mirror of
https://github.com/apple/container.git
synced 2026-07-14 21:47:01 +00:00
Sidhartha Mani
0885cdd6a9
This PR introduces the `Differ` with methods: ```swift // Differ protocol func diff(base: Snapshot?, target: Snapshot) async throws -> Descriptor func apply(descriptor: Descriptor, to base: Snapshot?) async throws -> Snapshot ``` It also introduces `DiffKey`, which is a MerkeTree based key for fast diff computations between two dirs
66 lines
2.3 KiB
Swift
66 lines
2.3 KiB
Swift
//===----------------------------------------------------------------------===//
|
|
// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
|
|
//
|
|
// 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 Crypto
|
|
import Foundation
|
|
|
|
public enum FileContentDiffResult: Equatable {
|
|
case attributeOnly
|
|
case contentChanged
|
|
}
|
|
|
|
/// Compares regular file byte content using a ContentHasher.
|
|
/// Notes:
|
|
/// - For symlinks and special files, treat as attribute-only; symlink target comparison is metadata.
|
|
/// - If either URL is nil (addition or deletion), treat as contentChanged.
|
|
public struct FileContentDiffer: Sendable {
|
|
private let hasher: any ContentHasher
|
|
|
|
public init(hasher: any ContentHasher = SHA256ContentHasher()) {
|
|
self.hasher = hasher
|
|
}
|
|
|
|
public func diff(oldURL: URL?, newURL: URL?, attributesOnly: Bool = false) throws -> FileContentDiffResult {
|
|
if attributesOnly { return .attributeOnly }
|
|
guard let lhs = oldURL, let rhs = newURL else { return .contentChanged }
|
|
let a = try hasher.hash(fileURL: lhs)
|
|
let b = try hasher.hash(fileURL: rhs)
|
|
return a == b ? .attributeOnly : .contentChanged
|
|
}
|
|
}
|
|
|
|
public struct SHA256ContentHasher: ContentHasher {
|
|
|
|
public init() {}
|
|
|
|
public func hash(fileURL: URL) throws -> Data {
|
|
let handle = try FileHandle(forReadingFrom: fileURL)
|
|
defer { try? handle.close() }
|
|
|
|
var hasher = SHA256()
|
|
let chunkSize = 4 * 1024 * 1024 // 4 MB
|
|
|
|
while true {
|
|
let data = try handle.read(upToCount: chunkSize) ?? Data()
|
|
if data.isEmpty { break }
|
|
hasher.update(data: data)
|
|
}
|
|
|
|
let digest = hasher.finalize()
|
|
return Data(digest)
|
|
}
|
|
}
|