Add a size parameter to SharedMemoryHandle.

base/memory/shared_memory_posix.cc

 // 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 "base/memory/shared_memory.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stddef.h>
 #include <sys/mman.h>
@@ skipping 58 matching lines @@
 int SharedMemory::GetFdFromSharedMemoryHandle(
     const SharedMemoryHandle& handle) {
   return handle.GetHandle();
 }
 
 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
   return CreateAnonymous(size) && Map(size);
 }
 
 #if !defined(OS_ANDROID)
-// static
-bool SharedMemory::GetSizeFromSharedMemoryHandle(
-    const SharedMemoryHandle& handle,
-    size_t* size) {
-  struct stat st;
-  if (fstat(handle.GetHandle(), &st) != 0)
-    return false;
-  if (st.st_size < 0)
-    return false;
-  *size = st.st_size;
-  return true;
-}
-
 // Chromium mostly only uses the unique/private shmem as specified by
 // "name == L"". The exception is in the StatsTable.
 // TODO(jrg): there is no way to "clean up" all unused named shmem if
 // we restart from a crash.  (That isn't a new problem, but it is a problem.)
 // In case we want to delete it later, it may be useful to save the value
 // of mem_filename after FilePathForMemoryName().
 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
   DCHECK(!shm_.IsValid());
   if (options.size == 0) return false;
 
@@ skipping 100 matching lines @@
     }
     return false;
   }
 
   int mapped_file = -1;
   int readonly_mapped_file = -1;
   bool result =
       PrepareMapFile(std::move(fp), std::move(readonly_fd), &mapped_file,
                      &readonly_mapped_file, &last_error_);
   shm_ = SharedMemoryHandle(base::FileDescriptor(mapped_file, false),
-                            UnguessableToken::Create());
-  readonly_shm_ = SharedMemoryHandle(
-      base::FileDescriptor(readonly_mapped_file, false), shm_.GetGUID());
+                            options.size, UnguessableToken::Create());
+  readonly_shm_ =
+      SharedMemoryHandle(base::FileDescriptor(readonly_mapped_file, false),
+                         options.size, shm_.GetGUID());
   return result;
 }
 
 // Our current implementation of shmem is with mmap()ing of files.
 // These files need to be deleted explicitly.
 // In practice this call is only needed for unit tests.
 bool SharedMemory::Delete(const std::string& name) {
   FilePath path;
   if (!FilePathForMemoryName(name, &path))
     return false;
@@ skipping 25 matching lines @@
       PrepareMapFile(std::move(fp), std::move(readonly_fd), &mapped_file,
                      &readonly_mapped_file, &last_error_);
   // This form of sharing shared memory is deprecated. https://crbug.com/345734.
   // However, we can't get rid of it without a significant refactor because its
   // used to communicate between two versions of the same service process, very
   // early in the life cycle.
   // Technically, we should also pass the GUID from the original shared memory
   // region. We don't do that - this means that we will overcount this memory,
   // which thankfully isn't relevant since Chrome only communicates with a
   // single version of the service process.
-  shm_ = SharedMemoryHandle(base::FileDescriptor(mapped_file, false),
+  // We pass the size |0|, which is a dummy size and wrong, but otherwise
+  // harmless.
+  shm_ = SharedMemoryHandle(base::FileDescriptor(mapped_file, false), 0u,
                             UnguessableToken::Create());
   readonly_shm_ = SharedMemoryHandle(
-      base::FileDescriptor(readonly_mapped_file, false), shm_.GetGUID());
+      base::FileDescriptor(readonly_mapped_file, false), 0, shm_.GetGUID());
   return result;
 }
 #endif  // !defined(OS_ANDROID)
 
 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
   if (!shm_.IsValid())
     return false;
 
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
@@ skipping 108 matching lines @@
   struct stat file_stat;
   if (HANDLE_EINTR(
           ::fstat(static_cast<int>(handle().GetHandle()), &file_stat)) != 0)
     return false;
   id->first = file_stat.st_dev;
   id->second = file_stat.st_ino;
   return true;
 }
 
 }  // namespace base