github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/pkg/sentry/vfs/mount_ring.go (about)

     1  package vfs
     2  
     3  // Entry is an element in the circular linked list.
     4  //
     5  // +stateify savable
     6  type mountEntry struct {
     7  	next      *mountEntry
     8  	prev      *mountEntry
     9  	container *Mount
    10  }
    11  
    12  // Init instantiates an Element to be an item in a ring (circularly-linked
    13  // list).
    14  //
    15  //go:nosplit
    16  func (e *mountEntry) Init(container *Mount) {
    17  	e.next = e
    18  	e.prev = e
    19  	e.container = container
    20  }
    21  
    22  // Add adds new to old's ring.
    23  //
    24  //go:nosplit
    25  func (e *mountEntry) Add(new *mountEntry) {
    26  	next := e.next
    27  	prev := e
    28  
    29  	next.prev = new
    30  	new.next = next
    31  	new.prev = prev
    32  	e.next = new
    33  }
    34  
    35  // Remove removes e from its ring and reinitializes it.
    36  //
    37  //go:nosplit
    38  func (e *mountEntry) Remove() {
    39  	next := e.next
    40  	prev := e.prev
    41  
    42  	next.prev = prev
    43  	prev.next = next
    44  	e.Init(e.container)
    45  }
    46  
    47  // Empty returns true if there are no other elements in the ring.
    48  //
    49  //go:nosplit
    50  func (e *mountEntry) Empty() bool {
    51  	return e.next == e
    52  }
    53  
    54  // Next returns the next containing object pointed to by the list.
    55  //
    56  //go:nosplit
    57  func (e *mountEntry) Next() *Mount {
    58  	return e.next.container
    59  }
    60  
    61  // Prev returns the previous containing object pointed to by the list.
    62  //
    63  //go:nosplit
    64  func (e *mountEntry) Prev() *Mount {
    65  	return e.prev.container
    66  }