwrite the 2 extra bytes |
| // written by the fast decode loop. So, we have to ignore both these 2 bytes and the |
| // previous chunk. |
| </span><span class="number">2 </span>=> INPUT_CHUNK_LEN + <span class="number">2</span>, |
| <span class="comment">// If this is 3 unpadded chars, then it would actually decode to 2 bytes. However, if this |
| // is an erroneous 2 chars + 1 pad char that would decode to 1 byte, then it should fail |
| // with an error, not panic from going past the bounds of the output slice, so we let it |
| // use stage 3 + 4. |
| </span><span class="number">3 </span>=> INPUT_CHUNK_LEN + <span class="number">3</span>, |
| <span class="comment">// This can also decode to one output byte because it may be 2 input chars + 2 padding |
| // chars, which would decode to 1 byte. |
| </span><span class="number">4 </span>=> INPUT_CHUNK_LEN + <span class="number">4</span>, |
| <span class="comment">// Everything else is a legal decode len (given that we don't require padding), and will |
| // decode to at least 2 bytes of output. |
| </span><span class="kw">_ </span>=> remainder_len, |
| }; |
| |
| <span class="comment">// rounded up to include partial chunks |
| </span><span class="kw">let </span><span class="kw-2">mut </span>remaining_chunks = num_chunks; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>input_index = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>output_index = <span class="number">0</span>; |
| |
| { |
| <span class="kw">let </span>length_of_fast_decode_chunks = input.len().saturating_sub(trailing_bytes_to_skip); |
| |
| <span class="comment">// Fast loop, stage 1 |
| // manual unroll to CHUNKS_PER_FAST_LOOP_BLOCK of u64s to amortize slice bounds checks |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_BLOCK_LEN) { |
| <span class="kw">while </span>input_index <= max_start_index { |
| <span class="kw">let </span>input_slice = <span class="kw-2">&</span>input[input_index..(input_index + INPUT_BLOCK_LEN)]; |
| <span class="kw">let </span>output_slice = <span class="kw-2">&mut </span>output[output_index..(output_index + DECODED_BLOCK_LEN)]; |
| |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">0</span>..], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">0</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">8</span>..], |
| input_index + <span class="number">8</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">6</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">16</span>..], |
| input_index + <span class="number">16</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">12</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">24</span>..], |
| input_index + <span class="number">24</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">18</span>..], |
| )<span class="question-mark">?</span>; |
| |
| input_index += INPUT_BLOCK_LEN; |
| output_index += DECODED_BLOCK_LEN - DECODED_CHUNK_SUFFIX; |
| remaining_chunks -= CHUNKS_PER_FAST_LOOP_BLOCK; |
| } |
| } |
| |
| <span class="comment">// Fast loop, stage 2 (aka still pretty fast loop) |
| // 8 bytes at a time for whatever we didn't do in stage 1. |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_CHUNK_LEN) { |
| <span class="kw">while </span>input_index < max_start_index { |
| decode_chunk( |
| <span class="kw-2">&</span>input[input_index..(input_index + INPUT_CHUNK_LEN)], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output |
| [output_index..(output_index + DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX)], |
| )<span class="question-mark">?</span>; |
| |
| output_index += DECODED_CHUNK_LEN; |
| input_index += INPUT_CHUNK_LEN; |
| remaining_chunks -= <span class="number">1</span>; |
| } |
| } |
| } |
| |
| <span class="comment">// Stage 3 |
| // If input length was such that a chunk had to be deferred until after the fast loop |
| // because decoding it would have produced 2 trailing bytes that wouldn't then be |
| // overwritten, we decode that chunk here. This way is slower but doesn't write the 2 |
| // trailing bytes. |
| // However, we still need to avoid the last chunk (partial or complete) because it could |
| // have padding, so we always do 1 fewer to avoid the last chunk. |
| </span><span class="kw">for _ in </span><span class="number">1</span>..remaining_chunks { |
| decode_chunk_precise( |
| <span class="kw-2">&</span>input[input_index..], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output[output_index..(output_index + DECODED_CHUNK_LEN)], |
| )<span class="question-mark">?</span>; |
| |
| input_index += INPUT_CHUNK_LEN; |
| output_index += DECODED_CHUNK_LEN; |
| } |
| |
| <span class="comment">// always have one more (possibly partial) block of 8 input |
| </span><span class="macro">debug_assert!</span>(input.len() - input_index > <span class="number">1 </span>|| input.is_empty()); |
