code gen flexbuffer verifier (#7207)

* code gen flexbuffer verifier

* remove verify nested flexbuffers from flexbuffers

* made function static, and placed higher in file

* moved function to own header

BUILD.bazel

@@ -49,6 +49,7 @@ filegroup(
         "include/flatbuffers/detached_buffer.h",
         "include/flatbuffers/flatbuffer_builder.h",
         "include/flatbuffers/flatbuffers.h",
+        "include/flatbuffers/flex_flat_util.h",
         "include/flatbuffers/flexbuffers.h",
         "include/flatbuffers/grpc.h",
         "include/flatbuffers/hash.h",

CMakeLists.txt

@@ -120,6 +120,7 @@ set(FlatBuffers_Library_SRCS
   include/flatbuffers/flatbuffer_builder.h
   include/flatbuffers/flatbuffers.h
   include/flatbuffers/flexbuffers.h
+  include/flatbuffers/flex_flat_util.h
   include/flatbuffers/hash.h
   include/flatbuffers/idl.h
   include/flatbuffers/minireflect.h

android/app/src/main/cpp/flatbuffers/CMakeLists.txt

@@ -26,6 +26,7 @@ set(FlatBuffers_Library_SRCS
         ${FLATBUFFERS_SRC}/include/flatbuffers/flatbuffer_builder.h
         ${FLATBUFFERS_SRC}/include/flatbuffers/flatbuffers.h
         ${FLATBUFFERS_SRC}/include/flatbuffers/flexbuffers.h
+        ${FLATBUFFERS_SRC}/include/flatbuffers/flex_flat_util.h
         ${FLATBUFFERS_SRC}/include/flatbuffers/hash.h
         ${FLATBUFFERS_SRC}/include/flatbuffers/idl.h
         ${FLATBUFFERS_SRC}/include/flatbuffers/minireflect.h

include/flatbuffers/flex_flat_util.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2022 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLATBUFFERS_FLEX_FLAT_UTIL_H_
+#define FLATBUFFERS_FLEX_FLAT_UTIL_H_
+
+#include "flatbuffers/flatbuffers.h"
+#include "flatbuffers/flexbuffers.h"
+
+namespace flexbuffers {
+
+// Verifies the `nested` flexbuffer within a flatbuffer vector is valid.
+inline bool VerifyNestedFlexBuffer(
+    const flatbuffers::Vector<uint8_t> *const nested,
+    flatbuffers::Verifier &verifier) {
+  if (!nested) return true;
+  return verifier.Check(flexbuffers::VerifyBuffer(
+      nested->data(), nested->size(), verifier.GetFlexReuseTracker()));
+}
+
+}  // namespace flexbuffers
+
+#endif  // FLATBUFFERS_FLEX_FLAT_UTIL_H_

include/flatbuffers/flexbuffers.h

@@ -156,6 +156,7 @@ inline uint64_t ReadUInt64(const uint8_t *data, uint8_t byte_width) {
   // TODO: GCC apparently replaces memcpy by a rep movsb, but only if count is a
   // constant, which here it isn't. Test if memcpy is still faster than
   // the conditionals in ReadSizedScalar. Can also use inline asm.
+
   // clang-format off
   #if defined(_MSC_VER) && defined(_M_X64) && !defined(_M_ARM64EC)
   // This is 64-bit Windows only, __movsb does not work on 32-bit Windows.
@@ -578,7 +579,7 @@ class Reference {
           // unquoted if it looks like an "identifier":
           const char *p = keys[i].AsKey();
           if (!flatbuffers::is_alpha(*p) && *p != '_') {
-              kq = true;
+            kq = true;
           } else {
             while (*++p) {
               if (!flatbuffers::is_alnum(*p) && *p != '_') {
@@ -1422,10 +1423,12 @@ class Builder FLATBUFFERS_FINAL_CLASS {
 
   template<typename T> static Type GetScalarType() {
     static_assert(flatbuffers::is_scalar<T>::value, "Unrelated types");
-    return flatbuffers::is_floating_point<T>::value ? FBT_FLOAT
-           : flatbuffers::is_same<T, bool>::value
-               ? FBT_BOOL
-               : (flatbuffers::is_unsigned<T>::value ? FBT_UINT : FBT_INT);
+    return flatbuffers::is_floating_point<T>::value
+               ? FBT_FLOAT
+               : flatbuffers::is_same<T, bool>::value
+                     ? FBT_BOOL
+                     : (flatbuffers::is_unsigned<T>::value ? FBT_UINT
+                                                           : FBT_INT);
   }
 
  public:
@@ -1876,18 +1879,6 @@ inline bool VerifyBuffer(const uint8_t *buf, size_t buf_len,
   return verifier.VerifyBuffer();
 }
 
