>Number:         35048
>Category:       bin
>Synopsis:       when compressing, gzip(1) unlinks input even if output can't be written
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 13 21:30:00 +0000 2006
>Originator:     Mathieu
>Release:        3.0.1
>Organization:
>Environment:
>Description:
If writing fails (like when the FS gets full), gzip will still delete the input file. Ouch.

>How-To-Repeat:
$ df -h .
Filesystem    Size      Used     Avail Capacity  Mounted on
/dev/vnd1a     19M     1.0K       18M     0%    /mnt
$ dd if=/dev/zero of=test bs=1m count=10
10+0 records in
10+0 records out
10485760 bytes transferred in 0.225 secs (46603377 bytes/sec)
$ cp /netbsd .                              
$ gzip netbsd                               

/mnt: write failed, file system is full
gzip: write: No space left on device
$ ls -l
total 10448
-rwx------  1 mathieu  wheel    196608 Nov 13 15:46 netbsd.gz
-rw-------  1 mathieu  wheel  10485760 Nov 13 15:46 test
$ gzip -t netbsd.gz 
gzip: netbsd.gz: unexpected end of file

>Fix:
/*      $NetBSD: gzip.c,v 1.71.2.5 2005/11/27 23:09:46 riz Exp $        */

--- gzip.c	2006-11-13 16:12:57.000000000 -0500
+++ gzip.c.orig	2006-11-13 16:13:45.000000000 -0500
@@ -561,7 +561,7 @@
 		if (z.avail_out == 0) {
 			if (write(out, outbufp, BUFLEN) != BUFLEN) {
 				maybe_warn("write");
-				in_tot = -1;
+				out_tot = -1;
 				goto out;
 			}


It seems like there's a simple typo there. I'm not sure if it fixes completely the problem yet... but it does seem to work here.

$ gzip netbsd
gzip: output file: netbsd.gz wrong size (2293760 != -1), deleting
gzip: leaving original netbsd
$ ls -l
total 16528
-rwx------  1 mathieu  wheel  8514752 Nov 13 16:12 netbsd
-rw-------  1 mathieu  wheel  8388608 Nov 13 15:58 test