Adds RemoveAppBackupOperation to remove backed up app data

AltStore/AltStore.entitlements

@@ -4,5 +4,9 @@
 <dict>
 	<key>aps-environment</key>
 	<string>development</string>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.com.rileytestut.AltStore</string>
+	</array>
 </dict>
 </plist>

AltStore/Extensions/FileManager+SharedDirectories.swift

@@ -0,0 +1,32 @@
+//
+//  FileManager+SharedDirectories.swift
+//  AltStore
+//
+//  Created by Riley Testut on 5/14/20.
+//  Copyright © 2020 Riley Testut. All rights reserved.
+//
+
+import Foundation
+
+import AltKit
+
+extension FileManager
+{
+    var altstoreSharedDirectory: URL? {
+        guard let appGroup = Bundle.main.appGroups.first else { return nil }
+        
+        let sharedDirectoryURL = self.containerURL(forSecurityApplicationGroupIdentifier: appGroup)
+        return sharedDirectoryURL
+    }
+    
+    var appBackupsDirectory: URL? {
+        let appBackupsDirectory = self.altstoreSharedDirectory?.appendingPathComponent("Backups", isDirectory: true)
+        return appBackupsDirectory
+    }
+    
+    func backupDirectoryURL(for app: InstalledApp) -> URL?
+    {
+        let backupDirectoryURL = self.appBackupsDirectory?.appendingPathComponent(app.bundleIdentifier, isDirectory: true)
+        return backupDirectoryURL
+    }
+}

AltStore/Info.plist

@@ -2,6 +2,10 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>ALTAppGroups</key>
+	<array>
+		<string>group.com.rileytestut.AltStore</string>
+	</array>
 	<key>ALTDeviceID</key>
 	<string>00008030-001948590202802E</string>
 	<key>ALTServerID</key>

AltStore/Operations/RemoveAppBackupOperation.swift

@@ -0,0 +1,79 @@
+//
+//  RemoveAppBackupOperation.swift
+//  AltStore
+//
+//  Created by Riley Testut on 5/13/20.
+//  Copyright © 2020 Riley Testut. All rights reserved.
+//
+
+import Foundation
+
+import AltKit
+
+@objc(RemoveAppBackupOperation)
+class RemoveAppBackupOperation: ResultOperation<Void>
+{
+    let context: InstallAppOperationContext
+    
+    private let coordinator = NSFileCoordinator()
+    private let coordinatorQueue = OperationQueue()
+    
+    init(context: InstallAppOperationContext)
+    {
+        self.context = context
+        
+        super.init()
+        
+        self.coordinatorQueue.name = "AltStore - RemoveAppBackupOperation Queue"
+    }
+    
+    override func main()
+    {
+        super.main()
+        
+        if let error = self.context.error
+        {
+            self.finish(.failure(error))
+            return
+        }
+        
+        guard let installedApp = self.context.installedApp else { return self.finish(.failure(OperationError.invalidParameters)) }
+        installedApp.managedObjectContext?.perform {
+            guard let backupDirectoryURL = FileManager.default.backupDirectoryURL(for: installedApp) else { return self.finish(.failure(OperationError.missingAppGroup)) }
+            
+            let intent = NSFileAccessIntent.writingIntent(with: backupDirectoryURL, options: [.forDeleting])
+            self.coordinator.coordinate(with: [intent], queue: self.coordinatorQueue) { (error) in
+                do
+                {
+                    if let error = error
+                    {
+                        throw error
+                    }
+                    
+                    try FileManager.default.removeItem(at: intent.url)
+                    
+                    self.finish(.success(()))
+                }
+                catch let error as CocoaError where error.code == CocoaError.Code.fileNoSuchFile
+                {
+                    #if DEBUG
+                    
+                    // When debugging, it's expected that app groups don't match, so ignore.
+                    self.finish(.success(()))
+                    
+                    #else
+                    
+                    print("Failed to remove app backup directory:", error)
+                    self.finish(.failure(error))
+                    
+                    #endif
+                }
+                catch
+                {
+                    print("Failed to remove app backup directory:", error)
+                    self.finish(.failure(error))
+                }
+            }
+        }
+    }
+}