2 gzip Compression and File Creation
The file/gzip library provides utilities to create archive files in gzip format, or simply to compress data using the pkzip “deflate” method.
in-file : path-string?
out-file : path-string? = (path-add-extension in-file ".gz" #".")
Compresses data to the same format as the gzip utility, writing the compressed data directly to a file. The in-file argument is the name of the file to compress. If the file named by out-file exists, it will be overwritten.
Changed in version 220.127.116.11 of package base: Changed default expression of out-file to use path-add-extension instead of string-append.
(gzip-through-ports in out orig-filename timestamp) → void? in : input-port? out : output-port? orig-filename : (or/c string? false/c) timestamp : exact-integer?
Reads the port in for data and compresses it to out, outputting the same format as the gzip utility. The orig-filename string is embedded in this output; orig-filename can be #f to omit the filename from the compressed stream. The timestamp number is also embedded in the output stream, as the modification date of the original file (in Unix seconds, as file-or-directory-modify-seconds would report on Unix).
(deflate in out) →
exact-nonnegative-integer? exact-nonnegative-integer? exact-nonnegative-integer? in : input-port? out : output-port?
Writes pkzip-format “deflated” data to the port out, compressing data from the port in. The data in a file created by gzip uses this format (preceded with header information).
The result is three values: the number of bytes read from in, the number of bytes written to out, and a cyclic redundancy check (CRC) value for the input.