| <!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/read/decoder.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>decoder.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="kw">use crate</span>::{decode_config_slice, Config, DecodeError}; |
| <span class="kw">use </span>std::io::Read; |
| <span class="kw">use </span>std::{cmp, fmt, io}; |
| |
| <span class="comment">// This should be large, but it has to fit on the stack. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const </span>BUF_SIZE: usize = <span class="number">1024</span>; |
| |
| <span class="comment">// 4 bytes of base64 data encode 3 bytes of raw data (modulo padding). |
| </span><span class="kw">const </span>BASE64_CHUNK_SIZE: usize = <span class="number">4</span>; |
| <span class="kw">const </span>DECODED_CHUNK_SIZE: usize = <span class="number">3</span>; |
| |
| <span class="doccomment">/// A `Read` implementation that decodes base64 data read from an underlying reader. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io::Read; |
| /// use std::io::Cursor; |
| /// |
| /// // use a cursor as the simplest possible `Read` -- in real code this is probably a file, etc. |
| /// let mut wrapped_reader = Cursor::new(b"YXNkZg=="); |
| /// let mut decoder = base64::read::DecoderReader::new( |
| /// &mut wrapped_reader, base64::STANDARD); |
| /// |
| /// // handle errors as you normally would |
| /// let mut result = Vec::new(); |
| /// decoder.read_to_end(&mut result).unwrap(); |
| /// |
| /// assert_eq!(b"asdf", &result[..]); |
| /// |
| /// ``` |
| </span><span class="kw">pub struct </span>DecoderReader<<span class="lifetime">'a</span>, R: <span class="lifetime">'a </span>+ io::Read> { |
| config: Config, |
| <span class="doccomment">/// Where b64 data is read from |
| </span>r: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, |
| |
| <span class="comment">// Holds b64 data read from the delegate reader. |
| </span>b64_buffer: [u8; BUF_SIZE], |
| <span class="comment">// The start of the pending buffered data in b64_buffer. |
| </span>b64_offset: usize, |
| <span class="comment">// The amount of buffered b64 data. |
| </span>b64_len: usize, |
| <span class="comment">// Since the caller may provide us with a buffer of size 1 or 2 that's too small to copy a |
| // decoded chunk in to, we have to be able to hang on to a few decoded bytes. |
| // Technically we only need to hold 2 bytes but then we'd need a separate temporary buffer to |
| // decode 3 bytes into and then juggle copying one byte into the provided read buf and the rest |
| // into here, which seems like a lot of complexity for 1 extra byte of storage. |
| </span>decoded_buffer: [u8; <span class="number">3</span>], |
| <span class="comment">// index of start of decoded data |
| </span>decoded_offset: usize, |
| <span class="comment">// length of decoded data |
| </span>decoded_len: usize, |
| <span class="comment">// used to provide accurate offsets in errors |
| </span>total_b64_decoded: usize, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, R: io::Read> fmt::Debug <span class="kw">for </span>DecoderReader<<span class="lifetime">'a</span>, R> { |
| <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 { |
| f.debug_struct(<span class="string">"DecoderReader"</span>) |
| .field(<span class="string">"config"</span>, <span class="kw-2">&</span><span class="self">self</span>.config) |
| .field(<span class="string">"b64_offset"</span>, <span class="kw-2">&</span><span class="self">self</span>.b64_offset) |
| .field(<span class="string">"b64_len"</span>, <span class="kw-2">&</span><span class="self">self</span>.b64_len) |
| .field(<span class="string">"decoded_buffer"</span>, <span class="kw-2">&</span><span class="self">self</span>.decoded_buffer) |
| .field(<span class="string">"decoded_offset"</span>, <span class="kw-2">&</span><span class="self">self</span>.decoded_offset) |
| .field(<span class="string">"decoded_len"</span>, <span class="kw-2">&</span><span class="self">self</span>.decoded_len) |
| .field(<span class="string">"total_b64_decoded"</span>, <span class="kw-2">&</span><span class="self">self</span>.total_b64_decoded) |
| .finish() |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, R: io::Read> DecoderReader<<span class="lifetime">'a</span>, R> { |
