text: // Copyright (c) 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.
  
  #include "content/browser/storage_partition_impl_map.h"
  
  #include "base/bind.h"
  #include "base/callback.h"
  #include "base/files/file_enumerator.h"
  #include "base/files/file_path.h"
  #include "base/files/file_util.h"
  #include "base/stl_util.h"
  #include "base/strings/string_number_conversions.h"
  #include "base/strings/string_util.h"
  #include "base/strings/stringprintf.h"
  #include "base/threading/sequenced_worker_pool.h"
  #include "content/browser/appcache/chrome_appcache_service.h"
  #include "content/browser/fileapi/browser_file_system_helper.h"
  #include "content/browser/fileapi/chrome_blob_storage_context.h"
  #include "content/browser/loader/resource_request_info_impl.h"
  #include "content/browser/resource_context_impl.h"
  #include "content/browser/service_worker/service_worker_request_handler.h"
  #include "content/browser/storage_partition_impl.h"
  #include "content/browser/streams/stream.h"
  #include "content/browser/streams/stream_context.h"
  #include "content/browser/streams/stream_registry.h"
  #include "content/browser/streams/stream_url_request_job.h"
  #include "content/browser/webui/url_data_manager_backend.h"
  #include "content/public/browser/browser_context.h"
  #include "content/public/browser/browser_thread.h"
  #include "content/public/browser/content_browser_client.h"
  #include "content/public/browser/storage_partition.h"
  #include "content/public/common/content_constants.h"
  #include "content/public/common/url_constants.h"
  #include "crypto/sha2.h"
  #include "net/url_request/url_request_context.h"
  #include "net/url_request/url_request_context_getter.h"
  #include "storage/browser/blob/blob_storage_context.h"
  #include "storage/browser/blob/blob_url_request_job_factory.h"
  #include "storage/browser/fileapi/file_system_url_request_job_factory.h"
  #include "storage/common/blob/blob_data.h"
  
  using storage::FileSystemContext;
  using storage::BlobStorageContext;
  
  namespace content {
  
  namespace {
  
  // A derivative that knows about Streams too.
  class BlobProtocolHandler : public net::URLRequestJobFactory::ProtocolHandler {
   public:
    BlobProtocolHandler(ChromeBlobStorageContext* blob_storage_context,
                        StreamContext* stream_context,
                        storage::FileSystemContext* file_system_context)
        : blob_storage_context_(blob_storage_context),
          stream_context_(stream_context),
          file_system_context_(file_system_context) {}
  
    virtual ~BlobProtocolHandler() {
    }
  
    virtual net::URLRequestJob* MaybeCreateJob(
        net::URLRequest* request,
        net::NetworkDelegate* network_delegate) const OVERRIDE {
      scoped_refptr<Stream> stream =
          stream_context_->registry()->GetStream(request->url());
      if (stream.get())
        return new StreamURLRequestJob(request, network_delegate, stream);
  
      if (!blob_protocol_handler_) {
        // Construction is deferred because 'this' is constructed on
        // the main thread but we want blob_protocol_handler_ constructed
        // on the IO thread.
        blob_protocol_handler_.reset(new storage::BlobProtocolHandler(
            blob_storage_context_->context(),
            file_system_context_.get(),
            BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE)
                .get()));
      }
      return blob_protocol_handler_->MaybeCreateJob(request, network_delegate);
    }
  
   private:
    const scoped_refptr<ChromeBlobStorageContext> blob_storage_context_;
    const scoped_refptr<StreamContext> stream_context_;
    const scoped_refptr<storage::FileSystemContext> file_system_context_;
    mutable scoped_ptr<storage::BlobProtocolHandler> blob_protocol_handler_;
    DISALLOW_COPY_AND_ASSIGN(BlobProtocolHandler);
  };
  
