Add UMA for testing whether device supports memory mapping APK files with executable permissions.

third_party/android_crazy_linker/src/src/crazy_linker_api.cpp

 // 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.
 
 // Implements the crazy linker C-based API exposed by <crazy_linker.h>
 
 #include <crazy_linker.h>
 
+#include <limits.h>
 #include <string.h>
 
 #include "crazy_linker_error.h"
 #include "crazy_linker_ashmem.h"
 #include "crazy_linker_globals.h"
 #include "crazy_linker_proc_maps.h"
 #include "crazy_linker_search_path_list.h"
 #include "crazy_linker_shared_library.h"
 #include "crazy_linker_thread.h"
 #include "crazy_linker_util.h"
 #include "crazy_linker_library_view.h"
 #include "crazy_linker_system.h"
 
 using crazy::Globals;
 using crazy::Error;
 using crazy::SearchPathList;
 using crazy::ScopedGlobalLock;
 using crazy::LibraryView;
+using crazy::FileDescriptor;
 
 //
 // crazy_context_t
 //
 
 struct crazy_context_t {
  public:
   crazy_context_t()
       : load_address(0),
         file_offset(0),
@@ skipping 343 matching lines @@
                                       crazy_context_t* context) {
   if (library) {
     ScopedDelayedCallbackPoster poster(context);
     ScopedGlobalLock lock;
     LibraryView* wrap = reinterpret_cast<LibraryView*>(library);
 
     Globals::GetLibraries()->UnloadLibrary(wrap);
   }
 }
 
+crazy_status_t crazy_linker_test_load_from_apk(const char* apkfile_name) {
+  FileDescriptor fd(apkfile_name);
+
+  LOG("%s: Memory mapping the first page of %s\n", __FUNCTION__, apkfile_name);
+  void* address = fd.Map(NULL, PAGE_SIZE, PROT_EXEC, MAP_PRIVATE, 0);
+
+  crazy_status_t status = CRAZY_STATUS_FAILURE;
+  if (address != MAP_FAILED) {
+    status = CRAZY_STATUS_SUCCESS;
+    munmap(address, PAGE_SIZE);
+  }

[picksi1, 2014/10/10 10:52:18]

I think this would be clearer is we swapped the if/else round and remove the
default status assignment, e.g.

crazy_status_t status;
if (address == MAP_FAILED) {
   status = CRAZY_STATUS_FAILURE
}
else {
   status = CRAZY_STATUS_SUCCESS;
   munmap(address, PAGE_SIZE);
}

[petrcermak, 2014/10/10 14:20:14]

Done.

+
+  LOG("  %s\n", status == CRAZY_STATUS_SUCCESS ? "supported" : "NOT supported");
+  return status;
+}
+
 }  // extern "C"