| <span class="doccomment">/// Create a new decoder that will read from the provided reader `r`. |
| </span><span class="kw">pub fn </span>new(r: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, config: Config) -> <span class="self">Self </span>{ |
| DecoderReader { |
| config, |
| r, |
| b64_buffer: [<span class="number">0</span>; BUF_SIZE], |
| b64_offset: <span class="number">0</span>, |
| b64_len: <span class="number">0</span>, |
| decoded_buffer: [<span class="number">0</span>; DECODED_CHUNK_SIZE], |
| decoded_offset: <span class="number">0</span>, |
| decoded_len: <span class="number">0</span>, |
| total_b64_decoded: <span class="number">0</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Write as much as possible of the decoded buffer into the target buffer. |
| /// Must only be called when there is something to write and space to write into. |
| /// Returns a Result with the number of (decoded) bytes copied. |
| </span><span class="kw">fn </span>flush_decoded_buf(<span class="kw-2">&mut </span><span class="self">self</span>, buf: <span class="kw-2">&mut </span>[u8]) -> io::Result<usize> { |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.decoded_len > <span class="number">0</span>); |
| <span class="macro">debug_assert!</span>(buf.len() > <span class="number">0</span>); |
| |
| <span class="kw">let </span>copy_len = cmp::min(<span class="self">self</span>.decoded_len, buf.len()); |
| <span class="macro">debug_assert!</span>(copy_len > <span class="number">0</span>); |
| <span class="macro">debug_assert!</span>(copy_len <= <span class="self">self</span>.decoded_len); |
| |
| buf[..copy_len].copy_from_slice( |
| <span class="kw-2">&</span><span class="self">self</span>.decoded_buffer[<span class="self">self</span>.decoded_offset..<span class="self">self</span>.decoded_offset + copy_len], |
| ); |
| |
| <span class="self">self</span>.decoded_offset += copy_len; |
| <span class="self">self</span>.decoded_len -= copy_len; |
| |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.decoded_len < DECODED_CHUNK_SIZE); |
| |
| <span class="prelude-val">Ok</span>(copy_len) |
| } |
| |
| <span class="doccomment">/// Read into the remaining space in the buffer after the current contents. |
| /// Must only be called when there is space to read into in the buffer. |
| /// Returns the number of bytes read. |
| </span><span class="kw">fn </span>read_from_delegate(<span class="kw-2">&mut </span><span class="self">self</span>) -> io::Result<usize> { |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len < BUF_SIZE); |
| |
| <span class="kw">let </span>read = <span class="self">self |
| </span>.r |
| .read(<span class="kw-2">&mut </span><span class="self">self</span>.b64_buffer[<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len..])<span class="question-mark">?</span>; |
| <span class="self">self</span>.b64_len += read; |
| |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len <= BUF_SIZE); |
| |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(read); |
| } |
| |
| <span class="doccomment">/// Decode the requested number of bytes from the b64 buffer into the provided buffer. It's the |
| /// caller's responsibility to choose the number of b64 bytes to decode correctly. |
| /// |
| /// Returns a Result with the number of decoded bytes written to `buf`. |
| </span><span class="kw">fn </span>decode_to_buf(<span class="kw-2">&mut </span><span class="self">self</span>, num_bytes: usize, buf: <span class="kw-2">&mut </span>[u8]) -> io::Result<usize> { |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_len >= num_bytes); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len <= BUF_SIZE); |
| <span class="macro">debug_assert!</span>(buf.len() > <span class="number">0</span>); |
| |
| <span class="kw">let </span>decoded = decode_config_slice( |
| <span class="kw-2">&</span><span class="self">self</span>.b64_buffer[<span class="self">self</span>.b64_offset..<span class="self">self</span>.b64_offset + num_bytes], |
| <span class="self">self</span>.config, |
| <span class="kw-2">&mut </span>buf[..], |
| ) |
| .map_err(|e| <span class="kw">match </span>e { |
