cp -p preserves extended attributes

[sylvestre]

Component

cp

Description

uutils cp -p preserves extended attributes, but GNU cp -p does not. GNU only preserves mode, ownership, and timestamps with -p; xattrs require explicit --preserve=xattr or -a.

Test / Reproduction Steps

Not necessary.

pub const DEFAULT: Self = Self {
    #[cfg(unix)]
    ownership: Preserve::Yes { required: true },
    mode: Preserve::Yes { required: true },
    timestamps: Preserve::Yes { required: true },
    xattr: Preserve::Yes { required: true },  // <----

Impact

This breaks compatibility with scripts expecting GNU behavior and creates a security risk when run as root.

File capabilities and SELinux labels stored as xattrs get copied unintentionally. It also causes hard failures on filesystems that don't support xattrs, while GNU cp -p would succeed.