The install-unwrap program restores qmail-queue, which disables virus scanning. File replacement is atomic, so this can safely be done while qmail is running.
Algorithm
qmail-queue is restored using the following steps:
The file bin/qscanq/qmail-queue is renamed bin/qmail-queue. This atomically replaces the symbolic link to qscanq.
The directory bin/qscanq/ is removed.
Security and Reliability
If bin/qscanq/ lives on a different filesystem than qmail's bin directory, then restoration will fail. If the wrong file appears as bin/qscanq/qmail-queue, then it will be used by qmail instead of the right program once isntall-unwrap completes.
In general, security considerations are about the same for install-wrap and install-unwrap.
