ro_layer.go 3.8 KB

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  1. package layer
  2. import (
  3. "fmt"
  4. "io"
  5. "github.com/docker/distribution"
  6. "github.com/opencontainers/go-digest"
  7. )
  8. type roLayer struct {
  9. chainID ChainID
  10. diffID DiffID
  11. parent *roLayer
  12. cacheID string
  13. size int64
  14. layerStore *layerStore
  15. descriptor distribution.Descriptor
  16. referenceCount int
  17. references map[Layer]struct{}
  18. }
  19. // TarStream for roLayer guarantees that the data that is produced is the exact
  20. // data that the layer was registered with.
  21. func (rl *roLayer) TarStream() (io.ReadCloser, error) {
  22. rc, err := rl.layerStore.getTarStream(rl)
  23. if err != nil {
  24. return nil, err
  25. }
  26. vrc, err := newVerifiedReadCloser(rc, digest.Digest(rl.diffID))
  27. if err != nil {
  28. return nil, err
  29. }
  30. return vrc, nil
  31. }
  32. // TarStreamFrom does not make any guarantees to the correctness of the produced
  33. // data. As such it should not be used when the layer content must be verified
  34. // to be an exact match to the registered layer.
  35. func (rl *roLayer) TarStreamFrom(parent ChainID) (io.ReadCloser, error) {
  36. var parentCacheID string
  37. for pl := rl.parent; pl != nil; pl = pl.parent {
  38. if pl.chainID == parent {
  39. parentCacheID = pl.cacheID
  40. break
  41. }
  42. }
  43. if parent != ChainID("") && parentCacheID == "" {
  44. return nil, fmt.Errorf("layer ID '%s' is not a parent of the specified layer: cannot provide diff to non-parent", parent)
  45. }
  46. return rl.layerStore.driver.Diff(rl.cacheID, parentCacheID)
  47. }
  48. func (rl *roLayer) ChainID() ChainID {
  49. return rl.chainID
  50. }
  51. func (rl *roLayer) DiffID() DiffID {
  52. return rl.diffID
  53. }
  54. func (rl *roLayer) Parent() Layer {
  55. if rl.parent == nil {
  56. return nil
  57. }
  58. return rl.parent
  59. }
  60. func (rl *roLayer) Size() (size int64, err error) {
  61. if rl.parent != nil {
  62. size, err = rl.parent.Size()
  63. if err != nil {
  64. return
  65. }
  66. }
  67. return size + rl.size, nil
  68. }
  69. func (rl *roLayer) DiffSize() (size int64, err error) {
  70. return rl.size, nil
  71. }
  72. func (rl *roLayer) Metadata() (map[string]string, error) {
  73. return rl.layerStore.driver.GetMetadata(rl.cacheID)
  74. }
  75. type referencedCacheLayer struct {
  76. *roLayer
  77. }
  78. func (rl *roLayer) getReference() Layer {
  79. ref := &referencedCacheLayer{
  80. roLayer: rl,
  81. }
  82. rl.references[ref] = struct{}{}
  83. return ref
  84. }
  85. func (rl *roLayer) hasReference(ref Layer) bool {
  86. _, ok := rl.references[ref]
  87. return ok
  88. }
  89. func (rl *roLayer) hasReferences() bool {
  90. return len(rl.references) > 0
  91. }
  92. func (rl *roLayer) deleteReference(ref Layer) {
  93. delete(rl.references, ref)
  94. }
  95. func (rl *roLayer) depth() int {
  96. if rl.parent == nil {
  97. return 1
  98. }
  99. return rl.parent.depth() + 1
  100. }
  101. func storeLayer(tx MetadataTransaction, layer *roLayer) error {
  102. if err := tx.SetDiffID(layer.diffID); err != nil {
  103. return err
  104. }
  105. if err := tx.SetSize(layer.size); err != nil {
  106. return err
  107. }
  108. if err := tx.SetCacheID(layer.cacheID); err != nil {
  109. return err
  110. }
  111. // Do not store empty descriptors
  112. if layer.descriptor.Digest != "" {
  113. if err := tx.SetDescriptor(layer.descriptor); err != nil {
  114. return err
  115. }
  116. }
  117. if layer.parent != nil {
  118. if err := tx.SetParent(layer.parent.chainID); err != nil {
  119. return err
  120. }
  121. }
  122. return nil
  123. }
  124. func newVerifiedReadCloser(rc io.ReadCloser, dgst digest.Digest) (io.ReadCloser, error) {
  125. return &verifiedReadCloser{
  126. rc: rc,
  127. dgst: dgst,
  128. verifier: dgst.Verifier(),
  129. }, nil
  130. }
  131. type verifiedReadCloser struct {
  132. rc io.ReadCloser
  133. dgst digest.Digest
  134. verifier digest.Verifier
  135. }
  136. func (vrc *verifiedReadCloser) Read(p []byte) (n int, err error) {
  137. n, err = vrc.rc.Read(p)
  138. if n > 0 {
  139. if n, err := vrc.verifier.Write(p[:n]); err != nil {
  140. return n, err
  141. }
  142. }
  143. if err == io.EOF {
  144. if !vrc.verifier.Verified() {
  145. err = fmt.Errorf("could not verify layer data for: %s. This may be because internal files in the layer store were modified. Re-pulling or rebuilding this image may resolve the issue", vrc.dgst)
  146. }
  147. }
  148. return
  149. }
  150. func (vrc *verifiedReadCloser) Close() error {
  151. return vrc.rc.Close()
  152. }