Struct SqpkCompressedBlock 

pub struct SqpkCompressedBlock { /* private fields */ }

One block of a SqpkFile AddFile payload, which may be DEFLATE-compressed or stored raw.

SqpkFile payloads are split into a sequence of these blocks. Each block begins with a 16-byte little-endian header that describes the compressed and decompressed sizes, followed by the data bytes padded to a 128-byte boundary.

Compression sentinel

The compressed_size field in the wire header uses the value 0x7d00 (decimal 32000) as a sentinel meaning “this block is not compressed”. Any other value means the data bytes are a raw DEFLATE stream (no zlib wrapper, no gzip header — just RFC 1951 raw deflate).

Wire format of one block (all little-endian)

┌─────────────────────────────────────────────────────────────────────┐
│ header_size     : i32 LE   always 16 in practice                   │  bytes 0–3
│ <pad>           : u32 LE   always zero                              │  bytes 4–7
│ compressed_size : i32 LE   byte count of DEFLATE data               │  bytes 8–11
│                             OR 0x7d00 (32000) if uncompressed       │
│ decompressed_size : i32 LE  byte count of decompressed output       │  bytes 12–15
│ data            : [u8]     compressed or raw bytes                  │  bytes 16–…
│ <alignment>     : [u8]     zero-padding to 128-byte boundary        │
└─────────────────────────────────────────────────────────────────────┘

128-byte alignment formula

The total byte count to read for a block’s data + alignment is:

block_len = (data_len + 143) & !127

where data_len is compressed_size if compressed, or decompressed_size if uncompressed. The constant 143 is 128 - 1 + 16 (subtract the 16-byte header that is not included in data_len, then round up to the next 128-byte boundary). The number of data bytes actually read is block_len - header_size; the alignment padding is consumed but discarded.

pub(crate) visibility

SqpkCompressedBlock is pub so that it appears in rustdoc and can be named in SqpkFile::blocks, but it can only be constructed via new (for tests) or by parsing a SqpkFile.

See SqpkFile.cs / ZiPatchConfig.cs in the XIVLauncher reference implementation.

Implementations

impl SqpkCompressedBlock

pub fn new(is_compressed: bool, decompressed_size: usize, data: Vec<u8>) -> Self

Construct a block directly from its component parts.

This constructor exists primarily for unit tests. Production code creates blocks by parsing a SqpkFile from a patch byte stream.

• is_compressed: true if data is a raw DEFLATE stream.
• decompressed_size: the expected number of bytes after decompression; used to pre-allocate the output buffer in decompress.
• data: raw compressed bytes or exact uncompressed bytes, depending on is_compressed.

pub fn decompress_into(&self, w: &mut impl Write) -> Result<()>

Stream the block’s decompressed bytes into w.

For uncompressed blocks, w.write_all(&self.data) is called directly. For compressed blocks, the data is piped through DeflateDecoder (raw DEFLATE, RFC 1951 — no zlib or gzip wrapper) before being written.

This is the primary write path used by the apply layer: each block in a SqpkFile AddFile operation is streamed into the target file handle in sequence.

Errors

• ZiPatchError::Decompress — the DEFLATE stream is malformed or truncated.
• ZiPatchError::Io — w.write_all failed.

pub fn decompress(&self) -> Result<Cow<'_, [u8]>>

Return the block’s decompressed bytes as a Cow.

Uncompressed blocks return Cow::Borrowed(&self.data) — a zero-copy borrow into the block’s existing buffer. Compressed blocks decompress into a newly allocated Vec and return Cow::Owned.

Use decompress_into instead when writing to a file handle, to avoid the intermediate allocation.

Errors

• ZiPatchError::Decompress — the DEFLATE stream is malformed or truncated (compressed blocks only).

Trait Implementations

impl Clone for SqpkCompressedBlock

fn clone(&self) -> SqpkCompressedBlock

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SqpkCompressedBlock

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

Formats the value using the given formatter.

impl PartialEq for SqpkCompressedBlock

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for SqpkCompressedBlock

impl StructuralPartialEq for SqpkCompressedBlock