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use core::fmt;
/// Errors that any algorithm in this crate may return.
///
/// A single crate-wide enum (instead of per-algorithm associated types) keeps
/// the [`Encoder`](crate::Encoder) / [`Decoder`](crate::Decoder) traits object
/// safe and lets the [`factory`](crate::factory) module hand back
/// `Box<dyn Encoder>` cleanly.
///
/// Marked `#[non_exhaustive]`: future variants (new error classes added as
/// algorithms grow more thorough about input validation) won't break
/// downstream code. Pattern-matching `Error` requires a `_ => …` arm.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[non_exhaustive]
pub enum Error {
/// The encoded stream is malformed.
Corrupt,
/// `finish` was called while the codec was mid-symbol and needs more input.
UnexpectedEnd,
/// The output buffer is too small for the codec to make any progress on
/// this call. Drain the buffer (or supply a larger one) and call again.
/// Only returned by algorithms that have a minimum atomic output size.
OutputTooSmall,
/// Container header (zlib CMF/FLG, gzip magic/method) is malformed.
BadHeader,
/// A deflate block declared `BTYPE = 11` (reserved).
InvalidBlockType,
/// Code lengths in a deflate dynamic-Huffman header don't form a valid
/// canonical prefix code.
InvalidHuffmanTree,
/// A deflate back-reference distance is zero, exceeds 32768, or points
/// past the start of the decoded data.
InvalidDistance,
/// Adler-32 or CRC-32 trailer didn't match the recomputed value.
ChecksumMismatch,
/// Gzip `ISIZE` (decoded length mod 2^32) didn't match the count of
/// bytes actually produced.
TrailerMismatch,
/// The stream uses an option or compression method this build does not
/// implement (e.g. zlib `CM != 8`, zlib `FDICT = 1`, gzip reserved flags).
Unsupported,
/// A [`LimitedDecoder`](crate::limit::LimitedDecoder) wrapper aborted
/// because the decompressed output would have exceeded the configured
/// `max_output_bytes` budget. Defends against decompression bombs
/// (small compressed input expanding to gigabytes); see
/// [`crate::limit`] for the wrapper.
OutputLimitExceeded,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Error::Corrupt => f.write_str("encoded stream is corrupt"),
Error::UnexpectedEnd => f.write_str("unexpected end of input"),
Error::OutputTooSmall => f.write_str("output buffer too small to make progress"),
Error::BadHeader => f.write_str("container header is malformed"),
Error::InvalidBlockType => f.write_str("invalid deflate block type"),
Error::InvalidHuffmanTree => f.write_str("invalid Huffman code lengths"),
Error::InvalidDistance => f.write_str("invalid LZ77 back-reference distance"),
Error::ChecksumMismatch => f.write_str("checksum mismatch"),
Error::TrailerMismatch => f.write_str("decoded length doesn't match trailer"),
Error::Unsupported => f.write_str("unsupported compression option"),
Error::OutputLimitExceeded => {
f.write_str("decompressed output would exceed the configured limit")
}
}
}
}
// std-only interop. The `std` feature pulls `alloc` and gives us
// `std::error::Error` plus a free conversion into `std::io::Error` so
// the streaming adapters in `crate::io` can use `?` on either error
// type without explicit `.map_err(...)`.
#[cfg(feature = "std")]
extern crate std;
#[cfg(feature = "std")]
impl std::error::Error for Error {}
#[cfg(feature = "std")]
impl From<Error> for std::io::Error {
fn from(e: Error) -> Self {
std::io::Error::other(e)
}
}