POSIX: Transfer network data using shared memory

base/shared_memory_posix.cc

 // Copyright (c) 2006-2008 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/shared_memory.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 
@@ skipping 11 matching lines @@
 }
 
 SharedMemory::SharedMemory()
     : mapped_file_(-1),
       memory_(NULL),
       read_only_(false),
       max_size_(0) {
 }
 
 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
-    : mapped_file_(handle),
+    : mapped_file_(handle.fd),
       memory_(NULL),
       read_only_(read_only),
       max_size_(0) {
 }
 
 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
                            ProcessHandle process)
-    : mapped_file_(handle),
+    : mapped_file_(handle.fd),
       memory_(NULL),
       read_only_(read_only),
       max_size_(0) {
   // We don't handle this case yet (note the ignored parameter); let's die if
   // someone comes calling.
   NOTREACHED();
 }
 
 SharedMemory::~SharedMemory() {
   Close();
 }
 
+// static
+bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
+  return handle.fd >= 0;
+}
+
 bool SharedMemory::Create(const std::wstring &name, bool read_only,
                           bool open_existing, size_t size) {
   read_only_ = read_only;
 
   int posix_flags = 0;
   posix_flags |= read_only ? O_RDONLY : O_RDWR;
   if (!open_existing || mapped_file_ <= 0)
     posix_flags |= O_CREAT;
 
   if (!CreateOrOpen(name, posix_flags, size))
@@ skipping 162 matching lines @@
 
   munmap(memory_, max_size_);
   memory_ = NULL;
   max_size_ = 0;
   return true;
 }
 
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle *new_handle,
                                         bool close_self) {
-  *new_handle = 0;
-  // TODO(awalker): figure out if we need this, and do the appropriate
-  // VM magic if so.
-  return false;
+  const int new_fd = dup(mapped_file_);
+  DCHECK(new_fd >= -1);
+  new_handle->fd = new_fd;
+  new_handle->auto_close = true;
+
+  if (close_self)
+    Close();
+
+  return true;
 }
 
 
 void SharedMemory::Close() {
 
   Unmap();
 
   std::string posix_name(WideToUTF8(name_));
   if (mapped_file_ > 0) {
     close(mapped_file_);
@@ skipping 21 matching lines @@
 }
 
 void SharedMemory::Lock() {
   LockOrUnlockCommon(F_LOCK);
 }
 
 void SharedMemory::Unlock() {
   LockOrUnlockCommon(F_ULOCK);
 }
 
+SharedMemoryHandle SharedMemory::handle() const {
+  return FileDescriptor(mapped_file_, false);
+}
+
 }  // namespace base