Add m-esr52 at 52.6.0

1 files changed, 209 insertions, 0 deletions

diff --git a/ipc/chromium/src/base/shared_memory.h b/ipc/chromium/src/base/shared_memory.h
new file mode 100644
index 000000000..15a0a95fe
--- /dev/null
+++ b/ipc/chromium/src/base/shared_memory.h
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// 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.
+
+#ifndef BASE_SHARED_MEMORY_H_
+#define BASE_SHARED_MEMORY_H_
+
+#include "build/build_config.h"
+
+#if defined(OS_POSIX)
+#include <sys/types.h>
+#include <semaphore.h>
+#include "base/file_descriptor_posix.h"
+#endif
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/process.h"
+
+namespace base {
+
+// SharedMemoryHandle is a platform specific type which represents
+// the underlying OS handle to a shared memory segment.
+#if defined(OS_WIN)
+typedef HANDLE SharedMemoryHandle;
+typedef HANDLE SharedMemoryLock;
+#elif defined(OS_POSIX)
+// A SharedMemoryId is sufficient to identify a given shared memory segment on a
+// system, but insufficient to map it.
+typedef FileDescriptor SharedMemoryHandle;
+typedef ino_t SharedMemoryId;
+// On POSIX, the lock is implemented as a lockf() on the mapped file,
+// so no additional member (or definition of SharedMemoryLock) is
+// needed.
+#endif
+
+// Platform abstraction for shared memory.  Provides a C++ wrapper
+// around the OS primitive for a memory mapped file.
+class SharedMemory {
+ public:
+  // Create a new SharedMemory object.
+  SharedMemory();
+
+  // Create a new SharedMemory object from an existing, open
+  // shared memory file.
+  SharedMemory(SharedMemoryHandle init_handle, bool read_only)
+    : SharedMemory() {
+    SetHandle(init_handle, read_only);
+  }
+
+  // Destructor.  Will close any open files.
+  ~SharedMemory();
+
+  // Initialize a new SharedMemory object from an existing, open
+  // shared memory file.
+  bool SetHandle(SharedMemoryHandle handle, bool read_only);
+
+  // Return true iff the given handle is valid (i.e. not the distingished
+  // invalid value; NULL for a HANDLE and -1 for a file descriptor)
+  static bool IsHandleValid(const SharedMemoryHandle& handle);
+
+  // Return invalid handle (see comment above for exact definition).
+  static SharedMemoryHandle NULLHandle();
+
+  // Creates or opens a shared memory segment based on a name.
+  // If read_only is true, opens the memory as read-only.
+  // If open_existing is true, and the shared memory already exists,
+  // opens the existing shared memory and ignores the size parameter.
+  // If name is the empty string, use a unique name.
+  // Returns true on success, false on failure.
+  bool Create(const std::string& name, bool read_only, bool open_existing,
+              size_t size);
+
+  // Deletes resources associated with a shared memory segment based on name.
+  // Not all platforms require this call.
+  bool Delete(const std::wstring& name);
+
+  // Opens a shared memory segment based on a name.
+  // If read_only is true, opens for read-only access.
+  // If name is the empty string, use a unique name.
+  // Returns true on success, false on failure.
+  bool Open(const std::wstring& name, bool read_only);
+
+  // Maps the shared memory into the caller's address space.
+  // Returns true on success, false otherwise.  The memory address
+  // is accessed via the memory() accessor.
+  bool Map(size_t bytes);
+
+  // Unmaps the shared memory from the caller's address space.
+  // Returns true if successful; returns false on error or if the
+  // memory is not mapped.
+  bool Unmap();
+
+  // Get the size of the opened shared memory backing file.
+  // Note:  This size is only available to the creator of the
+  // shared memory, and not to those that opened shared memory
+  // created externally.
+  // Returns 0 if not opened or unknown.
+  size_t max_size() const { return max_size_; }
+
+  // Gets a pointer to the opened memory space if it has been
+  // Mapped via Map().  Returns NULL if it is not mapped.
+  void *memory() const { return memory_; }
+
+  // Get access to the underlying OS handle for this segment.
+  // Use of this handle for anything other than an opaque
+  // identifier is not portable.
+  SharedMemoryHandle handle() const;
+
+#if defined(OS_POSIX)
+  // Return a unique identifier for this shared memory segment. Inode numbers
+  // are technically only unique to a single filesystem. However, we always
+  // allocate shared memory backing files from the same directory, so will end
+  // up on the same filesystem.
+  SharedMemoryId id() const { return inode_; }
+#endif
+
+  // Closes the open shared memory segment.
+  // It is safe to call Close repeatedly.
+  void Close(bool unmap_view = true);
+
+  // Share the shared memory to another process.  Attempts
+  // to create a platform-specific new_handle which can be
+  // used in a remote process to access the shared memory
+  // file.  new_handle is an ouput parameter to receive
+  // the handle for use in the remote process.
+  // Returns true on success, false otherwise.
+  bool ShareToProcess(base::ProcessId target_pid,
+                      SharedMemoryHandle* new_handle) {
+    return ShareToProcessCommon(target_pid, new_handle, false);
+  }
+
+  // Logically equivalent to:
+  //   bool ok = ShareToProcess(process, new_handle);
+  //   Close();
+  //   return ok;
+  // Note that the memory is unmapped by calling this method, regardless of the
+  // return value.
+  bool GiveToProcess(ProcessId target_pid,
+                     SharedMemoryHandle* new_handle) {
+    return ShareToProcessCommon(target_pid, new_handle, true);
+  }
+
+  // Lock the shared memory.
+  // This is a cross-process lock which may be recursively
+  // locked by the same thread.
+  // TODO(port):
+  // WARNING: on POSIX the lock only works across processes, not
+  // across threads.  2 threads in the same process can both grab the
+  // lock at the same time.  There are several solutions for this
+  // (futex, lockf+anon_semaphore) but none are both clean and common
+  // across Mac and Linux.
+  void Lock();
+
+  // Release the shared memory lock.
+  void Unlock();
+
+ private:
+#if defined(OS_POSIX)
+  bool CreateOrOpen(const std::wstring &name, int posix_flags, size_t size);
+  bool FilenameForMemoryName(const std::wstring &memname,
+                             std::wstring *filename);
+  void LockOrUnlockCommon(int function);
+
+#endif
+  bool ShareToProcessCommon(ProcessId target_pid,
+                            SharedMemoryHandle* new_handle,
+                            bool close_self);
+
+#if defined(OS_WIN)
+  std::wstring       name_;
+  HANDLE             mapped_file_;
+#elif defined(OS_POSIX)
+  int                mapped_file_;
+  ino_t              inode_;
+#endif
+  void*              memory_;
+  bool               read_only_;
+  size_t             max_size_;
+#if !defined(OS_POSIX)
+  SharedMemoryLock   lock_;
+#endif
+
+  DISALLOW_EVIL_CONSTRUCTORS(SharedMemory);
+};
+
+// A helper class that acquires the shared memory lock while
+// the SharedMemoryAutoLock is in scope.
+class SharedMemoryAutoLock {
+ public:
+  explicit SharedMemoryAutoLock(SharedMemory* shared_memory)
+      : shared_memory_(shared_memory) {
+    shared_memory_->Lock();
+  }
+
+  ~SharedMemoryAutoLock() {
+    shared_memory_->Unlock();
+  }
+
+ private:
+  SharedMemory* shared_memory_;
+  DISALLOW_EVIL_CONSTRUCTORS(SharedMemoryAutoLock);
+};
+
+}  // namespace base
+
+#endif  // BASE_SHARED_MEMORY_H_