Enum DecodeError 

pub enum DecodeError {
    Truncated,
    BadMagic,
    BadVersion(u8),
    BadTag,
    BadGeometry,
    BadSpan,
}

Why a byte buffer could not be decoded into a Frame.

Variants

Truncated

Ran out of bytes mid-field.

BadMagic

First two bytes are not the wire magic.

BadVersion(u8)

Unsupported format version.

BadTag

A tag/kind byte held a value outside its defined set.

BadGeometry

The frame’s own declared geometry is one no terminal can have: fewer than MIN_COLUMNS columns, or no rows at all (#663).

Distinct from BadSpan, and the distinction is the direction of the comparison rather than a shade of severity. BadSpan means a part of the frame does not fit the geometry the header declares; this means the header itself declares a geometry the engine defines as impossible and clamps away at every entry point (Term::with_scrollback and Term::resize widen cols to MIN_COLUMNS and rows to 1). Nothing this crate encodes can carry it, so it is malformed input by the same rule BadSpan applies one level in.

The floor imports no policy: xterm.js clamps to the same pair for the same reason (MINIMUM_COLS = 2, “Less than 2 can mess with wide chars”, and MINIMUM_ROWS = 1). There is deliberately no ceiling error — cols/rows are u16 on the wire and MAX_COLUMNS is u16::MAX for exactly that reason, so the upper end is bounded by the field and needs no check.

This variant is what BadSpan’s doc-comment deferred to “the next release that is breaking anyway” — #663 changes what decode accepts, so the version that carries it is that release, and the marginal cost of the enum growing is paid there rather than on its own. Measured at the time: no exhaustive match on DecodeError exists in this workspace, justerm-wasm-decode formats the variant with {:?} (so the name reaches JS unaided, #662), and penterm holds no reference to the type.

BadSpan

A part of the frame does not fit the geometry the frame itself declares: a span whose left is past its right (which would underflow the cell count), a span reaching past cols or sitting past rows, a sparse group entry keyed outside its own span, or a scroll region whose bottom is past the last row (#582).

One rule, one error: a coordinate describing a cell the frame says does not exist is malformed input, and the consumer must not be handed it.

A dedicated BadScroll was considered and not taken, and the trade is worth stating honestly rather than as a slogan. Against it: this enum is pub and not #[non_exhaustive], so a new variant is a breaking change for any downstream exhaustive match — of which there are, measured, none in this workspace; the cost is borne only by an external matcher nobody has seen. For it: this variant is now the whole diagnostic for six distinct malformations, and the JS side has no more to work with (justerm-wasm-decode formats the variant name into the thrown Error’s message, #662). The distinction is real but belongs to the next release that is breaking anyway — a version bump spent on a diagnostic label, on a crate published in lockstep with an npm package, is the more expensive half of this trade today.

That condition arrived, and only for the case it names (#663). BadGeometry split off because #663 changes what decode accepts, so its release is the breaking one this paragraph was waiting for. It is not a precedent for splitting the six below: the new variant answers a comparison pointing the other way (the header against the engine, not a part against the header), whereas BadScroll would still be one of these six re-labelled. The trade above is unchanged for them and they stay merged.

Trait Implementations

impl Clone for DecodeError

fn clone(&self) -> DecodeError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for DecodeError

impl Debug for DecodeError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for DecodeError

impl PartialEq for DecodeError

fn eq(&self, other: &DecodeError) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for DecodeError