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.
BuildFunctionNamesTable(Isolate * isolate,const WasmModule * module)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
GetWasmFunctionNameFromTable(Handle<ByteArray> func_names_array,uint32_t func_index)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