— Procedure: is-gzip-file? filename-or-port

Takes a filename or a binary input port and returns true if the file looks like a GZIP file. The port should have set-port-position! and port-position.

— Procedure: make-gzip-input-port binary-input-port id close-underlying-port?

Returns a new port that can be used to read decompressed GZIP data from the binary-input-port. The id is the name of the returned port.

If close-underlying-port? is true then at the end of the GZIP stream the binary-input-port will be closed.

— Procedure: open-gzip-file-input-port filename

Opens the file specified by filename and returns a binary input port that decompresses the file on-the-fly.

— Procedure: extract-gzip binary-input-port binary-output-port

Reads compressed data from binary-input-port and writes the decompressed data to binary-output-port. Returns a list of gzip headers, one for each gzip member of the file (gzip files can be concatenated).

— Procedure: get-gzip-header binary-input-port

Reads a GZIP header from binary-input-port and performs sanity checks.

— Procedure: gzip-text? hdr

True if the uncompressed data associated with hdr is believed to be text.

— Procedure: gzip-mtime hdr

The file's modification time as an SRFI-19 date or #f is none is available.

— Procedure: gzip-extra-data hdr

An “extra field” which some systems use to encode additional file attributes. This is an unparsed bytevector.

— Procedure: gzip-filename hdr

The file's original filename as a string or #f if none is available.

— Procedure: gzip-comment hdr

A file comment as a string or #f if none is available.

— Procedure: gzip-method hdr

The symbol slowest, fastest or an integer (probably denoting a different compression setting).

— Procedure: gzip-os hdr

The id number of the operating system that created the file. It is e.g. 0 for DOS, 1 for Amiga, 2 for VMS, 3 for Unix.