Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/sessions/session_service.mm

+// Copyright 2012 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/browser/sessions/session_service.h"
+
+#import <UIKit/UIKit.h>
+
+#include "base/files/file_path.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/mac/bind_objc_block.h"
+#include "base/mac/foundation_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/strings/sys_string_conversions.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/threading/thread_restrictions.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#import "ios/chrome/browser/sessions/session_window.h"
+#import "ios/web/navigation/crw_session_certificate_policy_manager.h"
+#import "ios/web/navigation/crw_session_controller.h"
+#import "ios/web/navigation/crw_session_entry.h"
+#include "ios/web/public/web_thread.h"
+
+// When C++ exceptions are disabled, the C++ library defines |try| and
+// |catch| so as to allow exception-expecting C++ code to build properly when
+// language support for exceptions is not present.  These macros interfere
+// with the use of |@try| and |@catch| in Objective-C files such as this one.
+// Undefine these macros here, after everything has been #included, since
+// there will be no C++ uses and only Objective-C uses from this point on.
+#undef try
+#undef catch
+
+const NSTimeInterval kSaveDelay = 2.5;  // Value taken from Desktop Chrome.
+
+@interface SessionWindowUnarchiver () {
+  ios::ChromeBrowserState* _browserState;
+}
+
+@end
+
+@implementation SessionWindowUnarchiver
+
+@synthesize browserState = _browserState;  // weak
+
+- (id)initForReadingWithData:(NSData*)data
+                browserState:(ios::ChromeBrowserState*)browserState {
+  if (self = [super initForReadingWithData:data]) {
+    _browserState = browserState;
+  }
+  return self;
+}
+
+@end
+
+@interface SessionServiceIOS () {
+ @private
+  // The SequencedTaskRunner on which File IO operations are performed.
+  scoped_refptr<base::SequencedTaskRunner> taskRunner_;
+
+  // Maps save directories to the pending SessionWindow for the delayed
+  // save behavior.
+  base::scoped_nsobject<NSMutableDictionary> pendingWindows_;
+}
+
+- (void)performSaveToDirectoryInBackground:(NSString*)directory;
+- (void)performSaveWindow:(SessionWindowIOS*)window
+              toDirectory:(NSString*)directory;
+@end
+
+@implementation SessionServiceIOS
+
++ (SessionServiceIOS*)sharedService {
+  static SessionServiceIOS* singleton = nil;
+  if (!singleton) {
+    singleton = [[[self class] alloc] init];
+  }
+  return singleton;
+}
+
+- (id)init {
+  self = [super init];
+  if (self) {
+    pendingWindows_.reset([[NSMutableDictionary alloc] init]);
+    auto pool = web::WebThread::GetBlockingPool();
+    taskRunner_ = pool->GetSequencedTaskRunner(pool->GetSequenceToken());
+  }
+  return self;
+}
+
+// Returns the path of the session file.
+- (NSString*)sessionFilePathForDirectory:(NSString*)directory {
+  return [directory stringByAppendingPathComponent:@"session.plist"];
+}
+
+// Do the work of saving on a background thread. Assumes |window| is threadsafe.
+- (void)performSaveToDirectoryInBackground:(NSString*)directory {
+  DCHECK(directory);
+  DCHECK([pendingWindows_ objectForKey:directory] != nil);
+  UIBackgroundTaskIdentifier identifier = [[UIApplication sharedApplication]
+      beginBackgroundTaskWithExpirationHandler:^{
+      }];
+  DCHECK(identifier != UIBackgroundTaskInvalid);
+
+  // Put the window into a local var so it can be retained for the block, yet
+  // we can remove it from the dictionary to allow queuing another save.
+  SessionWindowIOS* localWindow =
+      [[pendingWindows_ objectForKey:directory] retain];
+  [pendingWindows_ removeObjectForKey:directory];
+
+  taskRunner_->PostTask(
+      FROM_HERE, base::BindBlock(^{
+        @try {
+          [self performSaveWindow:localWindow toDirectory:directory];
+        } @catch (NSException* e) {
+          // Do nothing.
+        }
+        [localWindow release];
+        [[UIApplication sharedApplication] endBackgroundTask:identifier];
+      }));
+}
+
+// Saves a SessionWindowIOS in a given directory. In case the directory doesn't
+// exists it will be automatically created.