| DecodeError::InvalidByte(offset, byte) => { |
| DecodeError::InvalidByte(<span class="self">self</span>.total_b64_decoded + offset, byte) |
| } |
| DecodeError::InvalidLength => DecodeError::InvalidLength, |
| DecodeError::InvalidLastSymbol(offset, byte) => { |
| DecodeError::InvalidLastSymbol(<span class="self">self</span>.total_b64_decoded + offset, byte) |
| } |
| }) |
| .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))<span class="question-mark">?</span>; |
| |
| <span class="self">self</span>.total_b64_decoded += num_bytes; |
| <span class="self">self</span>.b64_offset += num_bytes; |
| <span class="self">self</span>.b64_len -= num_bytes; |
| |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len <= BUF_SIZE); |
| |
| <span class="prelude-val">Ok</span>(decoded) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, R: Read> Read <span class="kw">for </span>DecoderReader<<span class="lifetime">'a</span>, R> { |
| <span class="doccomment">/// Decode input from the wrapped reader. |
| /// |
| /// Under non-error circumstances, this returns `Ok` with the value being the number of bytes |
| /// written in `buf`. |
| /// |
| /// Where possible, this function buffers base64 to minimize the number of read() calls to the |
| /// delegate reader. |
| /// |
| /// # Errors |
| /// |
| /// Any errors emitted by the delegate reader are returned. Decoding errors due to invalid |
| /// base64 are also possible, and will have `io::ErrorKind::InvalidData`. |
| </span><span class="kw">fn </span>read(<span class="kw-2">&mut </span><span class="self">self</span>, buf: <span class="kw-2">&mut </span>[u8]) -> io::Result<usize> { |
| <span class="kw">if </span>buf.len() == <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(<span class="number">0</span>); |
| } |
| |
| <span class="comment">// offset == BUF_SIZE when we copied it all last time |
| </span><span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset <= BUF_SIZE); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len <= BUF_SIZE); |
| <span class="macro">debug_assert!</span>(<span class="kw">if </span><span class="self">self</span>.b64_offset == BUF_SIZE { |
| <span class="self">self</span>.b64_len == <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| <span class="self">self</span>.b64_len <= BUF_SIZE |
| }); |
| |
| <span class="macro">debug_assert!</span>(<span class="kw">if </span><span class="self">self</span>.decoded_len == <span class="number">0 </span>{ |
| <span class="comment">// can be = when we were able to copy the complete chunk |
| </span><span class="self">self</span>.decoded_offset <= DECODED_CHUNK_SIZE |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.decoded_offset < DECODED_CHUNK_SIZE |
| }); |
| |
| <span class="comment">// We shouldn't ever decode into here when we can't immediately write at least one byte into |
| // the provided buf, so the effective length should only be 3 momentarily between when we |
| // decode and when we copy into the target buffer. |
| </span><span class="macro">debug_assert!</span>(<span class="self">self</span>.decoded_len < DECODED_CHUNK_SIZE); |
| <span class="macro">debug_assert!</span>(<span class="self">self</span>.decoded_len + <span class="self">self</span>.decoded_offset <= DECODED_CHUNK_SIZE); |
| |
| <span class="kw">if </span><span class="self">self</span>.decoded_len > <span class="number">0 </span>{ |
| <span class="comment">// we have a few leftover decoded bytes; flush that rather than pull in more b64 |
| </span><span class="self">self</span>.flush_decoded_buf(buf) |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>at_eof = <span class="bool-val">false</span>; |
| <span class="kw">while </span><span class="self">self</span>.b64_len < BASE64_CHUNK_SIZE { |
| <span class="comment">// Work around lack of copy_within, which is only present in 1.37 |
| // Copy any bytes we have to the start of the buffer. |
| // We know we have < 1 chunk, so we can use a tiny tmp buffer. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>memmove_buf = [<span class="number">0_u8</span>; BASE64_CHUNK_SIZE]; |
| memmove_buf[..<span class="self">self</span>.b64_len].copy_from_slice( |
