Launch nexes from mojo_shell.

shell/dynamic_application_loader.cc

 // Copyright 2014 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 "shell/dynamic_application_loader.h"

[qsr, 2015/01/30 15:04:11]

I'm probably completely missing a point somewhere here, but why must this be
backed here and not in a content handler? What do you need here today that you
couldn't do in the StartApplication method of a content handler?

[Nick Bray (chromium), 2015/01/31 02:47:10]

It would be possible, but more complex (would need to generate and manage a
tempfile inside the content handler.)  The bigger issue, however, is that
eventually a file-handle-like API will be needed for random access, mmaping the
file in place, etc.  (Trying to treat native executables as data streams will
add ~100-500ms to the initial load time.)  The system will also need to be aware
it's interacting with a "native code loader" so that it opens files with
permissions to be mapped executable.

What that interface will ultimately look like is unclear to me, at the moment. 
It won't be like today's content loader.  Matching what we do for DSO loading is
simple and doesn't add any new concepts, so it works for now.

 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/process.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "crypto/secure_hash.h"
 #include "crypto/sha2.h"
 #include "mojo/common/common_type_converters.h"
 #include "mojo/common/data_pipe_utils.h"
 #include "mojo/public/cpp/system/data_pipe.h"
 #include "mojo/services/network/public/interfaces/url_loader.mojom.h"
 #include "shell/context.h"
 #include "shell/data_pipe_peek.h"
 #include "shell/filename_util.h"
+#if MOJO_USE_NACL
+#include "shell/nacl/nacl_service_runner.h"
+#endif
 #include "shell/switches.h"
 #include "url/url_util.h"
 
 namespace mojo {
 namespace shell {
 
 namespace {
 
 static const char kMojoMagic[] = "#!mojo ";
 static const size_t kMaxShebangLength = 2048;
@@ skipping 33 matching lines @@
   virtual ~Loader() {}
 
  protected:
   virtual URLResponsePtr AsURLResponse(base::TaskRunner* task_runner,
                                        uint32_t skip) = 0;
 
   virtual void AsPath(
       base::TaskRunner* task_runner,
       base::Callback<void(const base::FilePath&, bool)> callback) = 0;
 
+  virtual GURL URL() = 0;

[qsr, 2015/01/30 15:04:11]

Instead of this, just pass the URL in the constructor of this class, and expose
is as a const protected member.

[Nick Bray (chromium), 2015/01/31 02:47:10]

Not entirely convinced, but don't have strong feelings.  This would be the only
protected field in the hierarchy, and it would be the only case where
implementation details about the actual data being loaded would leak lower into
the hierarchy.  Opinions, James?

+
+  std::string Extension() {
+    std::string filename = URL().ExtractFileName();
+    size_t dot = filename.rfind('.');
+    if (dot != std::string::npos) {
+      return filename.substr(dot);
+    }
+    return "";
+  }
+
   virtual std::string MimeType() = 0;
 
   virtual bool HasMojoMagic() = 0;
 
   virtual bool PeekFirstLine(std::string* line) = 0;
 
   void Load() {
     // If the response begins with a #!mojo <content-handler-url>, use it.
     GURL url;
     std::string shebang;
@@ skipping 11 matching lines @@
           iter->second, application_request_.Pass(),
           AsURLResponse(context_->task_runners()->blocking_pool(), 0));
       return;
     }
 
     // TODO(aa): Sanity check that the thing we got looks vaguely like a mojo
     // application. That could either mean looking for the platform-specific dll
     // header, or looking for some specific mojo signature prepended to the
     // library.
 