+- (void)performSaveWindow:(SessionWindowIOS*)window
+              toDirectory:(NSString*)directory {
+  base::ThreadRestrictions::AssertIOAllowed();
+  NSFileManager* fileManager = [NSFileManager defaultManager];
+  BOOL isDir;
+  if (![fileManager fileExistsAtPath:directory isDirectory:&isDir]) {
+    NSError* error = nil;
+    BOOL result = [fileManager createDirectoryAtPath:directory
+                         withIntermediateDirectories:YES
+                                          attributes:nil
+                                               error:&error];
+    DCHECK(result);
+    if (!result) {
+      DLOG(ERROR) << "Error creating destination dir: "
+                  << base::SysNSStringToUTF8([error description]);
+      return;
+    }
+  } else {
+    DCHECK(isDir);
+    if (!isDir) {
+      DLOG(ERROR) << "Destination Directory already exists and is a file";
+      return;
+    }
+  }
+
+  NSString* filename = [self sessionFilePathForDirectory:directory];
+  if (filename) {
+    BOOL result = [NSKeyedArchiver archiveRootObject:window toFile:filename];
+    DCHECK(result);
+    if (!result)
+      DLOG(ERROR) << "Error writing session file to " << filename;
+    // Encrypt the session file (mostly for Incognito, but can't hurt to
+    // always do it).
+    NSDictionary* attributeDict =
+        [NSDictionary dictionaryWithObject:NSFileProtectionComplete
+                                    forKey:NSFileProtectionKey];
+    NSError* error = nil;
+    BOOL success = [[NSFileManager defaultManager] setAttributes:attributeDict
+                                                    ofItemAtPath:filename
+                                                           error:&error];
+    if (!success) {
+      DLOG(ERROR) << "Error encrypting session file"
+                  << base::SysNSStringToUTF8([error description]);
+    }
+  }
+}
+
+- (void)saveWindow:(SessionWindowIOS*)window
+    forBrowserState:(ios::ChromeBrowserState*)browserState
+        immediately:(BOOL)immediately {
+  NSString* stashPath =
+      base::SysUTF8ToNSString(browserState->GetStatePath().value());
+  // If there's an existing session window for |stashPath|, clear it before it's
+  // replaced.
+  SessionWindowIOS* pendingSession = base::mac::ObjCCast<SessionWindowIOS>(
+      [pendingWindows_ objectForKey:stashPath]);
+  [pendingSession clearSessions];
+  // Set |window| as the pending save for |stashPath|.
+  [pendingWindows_ setObject:window forKey:stashPath];
+  if (immediately) {
+    [NSObject cancelPreviousPerformRequestsWithTarget:self];
+    [self performSaveToDirectoryInBackground:stashPath];
+  } else if (!pendingSession) {
+    // If there wasn't previously a delayed save pending for |stashPath}|,
+    // enqueue one now.
+    [self performSelector:@selector(performSaveToDirectoryInBackground:)
+               withObject:stashPath
+               afterDelay:kSaveDelay];
+  }
+}
+
+- (SessionWindowIOS*)loadWindowForBrowserState:
+    (ios::ChromeBrowserState*)browserState {
+  NSString* stashPath =
+      base::SysUTF8ToNSString(browserState->GetStatePath().value());
+  SessionWindowIOS* window =
+      [self loadWindowFromPath:[self sessionFilePathForDirectory:stashPath]
+               forBrowserState:browserState];
+  return window;
+}
+
+- (SessionWindowIOS*)loadWindowFromPath:(NSString*)path
+                        forBrowserState:(ios::ChromeBrowserState*)browserState {
+  // HACK: Handle the case where we had to change the class name of a persisted
+  // class on disk.
+  [SessionWindowUnarchiver setClass:[CRWSessionCertificatePolicyManager class]
+                       forClassName:@"SessionCertificatePolicyManager"];
+  [SessionWindowUnarchiver setClass:[CRWSessionController class]
+                       forClassName:@"SessionController"];
+  [SessionWindowUnarchiver setClass:[CRWSessionEntry class]
+                       forClassName:@"SessionEntry"];
+  // TODO(crbug.com/661633): Remove this hack.
+  [SessionWindowUnarchiver setClass:[SessionWindowIOS class]
+                       forClassName:@"SessionWindow"];
+  SessionWindowIOS* window = nil;
+  @try {
+    NSData* data = [NSData dataWithContentsOfFile:path];
+    if (data) {
+      base::scoped_nsobject<SessionWindowUnarchiver> unarchiver([
+          [SessionWindowUnarchiver alloc] initForReadingWithData:data
+                                                    browserState:browserState]);
+      window = [[[unarchiver decodeObjectForKey:@"root"] retain] autorelease];
+    }
+  } @catch (NSException* exception) {
+    DLOG(ERROR) << "Error loading session.plist";
+  }
+  return window;
+}
+
+// Deletes the file containing the commands for the last session in the given
+// browserState directory.
+- (void)deleteLastSession:(NSString*)directory {
+  NSString* sessionFile = [self sessionFilePathForDirectory:directory];
+  taskRunner_->PostTask(
+      FROM_HERE, base::BindBlock(^{
+        base::ThreadRestrictions::AssertIOAllowed();
+        NSFileManager* fileManager = [NSFileManager defaultManager];
+        if (![fileManager fileExistsAtPath:sessionFile])
+          return;
+        if (![fileManager removeItemAtPath:sessionFile error:nil])
+          CHECK(false) << "Unable to delete session file.";
+      }));
+}
+
+@end