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https://github.com/wez/wezterm.git
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Add base91 crate
The plan is to use this to tunnel the mux protocol over a pty.
This commit is contained in:
Wez Furlong
parent
4c322e1c69
commit
a0a0bc0902
@ -29,6 +29,7 @@ winit = "0.18"
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boxfnonce = "0.1"
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rayon = "1.0"
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promise = { path = "promise" }
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base91 = { path = "base91" }
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[target.'cfg(unix)'.dependencies]
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harfbuzz-sys = "~0.3"
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7
base91/Cargo.toml
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7
base91/Cargo.toml
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@ -0,0 +1,7 @@
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[package]
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authors = ["Wez Furlong <wez@wezfurlong.org>"]
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name = "base91"
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version = "0.1.0"
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edition = "2018"
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[dependencies]
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257
base91/src/lib.rs
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257
base91/src/lib.rs
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@ -0,0 +1,257 @@
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//! Implements basE91 encoding; see http://base91.sourceforge.net/
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//! basE91 is an advanced method for encoding binary data as ASCII characters. It is similar to
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//! UUencode or base64, but is more efficient. The overhead produced by basE91 depends on the input
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//! data. It amounts at most to 23% (versus 33% for base64) and can range down to 14%, which
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//! typically occurs on 0-byte blocks. This makes basE91 very useful for transferring larger files
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//! over binary unsafe connections like e-mail or terminal lines.
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// This Rust implementation was made by Wez Furlong based on C code that is:
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// Copyright (c) 2000-2006 Joachim Henke
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// - Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// - Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// - Neither the name of Joachim Henke nor the names of his contributors may
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// be used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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use std::io::Write;
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const ENCTAB: [u8; 91] = *b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!#$%&()*+,./:;<=>?@[]^_`{|}~\"";
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/// An invalid mapping; used to represent positions in DECTAB that have no valid
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/// representation in the original input data. These are skipped; this accomodates
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/// breaking the data in eg: whitespace separated lines.
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const INV: u8 = 91;
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const DECTAB: [u8; 256] = [
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, 62, 90, 63, 64, 65, 66,
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INV, 67, 68, 69, 70, 71, INV, 72, 73, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 74, 75, 76, 77,
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78, 79, 80, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
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23, 24, 25, 81, INV, 82, 83, 84, 85, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
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40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 86, 87, 88, 89, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV, INV,
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INV, INV, INV, INV, INV, INV, INV, INV, INV,
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];
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/// `Base91Encoder` wraps an impl of `std::io::Write` and does itself impl `std::io::Write`,
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/// and performs a base91 encode operation on the bytes that are written to it.
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/// It is important to remember to `flush` the writer at end of the data, as the encoder
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/// maintains up to 2 bytes of pending data; the Drop impl will implicitly flush on
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/// your behalf, but will mask any error that may occur during the flush.
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pub struct Base91Encoder<'a> {
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writer: &'a mut Write,
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accumulator: u64,
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bits: u32,
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}
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impl<'a> Base91Encoder<'a> {
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/// Construct a Base91Encoder that writes encoded data to the supplied writer
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pub fn new(writer: &'a mut Write) -> Self {
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Self {
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writer,
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accumulator: 0,
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bits: 0,
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}
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}
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}
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impl<'a> Drop for Base91Encoder<'a> {
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fn drop(&mut self) {
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self.flush().ok();
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}
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}
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impl<'a> std::io::Write for Base91Encoder<'a> {
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fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
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for b in buf {
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self.accumulator |= u64::from(*b) << self.bits;
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self.bits += 8;
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if self.bits > 13 {
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let val = self.accumulator & 8191;
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let val = if val > 88 {
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self.accumulator >>= 13;
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self.bits -= 13;
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val as usize
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} else {
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// We can take 14 bits
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let val = self.accumulator & 16383;
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self.accumulator >>= 14;
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self.bits -= 14;
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val as usize
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};
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let out: [u8; 2] = [ENCTAB[val % 91], ENCTAB[val / 91]];
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self.writer.write_all(&out)?;
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}
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}
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Ok(buf.len())
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}
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fn flush(&mut self) -> std::io::Result<()> {
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if self.bits > 0 {
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let val = self.accumulator as usize;
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if self.bits > 7 || self.accumulator > 90 {
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let out: [u8; 2] = [ENCTAB[val % 91], ENCTAB[val / 91]];
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self.writer.write_all(&out)?;
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} else {
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let out: [u8; 1] = [ENCTAB[val % 91]];
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self.writer.write_all(&out)?;
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}
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}
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self.bits = 0;
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self.accumulator = 0;
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self.writer.flush()
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}
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}
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/// A convenience function that wraps Base91Encoder; it encodes a slice of data
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/// and returns a vector holding the base91 encoded data.
