diff options
| -rw-r--r-- | guix/lzlib.scm | 39 |
1 files changed, 19 insertions, 20 deletions
diff --git a/guix/lzlib.scm b/guix/lzlib.scm index a484315c0e..31d84971cb 100644 --- a/guix/lzlib.scm +++ b/guix/lzlib.scm @@ -494,29 +494,28 @@ 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 (if (eof-object? (feed-decoder! decoder)) + read + (loop read start))) + (n (loop (+ read n) (+ start n))))) + (else + read)))) (define (lzwrite! encoder source source-offset source-count target target-offset target-count) |