V8版本：8.2.0
操作系统：Ubuntu v18.04.3 LTS
体系结构：x64
哪些步骤将重现问题
- 遵循上的说明https://v8.dev/docs/source-code和https://v8.dev/docs/build构建和编译v8
- 编译samples文件夹中的shell.cc
- 成功编译后，执行shell应用程序
预期输出是多少
shell应用程序应该像d8 shell应用程序一样工作。在d8 shell中，当单击回车键时，将返回d8 shell提示，并且d8 shell不会退出应用程序。
你看到了什么
当我按下回车键时，我得到错误"Segmentation fault(Core Dump("，shell应用程序退出。
外壳中的代码.cc如下。与v8 samples文件夹中的代码相同https://github.com/v8/v8/blob/master/samples/shell.cc
#include <include/v8.h>
#include <include/libplatform/libplatform.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/**
* This sample program shows how to implement a simple javascript shell
* based on V8. This includes initializing V8 with command line options,
* creating global functions, compiling and executing strings.
*
* For a more sophisticated shell, consider using the debug shell D8.
*/
v8::Local<v8::Context> CreateShellContext(v8::Isolate* isolate);
void RunShell(v8::Local<v8::Context> context, v8::Platform* platform);
int RunMain(v8::Isolate* isolate, v8::Platform* platform, int argc,
char* argv[]);
bool ExecuteString(v8::Isolate* isolate, v8::Local<v8::String> source,
v8::Local<v8::Value> name, bool print_result,
bool report_exceptions);
void Print(const v8::FunctionCallbackInfo<v8::Value>& args);
void Read(const v8::FunctionCallbackInfo<v8::Value>& args);
void Load(const v8::FunctionCallbackInfo<v8::Value>& args);
void Quit(const v8::FunctionCallbackInfo<v8::Value>& args);
void Version(const v8::FunctionCallbackInfo<v8::Value>& args);
v8::MaybeLocal<v8::String> ReadFile(v8::Isolate* isolate, const char* name);
void ReportException(v8::Isolate* isolate, v8::TryCatch* handler);
static bool run_shell;
int main(int argc, char* argv[]) {
v8::V8::InitializeICUDefaultLocation(argv[0]);
v8::V8::InitializeExternalStartupData(argv[0]);
std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
v8::V8::InitializePlatform(platform.get());
v8::V8::Initialize();
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator =
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
v8::Isolate* isolate = v8::Isolate::New(create_params);
run_shell = (argc == 1);
int result;
{
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> context = CreateShellContext(isolate);
if (context.IsEmpty()) {
fprintf(stderr, "Error creating contextn");
return 1;
}
v8::Context::Scope context_scope(context);
result = RunMain(isolate, platform.get(), argc, argv);
if (run_shell) RunShell(context, platform.get());
}
isolate->Dispose();
v8::V8::Dispose();
v8::V8::ShutdownPlatform();
delete create_params.array_buffer_allocator;
return result;
}
// Extracts a C string from a V8 Utf8Value.
const char* ToCString(const v8::String::Utf8Value& value) {
return *value ? *value : "<string conversion failed>";
}
// Creates a new execution environment containing the built-in
// functions.
v8::Local<v8::Context> CreateShellContext(v8::Isolate* isolate) {
// Create a template for the global object.
v8::Local<v8::ObjectTemplate> global = v8::ObjectTemplate::New(isolate);
// Bind the global 'print' function to the C++ Print callback.
global->Set(
v8::String::NewFromUtf8(isolate, "print", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Print));
// Bind the global 'read' function to the C++ Read callback.
global->Set(v8::String::NewFromUtf8(
isolate, "read", v8::NewStringType::kNormal).ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Read));
// Bind the global 'load' function to the C++ Load callback.
global->Set(v8::String::NewFromUtf8(
isolate, "load", v8::NewStringType::kNormal).ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Load));
// Bind the 'quit' function
global->Set(v8::String::NewFromUtf8(
isolate, "quit", v8::NewStringType::kNormal).ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Quit));
// Bind the 'version' function
global->Set(
v8::String::NewFromUtf8(isolate, "version", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Version));
return v8::Context::New(isolate, NULL, global);
}
// The callback that is invoked by v8 whenever the JavaScript 'print'
// function is called. Prints its arguments on stdout separated by
// spaces and ending with a newline.
void Print(const v8::FunctionCallbackInfo<v8::Value>& args) {
bool first = true;
for (int i = 0; i < args.Length(); i++) {
v8::HandleScope handle_scope(args.GetIsolate());
if (first) {
first = false;
} else {
printf(" ");
}
v8::String::Utf8Value str(args.GetIsolate(), args[i]);
const char* cstr = ToCString(str);
printf("%s", cstr);
}
printf("n");
fflush(stdout);
}
// The callback that is invoked by v8 whenever the JavaScript 'read'
// function is called. This function loads the content of the file named in
// the argument into a JavaScript string.
