MultiWrite writes the contents of each image to the provided reader, in the V1 image tarball format. The contents are written in the following format: One manifest.json file at the top level containing information about several images. One repositories file mapping from the image /<repo na
(refToImage map[name.Reference]v1.Image, w io.Writer)
| 193 | // |
| 194 | // One file for the config blob, named after its SHA. |
| 195 | func MultiWrite(refToImage map[name.Reference]v1.Image, w io.Writer) error { |
| 196 | tf := tar.NewWriter(w) |
| 197 | defer tf.Close() |
| 198 | |
| 199 | sortedImages, imageToTags := dedupRefToImage(refToImage) |
| 200 | var m tarball.Manifest |
| 201 | repos := make(repositoriesTarDescriptor) |
| 202 | |
| 203 | seenLayerIDs := make(map[string]struct{}) |
| 204 | for _, img := range sortedImages { |
| 205 | tags := imageToTags[img] |
| 206 | |
| 207 | // Write the config. |
| 208 | cfgName, err := img.ConfigName() |
| 209 | if err != nil { |
| 210 | return err |
| 211 | } |
| 212 | cfgFileName := fmt.Sprintf("%s.json", cfgName.Hex) |
| 213 | cfgBlob, err := img.RawConfigFile() |
| 214 | if err != nil { |
| 215 | return err |
| 216 | } |
| 217 | if err := writeTarEntry(tf, cfgFileName, bytes.NewReader(cfgBlob), int64(len(cfgBlob))); err != nil { |
| 218 | return err |
| 219 | } |
| 220 | cfg, err := img.ConfigFile() |
| 221 | if err != nil { |
| 222 | return err |
| 223 | } |
| 224 | |
| 225 | // Store foreign layer info. |
| 226 | layerSources := make(map[v1.Hash]v1.Descriptor) |
| 227 | |
| 228 | // Write the layers. |
| 229 | layers, err := img.Layers() |
| 230 | if err != nil { |
| 231 | return err |
| 232 | } |
| 233 | history := filterEmpty(cfg.History) |
| 234 | // Create a blank config history if the config didn't have a history. |
| 235 | if len(history) == 0 && len(layers) != 0 { |
| 236 | history = make([]v1.History, len(layers)) |
| 237 | } else if len(layers) != len(history) { |
| 238 | return fmt.Errorf("image config had layer history which did not match the number of layers, got len(history)=%d, len(layers)=%d, want len(history)=len(layers)", len(history), len(layers)) |
| 239 | } |
| 240 | layerFiles := make([]string, len(layers)) |
| 241 | var prev *v1Layer |
| 242 | for i, l := range layers { |
| 243 | if err := updateLayerSources(layerSources, l, img); err != nil { |
| 244 | return fmt.Errorf("unable to update image metadata to include undistributable layer source information: %w", err) |
| 245 | } |
| 246 | var cur *v1Layer |
| 247 | if i < (len(layers) - 1) { |
| 248 | cur, err = newV1Layer(l, prev, history[i]) |
| 249 | } else { |
| 250 | cur, err = newTopV1Layer(l, prev, history[i], cfg, cfgBlob) |
| 251 | } |
| 252 | if err != nil { |
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