The Posix shared memory implementation.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@742 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 192 insertions, 2 deletions

diff --git a/base/build/base.vcproj b/base/build/base.vcproj
index 038eadf..428eb1e 100644
--- a/base/build/base.vcproj
+++ b/base/build/base.vcproj
@@ -582,7 +582,7 @@
 			>
 		</File>
 		<File
-			RelativePath="..\shared_memory.cc"
+			RelativePath="..\shared_memory_win.cc"
 			>
 		</File>
 		<File
diff --git a/base/shared_memory.h b/base/shared_memory.h
index 3fb7298..74888e8 100644
--- a/base/shared_memory.h
+++ b/base/shared_memory.h
@@ -39,8 +39,9 @@
 typedef HANDLE SharedMemoryHandle;
 typedef HANDLE SharedMemoryLock;
 #elif defined(OS_POSIX)
+#include <semaphore.h>
 typedef int SharedMemoryHandle;
-typedef int SharedMemoryLock;
+typedef sem_t* SharedMemoryLock;
 #endif
 
 // Platform abstraction for shared memory.  Provides a C++ wrapper
diff --git a/base/shared_memory_posix.cc b/base/shared_memory_posix.cc
new file mode 100644
index 0000000..9a4953c
--- /dev/null
+++ b/base/shared_memory_posix.cc
@@ -0,0 +1,189 @@
+// Copyright 2008, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "base/shared_memory.h"
+
+#include <sys/mman.h>
+
+#include "base/logging.h"
+#include "base/string_util.h"
+
+namespace {
+  // Paranoia. Semaphores and shared memory segments should live in different
+  // namespaces, but who knows what's out there.
+  const char kSemaphoreSuffix[] = "-sem";
+}
+
+SharedMemory::SharedMemory()
+    : mapped_file_(-1),
+      memory_(NULL),
+      read_only_(false),
+      max_size_(0),
+      lock_(NULL) {
+}
+
+SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
+    : mapped_file_(handle),
+      memory_(NULL),
+      read_only_(read_only),
+      max_size_(0),
+      lock_(NULL) {
+}
+
+SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
+                           ProcessHandle process)
+    : mapped_file_(handle),
+      memory_(NULL),
+      read_only_(read_only),
+      max_size_(0),
+      lock_(NULL) {
+  // We don't handle this case yet (note the ignored parameter); let's die if
+  // someone comes calling.
+  NOTREACHED();
+}
+
+SharedMemory::~SharedMemory() {
+  Close();
+  if (lock_ != NULL)
+    sem_close(lock_);
+}
+
+bool SharedMemory::Create(const std::wstring &name, bool read_only,
+                          bool open_existing, size_t size) {
+  DCHECK(mapped_file_ == -1);
+
+  name_ = L"/" + name;
+  read_only_ = read_only;
+
+  int posix_flags = 0;
+  posix_flags |= read_only ? O_RDONLY : O_RDWR;
+  posix_flags |= O_CREAT;
+  
+  int posix_mode = 0600;  // owner read/write
+  std::string posix_name(WideToUTF8(name_));
+  mapped_file_ = shm_open(posix_name.c_str(), posix_flags, posix_mode);
+  
+  if (mapped_file_ < 0)
+    return false;
+  ftruncate(mapped_file_, size);
+  
+  posix_name += kSemaphoreSuffix;
+  lock_ = sem_open(posix_name.c_str(), O_CREAT, posix_mode, 1);
+  if (lock_ == SEM_FAILED) {
+    close(mapped_file_);
+    mapped_file_ = -1;
+    shm_unlink(posix_name.c_str());
+    lock_ = NULL;
+    return false;
+  }
+
+  max_size_ = size;
+  return true;
+}
+
+bool SharedMemory::Open(const std::wstring &name, bool read_only) {
+  DCHECK(mapped_file_ == -1);
+
+  name_ = name;
+  read_only_ = read_only;
+  
+  int posix_flags = 0;
+  posix_flags |= read_only ? O_RDONLY : O_RDWR;
+  
+  int posix_mode = 0600;  // owner read/write
+  std::string posix_name(WideToUTF8(name_));
+  mapped_file_ = shm_open(posix_name.c_str(), posix_flags, posix_mode);
+  
+  return (mapped_file_ >= 0);
+}
+
+bool SharedMemory::Map(size_t bytes) {
+  if (mapped_file_ == -1)
+    return false;
+  
+  memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
+                 MAP_SHARED, mapped_file_, 0);
+
+  if (memory_)
+    max_size_ = bytes;
+
+  return (memory_ != NULL);
+}
+
+bool SharedMemory::Unmap() {
+  if (memory_ == NULL)
+    return false;
+
+  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;
+}
+
+
+void SharedMemory::Close() {
+  if (memory_ != NULL) {
+    munmap(memory_, max_size_);
+
+    memory_ = NULL;
+    max_size_ = 0;
+  }
+
+  std::string posix_name(WideToUTF8(name_));
+  if (mapped_file_) {
+    close(mapped_file_);
+    shm_unlink(posix_name.c_str());
+    mapped_file_ = -1;
+  }
+  
+  if (lock_) {
+    posix_name += kSemaphoreSuffix;
+    sem_unlink(posix_name.c_str());
+    lock_ = NULL;
+  }
+}
+
+void SharedMemory::Lock() {
+  DCHECK(lock_ != NULL);
+  sem_wait(lock_);
+}
+
+void SharedMemory::Unlock() {
+  DCHECK(lock_ != NULL);
+  sem_post(lock_);
+}
diff --git a/base/shared_memory.cc b/base/shared_memory_win.cc
index bd5023f..bd5023f 100644
--- a/base/shared_memory.cc
+++ b/base/shared_memory_win.cc