FICImageTable now knows about data protection. Some clients have experienced crashes when trying to read image table data while their app is in the background. These crashes occur when the image table's file has data protection enabled, and the device is passcode-locked. To prevent the client app from crashing, FICImageTable will do its best to prevent accessing the memory pages from a protected imageTable file at times when that data is inaccessible.

Author: Mallory Paine

FastImageCache/FICImageFormat.h

@@ -22,6 +22,12 @@ typedef NS_OPTIONS(NSUInteger, FICImageFormatStyle) {
     FICImageFormatStyle8BitGrayscale,
 };
 
+typedef NS_OPTIONS(NSUInteger, FICImageFormatProtectionMode) {
+    FICImageFormatProtectionModeNone,
+    FICImageFormatProtectionModeComplete,
+    FICImageFormatProtectionModeCompletUntilFirstUserAuthentication,
+};
+
 /**
  `FICImageFormat` acts as a definition for the types of images that are stored in the image cache. Each image format must have a unique name, but multiple formats can belong to the same family.
  All images associated with a particular format must have the same image dimentions and opacity preference. You can define the maximum number of entries that an image format can accommodate to
@@ -114,6 +120,10 @@ typedef NS_OPTIONS(NSUInteger, FICImageFormatStyle) {
  */
 @property (nonatomic, assign, readonly) BOOL isGrayscale;
 
+
+@property (nonatomic, assign) FICImageFormatProtectionMode protectionMode;
+@property (nonatomic, assign, readonly) NSString *protectionModeString;
+
 /**
  The dictionary representation of this image format.
  
@@ -142,6 +152,6 @@ typedef NS_OPTIONS(NSUInteger, FICImageFormatStyle) {
  
  @return An autoreleased instance of `<FICImageFormat>` or one of its subclasses, if any exist.
  */
-+ (instancetype)formatWithName:(NSString *)name family:(NSString *)family imageSize:(CGSize)imageSize style:(FICImageFormatStyle)style maximumCount:(NSInteger)maximumCount devices:(FICImageFormatDevices)devices;
++ (instancetype)formatWithName:(NSString *)name family:(NSString *)family imageSize:(CGSize)imageSize style:(FICImageFormatStyle)style maximumCount:(NSInteger)maximumCount devices:(FICImageFormatDevices)devices protectionMode:(FICImageFormatProtectionMode)protectionMode;
 
 @end

FastImageCache/FICImageFormat.m

@@ -19,6 +19,7 @@
 static NSString *const FICImageFormatStyleKey = @"style";
 static NSString *const FICImageFormatMaximumCountKey = @"maximumCount";
 static NSString *const FICImageFormatDevicesKey = @"devices";
+static NSString *const FICImageFormatProtectionModeKey = @"protectionMode";
 
 #pragma mark - Class Extension
 
@@ -30,6 +31,7 @@ @interface FICImageFormat () {
     FICImageFormatStyle _style;
     NSInteger _maximumCount;
     FICImageFormatDevices _devices;
+    FICImageFormatProtectionMode _protectionMode;
 }
 
 @end
@@ -45,6 +47,7 @@ @implementation FICImageFormat
 @synthesize style = _style;
 @synthesize maximumCount = _maximumCount;
 @synthesize devices = _devices;
+@synthesize protectionMode = _protectionMode;
 
 #pragma mark - Property Accessors
 
@@ -124,9 +127,25 @@ - (BOOL)isGrayscale {
     return isGrayscale;
 }
 
+- (NSString *)protectionModeString {
+    NSString *protectionModeString = nil;
+    switch (_protectionMode) {
+        case FICImageFormatProtectionModeNone:
+            protectionModeString = NSFileProtectionNone;
+            break;
+        case FICImageFormatProtectionModeComplete:
+            protectionModeString = NSFileProtectionComplete;
+            break;
+        case FICImageFormatProtectionModeCompletUntilFirstUserAuthentication:
+            protectionModeString = NSFileProtectionCompleteUntilFirstUserAuthentication;
+            break;
+    }
+    return protectionModeString;
+}
+
 #pragma mark - Object Lifecycle
 
