Linux: server side backing stores

chrome/common/transport_dib_linux.cc

 // Copyright (c) 2009 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 <errno.h>
 #include <stdlib.h>
 #include <sys/ipc.h>
 #include <sys/shm.h>
 
+#include "base/gfx/size.h"
 #include "base/logging.h"
 #include "chrome/common/transport_dib.h"
+#include "chrome/common/x11_util.h"
 
 // The shmat system call uses this as it's invalid return address
 static void *const kInvalidAddress = (void*) -1;
 
 TransportDIB::TransportDIB()
     : key_(-1),
       address_(kInvalidAddress),
+      x_shm_(0),
+      display_(NULL),
       size_(0) {
 }
 
 TransportDIB::~TransportDIB() {
   if (address_ != kInvalidAddress) {
     shmdt(address_);
     address_ = kInvalidAddress;
   }
+
+  if (x_shm_) {
+    DCHECK(display_);
+    x11_util::DetachSharedMemory(display_, x_shm_);
+  }
 }
 
 // static
 TransportDIB* TransportDIB::Create(size_t size, uint32 sequence_num) {
   // We use a mode of 0666 since the X server won't attach to memory which is
   // 0600 since it can't know if it (as a root process) is being asked to map
   // someone else's private shared memory region.
   const int shmkey = shmget(IPC_PRIVATE, size, 0666);
   if (shmkey == -1) {
     DLOG(ERROR) << "Failed to create SysV shared memory region"
@@ skipping 15 matching lines @@
   dib->address_ = address;
   dib->size_ = size;
   return dib;
 }
 
 TransportDIB* TransportDIB::Map(Handle shmkey) {
   struct shmid_ds shmst;
   if (shmctl(shmkey, IPC_STAT, &shmst) == -1)
     return NULL;
 
-  void* address = shmat(shmkey, NULL /* desired address */, 0 /* flags */);
+  void* address = shmat(shmkey, NULL /* desired address */, SHM_RDONLY);
   if (address == kInvalidAddress)
     return NULL;
 
   TransportDIB* dib = new TransportDIB;
 
   dib->address_ = address;
   dib->size_ = shmst.shm_segsz;
   dib->key_ = shmkey;
   return dib;
 }
 
 void* TransportDIB::memory() const {
   DCHECK_NE(address_, kInvalidAddress);
   return address_;
 }
 
 TransportDIB::Id TransportDIB::id() const {
   return key_;
 }
 
 TransportDIB::Handle TransportDIB::handle() const {
   return key_;
 }
+
+XID TransportDIB::MapToX(Display* display) {
+  if (!x_shm_) {
+    x_shm_ = x11_util::AttachSharedMemory(display, key_);
+    display_ = display;
+  }
+
+  return x_shm_;
+}