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compress

Decompression primitives. Each function takes raw bytes (Lua strings are byte buffers) and returns the decompressed bytes as a Lua string. Useful for fetching .gz / .xz / .zst payloads over HTTP and feeding them to a parser without shelling out.

Functions

• compress.gunzip(bytes) → string — Decompress gzip-encoded bytes.
• compress.unxz(bytes) → string — Decompress xz/LZMA2-encoded bytes.
• compress.unzstd(bytes) → string — Decompress zstd-encoded bytes.

Each raises a runtime error tagged with the function name (e.g. compress.gunzip: invalid gzip header) when the input is not a valid stream.

• compress.untar(archive_path, dest_path, opts) → integer — Extract a single member from a tar archive to disk (v0.15.5+). Writes via temp file + atomic rename.
  • archive_path (string): path to the tar archive
  • dest_path (string): destination file path; parent dirs are created if needed
  • opts (table, required):
    • member (string, required): path of the member inside the archive to extract
    • compression (string, optional): "gz" | "xz" | "zst" | "none". If omitted, auto-detected from the archive path extension.
  • Returns bytes written as an integer
  • Raises if opts.member is not found in the archive, or on IO failure

  local bytes = compress.untar(
    "/tmp/release.tar.gz",
    "/usr/local/bin/myapp",
    { member = "myapp/bin/myapp" }
  )
  

Example

local resp = http.get("https://pkgs.example.com/dists/noble/main/binary-amd64/Packages.gz")
local text = compress.gunzip(resp.body)
print(text:sub(1, 200))