| <span class="macro">debug_assert!</span>(input.len() - input_index <= <span class="number">8</span>); |
| |
| <span class="comment">// Stage 4 |
| // Finally, decode any leftovers that aren't a complete input block of 8 bytes. |
| // Use a u64 as a stack-resident 8 byte buffer. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>leftover_bits: u64 = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>morsels_in_leftover = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>padding_bytes = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>first_padding_index: usize = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>last_symbol = <span class="number">0_u8</span>; |
| <span class="kw">let </span>start_of_leftovers = input_index; |
| <span class="kw">for </span>(i, b) <span class="kw">in </span>input[start_of_leftovers..].iter().enumerate() { |
| <span class="comment">// '=' padding |
| </span><span class="kw">if </span><span class="kw-2">*</span>b == PAD_BYTE { |
| <span class="comment">// There can be bad padding in a few ways: |
| // 1 - Padding with non-padding characters after it |
| // 2 - Padding after zero or one non-padding characters before it |
| // in the current quad. |
| // 3 - More than two characters of padding. If 3 or 4 padding chars |
| // are in the same quad, that implies it will be caught by #2. |
| // If it spreads from one quad to another, it will be caught by |
| // #2 in the second quad. |
| |
| </span><span class="kw">if </span>i % <span class="number">4 </span>< <span class="number">2 </span>{ |
| <span class="comment">// Check for case #2. |
| </span><span class="kw">let </span>bad_padding_index = start_of_leftovers |
| + <span class="kw">if </span>padding_bytes > <span class="number">0 </span>{ |
| <span class="comment">// If we've already seen padding, report the first padding index. |
| // This is to be consistent with the faster logic above: it will report an |
| // error on the first padding character (since it doesn't expect to see |
| // anything but actual encoded data). |
| </span>first_padding_index |
| } <span class="kw">else </span>{ |
| <span class="comment">// haven't seen padding before, just use where we are now |
| </span>i |
| }; |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(bad_padding_index, <span class="kw-2">*</span>b)); |
| } |
| |
| <span class="kw">if </span>padding_bytes == <span class="number">0 </span>{ |
| first_padding_index = i; |
| } |
| |
| padding_bytes += <span class="number">1</span>; |
| <span class="kw">continue</span>; |
| } |
| |
| <span class="comment">// Check for case #1. |
| // To make '=' handling consistent with the main loop, don't allow |
| // non-suffix '=' in trailing chunk either. Report error as first |
| // erroneous padding. |
| </span><span class="kw">if </span>padding_bytes > <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| start_of_leftovers + first_padding_index, |
| PAD_BYTE, |
| )); |
| } |
| last_symbol = <span class="kw-2">*</span>b; |
| |
| <span class="comment">// can use up to 8 * 6 = 48 bits of the u64, if last chunk has no padding. |
| // To minimize shifts, pack the leftovers from left to right. |
| </span><span class="kw">let </span>shift = <span class="number">64 </span>- (morsels_in_leftover + <span class="number">1</span>) * <span class="number">6</span>; |
| <span class="comment">// tables are all 256 elements, lookup with a u8 index always succeeds |
| </span><span class="kw">let </span>morsel = decode_table[<span class="kw-2">*</span>b <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(start_of_leftovers + i, <span class="kw-2">*</span>b)); |
| } |
| |
| leftover_bits |= (morsel <span class="kw">as </span>u64) << shift; |
| morsels_in_leftover += <span class="number">1</span>; |
| } |
| |
| <span class="kw">let </span>leftover_bits_ready_to_append = <span class="kw">match </span>morsels_in_leftover { |
| <span class="number">0 </span>=> <span class="number">0</span>, |
| <span class="number">2 </span>=> <span class="number">8</span>, |
| <span class="number">3 </span>=> <span class="number">16</span>, |
| <span class="number">4 </span>=> <span class="number">24</span>, |
| <span class="number">6 </span>=> <span class="number">32</span>, |
| <span class="number">7 </span>=> <span class="number">40</span>, |
| <span class="number">8 </span>=> <span class="number">48</span>, |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>( |
| <span class="string">"Impossible: must only have 0 to 8 input bytes in last chunk, with no invalid lengths" |
| </span>), |
| }; |
| |
| <span class="comment">// if there are bits set outside the bits we care about, last symbol encodes trailing bits that |
| // will not be included in the output |
| </span><span class="kw">let </span>mask = !<span class="number">0 </span>>> leftover_bits_ready_to_append; |