| <span class="kw-2">&</span><span class="self">self</span>.b64_buffer[<span class="self">self</span>.b64_offset..<span class="self">self</span>.b64_offset + <span class="self">self</span>.b64_len], |
| ); |
| <span class="self">self</span>.b64_buffer[<span class="number">0</span>..<span class="self">self</span>.b64_len].copy_from_slice(<span class="kw-2">&</span>memmove_buf[..<span class="self">self</span>.b64_len]); |
| <span class="self">self</span>.b64_offset = <span class="number">0</span>; |
| |
| <span class="comment">// then fill in more data |
| </span><span class="kw">let </span>read = <span class="self">self</span>.read_from_delegate()<span class="question-mark">?</span>; |
| <span class="kw">if </span>read == <span class="number">0 </span>{ |
| <span class="comment">// we never pass in an empty buf, so 0 => we've hit EOF |
| </span>at_eof = <span class="bool-val">true</span>; |
| <span class="kw">break</span>; |
| } |
| } |
| |
| <span class="kw">if </span><span class="self">self</span>.b64_len == <span class="number">0 </span>{ |
| <span class="macro">debug_assert!</span>(at_eof); |
| <span class="comment">// we must be at EOF, and we have no data left to decode |
| </span><span class="kw">return </span><span class="prelude-val">Ok</span>(<span class="number">0</span>); |
| }; |
| |
| <span class="macro">debug_assert!</span>(<span class="kw">if </span>at_eof { |
| <span class="comment">// if we are at eof, we may not have a complete chunk |
| </span><span class="self">self</span>.b64_len > <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| <span class="comment">// otherwise, we must have at least one chunk |
| </span><span class="self">self</span>.b64_len >= BASE64_CHUNK_SIZE |
| }); |
| |
| <span class="macro">debug_assert_eq!</span>(<span class="number">0</span>, <span class="self">self</span>.decoded_len); |
| |
| <span class="kw">if </span>buf.len() < DECODED_CHUNK_SIZE { |
| <span class="comment">// caller requested an annoyingly short read |
| // have to write to a tmp buf first to avoid double mutable borrow |
| </span><span class="kw">let </span><span class="kw-2">mut </span>decoded_chunk = [<span class="number">0_u8</span>; DECODED_CHUNK_SIZE]; |
| <span class="comment">// if we are at eof, could have less than BASE64_CHUNK_SIZE, in which case we have |
| // to assume that these last few tokens are, in fact, valid (i.e. must be 2-4 b64 |
| // tokens, not 1, since 1 token can't decode to 1 byte). |
| </span><span class="kw">let </span>to_decode = cmp::min(<span class="self">self</span>.b64_len, BASE64_CHUNK_SIZE); |
| |
| <span class="kw">let </span>decoded = <span class="self">self</span>.decode_to_buf(to_decode, <span class="kw-2">&mut </span>decoded_chunk[..])<span class="question-mark">?</span>; |
| <span class="self">self</span>.decoded_buffer[..decoded].copy_from_slice(<span class="kw-2">&</span>decoded_chunk[..decoded]); |
| |
| <span class="self">self</span>.decoded_offset = <span class="number">0</span>; |
| <span class="self">self</span>.decoded_len = decoded; |
| |
| <span class="comment">// can be less than 3 on last block due to padding |
| </span><span class="macro">debug_assert!</span>(decoded <= <span class="number">3</span>); |
| |
| <span class="self">self</span>.flush_decoded_buf(buf) |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span>b64_bytes_that_can_decode_into_buf = (buf.len() / DECODED_CHUNK_SIZE) |
| .checked_mul(BASE64_CHUNK_SIZE) |
| .expect(<span class="string">"too many chunks"</span>); |
| <span class="macro">debug_assert!</span>(b64_bytes_that_can_decode_into_buf >= BASE64_CHUNK_SIZE); |
| |
| <span class="kw">let </span>b64_bytes_available_to_decode = <span class="kw">if </span>at_eof { |
| <span class="self">self</span>.b64_len |
| } <span class="kw">else </span>{ |
| <span class="comment">// only use complete chunks |
| </span><span class="self">self</span>.b64_len - <span class="self">self</span>.b64_len % <span class="number">4 |
| </span>}; |
| |
| <span class="kw">let </span>actual_decode_len = cmp::min( |
| b64_bytes_that_can_decode_into_buf, |
| b64_bytes_available_to_decode, |
| ); |
| <span class="self">self</span>.decode_to_buf(actual_decode_len, buf) |
| } |
| } |
| } |
| } |
| </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> |
