Upstream code and resources for Chrome on iOS extensions.

ios/chrome/today_extension/lock_screen_state.mm

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/today_extension/lock_screen_state.h"
+
+#import <UIKit/UIKit.h>
+
+#import "base/ios/weak_nsobject.h"
+
+namespace {
+
+// Name of the protected file used to detect if extension is triggered on lock
+// screen.
+NSString* const kLockScreenFileName = @"LockScreenDetector";
+
+// Return the path of a file that will always have NSFileProtectionComplete
+// protection option. This file cannot be accessed from the lock screen and can
+// be used to detect if the device is locked.
+NSString* LockedDeviceFilename() {
+  NSString* path = [NSSearchPathForDirectoriesInDomains(
+      NSLibraryDirectory, NSUserDomainMask, YES) objectAtIndex:0];
+  return [path stringByAppendingPathComponent:kLockScreenFileName];
+}
+
+}  // namespace
+
+@interface LockScreenState ()
+
+- (instancetype)init;
+
+// Returns if the protected file is accessible.
+// Note: the function tests the access to protected file. Access is revoked 10
+// seconds after screen is locked. So this method returns YES if screen has been
+// locked for more than 10 seconds.
+// Returns NO if CreateLockScreenDetector has never been called.
+- (BOOL)isProtectedFileAccessible;
+
+// Periodically checks (every second) if the protected file is still accessible.
+// Checks |remainingTests| times.
+- (void)recheckProtectedFile:(int)remainingTests;
+
+// Creates a protected file that will be used to detect if screen is locked.
+- (void)createLockScreenDetector;
+
+@end
+
+@implementation LockScreenState {
+  id<LockScreenStateDelegate> _delegate;
+  BOOL _screenLocked;
+  BOOL _lockScreenStateKnown;
+  BOOL _protectedFileCreated;
+}
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(screenLocked:)
+               name:UIApplicationProtectedDataWillBecomeUnavailable
+             object:nil];
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(screenUnlocked:)
+               name:UIApplicationProtectedDataDidBecomeAvailable
+             object:nil];
+    _delegate = nil;
+  }
+  return self;
+}
+
++ (instancetype)sharedInstance {
+  static LockScreenState* instance = [[LockScreenState alloc] init];
+  return instance;
+}
+
+- (void)screenLocked:(id)arguments {
+  _screenLocked = YES;
+  _lockScreenStateKnown = YES;
+  [_delegate lockScreenStateDidChange:self];
+}
+
+- (void)screenUnlocked:(id)arguments {
+  _screenLocked = NO;
+  _lockScreenStateKnown = YES;
+  [_delegate lockScreenStateDidChange:self];
+}
+
+- (void)setDelegate:(id)delegate {
+  _delegate = delegate;
+}
+
+- (BOOL)isScreenLocked {
+  if (_lockScreenStateKnown) {
+    return _screenLocked;
+  }
+  [self createLockScreenDetector];
+  if (!_protectedFileCreated) {
+    // File could not be created. Screen is locked.
+    _screenLocked = YES;
+    _lockScreenStateKnown = YES;
+    return YES;
+  }
+  _screenLocked = ![self isProtectedFileAccessible];
+  _lockScreenStateKnown = YES;
+
+  if (!_screenLocked) {
+    // This test is only valid if screen has been locked for more than 10
+    // seconds (https://www.apple.com/business/docs/iOS_Security_Guide.pdf).
+    // In that case, no notification is received after the delay.
+    // Reschedule tests every second for 15 seconds.
+    base::WeakNSObject<LockScreenState> weakSelf(self);
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
+                                 static_cast<int64_t>(1 * NSEC_PER_SEC)),
+                   dispatch_get_main_queue(), ^{
+                     [weakSelf recheckProtectedFile:14];
+                   });
+  }
+  return _screenLocked;
+}
+
+- (void)recheckProtectedFile:(int)remainingTests {
+  BOOL screenLocked = ![self isProtectedFileAccessible];
+  if (screenLocked) {
+    // |_screenLocked| may already be set to YES if we received a notification.
+    if (!_screenLocked) {
+      _screenLocked = YES;
+      [_delegate lockScreenStateDidChange:self];
+    }
+    return;
+  }
+  if (remainingTests) {
+    base::WeakNSObject<LockScreenState> weakSelf(self);
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
+                                 static_cast<int64_t>(1 * NSEC_PER_SEC)),
+                   dispatch_get_main_queue(), ^{
+                     [weakSelf recheckProtectedFile:remainingTests - 1];
+                   });
+  }
+}
+
+- (BOOL)isProtectedFileAccessible {
+  NSError* error = nil;
+  if (![[NSFileManager defaultManager]
+          fileExistsAtPath:LockedDeviceFilename()]) {
+    return NO;
+  }
+  [NSData dataWithContentsOfFile:LockedDeviceFilename()
+                         options:NSDataReadingMappedIfSafe
+                           error:&error];
+  return !error;
+}
+
+- (void)createLockScreenDetector {
+  if (_protectedFileCreated)
+    return;
+  NSError* error = nil;
+  if ([[NSFileManager defaultManager]
+          fileExistsAtPath:LockedDeviceFilename()]) {
+    NSDictionary* attributes = [[NSFileManager defaultManager]
+        attributesOfItemAtPath:LockedDeviceFilename()
+                         error:&error];
+    if ([[attributes valueForKey:NSFileProtectionKey]
+            isEqualToString:NSFileProtectionComplete]) {
+      _protectedFileCreated = YES;
+      return;
+    }
+    BOOL removed =
+        [[NSFileManager defaultManager] removeItemAtPath:LockedDeviceFilename()
+                                                   error:&error];
+    if (!removed || error) {
+      // File could not be removed. FileSystem may be locked ?
+      return;
+    }
+  }
+  BOOL created = [[NSFileManager defaultManager]
+      createFileAtPath:LockedDeviceFilename()
+              contents:[@"Unlock" dataUsingEncoding:NSUTF8StringEncoding]
+            attributes:@{NSFileProtectionKey : NSFileProtectionComplete}];
+  if (!created) {
+    // File could not be created. FileSystem may be locked ?
+    return;
+  }
+  NSDictionary* attributes = [[NSFileManager defaultManager]
+      attributesOfItemAtPath:LockedDeviceFilename()
+                       error:&error];
+  if ([[attributes valueForKey:NSFileProtectionKey]
+          isEqualToString:NSFileProtectionComplete]) {
+    _protectedFileCreated = YES;
+    return;
+  }
+  [[NSFileManager defaultManager] removeItemAtPath:LockedDeviceFilename()
+                                             error:&error];
+}
+
+@end