Method HasUniqueRef

pkg/sentry/pgalloc/pgalloc.go:1149–1168

HasUniqueRef returns true if all pages in the given range have exactly one reference. A return value of false is inherently racy, but if the caller holds a reference on the given range and is preventing other goroutines from copying it, then a return value of true is not racy. Preconditions: At lea

(fr memmap.FileRange)

//
// Preconditions: At least one reference must be held on all pages in fr.
func (f *MemoryFile) HasUniqueRef(fr memmap.FileRange) bool {
	hasUniqueRef := true
	f.mu.Lock()
	defer f.mu.Unlock()
	f.forEachChunk(fr, func(chunk *chunkInfo, chunkFR memmap.FileRange) bool {
		unfree := &f.unfreeSmall
		if chunk.huge {
			unfree = &f.unfreeHuge
		}
		unfree.VisitFullRange(fr, func(ufseg unfreeIterator) bool {
			if ufseg.ValuePtr().refs != 1 {
				hasUniqueRef = false
				return false
			}
			return true
		})
		return hasUniqueRef
	})
	return hasUniqueRef
}

// IncRef implements memmap.File.IncRef.
func (f *MemoryFile) IncRef(fr memmap.FileRange, memCgID uint32) {