zenflate 0.3.4

Pure Rust DEFLATE/zlib/gzip compression and decompression
Documentation 
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//! Error types for compression and decompression.

/// Error returned when compression fails.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[non_exhaustive]
pub enum CompressionError {
    /// The output buffer is too small to hold the compressed data.
    InsufficientSpace,
    /// The operation was stopped by a cooperative cancellation signal.
    Stopped(enough::StopReason),
}

/// Error returned when decompression fails.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[non_exhaustive]
pub enum DecompressionError {
    /// The compressed data is corrupt or structurally invalid.
    BadData,
    /// A zlib or gzip wrapper header is malformed.
    InvalidHeader,
    /// A checksum (CRC-32 or Adler-32) in the wrapper did not match the data.
    ChecksumMismatch,
    /// The output buffer is too small for the decompressed data.
    InsufficientSpace,
    /// Decompressed output exceeded the configured maximum size limit.
    ///
    /// Returned when [`Decompressor::with_max_output_size`] or
    /// [`StreamDecompressor::with_max_output_size`] is set and the
    /// decompressed data exceeds that limit. This defends against
    /// decompression bombs (small inputs that expand to enormous output).
    OutputLimitExceeded,
    /// The stream processed too many blocks without producing output,
    /// indicating a potential denial-of-service via crafted empty blocks.
    StallLimitExceeded,
    /// The operation was stopped by a cooperative cancellation signal.
    Stopped(enough::StopReason),
}

impl core::fmt::Display for CompressionError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::InsufficientSpace => write!(f, "output buffer too small for compressed data"),
            Self::Stopped(reason) => write!(f, "{reason}"),
        }
    }
}

impl From<enough::StopReason> for CompressionError {
    fn from(reason: enough::StopReason) -> Self {
        Self::Stopped(reason)
    }
}

impl core::fmt::Display for DecompressionError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::BadData => write!(f, "invalid or corrupt compressed data"),
            Self::InvalidHeader => write!(f, "invalid zlib or gzip header"),
            Self::ChecksumMismatch => write!(f, "checksum mismatch"),
            Self::InsufficientSpace => write!(f, "output buffer too small for decompressed data"),
            Self::OutputLimitExceeded => {
                write!(f, "decompressed output exceeded configured maximum size")
            }
            Self::StallLimitExceeded => {
                write!(f, "too many blocks processed without output progress")
            }
            Self::Stopped(reason) => write!(f, "{reason}"),
        }
    }
}

impl From<enough::StopReason> for DecompressionError {
    fn from(reason: enough::StopReason) -> Self {
        Self::Stopped(reason)
    }
}

/// Error from streaming decompression: either a decompression error or a source I/O error.
///
/// When `S: InputSource` has `Error = Infallible` (e.g., `&[u8]`), the `Source` variant
/// is uninhabited and the compiler eliminates it entirely.
#[cfg(feature = "alloc")]
#[derive(Debug)]
#[non_exhaustive]
pub enum StreamError<E> {
    /// The compressed data is invalid or corrupt.
    Decompress(DecompressionError),
    /// An error occurred reading from the input source.
    Source(E),
}

#[cfg(feature = "alloc")]
impl<E: core::fmt::Display> core::fmt::Display for StreamError<E> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::Decompress(e) => write!(f, "{e}"),
            Self::Source(e) => write!(f, "source error: {e}"),
        }
    }
}

#[cfg(feature = "alloc")]
impl<E> From<DecompressionError> for StreamError<E> {
    fn from(e: DecompressionError) -> Self {
        Self::Decompress(e)
    }
}

#[cfg(feature = "std")]
impl std::error::Error for CompressionError {}

#[cfg(feature = "std")]
impl std::error::Error for DecompressionError {}

#[cfg(feature = "std")]
impl<E: std::error::Error + 'static> std::error::Error for StreamError<E> {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::Decompress(e) => Some(e),
            Self::Source(e) => Some(e),
        }
    }
}