375f3cc136
This commit adds regular expression definitions for several string identifiers used througout the registry. The repository name regex supports up to five path path components and restricts repeated periods, dashes and underscores. The tag regex simply validates the length of the tag and that printable characters are required. Though we define a new package common, these definition should land in docker core.
71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
package common
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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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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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