silk/base64

Profiles: aarch64-apple-darwin, aarch64-unknown-linux-gnu, aarch64-unknown-linux-gnu-no-libc, wasm32-unknown-unknown, x86_64-unknown-linux-gnu, x86_64-unknown-linux-gnu-no-libc.

Strict standard-padded Base64 operations for caller-provided byte storage.

When to use

Use Base64 when a protocol requires the RFC 4648 standard alphabet and required padding. Use encodedLength or decodedLength to calculate exact storage before a write.

Details

encodeInto and decodeInto write to caller-owned slices without allocation. Decoding rejects whitespace, URL-safe characters, malformed padding, and nonzero unused pad bits. All failures occur before destination mutation. A successful write does not change the unused suffix.

Gotchas

This module does not implement MIME, PEM whitespace, URL-safe, unpadded, streaming, or allocating variants. Base64 is an encoding, not encryption.

Import as Base64 with import silk.base64 { Base64 }.

Public declarations: 3.

Base64Reason

pub enum Base64Reason

The reason a Base64 size calculation, validation, or caller-buffer operation failed.

InvalidLength

InvalidLength = 0

A nonempty encoded input does not contain a whole four-byte quantum.

InvalidByte

InvalidByte = 1

An input byte is outside the standard Base64 alphabet.

InvalidPadding

InvalidPadding = 2

A padding byte is misplaced, excessive, or missing from its required final position.

NonCanonicalPadBits

NonCanonicalPadBits = 3

Unused bits in the final significant sextet are nonzero.

SizeOverflow

SizeOverflow = 4

The encoded result length is not representable as usize for the selected target.

OutputTooSmall

OutputTooSmall = 5

The caller-provided output slice cannot hold the complete result.

Base64Error

pub struct Base64Error

A deterministic Base64 failure with details relevant to its reason.

Details

Validation failures populate offset. OutputTooSmall populates required and available. SizeOverflow has no additional fields, and unused fields are None.

Field reason

pub reason: Base64Reason

The stable failure category.

Field offset

pub offset: silk/option.Option<usize>

The offending input byte, input length, or final significant sextet position.

Field required

pub required: silk/option.Option<usize>

The exact output length needed by OutputTooSmall.

Field available

pub available: silk/option.Option<usize>

The supplied output length reported by OutputTooSmall.

Base64

pub struct Base64

The owner of strict standard-padded Base64 operations.

Associated function Base64.encodedLength

pub fn encodedLength(inputLength: usize) -> silk/result.Result<usize, silk/base64.Base64Error>

Returns the exact standard-padded encoded length without allocation.

Details

Zero returns zero. An unrepresentable result returns SizeOverflow without a trap. All optional error fields are None for SizeOverflow.

Associated function Base64.decodedLength

pub fn decodedLength<'life0>(input: &'life0 [u8]) -> silk/result.Result<usize, silk/base64.Base64Error>

Validates strict standard-padded Base64 and returns its exact decoded byte length.

Details

Empty input returns zero. A nonempty input must contain complete four-byte quanta. Validation checks bytes from left to right and accepts padding only in the final quantum.

Gotchas

The function rejects whitespace, URL-safe bytes, malformed padding, and nonzero unused pad bits. The returned error identifies the first failure offset.

Associated function Base64.encodeInto

pub fn encodeInto<'life0, 'life1>(output: &'life0 mut [u8], input: &'life1 [u8]) -> silk/result.Result<usize, silk/base64.Base64Error>

Encodes bytes into a caller-owned output prefix and returns the number of written bytes.

Details

The function checks the exact size and capacity before the first write. A failure does not change output. A successful write does not change bytes after the returned prefix.

Gotchas

The function returns SizeOverflow for an unrepresentable result. It returns OutputTooSmall with exact required and available values for insufficient output. It does not add a NUL terminator.

Associated function Base64.decodeInto

pub fn decodeInto<'life0, 'life1>(output: &'life0 mut [u8], input: &'life1 [u8]) -> silk/result.Result<usize, silk/base64.Base64Error>

Decodes strict standard-padded Base64 into an output prefix and returns the written length.

Details

The function completes strict validation and capacity checking before the first write. A failure does not change output. A successful write does not change the unused suffix.

Gotchas

An input-validation error takes precedence over OutputTooSmall. The function rejects whitespace, URL-safe bytes, malformed padding, and nonzero unused pad bits.