GZIP Decompress -- Data Loss Through File Deletion

[Ripduman Sohan]

There's a subtle bug in gzip (1.3.13) decompression when no suffixes are 
employed.

The command [gzip -d -S "" <infile>] will, as expected, ask to overwrite the 
output file.  However, it goes on to unlink the newly
created (decompressed file) resulting in data loss through file deletion.
I believe the attached patch should solve this problem.

Regards

rip



--- gzip.c.orig 2010-02-11 11:34:06.000000000 +0000
+++ gzip.c      2010-02-11 11:37:19.000000000 +0000
@@ -850,7 +850,7 @@
     if (!to_stdout)
       {
        sigset_t oldset;
-       int unlink_errno;
+       int unlink_errno = 0;

        copy_stat (&istat);
        if (close (ofd) != 0)
@@ -858,7 +858,8 @@

        sigprocmask (SIG_BLOCK, &caught_signals, &oldset);
        remove_ofname_fd = -1;
-       unlink_errno = xunlink (ifname) == 0 ? 0 : errno;
+       if (z_len != 0)
+         unlink_errno = xunlink (ifname) == 0 ? 0 : errno;
        sigprocmask (SIG_SETMASK, &oldset, NULL);

        if (unlink_errno)