  // These constants are used to create the directory structure under the profile
  // where renderers with a non-default storage partition keep their persistent
  // state. This will contain a set of directories that partially mirror the
  // directory structure of BrowserContext::GetPath().
  //
  // The kStoragePartitionDirname contains an extensions directory which is
  // further partitioned by extension id, followed by another level of directories
  // for the "default" extension storage partition and one directory for each
  // persistent partition used by a webview tag. Example:
  //
  //   Storage/ext/ABCDEF/def
  //   Storage/ext/ABCDEF/hash(partition name)
  //
  // The code in GetStoragePartitionPath() constructs these path names.
  //
  // TODO(nasko): Move extension related path code out of content.
  const base::FilePath::CharType kStoragePartitionDirname[] =
      FILE_PATH_LITERAL("Storage");
  const base::FilePath::CharType kExtensionsDirname[] =
      FILE_PATH_LITERAL("ext");
  const base::FilePath::CharType kDefaultPartitionDirname[] =
      FILE_PATH_LITERAL("def");
  const base::FilePath::CharType kTrashDirname[] =
      FILE_PATH_LITERAL("trash");
  
  // Because partition names are user specified, they can be arbitrarily long
  // which makes them unsuitable for paths names. We use a truncation of a
  // SHA256 hash to perform a deterministic shortening of the string. The
  // kPartitionNameHashBytes constant controls the length of the truncation.
  // We use 6 bytes, which gives us 99.999% reliability against collisions over
  // 1 million partition domains.
  //
  // Analysis:
  // We assume that all partition names within one partition domain are
  // controlled by the the same entity. Thus there is no chance for adverserial
  // attack and all we care about is accidental collision. To get 5 9s over
  // 1 million domains, we need the probability of a collision in any one domain
  // to be
  //
  //    p < nroot(1000000, .99999) ~= 10^-11
  //
  // We use the following birthday attack approximation to calculate the max
  // number of unique names for this probability:
  //
  //    n(p,H) = sqrt(2*H * ln(1/(1-p)))
  //
  // For a 6-byte hash, H = 2^(6*8).  n(10^-11, H) ~= 75
  //
  // An average partition domain is likely to have less than 10 unique
  // partition names which is far lower than 75.
  //
  // Note, that for 4 9s of reliability, the limit is 237 partition names per
  // partition domain.
  const int kPartitionNameHashBytes = 6;
  
  // Needed for selecting all files in ObliterateOneDirectory() below.
  #if defined(OS_POSIX)
  const int kAllFileTypes = base::FileEnumerator::FILES |
                            base::FileEnumerator::DIRECTORIES |
                            base::FileEnumerator::SHOW_SYM_LINKS;
  #else
  const int kAllFileTypes = base::FileEnumerator::FILES |
                            base::FileEnumerator::DIRECTORIES;
  #endif
  
  base::FilePath GetStoragePartitionDomainPath(
      const std::string& partition_domain) {
    CHECK(base::IsStringUTF8(partition_domain));
  
    return base::FilePath(kStoragePartitionDirname).Append(kExtensionsDirname)
        .Append(base::FilePath::FromUTF8Unsafe(partition_domain));
  }
  
  // Helper function for doing a depth-first deletion of the data on disk.
  // Examines paths directly in |current_dir| (no recursion) and tries to
  // delete from disk anything that is in, or isn't a parent of something in
  // |paths_to_keep|. Paths that need further expansion are added to
  // |paths_to_consider|.
  void ObliterateOneDirectory(const base::FilePath& current_dir,
                              const std::vector<base::FilePath>& paths_to_keep,
                              std::vector<base::FilePath>* paths_to_consider) {
    CHECK(current_dir.IsAbsolute());
  
    base::FileEnumerator enumerator(current_dir, false, kAllFileTypes);
    for (base::FilePath to_delete = enumerator.Next(); !to_delete.empty();
         to_delete = enumerator.Next()) {
      // Enum tracking which of the 3 possible actions to take for |to_delete|.
      enum { kSkip, kEnqueue, kDelete } action = kDelete;
  
      for (std::vector<base::FilePath>::const_iterator to_keep =
               paths_to_keep.begin();
           to_keep != paths_to_keep.end();
           ++to_keep) {
        if (to_delete == *to_keep) {
          action = kSkip;
          break;
        } else if (to_delete.IsParent(*to_keep)) {
          // |to_delete| contains a path to keep. Add to stack for further
          // processing.
          action = kEnqueue;
          break;
        }
      }
  
