mirror of
https://github.com/apple/container.git
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83 lines
2.6 KiB
Swift
83 lines
2.6 KiB
Swift
//===----------------------------------------------------------------------===//
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// Copyright © 2025 Apple Inc. and the Containerization project authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//===----------------------------------------------------------------------===//
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import Foundation
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// takes a pointer and converts its contents to native endian bytes
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public func withUnsafeLittleEndianBytes<T, Result>(of value: T, body: (UnsafeRawBufferPointer) throws -> Result)
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rethrows -> Result
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{
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switch Endian {
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case .little:
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return try withUnsafeBytes(of: value) { bytes in
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try body(bytes)
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}
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case .big:
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return try withUnsafeBytes(of: value) { buffer in
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let reversedBuffer = Array(buffer.reversed())
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return try reversedBuffer.withUnsafeBytes { buf in
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try body(buf)
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}
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}
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}
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}
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public func withUnsafeLittleEndianBuffer<T>(
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of value: UnsafeRawBufferPointer, body: (UnsafeRawBufferPointer) throws -> T
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) rethrows -> T {
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switch Endian {
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case .little:
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return try body(value)
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case .big:
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let reversed = Array(value.reversed())
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return try reversed.withUnsafeBytes { buf in
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try body(buf)
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}
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}
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}
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extension UnsafeRawBufferPointer {
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// loads littleEndian raw data, converts it native endian format and calls UnsafeRawBufferPointer.load
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public func loadLittleEndian<T>(as type: T.Type) -> T {
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switch Endian {
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case .little:
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return self.load(as: T.self)
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case .big:
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let buffer = Array(self.reversed())
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return buffer.withUnsafeBytes { ptr in
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ptr.load(as: T.self)
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}
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}
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}
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}
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public enum Endianness {
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case little
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case big
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}
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// returns current endianness
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public var Endian: Endianness {
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switch CFByteOrderGetCurrent() {
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case CFByteOrder(CFByteOrderLittleEndian.rawValue):
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return .little
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case CFByteOrder(CFByteOrderBigEndian.rawValue):
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return .big
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default:
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fatalError("impossible")
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}
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}
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