system: move out of internal

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/system/link.go

@@ -1,47 +0,0 @@
-package system
-
-import (
-	"fmt"
-	"os"
-)
-
-// Link registers an Op that links dst to src.
-func (sys *I) Link(oldname, newname string) *I { return sys.LinkFileType(Process, oldname, newname) }
-
-// LinkFileType registers a file linking Op labelled with type et.
-func (sys *I) LinkFileType(et Enablement, oldname, newname string) *I {
-	sys.lock.Lock()
-	defer sys.lock.Unlock()
-
-	sys.ops = append(sys.ops, &Hardlink{et, newname, oldname})
-
-	return sys
-}
-
-type Hardlink struct {
-	et       Enablement
-	dst, src string
-}
-
-func (l *Hardlink) Type() Enablement { return l.et }
-
-func (l *Hardlink) apply(sys *I) error {
-	sys.println("linking", l)
-	return sys.wrapErrSuffix(os.Link(l.src, l.dst),
-		fmt.Sprintf("cannot link %q:", l.dst))
-}
-
-func (l *Hardlink) revert(sys *I, ec *Criteria) error {
-	if ec.hasType(l) {
-		sys.printf("removing hard link %q", l.dst)
-		return sys.wrapErrSuffix(os.Remove(l.dst),
-			fmt.Sprintf("cannot remove hard link %q:", l.dst))
-	} else {
-		sys.printf("skipping hard link %q", l.dst)
-		return nil
-	}
-}
-
-func (l *Hardlink) Is(o Op) bool   { l0, ok := o.(*Hardlink); return ok && l0 != nil && *l == *l0 }
-func (l *Hardlink) Path() string   { return l.src }
-func (l *Hardlink) String() string { return fmt.Sprintf("%q from %q", l.dst, l.src) }