ac26fe7554
Also, updates some of the mzlib files to point at `racket/*' libraries rather than to `scheme/*' ones.
50 lines
2.0 KiB
Racket
50 lines
2.0 KiB
Racket
#lang scribble/doc
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@(require "common.rkt" (for-label file/gzip))
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@title[#:tag "gzip"]{@exec{gzip} Compression and File Creation}
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@defmodule[file/gzip]{The @racketmodname[file/gzip] library provides
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utilities to create archive files in @exec{gzip} format, or simply to
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compress data using the @exec{pkzip} ``deflate'' method.}
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@defproc[(gzip [in-file path-string?]
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[out-file path-string? (string-append in-file ".gz")])
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void?]{
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Compresses data to the same format as the @exec{gzip} utility, writing
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the compressed data directly to a file. The @racket[in-file] argument
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is the name of the file to compress. If the file named by
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@racket[out-file] exists, it will be overwritten.}
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@defproc[(gzip-through-ports [in input-port?]
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[out output-port?]
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[orig-filename (or/c string? false/c)]
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[timestamp exact-integer?])
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void?]{
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Reads the port @racket[in] for data and compresses it to @racket[out],
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outputting the same format as the @exec{gzip} utility. The
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@racket[orig-filename] string is embedded in this output;
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@racket[orig-filename] can be @racket[#f] to omit the filename from
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the compressed stream. The @racket[timestamp] number is also embedded
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in the output stream, as the modification date of the original file
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(in Unix seconds, as @racket[file-or-directory-modify-seconds] would
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report on Unix).}
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@defproc[(deflate [in input-port?]
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[out output-port?])
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(values exact-nonnegative-integer?
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exact-nonnegative-integer?
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exact-nonnegative-integer?)]{
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Writes @exec{pkzip}-format ``deflated'' data to the port @racket[out],
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compressing data from the port @racket[in]. The data in a file
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created by @exec{gzip} uses this format (preceded with header
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information).
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The result is three values: the number of bytes read from @racket[in],
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the number of bytes written to @racket[out], and a cyclic redundancy
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check (CRC) value for the input.}
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