Verifies Sources don’t contain duplicate bundle IDs

AltStore assumes all apps have unique bundle IDs per source. Weird bugs can occur when this is not the case (such as merging multiple store listings into one), so we now verify upfront whether source contains duplicate bundle IDs before saving.

AltStore/Operations/FetchSourceOperation.swift

@@ -12,6 +12,41 @@ import CoreData
 import AltStoreCore
 import Roxas
 
+extension SourceError
+{
+    enum Code: Int, ALTErrorCode
+    {
+        typealias Error = SourceError
+        
+        case unsupported
+        case duplicateBundleID
+    }
+    
+    static func unsupported(_ source: Source) -> SourceError { SourceError(code: .unsupported, source: source) }
+    static func duplicateBundleID(_ bundleID: String, source: Source) -> SourceError { SourceError(code: .duplicateBundleID, source: source, duplicateBundleID: bundleID) }
+}
+
+struct SourceError: ALTLocalizedError
+{
+    var code: Code
+    var errorTitle: String?
+    var errorFailure: String?
+    
+    @Managed var source: Source
+    var duplicateBundleID: String?
+    
+    var errorFailureReason: String {
+        switch self.code
+        {
+        case .unsupported: return String(format: NSLocalizedString("The source “%@” is not supported by this version of AltStore.", comment: ""), self.$source.name)
+        case .duplicateBundleID:
+            let bundleIDFragment = self.duplicateBundleID.map { String(format: NSLocalizedString("the bundle identifier %@", comment: ""), $0) } ?? NSLocalizedString("the same bundle identifier", comment: "")
+            let failureReason = String(format: NSLocalizedString("The source “%@” contains multiple apps with %@.", comment: ""), self.$source.name, bundleIDFragment)
+            return failureReason
+        }
+    }
+}
+
 @objc(FetchSourceOperation)
 class FetchSourceOperation: ResultOperation<Source>
 {
@@ -78,6 +113,8 @@ class FetchSourceOperation: ResultOperation<Source>
                     let source = try decoder.decode(Source.self, from: data)
                     let identifier = source.identifier
                     
+                    try self.verify(source)
+                    
                     try childContext.save()
                     
                     self.managedObjectContext.perform {
@@ -105,3 +142,23 @@ class FetchSourceOperation: ResultOperation<Source>
         dataTask.resume()
     }
 }
+
+private extension FetchSourceOperation
+{
+    func verify(_ source: Source) throws
+    {
+        #if !BETA
+        if let trustedSourceIDs = UserDefaults.shared.trustedSourceIDs
+        {
+            guard trustedSourceIDs.contains(source.identifier) || source.identifier == Source.altStoreIdentifier else { throw SourceError(code: .unsupported, source: source) }
+        }
+        #endif
+        
+        var bundleIDs = Set<String>()
+        for app in source.apps
+        {
+            guard !bundleIDs.contains(app.bundleIdentifier) else { throw SourceError.duplicateBundleID(app.bundleIdentifier, source: source) }
+            bundleIDs.insert(app.bundleIdentifier)
+        }
+    }
+}