| <span class="kw">if </span>!config.decode_allow_trailing_bits && (leftover_bits & mask) != <span class="number">0 </span>{ |
| <span class="comment">// last morsel is at `morsels_in_leftover` - 1 |
| </span><span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol( |
| start_of_leftovers + morsels_in_leftover - <span class="number">1</span>, |
| last_symbol, |
| )); |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>leftover_bits_appended_to_buf = <span class="number">0</span>; |
| <span class="kw">while </span>leftover_bits_appended_to_buf < leftover_bits_ready_to_append { |
| <span class="comment">// `as` simply truncates the higher bits, which is what we want here |
| </span><span class="kw">let </span>selected_bits = (leftover_bits >> (<span class="number">56 </span>- leftover_bits_appended_to_buf)) <span class="kw">as </span>u8; |
| output[output_index] = selected_bits; |
| output_index += <span class="number">1</span>; |
| |
| leftover_bits_appended_to_buf += <span class="number">8</span>; |
| } |
| |
| <span class="prelude-val">Ok</span>(output_index) |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>write_u64(output: <span class="kw-2">&mut </span>[u8], value: u64) { |
| output[..<span class="number">8</span>].copy_from_slice(<span class="kw-2">&</span>value.to_be_bytes()); |
| } |
| |
| <span class="doccomment">/// Decode 8 bytes of input into 6 bytes of output. 8 bytes of output will be written, but only the |
| /// first 6 of those contain meaningful data. |
| /// |
| /// `input` is the bytes to decode, of which the first 8 bytes will be processed. |
| /// `index_at_start_of_input` is the offset in the overall input (used for reporting errors |
| /// accurately) |
| /// `decode_table` is the lookup table for the particular base64 alphabet. |
| /// `output` will have its first 8 bytes overwritten, of which only the first 6 are valid decoded |
| /// data. |
| </span><span class="comment">// yes, really inline (worth 30-50% speedup) |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>decode_chunk( |
| input: <span class="kw-2">&</span>[u8], |
| index_at_start_of_input: usize, |
| decode_table: <span class="kw-2">&</span>[u8; <span class="number">256</span>], |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), DecodeError> { |
| <span class="kw">let </span><span class="kw-2">mut </span>accum: u64; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">0</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(index_at_start_of_input, input[<span class="number">0</span>])); |
| } |
| accum = (morsel <span class="kw">as </span>u64) << <span class="number">58</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">1</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">1</span>, |
| input[<span class="number">1</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">52</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">2</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">2</span>, |
| input[<span class="number">2</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">46</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">3</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">3</span>, |
| input[<span class="number">3</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">40</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">4</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">4</span>, |
| input[<span class="number">4</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">34</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">5</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">5</span>, |
| input[<span class="number">5</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">28</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">6</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">6</span>, |
| input[<span class="number">6</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">22</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">7</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == tables::INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">7</span>, |
| input[<span class="number">7</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">16</span>; |
| |
| write_u64(output, accum); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Decode an 8-byte chunk, but only write the 6 bytes actually decoded instead of including 2 |
| /// trailing garbage bytes. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">fn </span>decode_chunk_precise( |
| input: <span class="kw-2">&</span>[u8], |
| index_at_start_of_input: usize, |
| decode_table: <span class="kw-2">&</span>[u8; <span class="number">256</span>], |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), DecodeError> { |
