Implementing preflight(),loadWithErrorin NSBundle (#421)

* Implementing preflight(),loadWithErrorin NSBundle

Also includes the fix for segmentation fault issue when the NSBundle is created with an invalid path

* Done the changes as per the comments

Author: saiHemak

Foundation/NSBundle.swift

@@ -37,6 +37,9 @@ public class Bundle: NSObject {
 
         let url = URL(fileURLWithPath: resolvedPath)
         _bundle = CFBundleCreate(kCFAllocatorSystemDefault, unsafeBitCast(url, to: CFURL.self))
+        if (_bundle == nil) {
+            return nil
+        }
     }
 
     public convenience init?(url: URL) {
@@ -73,8 +76,27 @@ public class Bundle: NSObject {
     }
     public func unload() -> Bool { NSUnimplemented() }
 
-    public func preflight() throws { NSUnimplemented() }
-    public func loadAndReturnError() throws { NSUnimplemented() }
+    public func preflight() throws {
+        var unmanagedError:Unmanaged<CFError>? = nil
+        try withUnsafeMutablePointer(&unmanagedError) { (unmanagedCFError: UnsafeMutablePointer<Unmanaged<CFError>?>)  in
+            CFBundlePreflightExecutable(_bundle, unmanagedCFError)
+            if let error = unmanagedCFError.pointee {
+                throw   error.takeRetainedValue()._nsObject
+            }
+        }
+    }
+    
+    public func loadAndReturnError() throws {
+        var unmanagedError:Unmanaged<CFError>? = nil
+        try  withUnsafeMutablePointer(&unmanagedError) { (unmanagedCFError: UnsafeMutablePointer<Unmanaged<CFError>?>)  in
+            CFBundleLoadExecutableAndReturnError(_bundle, unmanagedCFError)
+            if let error = unmanagedCFError.pointee {
+                let retainedValue = error.takeRetainedValue()
+                throw  retainedValue._nsObject
+            }
+        }
+    }
+
 
     /* Methods for locating various components of a bundle. */
     public var bundleURL: URL {

TestFoundation/TestNSBundle.swift

@@ -29,6 +29,9 @@ class TestNSBundle : XCTestCase {
             ("test_localizations", test_localizations),
             ("test_URLsForResourcesWithExtension", test_URLsForResourcesWithExtension),
             ("test_bundleLoad", test_bundleLoad),
+            ("test_bundleLoadWithError", test_bundleLoadWithError),
+            ("test_bundleWithInvalidPath", test_bundleWithInvalidPath),
+            ("test_bundlePreflight", test_bundlePreflight),
         ]
     }
 
@@ -153,10 +156,46 @@ class TestNSBundle : XCTestCase {
 
         _cleanupPlayground(playground)
     }
+    
     func test_bundleLoad(){
         let bundle = Bundle.main()
         let _ = bundle.load()
         XCTAssertTrue(bundle.isLoaded)
     }
+    
+    func test_bundleLoadWithError(){
+        let bundleValid = Bundle.main()
+        //test valid load using loadAndReturnError
+        do{
+            try bundleValid.loadAndReturnError()
+        }catch{
+            XCTFail("should not fail to load")
+        }
+        // executable cannot be located
+        guard let playground = _setupPlayground() else { XCTFail("Unable to create playground"); return }
+        let bundle = Bundle(path: playground + _bundleName)
+        XCTAssertThrowsError(try bundle!.loadAndReturnError())
+        _cleanupPlayground(playground)
+    }
+    
+    func test_bundleWithInvalidPath(){
+        let bundleInvalid = Bundle(path: "/tmp/test.playground")
+        XCTAssertNil(bundleInvalid)
+    }
+    
+    func test_bundlePreflight(){
+        let bundleValid = Bundle.main()
+        do{
+            try bundleValid.preflight()
+        }catch{
+            XCTFail("should not fail to load")
+        }
+        // executable cannot be located ..preflight should report error
+        guard let playground = _setupPlayground() else { XCTFail("Unable to create playground"); return }
+        let bundle = Bundle(path: playground + _bundleName)
+        XCTAssertThrowsError(try bundle!.preflight())
+        _cleanupPlayground(playground)
+    }
+
 
 }