      switch (action) {
        case kDelete:
          base::DeleteFile(to_delete, true);
          break;
  
        case kEnqueue:
          paths_to_consider->push_back(to_delete);
          break;
  
        case kSkip:
          break;
      }
    }
  }
  
  // Synchronously attempts to delete |unnormalized_root|, preserving only
  // entries in |paths_to_keep|. If there are no entries in |paths_to_keep| on
  // disk, then it completely removes |unnormalized_root|. All paths must be
  // absolute paths.
  void BlockingObliteratePath(
      const base::FilePath& unnormalized_browser_context_root,
      const base::FilePath& unnormalized_root,
      const std::vector<base::FilePath>& paths_to_keep,
      const scoped_refptr<base::TaskRunner>& closure_runner,
      const base::Closure& on_gc_required) {
    // Early exit required because MakeAbsoluteFilePath() will fail on POSIX
    // if |unnormalized_root| does not exist. This is safe because there is
    // nothing to do in this situation anwyays.
    if (!base::PathExists(unnormalized_root)) {
      return;
    }
  
    // Never try to obliterate things outside of the browser context root or the
    // browser context root itself. Die hard.
    base::FilePath root = base::MakeAbsoluteFilePath(unnormalized_root);
    base::FilePath browser_context_root =
        base::MakeAbsoluteFilePath(unnormalized_browser_context_root);
    CHECK(!root.empty());
    CHECK(!browser_context_root.empty());
    CHECK(browser_context_root.IsParent(root) && browser_context_root != root);
  
    // Reduce |paths_to_keep| set to those under the root and actually on disk.
    std::vector<base::FilePath> valid_paths_to_keep;
    for (std::vector<base::FilePath>::const_iterator it = paths_to_keep.begin();
         it != paths_to_keep.end();
         ++it) {
      if (root.IsParent(*it) && base::PathExists(*it))
        valid_paths_to_keep.push_back(*it);
    }
  
    // If none of the |paths_to_keep| are valid anymore then we just whack the
    // root and be done with it.  Otherwise, signal garbage collection and do
    // a best-effort delete of the on-disk structures.
    if (valid_paths_to_keep.empty()) {
      base::DeleteFile(root, true);
      return;
    }
    closure_runner->PostTask(FROM_HERE, on_gc_required);
  
    // Otherwise, start at the root and delete everything that is not in
    // |valid_paths_to_keep|.
    std::vector<base::FilePath> paths_to_consider;
    paths_to_consider.push_back(root);
    while(!paths_to_consider.empty()) {
      base::FilePath path = paths_to_consider.back();
      paths_to_consider.pop_back();
      ObliterateOneDirectory(path, valid_paths_to_keep, &paths_to_consider);
    }
  }
  
  // Ensures each path in |active_paths| is a direct child of storage_root.
  void NormalizeActivePaths(const base::FilePath& storage_root,
                            base::hash_set<base::FilePath>* active_paths) {
    base::hash_set<base::FilePath> normalized_active_paths;
  
    for (base::hash_set<base::FilePath>::iterator iter = active_paths->begin();
         iter != active_paths->end(); ++iter) {
      base::FilePath relative_path;
      if (!storage_root.AppendRelativePath(*iter, &relative_path))
        continue;
  
      std::vector<base::FilePath::StringType> components;
      relative_path.GetComponents(&components);
  
      DCHECK(!relative_path.empty());
      normalized_active_paths.insert(storage_root.Append(components.front()));
    }
  
    active_paths->swap(normalized_active_paths);
  }
  
  // Deletes all entries inside the |storage_root| that are not in the
  // |active_paths|.  Deletion is done in 2 steps:
  //
  //   (1) Moving all garbage collected paths into a trash directory.
  //   (2) Asynchronously deleting the trash directory.
  //
  // The deletion is asynchronous because after (1) completes, calling code can
  // safely continue to use the paths that had just been garbage collected
  // without fear of race conditions.
  //
  // This code also ignores failed moves rather than attempting a smarter retry.
  // Moves shouldn't fail here unless there is some out-of-band error (eg.,
  // FS corruption). Retry logic is dangerous in the general case because
  // there is not necessarily a guaranteed case where the logic may succeed.
  //
  // This function is still named BlockingGarbageCollect() because it does
  // execute a few filesystem operations synchronously.
  void BlockingGarbageCollect(
      const base::FilePath& storage_root,
      const scoped_refptr<base::TaskRunner>& file_access_runner,
      scoped_ptr<base::hash_set<base::FilePath> > active_paths) {
    CHECK(storage_root.IsAbsolute());
  