| <span class="kw">let </span><span class="kw-2">mut </span>tmp_buf = [<span class="number">0_u8</span>; <span class="number">8</span>]; |
| |
| decode_chunk( |
| input, |
| index_at_start_of_input, |
| decode_table, |
| <span class="kw-2">&mut </span>tmp_buf[..], |
| )<span class="question-mark">?</span>; |
| |
| output[<span class="number">0</span>..<span class="number">6</span>].copy_from_slice(<span class="kw-2">&</span>tmp_buf[<span class="number">0</span>..<span class="number">6</span>]); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use crate</span>::{ |
| encode::encode_config_buf, |
| encode::encode_config_slice, |
| tests::{assert_encode_sanity, random_config}, |
| }; |
| |
| <span class="kw">use </span>rand::{ |
| distributions::{Distribution, Uniform}, |
| FromEntropy, Rng, |
| }; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_chunk_precise_writes_only_6_bytes() { |
| <span class="kw">let </span>input = <span class="string">b"Zm9vYmFy"</span>; <span class="comment">// "foobar" |
| </span><span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0_u8</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>]; |
| decode_chunk_precise(<span class="kw-2">&</span>input[..], <span class="number">0</span>, tables::STANDARD_DECODE, <span class="kw-2">&mut </span>output).unwrap(); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span><span class="macro">vec!</span>[<span class="string">b'f'</span>, <span class="string">b'o'</span>, <span class="string">b'o'</span>, <span class="string">b'b'</span>, <span class="string">b'a'</span>, <span class="string">b'r'</span>, <span class="number">6</span>, <span class="number">7</span>], <span class="kw-2">&</span>output); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_chunk_writes_8_bytes() { |
| <span class="kw">let </span>input = <span class="string">b"Zm9vYmFy"</span>; <span class="comment">// "foobar" |
| </span><span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0_u8</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>]; |
| decode_chunk(<span class="kw-2">&</span>input[..], <span class="number">0</span>, tables::STANDARD_DECODE, <span class="kw-2">&mut </span>output).unwrap(); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span><span class="macro">vec!</span>[<span class="string">b'f'</span>, <span class="string">b'o'</span>, <span class="string">b'o'</span>, <span class="string">b'b'</span>, <span class="string">b'a'</span>, <span class="string">b'r'</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="kw-2">&</span>output); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_into_nonempty_vec_doesnt_clobber_existing_prefix() { |
| <span class="kw">let </span><span class="kw-2">mut </span>orig_data = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>encoded_data = String::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>decoded_with_prefix = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>decoded_without_prefix = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>prefix = Vec::new(); |
| |
| <span class="kw">let </span>prefix_len_range = Uniform::new(<span class="number">0</span>, <span class="number">1000</span>); |
| <span class="kw">let </span>input_len_range = Uniform::new(<span class="number">0</span>, <span class="number">1000</span>); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = rand::rngs::SmallRng::from_entropy(); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">10_000 </span>{ |
| orig_data.clear(); |
| encoded_data.clear(); |
| decoded_with_prefix.clear(); |
| decoded_without_prefix.clear(); |
| prefix.clear(); |
| |
| <span class="kw">let </span>input_len = input_len_range.sample(<span class="kw-2">&mut </span>rng); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..input_len { |
| orig_data.push(rng.gen()); |
| } |
| |
| <span class="kw">let </span>config = random_config(<span class="kw-2">&mut </span>rng); |
| encode_config_buf(<span class="kw-2">&</span>orig_data, config, <span class="kw-2">&mut </span>encoded_data); |
| assert_encode_sanity(<span class="kw-2">&</span>encoded_data, config, input_len); |
| |
| <span class="kw">let </span>prefix_len = prefix_len_range.sample(<span class="kw-2">&mut </span>rng); |
| |
| <span class="comment">// fill the buf with a prefix |
| </span><span class="kw">for _ in </span><span class="number">0</span>..prefix_len { |
| prefix.push(rng.gen()); |
| } |
| |
| decoded_with_prefix.resize(prefix_len, <span class="number">0</span>); |
| decoded_with_prefix.copy_from_slice(<span class="kw-2">&</span>prefix); |
| |
| <span class="comment">// decode into the non-empty buf |
| </span>decode_config_buf(<span class="kw-2">&</span>encoded_data, config, <span class="kw-2">&mut </span>decoded_with_prefix).unwrap(); |
| <span class="comment">// also decode into the empty buf |
