[wasm] Implement WebAssembly.Module.customSections.

src/wasm/module-decoder.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_WASM_MODULE_DECODER_H_
 #define V8_WASM_MODULE_DECODER_H_
 
 #include "src/globals.h"
 #include "src/wasm/function-body-decoder.h"
 #include "src/wasm/wasm-module.h"
@@ skipping 38 matching lines @@
 
 // Extracts the function offset table from the wasm module bytes.
 // Returns a vector with <offset, length> entries, or failure if the wasm bytes
 // are detected as invalid. Note that this validation is not complete.
 FunctionOffsetsResult DecodeWasmFunctionOffsets(const byte* module_start,
                                                 const byte* module_end);
 
 V8_EXPORT_PRIVATE WasmInitExpr DecodeWasmInitExprForTesting(const byte* start,
                                                             const byte* end);
 
+struct CustomSectionOffset {
+  uint32_t section_start;
+  uint32_t name_offset;
+  uint32_t name_length;
+  uint32_t payload_offset;
+  uint32_t payload_length;
+  uint32_t section_length;
+};
+
+V8_EXPORT_PRIVATE std::vector<CustomSectionOffset> DecodeCustomSections(
+    const byte* start, const byte* end);
+
 // Extracts the mapping from wasm byte offset to asm.js source position per
 // function.
 // Returns a vector of vectors with <byte_offset, source_position> entries, or
 // failure if the wasm bytes are detected as invalid. Note that this validation
 // is not complete.
 AsmJsOffsetsResult DecodeAsmJsOffsets(const byte* module_start,
                                       const byte* module_end);
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MODULE_DECODER_H_