func pathFor()

in registry/storage/paths.go [114:254]
114 lines of code
32 McCabe index (conditional complexity)

func pathFor(spec pathSpec) (string, error) {
	// Switch on the path object type and return the appropriate path. At
	// first glance, one may wonder why we don't use an interface to
	// accomplish this. By keep the formatting separate from the pathSpec, we
	// keep separate the path generation componentized. These specs could be
	// passed to a completely different mapper implementation and generate a
	// different set of paths.
	//
	// For example, imagine migrating from one backend to the other: one could
	// build a filesystem walker that converts a string path in one version,
	// to an intermediate path object, than can be consumed and mapped by the
	// other version.

	rootPrefix := []string{storagePathRoot, storagePathVersion}
	repoPrefix := make([]string, len(rootPrefix), len(rootPrefix)+1)
	copy(repoPrefix, rootPrefix)
	repoPrefix = append(repoPrefix, "repositories")

	switch v := spec.(type) {
	case manifestRevisionsPathSpec:
		return path.Join(append(repoPrefix, v.name, "_manifests", "revisions")...), nil

	case manifestRevisionPathSpec:
		components, err := digestPathComponents(v.revision, false)
		if err != nil {
			return "", err
		}

		return path.Join(append(append(repoPrefix, v.name, "_manifests", "revisions"), components...)...), nil
	case manifestRevisionLinkPathSpec:
		root, err := pathFor(manifestRevisionPathSpec(v))
		if err != nil {
			return "", err
		}

		return path.Join(root, "link"), nil
	case manifestTagsPathSpec:
		return path.Join(append(repoPrefix, v.name, "_manifests", "tags")...), nil
	case manifestTagPathSpec:
		root, err := pathFor(manifestTagsPathSpec{
			name: v.name,
		})
		if err != nil {
			return "", err
		}

		return path.Join(root, v.tag), nil
	case manifestTagCurrentPathSpec:
		root, err := pathFor(manifestTagPathSpec(v))
		if err != nil {
			return "", err
		}

		return path.Join(root, "current", "link"), nil
	case manifestTagIndexPathSpec:
		root, err := pathFor(manifestTagPathSpec(v))
		if err != nil {
			return "", err
		}

		return path.Join(root, "index"), nil
	case manifestTagIndexEntryLinkPathSpec:
		root, err := pathFor(manifestTagIndexEntryPathSpec(v))
		if err != nil {
			return "", err
		}

		return path.Join(root, "link"), nil
	case manifestTagIndexEntryPathSpec:
		root, err := pathFor(manifestTagIndexPathSpec{
			name: v.name,
			tag:  v.tag,
		})
		if err != nil {
			return "", err
		}

		components, err := digestPathComponents(v.revision, false)
		if err != nil {
			return "", err
		}

		return path.Join(root, path.Join(components...)), nil
	case layerLinkPathSpec:
		components, err := digestPathComponents(v.digest, false)
		if err != nil {
			return "", err
		}

		blobLinkPathComponents := make([]string, len(repoPrefix), len(repoPrefix)+2)
		copy(blobLinkPathComponents, repoPrefix)
		blobLinkPathComponents = append(blobLinkPathComponents, v.name, "_layers")

		return path.Join(path.Join(append(blobLinkPathComponents, components...)...), "link"), nil
	case blobsPathSpec:
		blobsPathPrefix := make([]string, len(rootPrefix), len(rootPrefix)+1)
		copy(blobsPathPrefix, rootPrefix)
		blobsPathPrefix = append(blobsPathPrefix, "blobs")
		return path.Join(blobsPathPrefix...), nil
	case blobPathSpec:
		components, err := digestPathComponents(v.digest, true)
		if err != nil {
			return "", err
		}

		blobPathPrefix := make([]string, len(rootPrefix), len(rootPrefix)+1)
		copy(blobPathPrefix, rootPrefix)
		blobPathPrefix = append(blobPathPrefix, "blobs")
		return path.Join(append(blobPathPrefix, components...)...), nil
	case blobDataPathSpec:
		components, err := digestPathComponents(v.digest, true)
		if err != nil {
			return "", err
		}

		components = append(components, "data")
		blobPathPrefix := make([]string, len(rootPrefix), len(rootPrefix)+1)
		copy(blobPathPrefix, rootPrefix)
		blobPathPrefix = append(blobPathPrefix, "blobs")
		return path.Join(append(blobPathPrefix, components...)...), nil

	case uploadDataPathSpec:
		return path.Join(append(repoPrefix, v.name, "_uploads", v.id, "data")...), nil
	case uploadStartedAtPathSpec:
		return path.Join(append(repoPrefix, v.name, "_uploads", v.id, "startedat")...), nil
	case uploadHashStatePathSpec:
		offset := fmt.Sprintf("%d", v.offset)
		if v.list {
			offset = "" // Limit to the prefix for listing offsets.
		}
		return path.Join(append(repoPrefix, v.name, "_uploads", v.id, "hashstates", string(v.alg), offset)...), nil
	case repositoriesRootPathSpec:
		return path.Join(repoPrefix...), nil
	case repositoryRootPathSpec:
		return path.Join(append(repoPrefix, v.name)...), nil
	case lockFilePathSpec:
		return path.Join(storagePathRoot, "lockfiles", v.name), nil
	default:
		return "", fmt.Errorf("unknown path spec: %#v", v)
	}
}