| </span>decode_config_buf(<span class="kw-2">&</span>encoded_data, config, <span class="kw-2">&mut </span>decoded_without_prefix).unwrap(); |
| |
| <span class="macro">assert_eq!</span>( |
| prefix_len + decoded_without_prefix.len(), |
| decoded_with_prefix.len() |
| ); |
| <span class="macro">assert_eq!</span>(orig_data, decoded_without_prefix); |
| |
| <span class="comment">// append plain decode onto prefix |
| </span>prefix.append(<span class="kw-2">&mut </span>decoded_without_prefix); |
| |
| <span class="macro">assert_eq!</span>(prefix, decoded_with_prefix); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_into_slice_doesnt_clobber_existing_prefix_or_suffix() { |
| <span class="kw">let </span><span class="kw-2">mut </span>orig_data = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>encoded_data = String::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>decode_buf = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>decode_buf_copy: Vec<u8> = Vec::new(); |
| |
| <span class="kw">let </span>input_len_range = Uniform::new(<span class="number">0</span>, <span class="number">1000</span>); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = rand::rngs::SmallRng::from_entropy(); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">10_000 </span>{ |
| orig_data.clear(); |
| encoded_data.clear(); |
| decode_buf.clear(); |
| decode_buf_copy.clear(); |
| |
| <span class="kw">let </span>input_len = input_len_range.sample(<span class="kw-2">&mut </span>rng); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..input_len { |
| orig_data.push(rng.gen()); |
| } |
| |
| <span class="kw">let </span>config = random_config(<span class="kw-2">&mut </span>rng); |
| encode_config_buf(<span class="kw-2">&</span>orig_data, config, <span class="kw-2">&mut </span>encoded_data); |
| assert_encode_sanity(<span class="kw-2">&</span>encoded_data, config, input_len); |
| |
| <span class="comment">// fill the buffer with random garbage, long enough to have some room before and after |
| </span><span class="kw">for _ in </span><span class="number">0</span>..<span class="number">5000 </span>{ |
| decode_buf.push(rng.gen()); |
| } |
| |
| <span class="comment">// keep a copy for later comparison |
| </span>decode_buf_copy.extend(decode_buf.iter()); |
| |
| <span class="kw">let </span>offset = <span class="number">1000</span>; |
| |
| <span class="comment">// decode into the non-empty buf |
| </span><span class="kw">let </span>decode_bytes_written = |
| decode_config_slice(<span class="kw-2">&</span>encoded_data, config, <span class="kw-2">&mut </span>decode_buf[offset..]).unwrap(); |
| |
| <span class="macro">assert_eq!</span>(orig_data.len(), decode_bytes_written); |
| <span class="macro">assert_eq!</span>( |
| orig_data, |
| <span class="kw-2">&</span>decode_buf[offset..(offset + decode_bytes_written)] |
| ); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>decode_buf_copy[<span class="number">0</span>..offset], <span class="kw-2">&</span>decode_buf[<span class="number">0</span>..offset]); |
| <span class="macro">assert_eq!</span>( |
| <span class="kw-2">&</span>decode_buf_copy[offset + decode_bytes_written..], |
| <span class="kw-2">&</span>decode_buf[offset + decode_bytes_written..] |
| ); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_into_slice_fits_in_precisely_sized_slice() { |
| <span class="kw">let </span><span class="kw-2">mut </span>orig_data = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>encoded_data = String::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>decode_buf = Vec::new(); |
| |
| <span class="kw">let </span>input_len_range = Uniform::new(<span class="number">0</span>, <span class="number">1000</span>); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = rand::rngs::SmallRng::from_entropy(); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">10_000 </span>{ |
| orig_data.clear(); |
| encoded_data.clear(); |
| decode_buf.clear(); |
| |
| <span class="kw">let </span>input_len = input_len_range.sample(<span class="kw-2">&mut </span>rng); |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..input_len { |
| orig_data.push(rng.gen()); |
| } |
| |
| <span class="kw">let </span>config = random_config(<span class="kw-2">&mut </span>rng); |
| encode_config_buf(<span class="kw-2">&</span>orig_data, config, <span class="kw-2">&mut </span>encoded_data); |
| assert_encode_sanity(<span class="kw-2">&</span>encoded_data, config, input_len); |
| |
| decode_buf.resize(input_len, <span class="number">0</span>); |
| |
| <span class="comment">// decode into the non-empty buf |
| </span><span class="kw">let </span>decode_bytes_written = |
| decode_config_slice(<span class="kw-2">&</span>encoded_data, config, <span class="kw-2">&mut </span>decode_buf[..]).unwrap(); |
| |
| <span class="macro">assert_eq!</span>(orig_data.len(), decode_bytes_written); |
