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-rw-r--r--guix/lzlib.scm71
1 files changed, 71 insertions, 0 deletions
diff --git a/guix/lzlib.scm b/guix/lzlib.scm
index deb900f352..a484315c0e 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
@@ -515,6 +518,24 @@ the end-of-stream has been reached."
(loop rd)))
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)))
"Write up to COUNT bytes from BV at offset START into LZ-PORT. Return
@@ -597,6 +618,56 @@ 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."