ContainerRegistry: Reject other invalid characters in repository names

Author: euanh

Sources/ContainerRegistry/ImageReference.swift

@@ -17,6 +17,7 @@ import RegexBuilder
 public enum ReferenceError: Error, Equatable {
     case emptyString
     case containsUppercaseLetters(String)
+    case invalidReferenceFormat(String)
     case unexpected(String)
 }
 
@@ -66,6 +67,12 @@ public struct Repository: Sendable, Equatable, CustomStringConvertible, CustomDe
             throw ReferenceError.containsUppercaseLetters(rawValue)
         }
 
+        // https://github.com/opencontainers/distribution-spec/blob/main/spec.md#pulling-manifests
+        let regex = /[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*(\/[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*)*/
+        if try regex.wholeMatch(in: rawValue) == nil {
+            throw ReferenceError.invalidReferenceFormat(rawValue)
+        }
+
         value = rawValue
     }
 

Tests/ContainerRegistryTests/ImageReferenceTests.swift

@@ -146,6 +146,10 @@ struct ReferenceTests {
         #expect(throws: ReferenceError.containsUppercaseLetters("helloWorld")) {
             try ImageReference(fromString: "localhost:5555/helloWorld")
         }
+
+        #expect(throws: ReferenceError.invalidReferenceFormat("hello^world")) {
+            try ImageReference(fromString: "localhost:5555/hello^world")
+        }
     }
 
     @Test