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perf(encode): vec alloc & utf8 unchecked #180

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perf(encode): vec alloc & utf8 unchecked
AaronO Mar 6, 2022
392ec8f
fmt
AaronO Mar 6, 2022
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9 changes: 6 additions & 3 deletions src/encode.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use crate::engine::DEFAULT_ENGINE;
use crate::engine::{Config, Engine};
use crate::PAD_BYTE;
#[cfg(any(feature = "alloc", feature = "std", test))]
use alloc::{string::String, vec};
use alloc::string::String;

///Encode arbitrary octets as base64 using the [default engine](DEFAULT_ENGINE).
///Returns a `String`.
Expand Down Expand Up @@ -56,11 +56,14 @@ pub fn encode<T: AsRef<[u8]>>(input: T) -> String {
pub fn encode_engine<E: Engine, T: AsRef<[u8]>>(input: T, engine: &E) -> String {
let encoded_size = encoded_len(input.as_ref().len(), engine.config().encode_padding())
.expect("integer overflow when calculating buffer size");
let mut buf = vec![0; encoded_size];
let mut buf = Vec::with_capacity(encoded_size);
unsafe {
buf.set_len(encoded_size);
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@jonasbb jonasbb Mar 11, 2022 •
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The safety documentation of set_len is pretty clear that this is UB. Namely it states

The elements at old_len..new_len must be initialized.

I think it might be safe to call after encode_with_padding. If you need uninitialized memory you probably want to use MaybeUninit.

}

encode_with_padding(input.as_ref(), &mut buf[..], engine, encoded_size);

String::from_utf8(buf).expect("Invalid UTF8")
unsafe { String::from_utf8_unchecked(buf) }
}

///Encode arbitrary octets as base64.
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2 changes: 1 addition & 1 deletion src/lib.rs
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Expand Up @@ -85,7 +85,7 @@
variant_size_differences,
warnings
)]
#![forbid(unsafe_code)]
// #![forbid(unsafe_code)]
#![cfg_attr(not(any(feature = "std", test)), no_std)]

#[cfg(all(feature = "alloc", not(any(feature = "std", test))))]
Expand Down