-+ (instancetype)formatWithName:(NSString *)name family:(NSString *)family imageSize:(CGSize)imageSize style:(FICImageFormatStyle)style maximumCount:(NSInteger)maximumCount devices:(FICImageFormatDevices)devices {
++ (instancetype)formatWithName:(NSString *)name family:(NSString *)family imageSize:(CGSize)imageSize style:(FICImageFormatStyle)style maximumCount:(NSInteger)maximumCount devices:(FICImageFormatDevices)devices protectionMode:(FICImageFormatProtectionMode)protectionMode {
     FICImageFormat *imageFormat = [[FICImageFormat alloc] init];
 
     [imageFormat setName:name];
@@ -135,6 +154,7 @@ + (instancetype)formatWithName:(NSString *)name family:(NSString *)family imageS
     [imageFormat setStyle:style];
     [imageFormat setMaximumCount:maximumCount];
     [imageFormat setDevices:devices];
+    [imageFormat setProtectionMode:protectionMode];
 
     return imageFormat;
 }
@@ -151,6 +171,8 @@ - (NSDictionary *)dictionaryRepresentation {
     [dictionaryRepresentation setValue:[NSNumber numberWithInt:_style] forKey:FICImageFormatStyleKey];
     [dictionaryRepresentation setValue:[NSNumber numberWithUnsignedInteger:_maximumCount] forKey:FICImageFormatMaximumCountKey];
     [dictionaryRepresentation setValue:[NSNumber numberWithInt:_devices] forKey:FICImageFormatDevicesKey];
+    [dictionaryRepresentation setValue:[NSNumber numberWithUnsignedInteger:_protectionMode] forKey:FICImageFormatProtectionModeKey];
+
     [dictionaryRepresentation setValue:[NSNumber numberWithFloat:[[UIScreen mainScreen] scale]] forKey:FICImageTableScreenScaleKey];
     [dictionaryRepresentation setValue:[NSNumber numberWithUnsignedInteger:[FICImageTableEntry metadataVersion]] forKey:FICImageTableEntryDataVersionKey];
 
@@ -170,6 +192,7 @@ - (id)copyWithZone:(NSZone *)zone {
     [imageFormatCopy setStyle:[self style]];
     [imageFormatCopy setMaximumCount:[self maximumCount]];
     [imageFormatCopy setDevices:[self devices]];
+    [imageFormatCopy setProtectionMode:[self protectionMode]];
 
     return imageFormatCopy;
 }

FastImageCache/FICImageTable.m

@@ -62,6 +62,8 @@ @interface FICImageTable () {
     NSMutableOrderedSet *_MRUEntries;
     NSCountedSet *_inUseEntries;
     NSDictionary *_imageFormatDictionary;
+    
+    BOOL _isFileDataProtected;
 }
 
 @end
@@ -157,6 +159,19 @@ - (instancetype)initWithFormat:(FICImageFormat *)imageFormat {
 
         [self _loadMetadata];
 
+        NSFileManager *fileManager = [[NSFileManager alloc] init];
+        if ([fileManager fileExistsAtPath:_filePath] == NO) {
+            NSMutableDictionary *attributes = [NSMutableDictionary dictionary];
+            [attributes setValue:[_imageFormat protectionModeString] forKeyPath:NSFileProtectionKey];
+            [fileManager createFileAtPath:_filePath contents:nil attributes:attributes];
+        }
+       
+        NSDictionary *attributes = [fileManager attributesOfItemAtPath:_filePath error:NULL];
+        NSString *protectionMode = [attributes objectForKey:NSFileProtectionKey];
+        if (protectionMode) {
+            _isFileDataProtected = [protectionMode isEqualToString:NSFileProtectionNone] == NO;
+        }
+        
         _fileDescriptor = open([_filePath fileSystemRepresentation], O_RDWR | O_CREAT, 0666);
 
         if (_fileDescriptor >= 0) {
@@ -471,12 +486,24 @@ - (void)_setEntryCount:(NSInteger)entryCount {
     }
 }
 
