Don't perform heavy work in constructor

Sparkle/SUBasicUpdateDriver.m

@@ -357,18 +357,20 @@
     id<SUUpdaterPrivate> updater = self.updater;
     id<SUUnarchiverProtocol> unarchiver = [SUUnarchiver unarchiverForPath:self.downloadPath updatingHostBundlePath:self.host.bundlePath decryptionPassword:updater.decryptionPassword];
     
-    BOOL success;
+    BOOL success = NO;
     if (!unarchiver) {
         SULog(SULogLevelError, @"Error: No valid unarchiver for %@!", self.downloadPath);
-        
-        success = NO;
     } else {
+        self.updateValidator = [[SUUpdateValidator alloc] initWithDownloadPath:self.downloadPath signatures:self.updateItem.signatures host:self.host];
+
         // Currently unsafe archives are the only case where we can prevalidate before extraction, but that could change in the future
-        BOOL needsPrevalidation = [[unarchiver class] unsafeIfArchiveIsNotValidated];
-        
-        self.updateValidator = [[SUUpdateValidator alloc] initWithDownloadPath:self.downloadPath signatures:self.updateItem.signatures host:self.host performingPrevalidation:needsPrevalidation];
-        
-        success = self.updateValidator.canValidate;
+        BOOL needsPrevalidation = [[unarchiver class] mustValidateBeforeExtraction];
+
+        if (needsPrevalidation) {
+            success = [self.updateValidator validateDownloadPath];
+        } else {
+            success = YES;
+        }
     }
     
     if (!success) {

Sparkle/SUBinaryDeltaUnarchiver.m

@@ -33,7 +33,7 @@
     return [[path pathExtension] isEqualToString:@"delta"];
 }
 
-+ (BOOL)unsafeIfArchiveIsNotValidated
++ (BOOL)mustValidateBeforeExtraction
 {
     return YES;
 }

Sparkle/SUDiskImageUnarchiver.m

@@ -30,7 +30,7 @@
     return [[path pathExtension] isEqualToString:@"dmg"];
 }
 
-+ (BOOL)unsafeIfArchiveIsNotValidated
++ (BOOL)mustValidateBeforeExtraction
 {
     return NO;
 }

Sparkle/SUPipedUnarchiver.m

@@ -58,7 +58,7 @@
     return ([self commandAndArgumentsConformingToTypeOfPath:path] != nil);
 }
 
-+ (BOOL)unsafeIfArchiveIsNotValidated
++ (BOOL)mustValidateBeforeExtraction
 {
     return NO;
 }

Sparkle/SUUnarchiverProtocol.h

@@ -14,7 +14,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (BOOL)canUnarchivePath:(NSString *)path;
 
-+ (BOOL)unsafeIfArchiveIsNotValidated;
++ (BOOL)mustValidateBeforeExtraction;
 
 - (void)unarchiveWithCompletionBlock:(void (^)(NSError * _Nullable))completionBlock progressBlock:(void (^ _Nullable)(double))progressBlock;
 

Sparkle/SUUpdateValidator.h

@@ -13,13 +13,11 @@
 
 @interface SUUpdateValidator : NSObject
 
-// Pass YES to performingPrevalidation if archive validation must be done immediately, before extraction
-- (instancetype)initWithDownloadPath:(NSString *)downloadPath signatures:(SUSignatures *)signatures host:(SUHost *)host performingPrevalidation:(BOOL)performingPrevalidation;
+- (instancetype)initWithDownloadPath:(NSString *)downloadPath signatures:(SUSignatures *)signatures host:(SUHost *)host;
 
-// Indicates whether we can perform (post) validation later
-@property (nonatomic, readonly) BOOL canValidate;
+// This is "pre" validation, before the archive has been extracted
+- (BOOL)validateDownloadPath;
 
-// precondition: validation must be possible (see -canValidate)
 // This is "post" validation, after an archive has been extracted
 - (BOOL)validateWithUpdateDirectory:(NSString *)updateDirectory;
 

Sparkle/SUUpdateValidator.m

@@ -19,7 +19,8 @@
 @interface SUUpdateValidator ()
 
 @property (nonatomic, readonly) SUHost *host;
-@property (nonatomic, readonly) BOOL prevalidatedDsaSignature;
+@property (nonatomic) BOOL prevalidatedSignature;
+@property (nonatomic) BOOL downloadPrevalidationFailed;
 @property (nonatomic, readonly) SUSignatures *signatures;
 @property (nonatomic, readonly) NSString *downloadPath;
 