    NormalizeActivePaths(storage_root, active_paths.get());
  
    base::FileEnumerator enumerator(storage_root, false, kAllFileTypes);
    base::FilePath trash_directory;
    if (!base::CreateTemporaryDirInDir(storage_root, kTrashDirname,
                                       &trash_directory)) {
      // Unable to continue without creating the trash directory so give up.
      return;
    }
    for (base::FilePath path = enumerator.Next(); !path.empty();
         path = enumerator.Next()) {
      if (active_paths->find(path) == active_paths->end() &&
          path != trash_directory) {
        // Since |trash_directory| is unique for each run of this function there
        // can be no colllisions on the move.
        base::Move(path, trash_directory.Append(path.BaseName()));
      }
    }
  
    file_access_runner->PostTask(
        FROM_HERE,
        base::Bind(base::IgnoreResult(&base::DeleteFile), trash_directory, true));
  }
  
  }  // namespace
  
  // static
  base::FilePath StoragePartitionImplMap::GetStoragePartitionPath(
      const std::string& partition_domain,
      const std::string& partition_name) {
    if (partition_domain.empty())
      return base::FilePath();
  
    base::FilePath path = GetStoragePartitionDomainPath(partition_domain);
  
    // TODO(ajwong): Mangle in-memory into this somehow, either by putting
    // it into the partition_name, or by manually adding another path component
    // here.  Otherwise, it's possible to have an in-memory StoragePartition and
    // a persistent one that return the same FilePath for GetPath().
    if (!partition_name.empty()) {
      // For analysis of why we can ignore collisions, see the comment above
      // kPartitionNameHashBytes.
      char buffer[kPartitionNameHashBytes];
      crypto::SHA256HashString(partition_name, &buffer[0],
                               sizeof(buffer));
      return path.AppendASCII(base::HexEncode(buffer, sizeof(buffer)));
    }
  
    return path.Append(kDefaultPartitionDirname);
  }
  
  StoragePartitionImplMap::StoragePartitionImplMap(
      BrowserContext* browser_context)
      : browser_context_(browser_context),
        resource_context_initialized_(false) {
    // Doing here instead of initializer list cause it's just too ugly to read.
    base::SequencedWorkerPool* blocking_pool = BrowserThread::GetBlockingPool();
    file_access_runner_ =
        blocking_pool->GetSequencedTaskRunner(blocking_pool->GetSequenceToken());
  }
  
  StoragePartitionImplMap::~StoragePartitionImplMap() {
    STLDeleteContainerPairSecondPointers(partitions_.begin(),
                                         partitions_.end());
  }
  
  StoragePartitionImpl* StoragePartitionImplMap::Get(
      const std::string& partition_domain,
      const std::string& partition_name,
      bool in_memory) {
    // Find the previously created partition if it's available.
    StoragePartitionConfig partition_config(
        partition_domain, partition_name, in_memory);
  
    PartitionMap::const_iterator it = partitions_.find(partition_config);
    if (it != partitions_.end())
      return it->second;
  
    base::FilePath partition_path =
        browser_context_->GetPath().Append(
            GetStoragePartitionPath(partition_domain, partition_name));
    StoragePartitionImpl* partition =
        StoragePartitionImpl::Create(browser_context_, in_memory,
                                     partition_path);
    partitions_[partition_config] = partition;
  
