v3.4.2

Fixed

• Streaming PNG parsing for files with non-trivial IDAT — every
  real-world PNG (i.e. anything beyond a stripped-down test fixture)
  surfaced malformed iso-bmff box: PNG: bad signature from
  parse_exif / parse_image_metadata. Root cause was a two-part
  bug in the chunk walker: (a) ClearAndSkip(total - remaining)
  under-requested the skip distance by exactly cursor + remaining
  bytes — semantically the caller should advance the parser's
  logical position by cursor + total, not just past the buffer's
  end — leaving the parser stranded mid-IDAT; (b) on the resumed call
  extract_chunks always re-validated buf[..8] against the PNG
  signature, but the resumed buffer started mid-stream and the check
  failed. Fixed both: skip request is now cursor + total, and a new
  ParsingState::PngPastSignature tells the resumed call to skip the
  signature check. In-memory mode (from_memory) was unaffected
  because the full file is buffered at once and ClearAndSkip never
  fires. Fixes #55.

Fixed (behaviour)

• Error::Malformed.kind correctly identifies the failing
  structural unit. Previously every parse failure that flowed
  through From<ParsedError> for Error or
  From<nom::Err<...>> for Error was hard-coded as
  MalformedKind::IsoBmffBox / MalformedKind::TiffHeader
  respectively — misleading for PNG / JPEG / EBML inputs. The
  MalformedKind is now threaded through ParsingError::Failed,
  ParsedError::Failed, and LoopAction::Failed, and surfaced
  unchanged at the Error boundary. Downstream code that
  (incorrectly) matched on kind == IsoBmffBox to catch any
  parse failure will need updating; conformant code that uses a
  _ => arm (required by #[non_exhaustive]) is unaffected.

Added

• MalformedKind::PngChunk variant. MalformedKind is
  #[non_exhaustive], so adding a variant is non-breaking.

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Full changelog: CHANGELOG.md · crates.io: nom-exif 3.4.2