void Read(const v8::FunctionCallbackInfo<v8::Value>& args) {
if (args.Length() != 1) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Bad parameters",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
v8::String::Utf8Value file(args.GetIsolate(), args[0]);
if (*file == NULL) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
v8::Local<v8::String> source;
if (!ReadFile(args.GetIsolate(), *file).ToLocal(&source)) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
args.GetReturnValue().Set(source);
}
// The callback that is invoked by v8 whenever the JavaScript 'load'
// function is called. Loads, compiles and executes its argument
// JavaScript file.
void Load(const v8::FunctionCallbackInfo<v8::Value>& args) {
for (int i = 0; i < args.Length(); i++) {
v8::HandleScope handle_scope(args.GetIsolate());
v8::String::Utf8Value file(args.GetIsolate(), args[i]);
if (*file == NULL) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
v8::Local<v8::String> source;
if (!ReadFile(args.GetIsolate(), *file).ToLocal(&source)) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
if (!ExecuteString(args.GetIsolate(), source, args[i], false, false)) {
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error executing file",
v8::NewStringType::kNormal).ToLocalChecked());
return;
}
}
}
// The callback that is invoked by v8 whenever the JavaScript 'quit'
// function is called. Quits.
void Quit(const v8::FunctionCallbackInfo<v8::Value>& args) {
// If not arguments are given args[0] will yield undefined which
// converts to the integer value 0.
int exit_code =
args[0]->Int32Value(args.GetIsolate()->GetCurrentContext()).FromMaybe(0);
fflush(stdout);
fflush(stderr);
exit(exit_code);
}
void Version(const v8::FunctionCallbackInfo<v8::Value>& args) {
args.GetReturnValue().Set(
v8::String::NewFromUtf8(args.GetIsolate(), v8::V8::GetVersion(),
v8::NewStringType::kNormal).ToLocalChecked());
}
// Reads a file into a v8 string.
v8::MaybeLocal<v8::String> ReadFile(v8::Isolate* isolate, const char* name) {
FILE* file = fopen(name, "rb");
if (file == NULL) return v8::MaybeLocal<v8::String>();
fseek(file, 0, SEEK_END);
size_t size = ftell(file);
rewind(file);
char* chars = new char[size + 1];
chars[size] = ' ';
for (size_t i = 0; i < size;) {
i += fread(&chars[i], 1, size - i, file);
if (ferror(file)) {
fclose(file);
return v8::MaybeLocal<v8::String>();
}
}
fclose(file);
v8::MaybeLocal<v8::String> result = v8::String::NewFromUtf8(
isolate, chars, v8::NewStringType::kNormal, static_cast<int>(size));
delete[] chars;
return result;
}
// Process remaining command line arguments and execute files
int RunMain(v8::Isolate* isolate, v8::Platform* platform, int argc,
char* argv[]) {
for (int i = 1; i < argc; i++) {
const char* str = argv[i];
if (strcmp(str, "--shell") == 0) {
run_shell = true;
} else if (strcmp(str, "-f") == 0) {
// Ignore any -f flags for compatibility with the other stand-
// alone JavaScript engines.
continue;
} else if (strncmp(str, "--", 2) == 0) {
fprintf(stderr,
"Warning: unknown flag %s.nTry --help for optionsn", str);
} else if (strcmp(str, "-e") == 0 && i + 1 < argc) {
// Execute argument given to -e option directly.
v8::Local<v8::String> file_name =
v8::String::NewFromUtf8(isolate, "unnamed",
v8::NewStringType::kNormal).ToLocalChecked();
v8::Local<v8::String> source;
if (!v8::String::NewFromUtf8(isolate, argv[++i],
v8::NewStringType::kNormal)
.ToLocal(&source)) {
return 1;
}
bool success = ExecuteString(isolate, source, file_name, false, true);
while (v8::platform::PumpMessageLoop(platform, isolate)) continue;
if (!success) return 1;
} else {
// Use all other arguments as names of files to load and run.
v8::Local<v8::String> file_name =
v8::String::NewFromUtf8(isolate, str, v8::NewStringType::kNormal)
.ToLocalChecked();
v8::Local<v8::String> source;
if (!ReadFile(isolate, str).ToLocal(&source)) {
fprintf(stderr, "Error reading '%s'n", str);
continue;
}
bool success = ExecuteString(isolate, source, file_name, false, true);
while (v8::platform::PumpMessageLoop(platform, isolate)) continue;
if (!success) return 1;
}
}
return 0;
}
// The read-eval-execute loop of the shell.
void RunShell(v8::Local<v8::Context> context, v8::Platform* platform) {
fprintf(stderr, "V8 version %s [sample shell]n", v8::V8::GetVersion());
static const int kBufferSize = 256;
// Enter the execution environment before evaluating any code.
