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//===----------------------------------------------------------------------===//
//
// This source file is part of the SwiftNIO open source project
//
// Copyright (c) 2017-2023 Apple Inc. and the SwiftNIO project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
// This is a simplified vendored version from:
// https://github.com/fabianfett/swift-base64-kit
public extension String {
/// Base64 encode a collection of UInt8 to a string, without the use of Foundation.
@inlinable
init<Buffer: Collection>(base64Encoding bytes: Buffer) where Buffer.Element == UInt8 {
self = Base64.encode(bytes: bytes)
}
@inlinable
func base64Decoded() throws -> [UInt8] {
return try Base64.decode(string: self)
}
}
public enum Base64Error: Error {
case invalidLength
case invalidCharacter
}
@usableFromInline
internal struct Base64 {
@inlinable
static func encode<Buffer: Collection>(bytes: Buffer) -> String where Buffer.Element == UInt8 {
guard !bytes.isEmpty else {
return ""
}
// In Base64, 3 bytes become 4 output characters, and we pad to the
// nearest multiple of four.
let base64StringLength = ((bytes.count + 2) / 3) * 4
let alphabet = Base64.encodeBase64
return String(customUnsafeUninitializedCapacity: base64StringLength) { backingStorage in
var input = bytes.makeIterator()
var offset = 0
while let firstByte = input.next() {
let secondByte = input.next()
let thirdByte = input.next()
backingStorage[offset] = Base64.encode(alphabet: alphabet, firstByte: firstByte)
backingStorage[offset + 1] = Base64.encode(alphabet: alphabet, firstByte: firstByte, secondByte: secondByte)
backingStorage[offset + 2] = Base64.encode(alphabet: alphabet, secondByte: secondByte, thirdByte: thirdByte)
backingStorage[offset + 3] = Base64.encode(alphabet: alphabet, thirdByte: thirdByte)
offset += 4
}
return offset
}
}
@inlinable
static func decode(string: String) throws -> [UInt8] {
guard string.count % 4 == 0 else {
throw Base64Error.invalidLength
}
let bytes = string.utf8.map { $0 }
var decoded = [UInt8]()
// Go over the encoded string in groups of 4 characters,
// and build groups of 3 bytes from them.
for i in stride(from: 0, to: bytes.count, by: 4) {
guard let byte0Index = Base64.encodeBase64.firstIndex(of: bytes[i]),
let byte1Index = Base64.encodeBase64.firstIndex(of: bytes[i+1]) else {
throw Base64Error.invalidCharacter
}
let byte0 = (UInt8(byte0Index) << 2 | UInt8(byte1Index) >> 4)
decoded.append(byte0)
// Check if the 3rd char is not a padding character, and decode the 2nd byte
if bytes[i+2] != Base64.encodePaddingCharacter {
guard let byte2Index = Base64.encodeBase64.firstIndex(of: bytes[i+2]) else {
throw Base64Error.invalidCharacter
}
let second = (UInt8(byte1Index) << 4 | UInt8(byte2Index) >> 2)
decoded.append(second)
}
// Check if the 4th character is not a padding, and decode the 3rd byte
if bytes[i+3] != Base64.encodePaddingCharacter {
guard let byte3Index = Base64.encodeBase64.firstIndex(of: bytes[i+3]),
let byte2Index = Base64.encodeBase64.firstIndex(of: bytes[i+2]) else {
throw Base64Error.invalidCharacter
}
let third = (UInt8(byte2Index) << 6 | UInt8(byte3Index))
decoded.append(third)
}
}
return decoded
}
// MARK: Internal
// The base64 unicode table.
