1 // Copyright 2016 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "src/wasm/wasm-function-name-table.h" 6 7 #include "src/wasm/wasm-module.h" 8 9 namespace v8 { 10 namespace internal { 11 namespace wasm { 12 13 // Build an array with all function names. If there are N functions in the 14 // module, then the first (kIntSize * (N+1)) bytes are integer entries. 15 // The first integer entry encodes the number of functions in the module. 16 // The entries 1 to N contain offsets into the second part of this array. 17 // If a function is unnamed (not to be confused with an empty name), then the 18 // integer entry is the negative offset of the next function name. 19 // After these N+1 integer entries, the second part begins, which holds a 20 // concatenation of all function names. 21 Handle<ByteArray> BuildFunctionNamesTable(Isolate* isolate, 22 const WasmModule* module) { 23 uint64_t func_names_length = 0; 24 for (auto& func : module->functions) func_names_length += func.name_length; 25 int num_funcs_int = static_cast<int>(module->functions.size()); 26 int current_offset = (num_funcs_int + 1) * kIntSize; 27 uint64_t total_array_length = current_offset + func_names_length; 28 int total_array_length_int = static_cast<int>(total_array_length); 29 // Check for overflow. 30 CHECK(total_array_length_int == total_array_length && num_funcs_int >= 0 && 31 num_funcs_int == module->functions.size()); 32 Handle<ByteArray> func_names_array = 33 isolate->factory()->NewByteArray(total_array_length_int, TENURED); 34 func_names_array->set_int(0, num_funcs_int); 35 int func_index = 0; 36 for (const WasmFunction& fun : module->functions) { 37 WasmName name = module->GetNameOrNull(&fun); 38 if (name.start() == nullptr) { 39 func_names_array->set_int(func_index + 1, -current_offset); 40 } else { 41 func_names_array->copy_in(current_offset, 42 reinterpret_cast<const byte*>(name.start()), 43 name.length()); 44 func_names_array->set_int(func_index + 1, current_offset); 45 current_offset += name.length(); 46 } 47 ++func_index; 48 } 49 return func_names_array; 50 } 51 52 MaybeHandle<String> GetWasmFunctionNameFromTable( 53 Handle<ByteArray> func_names_array, uint32_t func_index) { 54 uint32_t num_funcs = static_cast<uint32_t>(func_names_array->get_int(0)); 55 DCHECK(static_cast<int>(num_funcs) >= 0); 56 Factory* factory = func_names_array->GetIsolate()->factory(); 57 if (func_index >= num_funcs) return {}; 58 int offset = func_names_array->get_int(func_index + 1); 59 if (offset < 0) return {}; 60 int next_offset = func_index == num_funcs - 1 61 ? func_names_array->length() 62 : abs(func_names_array->get_int(func_index + 2)); 63 ScopedVector<byte> buffer(next_offset - offset); 64 func_names_array->copy_out(offset, buffer.start(), next_offset - offset); 65 if (!unibrow::Utf8::Validate(buffer.start(), buffer.length())) return {}; 66 return factory->NewStringFromUtf8(Vector<const char>::cast(buffer)); 67 } 68 69 } // namespace wasm 70 } // namespace internal 71 } // namespace v8 72
