zig/zstd.zig

Página generada desde conduit@conduit-0.1.0-f7J_7zg5DwCsHBHItwdOz9ZVq8cvH7ceFsk7-m3-T61t (zig/root.zig). No se edita a mano: bun run docs:gen la regenera y bun run docs:check falla si difiere.

Content-Encoding: zstd for wire v2 (spec/wire-v2.md §7), without C and without dependencies, so the same code runs in the CLI, the C-ABI library and WASM:

• Compressor: an LZ77 encoder (greedy, one hash probe) that writes standard zstd frames (RFC 8878): raw literals, sequences with the predefined FSE tables, RLE and raw blocks. It trades ratio for simplicity and speed; any zstd decoder reads its frames (checked against std.compress.zstd, the zstd CLI and Bun in the tests).
• decodeFrame: the server's bounded decoder. It checks the frame header against the wire rules before allocating anything (one frame, no skippable frame, no dictionary, window ≤ 8 MiB, content size equal to the range when present), then decodes with std.compress.zstd.Decompress into a buffer of exactly window + 128 KiB and hands the bytes to a sink, which bounds the output. The encoded input is bounded too (max_input, the range length), whether or not the body had a Content-Length. Trailing bytes after the frame are refused.
• Policy: the client rule (§7): never encode video, audio or data that is already compressed (sniffed from the first bytes), and only encode when a 64 KiB sample shrinks to ≤ 90 %.

zstd.max_windowCopiar enlace

const · línea 30

pub const max_window: u64 = 8 << 20

Largest window the wire accepts (Window_Size ≤ 8 MiB).

zstd.block_maxCopiar enlace

const · línea 31

pub const block_max: usize = zstd.block_size_max

Sin ///.

zstd.magicCopiar enlace

const · línea 32

pub const magic: u32 = 0xFD2FB528

Sin ///.

zstd.max_header_lenCopiar enlace

const · línea 35

pub const max_header_len = 18

Longest frame header: magic, descriptor, window, 4-byte dictionary id, 8-byte content size.

zstd.min_input_bufferCopiar enlace

const · línea 38

pub const min_input_buffer = 2048

The decoder peeks up to 2048 bytes for an FSE table description, so the reader it reads from (decodeFrame's own, over the body) holds at least this.

zstd.HeaderCopiar enlace

type · línea 42

pub const Header = struct

Sin ///.

zstd.HeaderErrorCopiar enlace

const · línea 48

pub const HeaderError = error{ /// Not a zstd frame, or one the wire forbids (skippable, dictionary, /// window over 8 MiB, reserved bit). BadFrame, /// The header says the frame holds more bytes than …

Sin ///.

zstd.parseHeaderCopiar enlace

fn · línea 60

pub fn parseHeader(bytes: []const u8, expected: u64) HeaderError!Header

Check a frame header against spec/wire-v2.md §7. expected is the decoded length the request must produce (the range length).

zstd.DecodeErrorCopiar enlace

const · línea 113

pub const DecodeError = error{ BadFrame, /// More decoded bytes than `expected` (or the header said so). TooLarge, /// More encoded bytes than `max_input`: whatever the transport framing /// (a `Trans …

Sin ///.

zstd.SinkCopiar enlace

type · línea 129

pub const Sink = struct

Where decoded bytes go. writeFn may refuse (it bounds the output).

zstd.decoderMemoryCopiar enlace

fn · línea 136

pub fn decoderMemory(w: u64) u64

Bytes a decoder holds for a frame with window w.

zstd.decodeFrameCopiar enlace

fn · línea 145

pub fn decodeFrame(gpa: Allocator, in: *Reader, sink: *Sink, expected: u64, max_input: u64) DecodeError!u64

Decode exactly one zstd frame from in into sink. in must hold the encoded body and nothing else (it ends where the body ends); its buffer may be any size. At most max_input encoded bytes are read: one more is InputTooLarge, never decoded past. Returns the decoded length; anything after the frame is BadFrame.

zstd.CompressorCopiar enlace

type · línea 409

pub const Compressor = struct

Reusable encoder state (~800 KiB): one per worker.

zstd.Compressor.initCopiar enlace

fn · línea 419

pub fn init(gpa: Allocator) Allocator.Error!Compressor

Sin ///.

zstd.Compressor.deinitCopiar enlace

fn · línea 432

pub fn deinit(c: *Compressor) void

Sin ///.

zstd.Compressor.compressCopiar enlace

fn · línea 445

pub fn compress(c: *Compressor, src: []const u8, dst: []u8) ?usize

Compress src into one zstd frame in dst. Null when the frame does not fit dst (pass dst.len < src.len to get "only if it shrinks"). The frame carries the content size and a window of at most 8 MiB, the limits decodeFrame enforces.

zstd.sample_lenCopiar enlace

const · línea 652

pub const sample_len = 64 * 1024

Sin ///.

zstd.SniffCopiar enlace

type · línea 655

pub const Sniff = enum

What the first bytes of a file say about its payload.

zstd.sniffCopiar enlace

fn · línea 658

pub fn sniff(head: []const u8) Sniff

Video, audio and already-compressed containers by their magic bytes.

zstd.worthEncodingCopiar enlace

fn · línea 679

pub fn worthEncoding(c: *Compressor, head: []const u8) bool

Spec §7 client policy on the file's first bytes: encode only payload that is neither media nor compressed and whose first 64 KiB shrink to ≤ 90 %. c is any compressor (it is reset by compress).