xz should warn before overwriting read-only files

[Guy Taylor]

running xz --decompress (unxz) on a readonly file will not show any warning before writing over the file and changing the extension.

This is technically expected behaviour but not sympathetic to the end user.

[Rolf Leggewie (r0lf)]

Are you still affected? I cannot reproduce this on trusty.

$ echo "test" |xz > /tmp/test.txt.xz
$ chmod uog-rwx /tmp/test.txt.xz
$ unxz /tmp/test.txt.xz

[Rolf Leggewie (r0lf)]

OK, I was able to verify it now, made a mistake earlier. I'll let somebody else decide if this is desired behaviour.

Steps to reproduce:
$ echo "test" |xz > /tmp/test.txt.xz
$ chmod 444 /tmp/test.txt.xz
$ unxz /tmp/test.txt.xz
$ ls -la /tmp/test.txt*
-r--r--r-- 1 rolf rolf 5 Jun 4 13:06 /tmp/test.txt

gunzip exhibits the same behaviour, by the way.