From cb145c06bcba6a127eb4cb8eaa67e342029b692a Mon Sep 17 00:00:00 2001
From: Gereon Steffens <gereon@snabble.io>
Date: Fri, 24 May 2019 17:03:06 +0200
Subject: [PATCH] Swift 5 compatibility

---
 OneTimePassword.podspec                   |  2 +-
 OneTimePassword.xcodeproj/project.pbxproj |  4 ++--
 Sources/Crypto.swift                      |  8 ++++++++
 Sources/Generator.swift                   | 11 +++++++++++
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/OneTimePassword.podspec b/OneTimePassword.podspec
index 6907565d..91b3c1a5 100644
--- a/OneTimePassword.podspec
+++ b/OneTimePassword.podspec
@@ -5,7 +5,7 @@ Pod::Spec.new do |s|
   s.homepage     = "https://github.com/mattrubin/OneTimePassword"
   s.license      = "MIT"
   s.author       = "Matt Rubin"
-  s.swift_version             = "4.2"
+  s.swift_versions            = ["4.2", "5.0"]
   s.ios.deployment_target     = "8.0"
   s.watchos.deployment_target = "2.0"
   s.source       = { :git => "https://github.com/mattrubin/OneTimePassword.git", :tag => s.version }
diff --git a/OneTimePassword.xcodeproj/project.pbxproj b/OneTimePassword.xcodeproj/project.pbxproj
index 0d4e142f..7ce32c72 100644
--- a/OneTimePassword.xcodeproj/project.pbxproj
+++ b/OneTimePassword.xcodeproj/project.pbxproj
@@ -684,7 +684,7 @@
 			buildSettings = {
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				SWIFT_TREAT_WARNINGS_AS_ERRORS = NO;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				WATCHOS_DEPLOYMENT_TARGET = 2.0;
 			};
 			name = Debug;
@@ -695,7 +695,7 @@
 			buildSettings = {
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				SWIFT_TREAT_WARNINGS_AS_ERRORS = NO;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				WATCHOS_DEPLOYMENT_TARGET = 2.0;
 			};
 			name = Release;
diff --git a/Sources/Crypto.swift b/Sources/Crypto.swift
index e3ea067d..afdfe7e5 100644
--- a/Sources/Crypto.swift
+++ b/Sources/Crypto.swift
@@ -34,11 +34,19 @@ func HMAC(algorithm: Generator.Algorithm, key: Data, data: Data) -> Data {
         macOut.deallocate()
     }
 
+    #if swift(>=5.0)
+    key.withUnsafeBytes { keyBytes in
+        data.withUnsafeBytes { dataBytes in
+            CCHmac(hashFunction, keyBytes.baseAddress, key.count, dataBytes.baseAddress, data.count, macOut)
+        }
+    }
+    #else
     key.withUnsafeBytes { keyBytes in
         data.withUnsafeBytes { dataBytes in
             CCHmac(hashFunction, keyBytes, key.count, dataBytes, data.count, macOut)
         }
     }
+    #endif
 
     return Data(bytes: macOut, count: hashLength)
 }
diff --git a/Sources/Generator.swift b/Sources/Generator.swift
index 716ad486..b0f420d7 100644
--- a/Sources/Generator.swift
+++ b/Sources/Generator.swift
@@ -86,6 +86,16 @@ public struct Generator: Equatable {
         let counterData = Data(bytes: &bigCounter, count: MemoryLayout<UInt64>.size)
         let hash = HMAC(algorithm: algorithm, key: secret, data: counterData)
 
+        #if swift(>=5.0)
+        var truncatedHash = hash.withUnsafeBytes { ptr -> UInt32 in
+            // Use the last 4 bits of the hash as an offset (0 <= offset <= 15)
+            let offset = ptr[hash.count - 1] & 0x0f
+
+            // Take 4 bytes from the hash, starting at the given byte offset
+            let truncatedHashPtr = ptr.baseAddress! + Int(offset)
+            return truncatedHashPtr.bindMemory(to: UInt32.self, capacity: 1).pointee
+        }
+        #else
         var truncatedHash = hash.withUnsafeBytes { (ptr: UnsafePointer<UInt8>) -> UInt32 in
             // Use the last 4 bits of the hash as an offset (0 <= offset <= 15)
             let offset = ptr[hash.count - 1] & 0x0f
@@ -96,6 +106,7 @@ public struct Generator: Equatable {
                 $0.pointee
             }
         }
+        #endif
 
         // Ensure the four bytes taken from the hash match the current endian format
         truncatedHash = UInt32(bigEndian: truncatedHash)