@usableFromInline
static let encodeBase64: [UInt8] = [
UInt8(ascii: "A"), UInt8(ascii: "B"), UInt8(ascii: "C"), UInt8(ascii: "D"),
UInt8(ascii: "E"), UInt8(ascii: "F"), UInt8(ascii: "G"), UInt8(ascii: "H"),
UInt8(ascii: "I"), UInt8(ascii: "J"), UInt8(ascii: "K"), UInt8(ascii: "L"),
UInt8(ascii: "M"), UInt8(ascii: "N"), UInt8(ascii: "O"), UInt8(ascii: "P"),
UInt8(ascii: "Q"), UInt8(ascii: "R"), UInt8(ascii: "S"), UInt8(ascii: "T"),
UInt8(ascii: "U"), UInt8(ascii: "V"), UInt8(ascii: "W"), UInt8(ascii: "X"),
UInt8(ascii: "Y"), UInt8(ascii: "Z"), UInt8(ascii: "a"), UInt8(ascii: "b"),
UInt8(ascii: "c"), UInt8(ascii: "d"), UInt8(ascii: "e"), UInt8(ascii: "f"),
UInt8(ascii: "g"), UInt8(ascii: "h"), UInt8(ascii: "i"), UInt8(ascii: "j"),
UInt8(ascii: "k"), UInt8(ascii: "l"), UInt8(ascii: "m"), UInt8(ascii: "n"),
UInt8(ascii: "o"), UInt8(ascii: "p"), UInt8(ascii: "q"), UInt8(ascii: "r"),
UInt8(ascii: "s"), UInt8(ascii: "t"), UInt8(ascii: "u"), UInt8(ascii: "v"),
UInt8(ascii: "w"), UInt8(ascii: "x"), UInt8(ascii: "y"), UInt8(ascii: "z"),
UInt8(ascii: "0"), UInt8(ascii: "1"), UInt8(ascii: "2"), UInt8(ascii: "3"),
UInt8(ascii: "4"), UInt8(ascii: "5"), UInt8(ascii: "6"), UInt8(ascii: "7"),
UInt8(ascii: "8"), UInt8(ascii: "9"), UInt8(ascii: "+"), UInt8(ascii: "/"),
]
@usableFromInline
static let encodePaddingCharacter: UInt8 = UInt8(ascii: "=")
@usableFromInline
static func encode(alphabet: [UInt8], firstByte: UInt8) -> UInt8 {
let index = firstByte >> 2
return alphabet[Int(index)]
}
@usableFromInline
static func encode(alphabet: [UInt8], firstByte: UInt8, secondByte: UInt8?) -> UInt8 {
var index = (firstByte & 0b00000011) << 4
if let secondByte = secondByte {
index += (secondByte & 0b11110000) >> 4
}
return alphabet[Int(index)]
}
@usableFromInline
static func encode(alphabet: [UInt8], secondByte: UInt8?, thirdByte: UInt8?) -> UInt8 {
guard let secondByte = secondByte else {
// No second byte means we are just emitting padding.
return Base64.encodePaddingCharacter
}
var index = (secondByte & 0b00001111) << 2
if let thirdByte = thirdByte {
index += (thirdByte & 0b11000000) >> 6
}
return alphabet[Int(index)]
}
@usableFromInline
static func encode(alphabet: [UInt8], thirdByte: UInt8?) -> UInt8 {
guard let thirdByte = thirdByte else {
// No third byte means just padding.
return Base64.encodePaddingCharacter
}
let index = thirdByte & 0b00111111
return alphabet[Int(index)]
}
}
extension String {
/// This is a backport of a proposed String initializer that will allow writing directly into an uninitialized String's backing memory.
///
/// As this API does not exist prior to 5.3 on Linux, or on older Apple platforms, we fake it out with a pointer and accept the extra copy.
@inlinable
init(backportUnsafeUninitializedCapacity capacity: Int,
initializingUTF8With initializer: (_ buffer: UnsafeMutableBufferPointer<UInt8>) throws -> Int) rethrows {
// The buffer will store zero terminated C string
let buffer = UnsafeMutableBufferPointer<UInt8>.allocate(capacity: capacity + 1)
defer {
buffer.deallocate()
}
let initializedCount = try initializer(buffer)
precondition(initializedCount <= capacity, "Overran buffer in initializer!")
// add zero termination
buffer[initializedCount] = 0
self = String(cString: buffer.baseAddress!)
}
}
// Frustratingly, Swift 5.3 shipped before the macOS 11 SDK did, so we cannot gate the availability of
// this declaration on having the 5.3 compiler. This has caused a number of build issues. While updating
// to newer Xcodes does work, we can save ourselves some hassle and just wait until 5.4 to get this
// enhancement on Apple platforms.
extension String {
@inlinable
init(customUnsafeUninitializedCapacity capacity: Int,
initializingUTF8With initializer: (_ buffer: UnsafeMutableBufferPointer<UInt8>) throws -> Int) rethrows {
if #available(macOS 11.0, iOS 14.0, tvOS 14.0, watchOS 7.0, *) {
try self.init(unsafeUninitializedCapacity: capacity, initializingUTF8With: initializer)
} else {
try self.init(backportUnsafeUninitializedCapacity: capacity, initializingUTF8With: initializer)
}
}
}
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