    ChromeBlobStorageContext* blob_storage_context =
        ChromeBlobStorageContext::GetFor(browser_context_);
    StreamContext* stream_context = StreamContext::GetFor(browser_context_);
    ProtocolHandlerMap protocol_handlers;
    protocol_handlers[url::kBlobScheme] =
        linked_ptr<net::URLRequestJobFactory::ProtocolHandler>(
            new BlobProtocolHandler(blob_storage_context,
                                    stream_context,
                                    partition->GetFileSystemContext()));
    protocol_handlers[url::kFileSystemScheme] =
        linked_ptr<net::URLRequestJobFactory::ProtocolHandler>(
            CreateFileSystemProtocolHandler(partition_domain,
                                            partition->GetFileSystemContext()));
    protocol_handlers[kChromeUIScheme] =
        linked_ptr<net::URLRequestJobFactory::ProtocolHandler>(
            URLDataManagerBackend::CreateProtocolHandler(
                browser_context_->GetResourceContext(),
                browser_context_->IsOffTheRecord(),
                partition->GetAppCacheService(),
                blob_storage_context));
    std::vector<std::string> additional_webui_schemes;
    GetContentClient()->browser()->GetAdditionalWebUISchemes(
        &additional_webui_schemes);
    for (std::vector<std::string>::const_iterator it =
             additional_webui_schemes.begin();
         it != additional_webui_schemes.end();
         ++it) {
      protocol_handlers[*it] =
          linked_ptr<net::URLRequestJobFactory::ProtocolHandler>(
              URLDataManagerBackend::CreateProtocolHandler(
                  browser_context_->GetResourceContext(),
                  browser_context_->IsOffTheRecord(),
                  partition->GetAppCacheService(),
                  blob_storage_context));
    }
    protocol_handlers[kChromeDevToolsScheme] =
        linked_ptr<net::URLRequestJobFactory::ProtocolHandler>(
            CreateDevToolsProtocolHandler(browser_context_->GetResourceContext(),
                                          browser_context_->IsOffTheRecord()));
  
    URLRequestInterceptorScopedVector request_interceptors;
    request_interceptors.push_back(
        ServiceWorkerRequestHandler::CreateInterceptor().release());
  
    // These calls must happen after StoragePartitionImpl::Create().
    if (partition_domain.empty()) {
      partition->SetURLRequestContext(
          GetContentClient()->browser()->CreateRequestContext(
              browser_context_,
              &protocol_handlers,
              request_interceptors.Pass()));
    } else {
      partition->SetURLRequestContext(
          GetContentClient()->browser()->CreateRequestContextForStoragePartition(
              browser_context_,
              partition->GetPath(),
              in_memory,
              &protocol_handlers,
              request_interceptors.Pass()));
    }
    partition->SetMediaURLRequestContext(
        partition_domain.empty() ?
        browser_context_->GetMediaRequestContext() :
        browser_context_->GetMediaRequestContextForStoragePartition(
            partition->GetPath(), in_memory));
  
    PostCreateInitialization(partition, in_memory);
  
    return partition;
  }
  
  void StoragePartitionImplMap::AsyncObliterate(
      const GURL& site,
      const base::Closure& on_gc_required) {
    // This method should avoid creating any StoragePartition (which would
    // create more open file handles) so that it can delete as much of the
    // data off disk as possible.
    std::string partition_domain;
    std::string partition_name;
    bool in_memory = false;
    GetContentClient()->browser()->GetStoragePartitionConfigForSite(
        browser_context_, site, false, &partition_domain,
        &partition_name, &in_memory);
  
    // Find the active partitions for the domain. Because these partitions are
    // active, it is not possible to just delete the directories that contain
    // the backing data structures without causing the browser to crash. Instead,
    // of deleteing the directory, we tell each storage context later to
    // remove any data they have saved. This will leave the directory structure
    // intact but it will only contain empty databases.
    std::vector<StoragePartitionImpl*> active_partitions;
    std::vector<base::FilePath> paths_to_keep;
    for (PartitionMap::const_iterator it = partitions_.begin();
         it != partitions_.end();
         ++it) {
      const StoragePartitionConfig& config = it->first;
      if (config.partition_domain == partition_domain) {
        it->second->ClearData(
            // All except shader cache.
            ~StoragePartition::REMOVE_DATA_MASK_SHADER_CACHE,
            StoragePartition::QUOTA_MANAGED_STORAGE_MASK_ALL,
            GURL(),
            StoragePartition::OriginMatcherFunction(),
            base::Time(), base::Time::Max(),
            base::Bind(&base::DoNothing));
        if (!config.in_memory) {
          paths_to_keep.push_back(it->second->GetPath());
        }
      }
    }
  