+// There's inherently a race condition between when you ask whether the data is
+// accessible and when you try to use that data. Sidestep this issue altogether
+// by using NSFileProtectionNone
+- (BOOL)canAccessEntryData {
+    BOOL result = YES;
+    if (_isFileDataProtected) {
+        result = [[UIApplication sharedApplication] isProtectedDataAvailable];
+    }
+    return result;
+}
+
 - (FICImageTableEntry *)_entryDataAtIndex:(NSInteger)index {
     FICImageTableEntry *entryData = nil;
 
     [_lock lock];
-    
-    if (index < _entryCount) {
+
+    BOOL canAccessData = [self canAccessEntryData];
+    if (index < _entryCount && canAccessData) {
         off_t entryOffset = index * _entryLength;
         size_t chunkIndex = (size_t)(entryOffset / _chunkLength);
 
@@ -503,7 +530,12 @@ - (FICImageTableEntry *)_entryDataAtIndex:(NSInteger)index {
     [_lock unlock];
 
     if (!entryData) {
-        NSString *message = [NSString stringWithFormat:@"*** FIC Error: %s failed to get entry for index %ld.", __PRETTY_FUNCTION__, (long)index];
+        NSString *message = nil;
+        if (canAccessData) {
+            message = [NSString stringWithFormat:@"*** FIC Error: %s failed to get entry for index %ld.", __PRETTY_FUNCTION__, (long)index];
+        } else {
+            message = [NSString stringWithFormat:@"*** FIC Error: %s. Cannot get entry data because imageTable's file has data protection enabled and that data is not currently accessible.", __PRETTY_FUNCTION__];
+        }
         [[FICImageCache sharedImageCache] _logMessage:message];
     }
 

FastImageCacheDemo/Classes/FICDAppDelegate.m

@@ -32,25 +32,25 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
 
     // ...32-bit BGR
     FICImageFormat *squareImageFormat32BitBGRA = [FICImageFormat formatWithName:FICDPhotoSquareImage32BitBGRAFormatName family:FICDPhotoImageFormatFamily imageSize:FICDPhotoSquareImageSize style:FICImageFormatStyle32BitBGRA
-        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices];
+        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
 
     [mutableImageFormats addObject:squareImageFormat32BitBGRA];
 
     // ...32-bit BGR
     FICImageFormat *squareImageFormat32BitBGR = [FICImageFormat formatWithName:FICDPhotoSquareImage32BitBGRFormatName family:FICDPhotoImageFormatFamily imageSize:FICDPhotoSquareImageSize style:FICImageFormatStyle32BitBGR
-        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices];
+        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
 
     [mutableImageFormats addObject:squareImageFormat32BitBGR];
 
     // ...16-bit BGR
     FICImageFormat *squareImageFormat16BitBGR = [FICImageFormat formatWithName:FICDPhotoSquareImage16BitBGRFormatName family:FICDPhotoImageFormatFamily imageSize:FICDPhotoSquareImageSize style:FICImageFormatStyle16BitBGR
-        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices];
+        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
 
     [mutableImageFormats addObject:squareImageFormat16BitBGR];
 
     // ...8-bit Grayscale
     FICImageFormat *squareImageFormat8BitGrayscale = [FICImageFormat formatWithName:FICDPhotoSquareImage8BitGrayscaleFormatName family:FICDPhotoImageFormatFamily imageSize:FICDPhotoSquareImageSize style:FICImageFormatStyle8BitGrayscale
-        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices];
+        maximumCount:squareImageFormatMaximumCount devices:squareImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
 
     [mutableImageFormats addObject:squareImageFormat8BitGrayscale];
 
@@ -60,7 +60,7 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
         FICImageFormatDevices pixelImageFormatDevices = FICImageFormatDevicePhone | FICImageFormatDevicePad;
 
         FICImageFormat *pixelImageFormat = [FICImageFormat formatWithName:FICDPhotoPixelImageFormatName family:FICDPhotoImageFormatFamily imageSize:FICDPhotoPixelImageSize style:FICImageFormatStyle32BitBGR
-            maximumCount:pixelImageFormatMaximumCount devices:pixelImageFormatDevices];
+            maximumCount:pixelImageFormatMaximumCount devices:pixelImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
 
         [mutableImageFormats addObject:pixelImageFormat];
     }