github.com/lazyboychen7/engine@v17.12.1-ce-rc2+incompatible/image/rootfs.go (about)

     1  package image
     2  
     3  import (
     4  	"runtime"
     5  
     6  	"github.com/docker/docker/layer"
     7  	"github.com/sirupsen/logrus"
     8  )
     9  
    10  // TypeLayers is used for RootFS.Type for filesystems organized into layers.
    11  const TypeLayers = "layers"
    12  
    13  // typeLayersWithBase is an older format used by Windows up to v1.12. We
    14  // explicitly handle this as an error case to ensure that a daemon which still
    15  // has an older image like this on disk can still start, even though the
    16  // image itself is not usable. See https://github.com/docker/docker/pull/25806.
    17  const typeLayersWithBase = "layers+base"
    18  
    19  // RootFS describes images root filesystem
    20  // This is currently a placeholder that only supports layers. In the future
    21  // this can be made into an interface that supports different implementations.
    22  type RootFS struct {
    23  	Type    string         `json:"type"`
    24  	DiffIDs []layer.DiffID `json:"diff_ids,omitempty"`
    25  }
    26  
    27  // NewRootFS returns empty RootFS struct
    28  func NewRootFS() *RootFS {
    29  	return &RootFS{Type: TypeLayers}
    30  }
    31  
    32  // Append appends a new diffID to rootfs
    33  func (r *RootFS) Append(id layer.DiffID) {
    34  	r.DiffIDs = append(r.DiffIDs, id)
    35  }
    36  
    37  // Clone returns a copy of the RootFS
    38  func (r *RootFS) Clone() *RootFS {
    39  	newRoot := NewRootFS()
    40  	newRoot.Type = r.Type
    41  	newRoot.DiffIDs = append(r.DiffIDs)
    42  	return newRoot
    43  }
    44  
    45  // ChainID returns the ChainID for the top layer in RootFS.
    46  func (r *RootFS) ChainID() layer.ChainID {
    47  	if runtime.GOOS == "windows" && r.Type == typeLayersWithBase {
    48  		logrus.Warnf("Layer type is unsupported on this platform. DiffIDs: '%v'", r.DiffIDs)
    49  		return ""
    50  	}
    51  	return layer.CreateChainID(r.DiffIDs)
    52  }