-#ifdef FLATBUFFERS_H_
-// This is a verifier utility function that works together with the
-// FlatBuffers verifier, which should only be present if flatbuffer.h
-// has been included (which it typically is in generated code).
-inline bool VerifyNestedFlexBuffer(const flatbuffers::Vector<uint8_t> *nv,
-                                   flatbuffers::Verifier &verifier) {
-  if (!nv) return true;
-  return verifier.Check(flexbuffers::VerifyBuffer(
-      nv->data(), nv->size(), verifier.GetFlexReuseTracker()));
-}
-#endif
-
 }  // namespace flexbuffers
 
 #if defined(_MSC_VER)

src/idl_gen_cpp.cpp

@@ -377,6 +377,7 @@ class CppGenerator : public BaseGenerator {
     code_ += "#include \"flatbuffers/flatbuffers.h\"";
     if (parser_.uses_flexbuffers_) {
       code_ += "#include \"flatbuffers/flexbuffers.h\"";
+      code_ += "#include \"flatbuffers/flex_flat_util.h\"";
     }
     code_ += "";
     GenFlatbuffersVersionCheck();

tests/cpp17/generated_cpp17/monster_test_generated.h

@@ -6,6 +6,7 @@
 
 #include "flatbuffers/flatbuffers.h"
 #include "flatbuffers/flexbuffers.h"
+#include "flatbuffers/flex_flat_util.h"
 
 // Ensure the included flatbuffers.h is the same version as when this file was
 // generated, otherwise it may not be compatible.

tests/cpp17/test_cpp17.cpp

@@ -20,6 +20,7 @@
 // This is an experimental feature and could change at any time.
 
 #include "flatbuffers/flatbuffers.h"
+#include "flatbuffers/flex_flat_util.h"
 #include "flatbuffers/flexbuffers.h"
 #include "flatbuffers/idl.h"
 #include "flatbuffers/minireflect.h"
@@ -167,13 +168,13 @@ void StringifyAnyFlatbuffersTypeTest() {
 ** Test Traits::FieldType
 *******************************************************************************/
 using pos_type = Monster::Traits::FieldType<0>;
-static_assert(std::is_same_v<pos_type, const Vec3*>);
+static_assert(std::is_same_v<pos_type, const Vec3 *>);
 
 using mana_type = Monster::Traits::FieldType<1>;
 static_assert(std::is_same_v<mana_type, int16_t>);
 
 using name_type = Monster::Traits::FieldType<3>;
-static_assert(std::is_same_v<name_type, const flatbuffers::String*>);
+static_assert(std::is_same_v<name_type, const flatbuffers::String *>);
 
 /*******************************************************************************
 ** Generic Create Function Test.

tests/fuzzer/CMakeLists.txt

@@ -95,6 +95,7 @@ set(FlatBuffers_Library_SRCS
     ${FLATBUFFERS_DIR}/include/flatbuffers/flatbuffer_builder.h
     ${FLATBUFFERS_DIR}/include/flatbuffers/flatbuffers.h
     ${FLATBUFFERS_DIR}/include/flatbuffers/flexbuffers.h
+    ${FLATBUFFERS_DIR}/include/flatbuffers/flex_flat_util.h
     ${FLATBUFFERS_DIR}/include/flatbuffers/hash.h
     ${FLATBUFFERS_DIR}/include/flatbuffers/idl.h
     ${FLATBUFFERS_DIR}/include/flatbuffers/minireflect.h

tests/monster_test_generated.h

@@ -6,6 +6,7 @@
 
 #include "flatbuffers/flatbuffers.h"
 #include "flatbuffers/flexbuffers.h"
+#include "flatbuffers/flex_flat_util.h"
 
 // Ensure the included flatbuffers.h is the same version as when this file was
 // generated, otherwise it may not be compatible.