variables: Catch out of memory errors cloning the stack

When we do global variable operations, we may need to clone objects
that are on the stack. This may fail. We need to correctly propagate
the error when that happens.

Signed-off-by: Christophe de Dinechin <christophe@dinechin.org>

Author: c3d

src/runtime.cc

@@ -979,7 +979,7 @@ object_p runtime::clone(object_p source)
 }
 
 
-object_p runtime::clone_global(object_p global, size_t sz)
+bool runtime::clone_global(object_p global, size_t sz)
 // ----------------------------------------------------------------------------
 //   Check if any entry in the stack points to a given global, if so clone it
 // ----------------------------------------------------------------------------
@@ -997,11 +997,15 @@ object_p runtime::clone_global(object_p global, size_t sz)
         if (*s >= global && *s < global + sz)
         {
             if (!cloned)
+            {
                 cloned = clone(global);
+                if (!cloned)
+                    return false;
+            }
             *s = cloned + (*s - global);
         }
     }
-    return cloned;
+    return true;
 }
 
 

src/runtime.h

@@ -209,7 +209,7 @@ struct runtime
     //   Clone an object into the temporaries area
     // ------------------------------------------------------------------------
 
-    object_p clone_global(object_p source, size_t sz);
+    bool clone_global(object_p source, size_t sz);
     // ------------------------------------------------------------------------
     //   Clone values in the stack that point to a global we will change
     // ------------------------------------------------------------------------

src/variables.cc

@@ -289,11 +289,16 @@ object_p directory::store(object_g name, object_g value)
         delta = vs - es;
 
         // Clone any value in the stack that points to the existing value
-        rt.clone_global(evalue, es);
+        if (!rt.clone_global(evalue, es))
+            return nullptr;     // Out of memory, bail out
 
         // Clone input value if it is within object being replaced
         if (+value >= +evalue && +value < +evalue + es)
+        {
             value = rt.clone(value);
+            if (!value)
+                return nullptr;
+        }
 
         // Move memory above storage if necessary
         if (vs != es)
@@ -643,7 +648,8 @@ size_t directory::purge(object_p name)
         object_p body   = header;
         size_t   old    = leb128<size_t>(body); // Old size of directory
 
-        rt.clone_global(value, vs);
+        if (!rt.clone_global(value, vs))
+            return 0;           // Out of memory, bail out
         rt.move_globals(name, name + purged);
 
         if (old < purged)