v8::Context::Scope context_scope(context);
v8::Local<v8::String> name(
v8::String::NewFromUtf8(context->GetIsolate(), "(shell)",
v8::NewStringType::kNormal).ToLocalChecked());
while (true) {
char buffer[kBufferSize];
fprintf(stderr, "> ");
char* str = fgets(buffer, kBufferSize, stdin);
if (str == NULL) break;
v8::HandleScope handle_scope(context->GetIsolate());
ExecuteString(
context->GetIsolate(),
v8::String::NewFromUtf8(context->GetIsolate(), str,
v8::NewStringType::kNormal).ToLocalChecked(),
name, true, true);
while (v8::platform::PumpMessageLoop(platform, context->GetIsolate()))
continue;
}
fprintf(stderr, "n");
}
// Executes a string within the current v8 context.
bool ExecuteString(v8::Isolate* isolate, v8::Local<v8::String> source,
v8::Local<v8::Value> name, bool print_result,
bool report_exceptions) {
v8::HandleScope handle_scope(isolate);
v8::TryCatch try_catch(isolate);
v8::ScriptOrigin origin(name);
v8::Local<v8::Context> context(isolate->GetCurrentContext());
v8::Local<v8::Script> script;
if (!v8::Script::Compile(context, source, &origin).ToLocal(&script)) {
// Print errors that happened during compilation.
if (report_exceptions)
ReportException(isolate, &try_catch);
return false;
} else {
v8::Local<v8::Value> result;
if (!script->Run(context).ToLocal(&result)) {
assert(try_catch.HasCaught());
// Print errors that happened during execution.
if (report_exceptions)
ReportException(isolate, &try_catch);
return false;
} else {
assert(!try_catch.HasCaught());
if (print_result && !result->IsUndefined()) {
// If all went well and the result wasn't undefined then print
// the returned value.
v8::String::Utf8Value str(isolate, result);
const char* cstr = ToCString(str);
printf("%sn", cstr);
}
return true;
}
}
}
void ReportException(v8::Isolate* isolate, v8::TryCatch* try_catch) {
v8::HandleScope handle_scope(isolate);
v8::String::Utf8Value exception(isolate, try_catch->Exception());
const char* exception_string = ToCString(exception);
v8::Local<v8::Message> message = try_catch->Message();
if (message.IsEmpty()) {
// V8 didn't provide any extra information about this error; just
// print the exception.
fprintf(stderr, "%sn", exception_string);
} else {
// Print (filename):(line number): (message).
v8::String::Utf8Value filename(isolate,
message->GetScriptOrigin().ResourceName());
v8::Local<v8::Context> context(isolate->GetCurrentContext());
const char* filename_string = ToCString(filename);
int linenum = message->GetLineNumber(context).FromJust();
fprintf(stderr, "%s:%i: %sn", filename_string, linenum, exception_string);
// Print line of source code.
v8::String::Utf8Value sourceline(
isolate, message->GetSourceLine(context).ToLocalChecked());
const char* sourceline_string = ToCString(sourceline);
fprintf(stderr, "%sn", sourceline_string);
// Print wavy underline (GetUnderline is deprecated).
int start = message->GetStartColumn(context).FromJust();
for (int i = 0; i < start; i++) {
fprintf(stderr, " ");
}
int end = message->GetEndColumn(context).FromJust();
for (int i = start; i < end; i++) {
fprintf(stderr, "^");
}
fprintf(stderr, "n");
v8::Local<v8::Value> stack_trace_string;
if (try_catch->StackTrace(context).ToLocal(&stack_trace_string) &&
stack_trace_string->IsString() &&
v8::Local<v8::String>::Cast(stack_trace_string)->Length() > 0) {
v8::String::Utf8Value stack_trace(isolate, stack_trace_string);
const char* stack_trace_string = ToCString(stack_trace);
fprintf(stderr, "%sn", stack_trace_string);
}
}
}
最终输出：
➜ cd v8
➜ ./shell
V8 version 8.2.0 (candidate) [sample shell]
>
[1] 2119 segmentation fault (core dumped) ./shell
➜
尝试了错误报告，但没有响应
这个错误似乎是https://bugs.chromium.org/p/v8/issues/detail?id=10214；在我写这篇文章的时候，这个bug是在8小时前提交的，这个问题是在6小时前提出的，所以你在一个星期天(没有人在工作(等了整整2个小时才放弃？
我收到错误"Segmentation fault(Core Dump("，shell应用程序退出
当你在任何C/C++程序中得到一个segfault时，你要做的是：
- 在调试模式下编译
- 在调试器中运行
- 触发碰撞
- 获取回溯
回溯会告诉你出了什么问题，或者至少它会为任何试图帮助你的人提供重要信息。
请不要将文本(包括控制台输出(作为图像发布！屏幕截图和实际照片都不合适。复制粘贴文本！
FWIW，官方shell示例运行良好(我刚刚尝试过：ninja -C out/x64.debug v8_shell && out/x64.debug/v8_shell(。你肯定在做一些不同的事情，但你没有说可能是什么。