chore: import upstream snapshot with attribution

Sources/ContainerPersistence/MemorySize.swift

@@ -0,0 +1,62 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the container project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+/// This is a thin wrapper around Measurement<UnitInformationStorage> to enable
+/// better Codable implementations for user provided options. With this wrapper
+/// values will get encoded and decoded from the format "1g" or "10mb".
+public struct MemorySize: Codable, Sendable, Equatable, CustomStringConvertible {
+    public var description: String { formatted }
+
+    public let measurement: Measurement<UnitInformationStorage>
+
+    public init(_ string: String) throws {
+        self.measurement = try .parse(parsing: string)
+    }
+
+    public init(from decoder: any Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        let string = try container.decode(String.self)
+        try self.init(string)
+    }
+
+    public func encode(to encoder: any Encoder) throws {
+        var container = encoder.singleValueContainer()
+        try container.encode(formatted)
+    }
+
+    private static let unitLabels: [UnitInformationStorage: String] = [
+        .bytes: "b",
+        .kibibytes: "kb",
+        .mebibytes: "mb",
+        .gibibytes: "gb",
+        .tebibytes: "tb",
+        .pebibytes: "pb",
+    ]
+
+    public var formatted: String {
+        let value = Int64(measurement.value)
+        let label = Self.unitLabels[measurement.unit] ?? "unknown"
+        return "\(value)\(label)"
+    }
+}
+
+extension MemorySize {
+    public func toUInt64(unit: UnitInformationStorage) -> UInt64 {
+        UInt64(self.measurement.converted(to: unit).value.rounded())
+    }
+}