Fix up SharedMemory implementation so that it is more equivalent on Windows vs Posix and enforces exclusive creates.

Clean up some naming to make it clearer what size you are getting by changing max_size to created_size.

BUG=NONE
TEST=BUILD

Review URL: http://codereview.chromium.org/4034006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64097 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 27 insertions, 12 deletions

diff --git a/base/shared_memory_win.cc b/base/shared_memory_win.cc
index f35ada1..a0b2a5a 100644
--- a/base/shared_memory_win.cc
+++ b/base/shared_memory_win.cc
@@ -13,7 +13,7 @@ SharedMemory::SharedMemory()
     : mapped_file_(NULL),
       memory_(NULL),
       read_only_(false),
-      max_size_(0),
+      created_size_(0),
       lock_(NULL) {
 }
 
@@ -21,7 +21,7 @@ SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
     : mapped_file_(handle),
       memory_(NULL),
       read_only_(read_only),
-      max_size_(0),
+      created_size_(0),
       lock_(NULL) {
 }
 
@@ -30,7 +30,7 @@ SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
     : mapped_file_(NULL),
       memory_(NULL),
       read_only_(read_only),
-      max_size_(0),
+      created_size_(0),
       lock_(NULL) {
   ::DuplicateHandle(process, handle,
                     GetCurrentProcess(), &mapped_file_,
@@ -61,9 +61,19 @@ void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   ::CloseHandle(handle);
 }
 
-bool SharedMemory::Create(const std::string& name, bool read_only,
-                          bool open_existing, uint32 size) {
+bool SharedMemory::CreateAndMapAnonymous(uint32 size) {
+  return CreateAnonymous(size) && Map(size);
+}
+
+bool SharedMemory::CreateAnonymous(uint32 size) {
+  return CreateNamed("", false, size);
+}
+
+bool SharedMemory::CreateNamed(const std::string& name,
+                               bool open_existing, uint32 size) {
   DCHECK(mapped_file_ == NULL);
+  if (size == 0)
+    return false;
 
   // NaCl's memory allocator requires 0mod64K alignment and size for
   // shared memory objects.  To allow passing shared memory to NaCl,
@@ -72,20 +82,25 @@ bool SharedMemory::Create(const std::string& name, bool read_only,
   // actual requested size.
   uint32 rounded_size = (size + 0xffff) & ~0xffff;
   name_ = ASCIIToWide(name);
-  read_only_ = read_only;
   mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
-      read_only_ ? PAGE_READONLY : PAGE_READWRITE, 0,
-      static_cast<DWORD>(rounded_size),
+      PAGE_READWRITE, 0, static_cast<DWORD>(rounded_size),
       name_.empty() ? NULL : name_.c_str());
   if (!mapped_file_)
     return false;
 
+  created_size_ = size;
+
   // Check if the shared memory pre-exists.
-  if (GetLastError() == ERROR_ALREADY_EXISTS && !open_existing) {
-    Close();
-    return false;
+  if (GetLastError() == ERROR_ALREADY_EXISTS) {
+    // If the file already existed, set created_size_ to 0 to show that
+    // we don't know the size.
+    created_size_ = 0;
+    if (!open_existing) {
+      Close();
+      return false;
+    }
   }
-  max_size_ = size;
+
   return true;
 }