    // Start a best-effort delete of the on-disk storage excluding paths that are
    // known to still be in use. This is to delete any previously created
    // StoragePartition state that just happens to not have been used during this
    // run of the browser.
    base::FilePath domain_root = browser_context_->GetPath().Append(
        GetStoragePartitionDomainPath(partition_domain));
  
    BrowserThread::PostBlockingPoolTask(
        FROM_HERE,
        base::Bind(&BlockingObliteratePath, browser_context_->GetPath(),
                   domain_root, paths_to_keep,
                   base::MessageLoopProxy::current(), on_gc_required));
  }
  
  void StoragePartitionImplMap::GarbageCollect(
      scoped_ptr<base::hash_set<base::FilePath> > active_paths,
      const base::Closure& done) {
    // Include all paths for current StoragePartitions in the active_paths since
    // they cannot be deleted safely.
    for (PartitionMap::const_iterator it = partitions_.begin();
         it != partitions_.end();
         ++it) {
      const StoragePartitionConfig& config = it->first;
      if (!config.in_memory)
        active_paths->insert(it->second->GetPath());
    }
  
    // Find the directory holding the StoragePartitions and delete everything in
    // there that isn't considered active.
    base::FilePath storage_root = browser_context_->GetPath().Append(
        GetStoragePartitionDomainPath(std::string()));
    file_access_runner_->PostTaskAndReply(
        FROM_HERE,
        base::Bind(&BlockingGarbageCollect, storage_root,
                   file_access_runner_,
                   base::Passed(&active_paths)),
        done);
  }
  
  void StoragePartitionImplMap::ForEach(
      const BrowserContext::StoragePartitionCallback& callback) {
    for (PartitionMap::const_iterator it = partitions_.begin();
         it != partitions_.end();
         ++it) {
      callback.Run(it->second);
    }
  }
  
  void StoragePartitionImplMap::PostCreateInitialization(
      StoragePartitionImpl* partition,
      bool in_memory) {
    // TODO(ajwong): ResourceContexts no longer have any storage related state.
    // We should move this into a place where it is called once per
    // BrowserContext creation rather than piggybacking off the default context
    // creation.
    // Note: moving this into Get() before partitions_[] is set causes reentrency.
    if (!resource_context_initialized_) {
      resource_context_initialized_ = true;
      InitializeResourceContext(browser_context_);
    }
  
    // Check first to avoid memory leak in unittests.
    if (BrowserThread::IsMessageLoopValid(BrowserThread::IO)) {
      BrowserThread::PostTask(
          BrowserThread::IO, FROM_HERE,
          base::Bind(&ChromeAppCacheService::InitializeOnIOThread,
                     partition->GetAppCacheService(),
                     in_memory ? base::FilePath() :
                         partition->GetPath().Append(kAppCacheDirname),
                     browser_context_->GetResourceContext(),
                     make_scoped_refptr(partition->GetURLRequestContext()),
                     make_scoped_refptr(
                         browser_context_->GetSpecialStoragePolicy())));
  
      BrowserThread::PostTask(
          BrowserThread::IO,
          FROM_HERE,
          base::Bind(&ServiceWorkerContextWrapper::SetBlobParametersForCache,
                     partition->GetServiceWorkerContext(),
                     make_scoped_refptr(partition->GetURLRequestContext()),
                     make_scoped_refptr(
                         ChromeBlobStorageContext::GetFor(browser_context_))));
  
      // We do not call InitializeURLRequestContext() for media contexts because,
      // other than the HTTP cache, the media contexts share the same backing
      // objects as their associated "normal" request context.  Thus, the previous
      // call serves to initialize the media request context for this storage
      // partition as well.
    }
  }
  
  }  // namespace content
  