[mojo] Allow value deserialization to fail

This changes mojo::Deserialize_ et al to return a bool, opening
the door for deserialization code which performs custom validation
(in addition to baked-in mojom wire format validation) and may
reject incoming messages at the bindings layer.

Part of a series of changes to support custom mojom serialization:

  1. https://codereview.chromium.org/1515423002
  2. https://codereview.chromium.org/1517043004
  3. https://codereview.chromium.org/1524693002
  4. This CL
  5. https://codereview.chromium.org/1524613002
  6. https://codereview.chromium.org/1526533002
  7. https://codereview.chromium.org/1524703002

BUG=569669

Review URL: https://codereview.chromium.org/1520153002

Cr-Commit-Position: refs/heads/master@{#365728}

6 files changed, 22 insertions, 11 deletions

diff --git a/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
index 9889f8b..a445313 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
@@ -7,10 +7,13 @@
 {%- set namespace_as_string = "%s"|format(namespace|replace(".","::")) %}
 
 {%- macro alloc_params(struct, serialization_context) %}
+  bool success = true;
 {%-   for param in struct.packed.packed_fields_in_ordinal_order %}
   {{param.field.kind|cpp_result_type}} p_{{param.field.name}}{};
 {%-   endfor %}
-  {{struct_macros.deserialize(struct, "params", "p_%s", serialization_context)}}
+  {{struct_macros.deserialize(struct, "params", "p_%s", serialization_context, "success")}}
+  if (!success)
+    return false;
 {%- endmacro %}
 
 {%- macro pass_params(parameters) %}
@@ -224,11 +227,11 @@ bool {{class_name}}Stub::AcceptWithResponder(
               message->mutable_payload());
 
       params->DecodePointersAndHandles(message->mutable_handles());
+      {{alloc_params(method.param_struct, "&serialization_context_")|indent(4)}}
       {{class_name}}::{{method.name}}Callback::Runnable* runnable =
           new {{class_name}}_{{method.name}}_ProxyToResponder(
               message->request_id(), responder);
       {{class_name}}::{{method.name}}Callback callback(runnable);
-      {{alloc_params(method.param_struct, "&serialization_context_")|indent(4)}}
       // A null |sink_| means no implementation was bound.
       assert(sink_);
       TRACE_EVENT0("mojom", "{{class_name}}::{{method.name}}");
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
index f28948a..0898949 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
@@ -113,7 +113,8 @@
     - method parameters/response parameters: the output is a list of
       arguments. #}
     |context| is the name of the serialization context.
-{%- macro deserialize(struct, input, output_field_pattern, context) -%}
+    |success| is the name of a bool variable to track success of the operation.
+{%- macro deserialize(struct, input, output_field_pattern, context, success) -%}
   do {
     // NOTE: The memory backing |{{input}}| may has be smaller than
     // |sizeof(*{{input}})| if the message comes from an older version.
@@ -133,9 +134,11 @@
 {%-     endif %}
 {%-     if kind|is_object_kind %}
 {%-       if kind|is_union_kind %}
-    Deserialize_(&{{input}}->{{name}}, &{{output_field}}, {{context}});
+    if (!Deserialize_(&{{input}}->{{name}}, &{{output_field}}, {{context}}))
+      {{success}} = false;
 {%-       else %}
-    Deserialize_({{input}}->{{name}}.ptr, &{{output_field}}, {{context}});
+    if (!Deserialize_({{input}}->{{name}}.ptr, &{{output_field}}, {{context}}))
+      {{success}} = false;
 {%-       endif %}
 {%-     elif kind|is_interface_kind %}
     mojo::internal::InterfaceDataToPointer(&{{input}}->{{name}}, &{{output_field}});
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl
index 1f02481..5ded622 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl
@@ -1,6 +1,6 @@
 size_t GetSerializedSize_(const {{struct.name}}Ptr& input);
 void Serialize_({{struct.name}}Ptr input, mojo::internal::Buffer* buffer,
                 internal::{{struct.name}}_Data** output);
-void Deserialize_(internal::{{struct.name}}_Data* input,
+bool Deserialize_(internal::{{struct.name}}_Data* input,
                   {{struct.name}}Ptr* output,
                   mojo::internal::SerializationContext* context);
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
index 24cc767..5c14ea0 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_definition.tmpl
@@ -16,14 +16,16 @@ void Serialize_({{struct.name}}Ptr input, mojo::internal::Buffer* buf,
   }
 }
 
-void Deserialize_(internal::{{struct.name}}_Data* input,
+bool Deserialize_(internal::{{struct.name}}_Data* input,
                   {{struct.name}}Ptr* output,
                   mojo::internal::SerializationContext* context) {
+  bool success = true;
   if (input) {
     {{struct.name}}Ptr result({{struct.name}}::New());
-    {{struct_macros.deserialize(struct, "input", "result->%s", "context")|indent(2)}}
+    {{struct_macros.deserialize(struct, "input", "result->%s", "context", "success")|indent(2)}}
     *output = result.Pass();
   } else {
     output->reset();
   }
+  return success;
 }
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl
index 6773486..3604763 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl
@@ -1,6 +1,6 @@
 size_t GetSerializedSize_(const {{union.name}}Ptr& input, bool inlined);
 void SerializeUnion_({{union.name}}Ptr input, mojo::internal::Buffer* buffer,
                      internal::{{union.name}}_Data** output, bool inlined);
-void Deserialize_(internal::{{union.name}}_Data* input,
+bool Deserialize_(internal::{{union.name}}_Data* input,
                   {{union.name}}Ptr* output,
                   mojo::internal::SerializationContext* context);
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
index 3471932..73f6c95 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
@@ -93,9 +93,10 @@ void SerializeUnion_({{union.name}}Ptr input, mojo::internal::Buffer* buf,
   *output = result;
 }
 
-void Deserialize_(internal::{{union.name}}_Data* input,
+bool Deserialize_(internal::{{union.name}}_Data* input,
                   {{union.name}}Ptr* output,
                   mojo::internal::SerializationContext* context) {
+  bool success = true;
   if (input && !input->is_null()) {
     {{union.name}}Ptr result({{union.name}}::New());
     mojo::internal::UnionAccessor<{{union.name}}> result_acc(result.get());
@@ -104,7 +105,8 @@ void Deserialize_(internal::{{union.name}}_Data* input,
       case {{union.name}}::Tag::{{field.name|upper}}: {
 {%    if field.kind|is_object_kind %}
         result_acc.SwitchActive({{union.name}}::Tag::{{field.name|upper}});
-        Deserialize_(input->data.f_{{field.name}}.ptr, result_acc.data()->{{field.name}}, context);
+        if (!Deserialize_(input->data.f_{{field.name}}.ptr, result_acc.data()->{{field.name}}, context))
+          success = false;
 {%    elif field.kind|is_any_handle_kind %}
         {{field.kind|cpp_wrapper_type}}* {{field.name}} =
             reinterpret_cast<{{field.kind|cpp_wrapper_type}}*>(&input->data.f_{{field.name}});
@@ -132,4 +134,5 @@ void Deserialize_(internal::{{union.name}}_Data* input,
   } else {
     output->reset();
   }
+  return success;
 }