make base::SharedMemoryHandle a class on POSIX.

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 15 matching lines @@
 #include "build/build_config.h"
 
 #if defined(OS_ANDROID)
 #include "base/os_compat_android.h"
 #include "third_party/ashmem/ashmem.h"
 #endif
 
 namespace base {
 
 SharedMemory::SharedMemory()
-    : mapped_file_(-1),
-      readonly_mapped_file_(-1),
+    : readonly_mapped_file_(-1),
       mapped_size_(0),
       memory_(NULL),
       read_only_(false),
-      requested_size_(0) {
-}
+      requested_size_(0) {}
 
 SharedMemory::SharedMemory(const SharedMemoryHandle& handle, bool read_only)
-    : mapped_file_(handle.fd),
+    : shm_(handle),
       readonly_mapped_file_(-1),
       mapped_size_(0),
       memory_(NULL),
       read_only_(read_only),
-      requested_size_(0) {
-}
+      requested_size_(0) {}
 
 SharedMemory::~SharedMemory() {
   Unmap();
   Close();
 }
 
 // static
 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
-  return handle.fd >= 0;
+  return handle.IsValid();
 }
 
 // static
 SharedMemoryHandle SharedMemory::NULLHandle() {
   return SharedMemoryHandle();
 }
 
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
-  DCHECK_GE(handle.fd, 0);
-  if (IGNORE_EINTR(close(handle.fd)) < 0)
-    DPLOG(ERROR) << "close";
+  DCHECK(handle.IsValid());
+  handle.Close();
 }
 
 // static
 size_t SharedMemory::GetHandleLimit() {
   return base::GetMaxFds();
 }
 
 // static
 SharedMemoryHandle SharedMemory::DuplicateHandle(
     const SharedMemoryHandle& handle) {
-  int duped_handle = HANDLE_EINTR(dup(handle.fd));
-  if (duped_handle < 0)
-    return base::SharedMemory::NULLHandle();
-  return base::FileDescriptor(duped_handle, true);
+  return handle.Duplicate();
 }
 
 // static
 int SharedMemory::GetFdFromSharedMemoryHandle(
     const SharedMemoryHandle& handle) {
-  return handle.fd;
+  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.fd, &st) != 0)
+  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_EQ(-1, mapped_file_);
+  DCHECK(!shm_.IsValid());
   if (options.size == 0) return false;
 
   if (options.size > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
   // This function theoretically can block on the disk, but realistically
   // the temporary files we create will just go into the buffer cache
   // and be deleted before they ever make it out to disk.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
@@ skipping 81 matching lines @@
     if (access(dir.value().c_str(), W_OK | X_OK) < 0) {
       PLOG(ERROR) << "Unable to access(W_OK|X_OK) " << dir.value();
       if (dir.value() == "/dev/shm") {
         LOG(FATAL) << "This is frequently caused by incorrect permissions on "
                    << "/dev/shm.  Try 'sudo chmod 1777 /dev/shm' to fix.";
       }
     }
     return false;
   }
 
-  return PrepareMapFile(std::move(fp), std::move(readonly_fd), &mapped_file_,
-                        &readonly_mapped_file_);
+  int mapped_file = -1;
+  bool result = PrepareMapFile(std::move(fp), std::move(readonly_fd),
+                               &mapped_file, &readonly_mapped_file_);
+  shm_ = SharedMemoryHandle::ImportHandle(mapped_file);
+  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 11 matching lines @@
 
   read_only_ = read_only;
 
   const char *mode = read_only ? "r" : "r+";
   ScopedFILE fp(base::OpenFile(path, mode));
   ScopedFD readonly_fd(HANDLE_EINTR(open(path.value().c_str(), O_RDONLY)));
   if (!readonly_fd.is_valid()) {
     DPLOG(ERROR) << "open(\"" << path.value() << "\", O_RDONLY) failed";
     return false;
   }
-  return PrepareMapFile(std::move(fp), std::move(readonly_fd), &mapped_file_,
-                        &readonly_mapped_file_);
+  int mapped_file = -1;
+  bool result = PrepareMapFile(std::move(fp), std::move(readonly_fd),
+                               &mapped_file, &readonly_mapped_file_);
+  shm_ = SharedMemoryHandle::ImportHandle(mapped_file);
+  return result;
 }
 #endif  // !defined(OS_ANDROID)
 
 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
-  if (mapped_file_ == -1)
+  if (!shm_.IsValid())
     return false;
 