| <span class="macro">assert_eq!</span>(orig_data, decode_buf); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>detect_invalid_last_symbol_two_bytes() { |
| <span class="kw">let </span>decode = |
| |input, forgiving| decode_config(input, STANDARD.decode_allow_trailing_bits(forgiving)); |
| |
| <span class="comment">// example from https://github.com/marshallpierce/rust-base64/issues/75 |
| </span><span class="macro">assert!</span>(decode(<span class="string">"iYU="</span>, <span class="bool-val">false</span>).is_ok()); |
| <span class="comment">// trailing 01 |
| </span><span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">2</span>, <span class="string">b'V'</span>)), |
| decode(<span class="string">"iYV="</span>, <span class="bool-val">false</span>) |
| ); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[<span class="number">137</span>, <span class="number">133</span>]), decode(<span class="string">"iYV="</span>, <span class="bool-val">true</span>)); |
| <span class="comment">// trailing 10 |
| </span><span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">2</span>, <span class="string">b'W'</span>)), |
| decode(<span class="string">"iYW="</span>, <span class="bool-val">false</span>) |
| ); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[<span class="number">137</span>, <span class="number">133</span>]), decode(<span class="string">"iYV="</span>, <span class="bool-val">true</span>)); |
| <span class="comment">// trailing 11 |
| </span><span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">2</span>, <span class="string">b'X'</span>)), |
| decode(<span class="string">"iYX="</span>, <span class="bool-val">false</span>) |
| ); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[<span class="number">137</span>, <span class="number">133</span>]), decode(<span class="string">"iYV="</span>, <span class="bool-val">true</span>)); |
| |
| <span class="comment">// also works when there are 2 quads in the last block |
| </span><span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">6</span>, <span class="string">b'X'</span>)), |
| decode(<span class="string">"AAAAiYX="</span>, <span class="bool-val">false</span>) |
| ); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">137</span>, <span class="number">133</span>]), decode(<span class="string">"AAAAiYX="</span>, <span class="bool-val">true</span>)); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>detect_invalid_last_symbol_one_byte() { |
| <span class="comment">// 0xFF -> "/w==", so all letters > w, 0-9, and '+', '/' should get InvalidLastSymbol |
| |
| </span><span class="macro">assert!</span>(decode(<span class="string">"/w=="</span>).is_ok()); |
| <span class="comment">// trailing 01 |
| </span><span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'x'</span>)), decode(<span class="string">"/x=="</span>)); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'z'</span>)), decode(<span class="string">"/z=="</span>)); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'0'</span>)), decode(<span class="string">"/0=="</span>)); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'9'</span>)), decode(<span class="string">"/9=="</span>)); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'+'</span>)), decode(<span class="string">"/+=="</span>)); |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, <span class="string">b'/'</span>)), decode(<span class="string">"//=="</span>)); |
| |
| <span class="comment">// also works when there are 2 quads in the last block |
| </span><span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">5</span>, <span class="string">b'x'</span>)), |
| decode(<span class="string">"AAAA/x=="</span>) |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>detect_invalid_last_symbol_every_possible_three_symbols() { |
| <span class="kw">let </span><span class="kw-2">mut </span>base64_to_bytes = ::std::collections::HashMap::new(); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>bytes = [<span class="number">0_u8</span>; <span class="number">2</span>]; |
| <span class="kw">for </span>b1 <span class="kw">in </span><span class="number">0_u16</span>..<span class="number">256 </span>{ |
| bytes[<span class="number">0</span>] = b1 <span class="kw">as </span>u8; |
| <span class="kw">for </span>b2 <span class="kw">in </span><span class="number">0_u16</span>..<span class="number">256 </span>{ |
| bytes[<span class="number">1</span>] = b2 <span class="kw">as </span>u8; |
| <span class="kw">let </span><span class="kw-2">mut </span>b64 = <span class="macro">vec!</span>[<span class="number">0_u8</span>; <span class="number">4</span>]; |
| <span class="macro">assert_eq!</span>(<span class="number">4</span>, encode_config_slice(<span class="kw-2">&</span>bytes, STANDARD, <span class="kw-2">&mut </span>b64[..])); |
