8be20212f1
In preparation for removing the common package, the tarsum utilities are being moved to the more relevant digest package. This functionality will probably go away in the future, but it's maintained here for the time being. Signed-off-by: Stephen J Day <stephen.day@docker.com>
73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
package digest
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import (
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"fmt"
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"regexp"
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)
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// TarSumRegexp defines a reguler expression to match tarsum identifiers.
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var TarsumRegexp = regexp.MustCompile("tarsum(?:.[a-z0-9]+)?\\+[a-zA-Z0-9]+:[A-Fa-f0-9]+")
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// TarsumRegexpCapturing defines a reguler expression to match tarsum identifiers with
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// capture groups corresponding to each component.
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var TarsumRegexpCapturing = regexp.MustCompile("(tarsum)(.([a-z0-9]+))?\\+([a-zA-Z0-9]+):([A-Fa-f0-9]+)")
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// TarSumInfo contains information about a parsed tarsum.
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type TarSumInfo struct {
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// Version contains the version of the tarsum.
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Version string
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// Algorithm contains the algorithm for the final digest
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Algorithm string
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// Digest contains the hex-encoded digest.
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Digest string
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}
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// InvalidTarSumError provides informations about a TarSum that cannot be parsed
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// by ParseTarSum.
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type InvalidTarSumError struct {
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TarSum string
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}
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func (e InvalidTarSumError) Error() string {
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return fmt.Sprintf("invalid tarsum: %q", e.TarSum)
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}
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// ParseTarSum parses a tarsum string into its components of interest. For
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// example, this method may receive the tarsum in the following format:
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//
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// tarsum.v1+sha256:220a60ecd4a3c32c282622a625a54db9ba0ff55b5ba9c29c7064a2bc358b6a3e
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//
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// The function will return the following:
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//
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// TarSumInfo{
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// Version: "v1",
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// Algorithm: "sha256",
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// Digest: "220a60ecd4a3c32c282622a625a54db9ba0ff55b5ba9c29c7064a2bc358b6a3e",
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// }
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//
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func ParseTarSum(tarSum string) (tsi TarSumInfo, err error) {
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components := TarsumRegexpCapturing.FindStringSubmatch(tarSum)
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if len(components) != 1+TarsumRegexpCapturing.NumSubexp() {
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return TarSumInfo{}, InvalidTarSumError{TarSum: tarSum}
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}
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return TarSumInfo{
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Version: components[3],
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Algorithm: components[4],
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Digest: components[5],
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}, nil
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}
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// String returns the valid, string representation of the tarsum info.
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func (tsi TarSumInfo) String() string {
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if tsi.Version == "" {
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return fmt.Sprintf("tarsum+%s:%s", tsi.Algorithm, tsi.Digest)
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}
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return fmt.Sprintf("tarsum.%s+%s:%s", tsi.Version, tsi.Algorithm, tsi.Digest)
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}
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