+    // TODO(ncbray) sniff or infer the content type at a previous stage in the
+    // pipeline.
+    if (Extension() == ".nexe") {
+      AsPath(context_->task_runners()->blocking_pool(),
+             base::Bind(&Loader::RunNexe, weak_ptr_factory_.GetWeakPtr()));
+      return;
+    }
+
     AsPath(context_->task_runners()->blocking_pool(),
            base::Bind(&Loader::RunLibrary, weak_ptr_factory_.GetWeakPtr()));
   }
 
   void ReportComplete() { loader_complete_callback_.Run(this); }
 
  private:
   bool PeekContentHandler(std::string* mojo_shebang,
                           GURL* mojo_content_handler_url) {
     std::string shebang;
@@ skipping 17 matching lines @@
       ReportComplete();
       return;
     }
 
     runner_ = runner_factory_->Create(context_);
     runner_->Start(
         path, cleanup_behavior_, application_request_.Pass(),
         base::Bind(&Loader::ReportComplete, weak_ptr_factory_.GetWeakPtr()));
   }
 
+  void RunNexe(const base::FilePath& path, bool path_exists) {
+    DCHECK(application_request_.is_pending());
+
+    if (!path_exists) {
+      LOG(ERROR) << "Library not started because library path '" << path.value()
+                 << "' does not exist.";
+      ReportComplete();
+      return;
+    }
+
+#if MOJO_USE_NACL
+    nacl_runner_.reset(new NaClServiceRunner(context_));
+    nacl_runner_->Start(path, application_request_.Pass());
+#else
+    LOG(ERROR) << "Library not started because Native Client is not enabled.";
+    ReportComplete();
+#endif
+  }
+
   DynamicServiceRunner::CleanupBehavior cleanup_behavior_;
   InterfaceRequest<Application> application_request_;
   ApplicationLoader::LoadCallback load_callback_;
   LoaderCompleteCallback loader_complete_callback_;
   Context* context_;
   MimeTypeToURLMap* mime_type_to_url_;
   DynamicServiceRunnerFactory* runner_factory_;
   scoped_ptr<DynamicServiceRunner> runner_;
+#if MOJO_USE_NACL
+  scoped_ptr<NaClServiceRunner> nacl_runner_;
+#endif
   base::WeakPtrFactory<Loader> weak_ptr_factory_;
 };
 
 // A loader for local files.
 class DynamicApplicationLoader::LocalLoader : public Loader {
  public:
   LocalLoader(const GURL& url,
               MimeTypeToURLMap* mime_type_to_url,
               Context* context,
               DynamicServiceRunnerFactory* runner_factory,
@@ skipping 47 matching lines @@
   }
 
   void AsPath(
       base::TaskRunner* task_runner,
       base::Callback<void(const base::FilePath&, bool)> callback) override {
     // Async for consistency with network case.
     base::MessageLoop::current()->PostTask(
         FROM_HERE, base::Bind(callback, path_, base::PathExists(path_)));
   }
 
+  GURL URL() override { return url_; }
+
   std::string MimeType() override { return ""; }
 
   bool HasMojoMagic() override {
     std::string magic;
     ReadFileToString(path_, &magic, strlen(kMojoMagic));
     return magic == kMojoMagic;
   }
 
   bool PeekFirstLine(std::string* line) override {
     std::string start_of_file;
@@ skipping 147 matching lines @@
           FROM_HERE, base::Bind(callback, path_, base::PathExists(path_)));
       return;
     }
 
     base::CreateTemporaryFile(&path_);
     common::CopyToFile(response_->body.Pass(), path_, task_runner,
                        base::Bind(&NetworkLoader::CopyCompleted,
                                   weak_ptr_factory_.GetWeakPtr(), callback));
   }
 
+  GURL URL() override { return url_; }
+
   std::string MimeType() override {
     DCHECK(response_);
     return response_->mime_type;
   }
 
   bool HasMojoMagic() override {
     std::string magic;
     return BlockingPeekNBytes(response_->body.get(), &magic, strlen(kMojoMagic),
                               kPeekTimeout) &&
            magic == kMojoMagic;
@@ skipping 93 matching lines @@
   // TODO(darin): What should we do about service errors? This implies that
   // the app closed its handle to the service manager. Maybe we don't care?
 }
 
 void DynamicApplicationLoader::LoaderComplete(Loader* loader) {
   loaders_.erase(std::find(loaders_.begin(), loaders_.end(), loader));
 }
 
 }  // namespace shell
 }  // namespace mojo