Bug 570099: Allow Shmems to be used in IPDL structs. r=benjamn

ipc/glue/Shmem.h

@@ -145,6 +145,17 @@ public:
     return *this;
   }
 
+  bool operator==(const Shmem& aRhs) const
+  {
+    // need to compare IDs because of AdoptShmem(); two Shmems might
+    // refer to the same segment but with different IDs for different
+    // protocol trees.  (NB: it's possible for this method to
+    // spuriously return true if AdoptShmem() gives the same ID for
+    // two protocol trees, but I don't think that can cause any
+    // problems since the Shmems really would be indistinguishable.)
+    return mSegment == aRhs.mSegment && mId == aRhs.mId;
+  }
+
   // Returns whether this Shmem is writable by you, and thus whether you can
   // transfer writability to another actor.
   bool

ipc/ipdl/ipdl/lower.py

@@ -605,6 +605,13 @@ class _StructField(_CompoundTypeComponent):
             ref = ExprDeref(ref)
         return ref
 
+    def constRefExpr(self, thisexpr=None):
+        # sigh, gross hack
+        refexpr = self.refExpr(thisexpr)
+        if 'Shmem' == self.ipdltype.name():
+            refexpr = ExprCast(refexpr, Type('Shmem', ref=1), const=1)
+        return refexpr
+
     def argVar(self):
         return ExprVar('_'+ self.name)
 
@@ -1488,6 +1495,12 @@ stmt.  Some types generate both kinds.'''
     def visitArrayType(self, t):
         return TypeVisitor.visitArrayType(self, t)
 
+    def visitShmemType(self, s):
+        if s in self.visited: return
+        self.visited.add(s)
+        self.usingTypedefs.append(Typedef(Type('mozilla::ipc::Shmem'),
+                                          'Shmem'))
+
     def visitVoidType(self, v): assert 0
     def visitMessageType(self, v): assert 0
     def visitProtocolType(self, v): assert 0
@@ -1587,9 +1600,11 @@ def _generateCxxStruct(sd):
                                     force_inline=1))
         get.addstmt(StmtReturn(f.refExpr()))
 
-        getconst = deepcopy(get)
-        getconst.decl.ret = f.constRefType()
-        getconst.decl.const = 1
+        getconstdecl = deepcopy(get.decl)
+        getconstdecl.ret = f.constRefType()
+        getconstdecl.const = 1
+        getconst = MethodDefn(getconstdecl)
+        getconst.addstmt(StmtReturn(f.constRefExpr()))
 
         struct.addstmts([ get, getconst, Whitespace.NL ])
 

ipc/ipdl/test/cxx/PTestDataStructures.ipdl

@@ -87,6 +87,11 @@ struct SetAttrs {
 };
 union Op { null_t; SetAttrs; };
 
+struct ShmemStruct {
+    int i;
+    Shmem mem;
+};
+
 } // namespace _foo
 } // namespace mozilla