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02/03: zlib: Protect against non-empty port internal buffers.
From: |
Ludovic Courtès |
Subject: |
02/03: zlib: Protect against non-empty port internal buffers. |
Date: |
Wed, 27 Jul 2016 10:46:53 +0000 (UTC) |
civodul pushed a commit to branch master
in repository guix.
commit 688ec13c459602d475bccd3638a6802dc0a6ce23
Author: Ludovic Courtès <address@hidden>
Date: Wed Jul 27 12:39:27 2016 +0200
zlib: Protect against non-empty port internal buffers.
* guix/zlib.scm (make-gzip-input-port)[gzfile]: Error out
if (drain-input port) returns a non-empty string.
* guix/zlib.scm (make-gzip-output-port)[gzfile]: Call 'force-output'.
---
guix/zlib.scm | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/guix/zlib.scm b/guix/zlib.scm
index 40f5294..7442012 100644
--- a/guix/zlib.scm
+++ b/guix/zlib.scm
@@ -168,9 +168,18 @@ closed even if closing GZFILE triggers an exception."
"Return an input port that decompresses data read from PORT, a file port.
PORT is automatically closed when the resulting port is closed. BUFFER-SIZE
is the size in bytes of the internal buffer, 8 KiB by default; using a larger
-buffer increases decompression speed."
+buffer increases decompression speed. An error is thrown if PORT contains
+buffered input, which would be lost (and is lost anyway)."
(define gzfile
- (gzdopen (fileno port) "r"))
+ (match (drain-input port)
+ ("" ;PORT's buffer is empty
+ (gzdopen (fileno port) "r"))
+ (_
+ ;; This is unrecoverable but it's better than having the buffered input
+ ;; be lost, leading to unclear end-of-file or corrupt-data errors down
+ ;; the path.
+ (throw 'zlib-error 'make-gzip-input-port
+ "port contains buffered input" port))))
(define (read! bv start count)
(gzread! gzfile bv start count))
@@ -189,8 +198,10 @@ buffer increases decompression speed."
a file port, as its sink. PORT is automatically closed when the resulting
port is closed."
(define gzfile
- (gzdopen (fileno port)
- (string-append "w" (number->string level))))
+ (begin
+ (force-output port) ;empty PORT's buffer
+ (gzdopen (fileno port)
+ (string-append "w" (number->string level)))))
(define (write! bv start count)
(gzwrite gzfile bv start count))