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pub fn encode(buf: &[u8]) -> Vec<u8> {
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let mut result = Vec::with_capacity((buf.len() * 123) / 100);
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{
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let mut writer = Base91Encoder::new(&mut result);
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writer.write_all(buf).unwrap();
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writer.flush().unwrap();
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}
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result
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}
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/// `Base91Decoder` wraps an impl of `std::io::Write` and does itself impl `std::io::Write`,
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/// and performs a base91 decode operation on the bytes that are written to it.
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/// It is important to remember to `flush` the writer at end of the data, as the encoder
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/// maintains up to 1 byte of pending data; the Drop impl will implicitly flush on
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/// your behalf, but will mask any error that may occur during the flush.
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pub struct Base91Decoder<'a> {
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writer: &'a mut Write,
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accumulator: u64,
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bits: u32,
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value: Option<u8>,
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}
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impl<'a> Base91Decoder<'a> {
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pub fn new(writer: &'a mut Write) -> Self {
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Self {
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writer,
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accumulator: 0,
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bits: 0,
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value: None,
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}
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}
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}
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impl<'a> Drop for Base91Decoder<'a> {
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fn drop(&mut self) {
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self.flush().ok();
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}
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}
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impl<'a> std::io::Write for Base91Decoder<'a> {
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fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
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for b in buf {
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let d = DECTAB[usize::from(*b)];
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if d == INV {
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// non-alphabet; skip
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continue;
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}
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if let Some(value) = self.value.take() {
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let value = (value as u64) + (d as u64) * 91;
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self.accumulator |= value << self.bits;
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self.bits += if (value & 8191) > 88 { 13 } else { 14 };
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loop {
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let out: [u8; 1] = [(self.accumulator & 0xff) as u8];
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self.writer.write_all(&out)?;
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self.accumulator >>= 8;
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self.bits -= 8;
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if self.bits < 8 {
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break;
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}
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}
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} else {
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// Starting next value
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self.value = Some(d);
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}
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}
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Ok(buf.len())
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}
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fn flush(&mut self) -> std::io::Result<()> {
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if let Some(value) = self.value.take() {
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let out: [u8; 1] = [(self.accumulator & 0xff) as u8 | (value << self.bits)];
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self.writer.write_all(&out)?;
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}
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self.bits = 0;
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self.accumulator = 0;
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self.writer.flush()
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}
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}
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/// A convenience function that wraps Base91Decoder; it decodes a slice of data
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/// and returns a vector holding the unencoded binary data.
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pub fn decode(buf: &[u8]) -> Vec<u8> {
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let mut result = Vec::with_capacity(buf.len());
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{
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let mut writer = Base91Decoder::new(&mut result);
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writer.write_all(buf).unwrap();
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writer.flush().unwrap();
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}
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result
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test() {
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assert_eq!(encode(b"hello\n"), b"TPwJh>UA");
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assert_eq!(decode(b"TPwJh>UA"), b"hello\n");
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}
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#[test]
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fn test_bin() {
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for reps in 0..=4 {
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let mut bin = Vec::with_capacity(256);
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for i in 0..=255u8 {
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for _ in 0..reps {
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bin.push(i);
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}
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}
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let encoded = encode(&bin);
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eprintln!("encoded as {}", String::from_utf8(encoded.clone()).unwrap());
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let decoded = decode(&encoded);
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assert_eq!(decoded, bin);
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}
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}
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}
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