chibi-scheme/lib/chibi/zlib.scm

78 lines
2.5 KiB
Scheme

;; Temporary hack, need to rewrite in pure Scheme.
;;> Gzip compress a file in place, renaming with a .gz suffix.
(define (gzip-file path)
(system "gzip" path))
;;> Gunzip decompress a file in place, removing any .gz suffix.
(define (gunzip-file path)
(system "gzip" "-d" path))
;; Utility to filter a bytevector to a process and return the
;; accumulated output as a new bytevector.
;; (define (process-pipe-bytevector cmd bvec)
;; (call-with-process-io
;; cmd
;; (lambda (pid proc-in proc-out proc-err)
;; (let ((len (bytevector-length bvec))
;; (out (open-output-bytevector)))
;; (let lp ((i 0))
;; (cond
;; ((u8-ready? proc-out)
;; (let ((u8 (read-u8 proc-out)))
;; (cond
;; ((eof-object? u8)
;; (get-output-bytevector out))
;; (else
;; (write-u8 u8 out)
;; (lp i)))))
;; ((< i len)
;; (write-u8 (bytevector-u8-ref bvec i) proc-in)
;; (lp (+ i 1)))
;; (else
;; ;; Once we've completed sending the input we busy wait
;; ;; until all output has been read. We can't just waitpid
;; ;; here because the remaining output may still overflow the
;; ;; pipe buffer.
;; (close-output-port proc-in)
;; (let lp ()
;; (let ((u8 (read-u8 proc-out)))
;; (cond
;; ((eof-object? u8)
;; (get-output-bytevector out))
;; (else
;; (write-u8 u8 out)
;; (lp))))))))))))
;; Use a temp file to avoid dead-lock issues with pipes.
(define (process-run-bytevector cmd bvec)
(call-with-temp-file "bvec"
(lambda (path out preserve)
(write-bytevector bvec out)
(close-output-port out)
(process->bytevector (append cmd (list path))))))
;;> Gzip compress a string or bytevector in memory.
(define (gzip x)
(if (string? x)
(gzip (string->utf8 x))
(process-run-bytevector '("gzip" "-c") x)))
;;> Gunzip decompress a bytevector in memory.
(define (gunzip bvec)
(process-run-bytevector '("gzip" "-c" "-d") bvec))
;;> Gunzip decompress a bytevector in memory if it has been
;;> compressed, or return as-is otherwise.
(define (maybe-gunzip bvec)
(if (and (>= (bytevector-length bvec) 10)
(eqv? #x1f (bytevector-u8-ref bvec 0))
(eqv? #x8b (bytevector-u8-ref bvec 1)))
(gunzip bvec)
bvec))