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
   if (memory_)
     return false;
 
 #if defined(OS_ANDROID)
   // On Android, Map can be called with a size and offset of zero to use the
   // ashmem-determined size.
   if (bytes == 0) {
     DCHECK_EQ(0, offset);
-    int ashmem_bytes = ashmem_get_size_region(mapped_file_);
+    int ashmem_bytes = ashmem_get_size_region(shm_.GetHandle());
     if (ashmem_bytes < 0)
       return false;
     bytes = ashmem_bytes;
   }
 #endif
 
   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
-                 MAP_SHARED, mapped_file_, offset);
+                 MAP_SHARED, shm_.GetHandle(), offset);
 
   bool mmap_succeeded = memory_ != (void*)-1 && memory_ != NULL;
   if (mmap_succeeded) {
     mapped_size_ = bytes;
     DCHECK_EQ(0U,
               reinterpret_cast<uintptr_t>(memory_) &
                   (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
     SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
   } else {
     memory_ = NULL;
   }
 
   return mmap_succeeded;
 }
 
 bool SharedMemory::Unmap() {
   if (memory_ == NULL)
     return false;
 
   munmap(memory_, mapped_size_);
   SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);
   memory_ = NULL;
   mapped_size_ = 0;
   return true;
 }
 
 SharedMemoryHandle SharedMemory::handle() const {
-  return FileDescriptor(mapped_file_, false);
+  return shm_;
 }
 
 SharedMemoryHandle SharedMemory::TakeHandle() {
-  FileDescriptor handle(mapped_file_, true);
-  mapped_file_ = -1;
+  SharedMemoryHandle handle_copy = shm_;
+  handle_copy.SetOwnershipPassesToIPC(true);
+  shm_ = SharedMemoryHandle();
   memory_ = nullptr;
   mapped_size_ = 0;
-  return handle;
+  return handle_copy;
 }
 
 void SharedMemory::Close() {
-  if (mapped_file_ > 0) {
-    if (IGNORE_EINTR(close(mapped_file_)) < 0)
-      PLOG(ERROR) << "close";
-    mapped_file_ = -1;
+  if (shm_.IsValid()) {
+    shm_.Close();
+    shm_ = SharedMemoryHandle();
   }
   if (readonly_mapped_file_ > 0) {
     if (IGNORE_EINTR(close(readonly_mapped_file_)) < 0)
       PLOG(ERROR) << "close";
     readonly_mapped_file_ = -1;
   }
 }
 
 #if !defined(OS_ANDROID)
 // For the given shmem named |mem_name|, return a filename to mmap()
@@ skipping 20 matching lines @@
 }
 #endif  // !defined(OS_ANDROID)
 
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle* new_handle,
                                         bool close_self,
                                         ShareMode share_mode) {
   int handle_to_dup = -1;
   switch(share_mode) {
     case SHARE_CURRENT_MODE:
-      handle_to_dup = mapped_file_;
+      handle_to_dup = shm_.GetHandle();
       break;
     case SHARE_READONLY:
       // We could imagine re-opening the file from /dev/fd, but that can't make
       // it readonly on Mac: https://codereview.chromium.org/27265002/#msg10
       CHECK_GE(readonly_mapped_file_, 0);
       handle_to_dup = readonly_mapped_file_;
       break;
   }
 
   const int new_fd = HANDLE_EINTR(dup(handle_to_dup));
   if (new_fd < 0) {
     if (close_self) {
       Unmap();
       Close();
     }
     DPLOG(ERROR) << "dup() failed.";
     return false;
   }
 
-  new_handle->fd = new_fd;
-  new_handle->auto_close = true;
+  new_handle->SetHandle(new_fd);
+  new_handle->SetOwnershipPassesToIPC(true);
 
   if (close_self) {
     Unmap();
     Close();
   }
 
   return true;
 }
 
 bool SharedMemory::GetUniqueId(SharedMemory::UniqueId* id) const {
   // This function is called just after mmap. fstat is a system call that might
   // cause I/O. It's safe to call fstat here because mmap for shared memory is
   // called in two cases:
   // 1) To handle file-mapped memory
   // 2) To handle annonymous shared memory
   // In 1), I/O is already permitted. In 2), the backend is on page cache and
   // fstat doesn't cause I/O access to the disk. See the discussion at
   // crbug.com/604726#c41.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
   struct stat file_stat;
-  if (HANDLE_EINTR(::fstat(static_cast<int>(handle().fd), &file_stat)) != 0)
+  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