diff options
Diffstat (limited to 'guix/lzlib.scm')
| -rw-r--r-- | guix/lzlib.scm | 116 |
1 files changed, 95 insertions, 21 deletions
diff --git a/guix/lzlib.scm b/guix/lzlib.scm index a6dac46049..24c7b4b448 100644 --- a/guix/lzlib.scm +++ b/guix/lzlib.scm @@ -1,5 +1,6 @@ ;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2019 Pierre Neidhardt <mail@ambrevar.xyz> +;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org> ;;; ;;; This file is part of GNU Guix. ;;; @@ -23,9 +24,11 @@ #:use-module (ice-9 match) #:use-module (system foreign) #:use-module (guix config) + #:use-module (srfi srfi-11) #:export (lzlib-available? make-lzip-input-port make-lzip-output-port + make-lzip-input-port/compressed call-with-lzip-input-port call-with-lzip-output-port %default-member-length-limit @@ -168,7 +171,7 @@ so use it only when needed. " (let ((proc (lzlib-procedure int "LZ_compress_read" (list '* '* int)))) (lambda* (encoder lzfile-bv #:optional (start 0) (count (bytevector-length lzfile-bv))) "Read up to COUNT bytes from the encoder stream, storing the results in LZFILE-BV. -Return the number of uncompressed bytes written, a strictly positive integer." +Return the number of uncompressed bytes written, a positive integer." (let ((ret (proc (lz-encoder->pointer encoder) (bytevector->pointer lzfile-bv start) count))) @@ -491,29 +494,50 @@ perhaps not yet read." ;; High level functions. -(define* (lzread! decoder file-port bv + +(define* (lzread! decoder port bv #:optional (start 0) (count (bytevector-length bv))) - "Read up to COUNT bytes from FILE-PORT into BV at offset START. Return the + "Read up to COUNT bytes from PORT into BV at offset START. Return the number of uncompressed bytes actually read; it is zero if COUNT is zero or if the end-of-stream has been reached." - ;; WARNING: Because we don't alternate between lz-reads and lz-writes, we can't - ;; process more than lz-decompress-write-size from the file-port. - (when (> count (lz-decompress-write-size decoder)) - (set! count (lz-decompress-write-size decoder))) - (let ((file-bv (get-bytevector-n file-port count))) - (unless (eof-object? file-bv) - (lz-decompress-write decoder file-bv 0 (bytevector-length file-bv)))) - (let ((read 0)) - (let loop ((rd 0)) - (if (< start (bytevector-length bv)) - (begin - (set! rd (lz-decompress-read decoder bv start (- (bytevector-length bv) start))) - (set! start (+ start rd)) - (set! read (+ read rd))) - (set! rd 0)) - (unless (= rd 0) - (loop rd))) - read)) + (define (feed-decoder! decoder) + ;; Feed DECODER with data read from PORT. + (match (get-bytevector-n port (lz-decompress-write-size decoder)) + ((? eof-object? eof) eof) + (bv (lz-decompress-write decoder bv)))) + + (let loop ((read 0) + (start start)) + (cond ((< read count) + (match (lz-decompress-read decoder bv start (- count read)) + (0 (cond ((lz-decompress-finished? decoder) + read) + ((eof-object? (feed-decoder! decoder)) + (lz-decompress-finish decoder) + (loop read start)) + (else ;read again + (loop read start)))) + (n (loop (+ read n) (+ start n))))) + (else + read)))) + +(define (lzwrite! encoder source source-offset source-count + target target-offset target-count) + "Write up to SOURCE-COUNT bytes from SOURCE to ENCODER, and read up to +TARGET-COUNT bytes into TARGET at TARGET-OFFSET. Return two values: the +number of bytes read from SOURCE, and the number of bytes written to TARGET, +possibly zero." + (define read + (if (> (lz-compress-write-size encoder) 0) + (match (lz-compress-write encoder source source-offset source-count) + (0 (lz-compress-finish encoder) 0) + (n n)) + 0)) + + (define written + (lz-compress-read encoder target target-offset target-count)) + + (values read written)) (define* (lzwrite encoder bv lz-port #:optional (start 0) (count (bytevector-length bv))) @@ -597,6 +621,56 @@ port is closed." (lz-compress-close encoder) (close-port port)))) +(define* (make-lzip-input-port/compressed port + #:key + (level %default-compression-level)) + "Return an input port that compresses data read from PORT, with the given LEVEL. +PORT is automatically closed when the resulting port is closed." + (define encoder (apply lz-compress-open + (car (assoc-ref %compression-levels level)))) + + (define input-buffer (make-bytevector 8192)) + (define input-len 0) + (define input-offset 0) + + (define input-eof? #f) + + (define (read! bv start count) + (cond + (input-eof? + (match (lz-compress-read encoder bv start count) + (0 (if (lz-compress-finished? encoder) + 0 + (read! bv start count))) + (n n))) + ((= input-offset input-len) + (match (get-bytevector-n! port input-buffer 0 + (bytevector-length input-buffer)) + ((? eof-object?) + (set! input-eof? #t) + (lz-compress-finish encoder)) + (count + (set! input-offset 0) + (set! input-len count))) + (read! bv start count)) + (else + (let-values (((read written) + (lzwrite! encoder + input-buffer input-offset + (- input-len input-offset) + bv start count))) + (set! input-offset (+ input-offset read)) + + ;; Make sure we don't return zero except on EOF. + (if (= 0 written) + (read! bv start count) + written))))) + + (make-custom-binary-input-port "lzip-input/compressed" + read! #f #f + (lambda () + (close-port port)))) + (define* (call-with-lzip-input-port port proc) "Call PROC with a port that wraps PORT and decompresses data read from it. PORT is closed upon completion." |