@@ -28,41 +29,15 @@
 @implementation SUUpdateValidator
 
 @synthesize host = _host;
-@synthesize canValidate = _canValidate;
-@synthesize prevalidatedDsaSignature = _prevalidatedDsaSignature;
+@synthesize prevalidatedSignature = _prevalidatedSignature;
 @synthesize signatures = _signatures;
+@synthesize downloadPrevalidationFailed = _downloadPrevalidationFailed;
 @synthesize downloadPath = _downloadPath;
 
-- (instancetype)initWithDownloadPath:(NSString *)downloadPath signatures:(SUSignatures *)signatures host:(SUHost *)host performingPrevalidation:(BOOL)performingPrevalidation
+- (instancetype)initWithDownloadPath:(NSString *)downloadPath signatures:(SUSignatures *)signatures host:(SUHost *)host
 {
     self = [super init];
     if (self != nil) {
-        BOOL canValidate;
-        BOOL prevalidatedDsaSignature;
-        if (performingPrevalidation) {
-            SUPublicKeys *publicKeys = host.publicKeys;
-
-            if (publicKeys.dsaPubKey == nil) {
-                prevalidatedDsaSignature = NO;
-                SULog(SULogLevelError, @"Failed to validate update before unarchiving because no DSA public key was found in the old app");
-            } else if (signatures == nil || signatures.dsaSignature == nil) {
-                prevalidatedDsaSignature = NO;
-                SULog(SULogLevelError, @"Failed to validate update before unarchiving because no DSA signature was found");
-            } else {
-                prevalidatedDsaSignature = [SUSignatureVerifier validatePath:downloadPath withSignatures:signatures withPublicKeys:publicKeys];
-                if (!prevalidatedDsaSignature) {
-                    SULog(SULogLevelError, @"DSA signature validation before unarchiving failed for update %@", downloadPath);
-                }
-            }
-
-            canValidate = prevalidatedDsaSignature;
-        } else {
-            prevalidatedDsaSignature = NO;
-            canValidate = YES;
-        }
-
-        _canValidate = canValidate;
-        _prevalidatedDsaSignature = prevalidatedDsaSignature;
         _downloadPath = [downloadPath copy];
         _signatures = [signatures copy];
         _host = host;
@@ -70,17 +45,36 @@
     return self;
 }
 
+- (BOOL)validateDownloadPath {
+    SUPublicKeys *publicKeys = self.host.publicKeys;
+    SUSignatures *signatures = self.signatures;
+
+    if (publicKeys.dsaPubKey == nil) {
+        SULog(SULogLevelError, @"Failed to validate update before unarchiving because no DSA public key was found in the old app");
+    } else if (signatures == nil || signatures.dsaSignature == nil) {
+        SULog(SULogLevelError, @"Failed to validate update before unarchiving because no DSA signature was found");
+    } else {
+        if ([SUSignatureVerifier validatePath:self.downloadPath withSignatures:signatures withPublicKeys:publicKeys]) {
+            self.prevalidatedSignature = YES;
+            return YES;
+        }
+        SULog(SULogLevelError, @"DSA signature validation before unarchiving failed for update %@", self.downloadPath);
+    }
+    self.downloadPrevalidationFailed = YES;
+    return NO;
+}
+
 - (BOOL)validateWithUpdateDirectory:(NSString *)updateDirectory
 {
-    assert(self.canValidate);
+    if (self.downloadPrevalidationFailed) {
+        return NO;
+    }
 
     SUSignatures *signatures = self.signatures;
     SUPublicKeys *publicKeys = self.host.publicKeys;
     NSString *downloadPath = self.downloadPath;
     SUHost *host = self.host;
 
-    BOOL prevalidatedDsaSignature = self.prevalidatedDsaSignature;
-
     BOOL isPackage = NO;
 
     // install source could point to a new bundle or a package
@@ -92,7 +86,7 @@
 
     NSURL *installSourceURL = [NSURL fileURLWithPath:installSource];
 
-    if (!prevalidatedDsaSignature) {
+    if (!self.prevalidatedSignature) {
         // Check to see if we have a package or bundle to validate
         if (isPackage) {
             // For package type updates, all we do is check if the DSA signature is valid