| <span class="kw">let </span><span class="kw-2">mut </span>v = ::std::vec::Vec::with_capacity(<span class="number">2</span>); |
| v.extend_from_slice(<span class="kw-2">&</span>bytes[..]); |
| |
| <span class="macro">assert!</span>(base64_to_bytes.insert(b64, v).is_none()); |
| } |
| } |
| |
| <span class="comment">// every possible combination of symbols must either decode to 2 bytes or get InvalidLastSymbol |
| |
| </span><span class="kw">let </span><span class="kw-2">mut </span>symbols = [<span class="number">0_u8</span>; <span class="number">4</span>]; |
| <span class="kw">for </span><span class="kw-2">&</span>s1 <span class="kw">in </span>STANDARD.char_set.encode_table().iter() { |
| symbols[<span class="number">0</span>] = s1; |
| <span class="kw">for </span><span class="kw-2">&</span>s2 <span class="kw">in </span>STANDARD.char_set.encode_table().iter() { |
| symbols[<span class="number">1</span>] = s2; |
| <span class="kw">for </span><span class="kw-2">&</span>s3 <span class="kw">in </span>STANDARD.char_set.encode_table().iter() { |
| symbols[<span class="number">2</span>] = s3; |
| symbols[<span class="number">3</span>] = PAD_BYTE; |
| |
| <span class="kw">match </span>base64_to_bytes.get(<span class="kw-2">&</span>symbols[..]) { |
| <span class="prelude-val">Some</span>(bytes) => { |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(bytes.to_vec()), decode_config(<span class="kw-2">&</span>symbols, STANDARD)) |
| } |
| <span class="prelude-val">None </span>=> <span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">2</span>, s3)), |
| decode_config(<span class="kw-2">&</span>symbols[..], STANDARD) |
| ), |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>detect_invalid_last_symbol_every_possible_two_symbols() { |
| <span class="kw">let </span><span class="kw-2">mut </span>base64_to_bytes = ::std::collections::HashMap::new(); |
| |
| <span class="kw">for </span>b <span class="kw">in </span><span class="number">0_u16</span>..<span class="number">256 </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>b64 = <span class="macro">vec!</span>[<span class="number">0_u8</span>; <span class="number">4</span>]; |
| <span class="macro">assert_eq!</span>(<span class="number">4</span>, encode_config_slice(<span class="kw-2">&</span>[b <span class="kw">as </span>u8], STANDARD, <span class="kw-2">&mut </span>b64[..])); |
| <span class="kw">let </span><span class="kw-2">mut </span>v = ::std::vec::Vec::with_capacity(<span class="number">1</span>); |
| v.push(b <span class="kw">as </span>u8); |
| |
| <span class="macro">assert!</span>(base64_to_bytes.insert(b64, v).is_none()); |
| } |
| |
| <span class="comment">// every possible combination of symbols must either decode to 1 byte or get InvalidLastSymbol |
| |
| </span><span class="kw">let </span><span class="kw-2">mut </span>symbols = [<span class="number">0_u8</span>; <span class="number">4</span>]; |
| <span class="kw">for </span><span class="kw-2">&</span>s1 <span class="kw">in </span>STANDARD.char_set.encode_table().iter() { |
| symbols[<span class="number">0</span>] = s1; |
| <span class="kw">for </span><span class="kw-2">&</span>s2 <span class="kw">in </span>STANDARD.char_set.encode_table().iter() { |
| symbols[<span class="number">1</span>] = s2; |
| symbols[<span class="number">2</span>] = PAD_BYTE; |
| symbols[<span class="number">3</span>] = PAD_BYTE; |
| |
| <span class="kw">match </span>base64_to_bytes.get(<span class="kw-2">&</span>symbols[..]) { |
| <span class="prelude-val">Some</span>(bytes) => { |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(bytes.to_vec()), decode_config(<span class="kw-2">&</span>symbols, STANDARD)) |
| } |
| <span class="prelude-val">None </span>=> <span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Err</span>(DecodeError::InvalidLastSymbol(<span class="number">1</span>, s2)), |
| decode_config(<span class="kw-2">&</span>symbols[..], STANDARD) |
| ), |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_config_estimation_works_for_various_lengths() { |
| <span class="kw">for </span>num_prefix_quads <span class="kw">in </span><span class="number">0</span>..<span class="number">100 </span>{ |
| <span class="kw">for </span>suffix <span class="kw">in </span><span class="kw-2">&</span>[<span class="string">"AA"</span>, <span class="string">"AAA"</span>, <span class="string">"AAAA"</span>] { |
| <span class="kw">let </span><span class="kw-2">mut </span>prefix = <span class="string">"AAAA"</span>.repeat(num_prefix_quads); |
| prefix.push_str(suffix); |
| <span class="comment">// make sure no overflow (and thus a panic) occurs |
| </span><span class="kw">let </span>res = decode_config(prefix, STANDARD); |
| <span class="macro">assert!</span>(res.is_ok()); |
| } |
| } |
| } |
| } |
| </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> |
