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shell.cc

A simple shell that takes a list of expressions on the command-line and executes them.

// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
v8::Global<v8::Context> CreateShellContext(v8::Isolate* isolate);
void RunShell(v8::Isolate* isolate, const v8::Global<v8::Context>& context,
v8::Platform* platform);
int RunMain(v8::Isolate* isolate, const v8::Global<v8::Context>& context,
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>& info);
void Read(const v8::FunctionCallbackInfo<v8::Value>& info);
void Load(const v8::FunctionCallbackInfo<v8::Value>& info);
void Quit(const v8::FunctionCallbackInfo<v8::Value>& info);
void Version(const v8::FunctionCallbackInfo<v8::Value>& info);
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[]) {
std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
v8::V8::InitializePlatform(platform.get());
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
create_params.array_buffer_allocator =
v8::Isolate* isolate = v8::Isolate::New(create_params);
run_shell = (argc == 1);
int result;
{
v8::Isolate::Scope isolate_scope(isolate);
v8::Global<v8::Context> context = CreateShellContext(isolate);
if (context.IsEmpty()) {
fprintf(stderr, "Error creating context\n");
return 1;
}
result = RunMain(isolate, context, platform.get(), argc, argv);
if (run_shell) RunShell(isolate, context, platform.get());
}
isolate->Dispose();
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::Global<v8::Context> CreateShellContext(v8::Isolate* isolate) {
v8::HandleScope handle_scope(isolate);
// Create a template for the global object.
// Bind the global 'print' function to the C++ Print callback.
global->Set(isolate, "print", v8::FunctionTemplate::New(isolate, Print));
// Bind the global 'read' function to the C++ Read callback.
global->Set(isolate, "read", v8::FunctionTemplate::New(isolate, Read));
// Bind the global 'load' function to the C++ Load callback.
global->Set(isolate, "load", v8::FunctionTemplate::New(isolate, Load));
// Bind the 'quit' function
global->Set(isolate, "quit", v8::FunctionTemplate::New(isolate, Quit));
// Bind the 'version' function
global->Set(isolate, "version", v8::FunctionTemplate::New(isolate, Version));
// Return the context.
v8::Local<v8::Context> context = v8::Context::New(isolate, nullptr, global);
return v8::Global<v8::Context>(isolate, context);
}
// 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>& info) {
bool first = true;
for (int i = 0; i < info.Length(); i++) {
v8::HandleScope handle_scope(info.GetIsolate());
if (first) {
first = false;
} else {
printf(" ");
}
v8::String::Utf8Value str(info.GetIsolate(), info[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>& info) {
if (info.Length() != 1) {
info.GetIsolate()->ThrowError("Bad parameters");
return;
}
v8::String::Utf8Value file(info.GetIsolate(), info[0]);
if (*file == nullptr) {
info.GetIsolate()->ThrowError("Error loading file");
return;
}
if (!ReadFile(info.GetIsolate(), *file).ToLocal(&source)) {
info.GetIsolate()->ThrowError("Error loading file");
return;
}
info.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>& info) {
for (int i = 0; i < info.Length(); i++) {
v8::HandleScope handle_scope(info.GetIsolate());
v8::String::Utf8Value file(info.GetIsolate(), info[i]);
if (*file == nullptr) {
info.GetIsolate()->ThrowError("Error loading file");
return;
}
if (!ReadFile(info.GetIsolate(), *file).ToLocal(&source)) {
info.GetIsolate()->ThrowError("Error loading file");
return;
}
if (!ExecuteString(info.GetIsolate(), source, info[i], false, false)) {
info.GetIsolate()->ThrowError("Error executing file");
return;
}
}
}
// The callback that is invoked by v8 whenever the JavaScript 'quit'
// function is called. Quits.
void Quit(const v8::FunctionCallbackInfo<v8::Value>& info) {
// If not arguments are given info[0] will yield undefined which
// converts to the integer value 0.
int exit_code =
info[0]->Int32Value(info.GetIsolate()->GetCurrentContext()).FromMaybe(0);
fflush(stdout);
fflush(stderr);
exit(exit_code);
}
// The callback that is invoked by v8 whenever the JavaScript 'version'
// function is called. Returns a string containing the current V8 version.
void Version(const v8::FunctionCallbackInfo<v8::Value>& info) {
info.GetReturnValue().Set(
.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 == nullptr) return {};
fseek(file, 0, SEEK_END);
size_t size = ftell(file);
rewind(file);
char* chars = new char[size + 1];
chars[size] = '\0';
for (size_t i = 0; i < size;) {
i += fread(&chars[i], 1, size - i, file);
if (ferror(file)) {
fclose(file);
return {};
}
}
fclose(file);
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, const v8::Global<v8::Context>& context,
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 options\n", str);
} else if (strcmp(str, "-e") == 0 && i + 1 < argc) {
// Execute argument given to -e option directly.
bool success;
{
// Enter the execution environment before evaluating any code.
v8::HandleScope handle_scope(isolate);
v8::Context::Scope context_scope(context.Get(isolate));
v8::String::NewFromUtf8Literal(isolate, "unnamed");
if (!v8::String::NewFromUtf8(isolate, argv[++i]).ToLocal(&source)) {
return 1;
}
success = ExecuteString(isolate, source, file_name, false, true);
}
// It is important not to pump the message loop when there are v8::Local
// handles on the stack, as this may trigger a stackless GC.
while (v8::platform::PumpMessageLoop(platform, isolate)) continue;
if (!success) return 1;
} else {
// Use all other arguments as names of files to load and run.
bool success;
{
// Enter the execution environment before evaluating any code.
v8::HandleScope handle_scope(isolate);
v8::Context::Scope context_scope(context.Get(isolate));
v8::String::NewFromUtf8(isolate, str).ToLocalChecked();
if (!ReadFile(isolate, str).ToLocal(&source)) {
fprintf(stderr, "Error reading '%s'\n", str);
continue;
}
success = ExecuteString(isolate, source, file_name, false, true);
}
// It is important not to pump the message loop when there are v8::Local
// handles on the stack, as this may trigger a stackless GC.
while (v8::platform::PumpMessageLoop(platform, isolate)) continue;
if (!success) return 1;
}
}
return 0;
}
// The read-eval-execute loop of the shell.
void RunShell(v8::Isolate* isolate, const v8::Global<v8::Context>& context,
v8::Platform* platform) {
fprintf(stderr, "V8 version %s [sample shell]\n", v8::V8::GetVersion());
static const int kBufferSize = 256;
while (true) {
char buffer[kBufferSize];
fprintf(stderr, "> ");
char* str = fgets(buffer, kBufferSize, stdin);
if (str == nullptr) break;
{
// Enter the execution environment before evaluating any code.
v8::HandleScope handle_scope(isolate);
v8::Context::Scope context_scope(context.Get(isolate));
v8::String::NewFromUtf8Literal(isolate, "(shell)"));
ExecuteString(isolate,
v8::String::NewFromUtf8(isolate, str).ToLocalChecked(),
name, true, true);
}
// It is important not to pump the message loop when there are v8::Local
// handles on the stack, as this may trigger a stackless GC.
while (v8::platform::PumpMessageLoop(platform, isolate)) 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);
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 {
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("%s\n", 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, "%s\n", exception_string);
} else {
// Print (filename):(line number): (message).
v8::String::Utf8Value filename(isolate,
message->GetScriptOrigin().ResourceName());
const char* filename_string = ToCString(filename);
int linenum = message->GetLineNumber(context).FromJust();
fprintf(stderr, "%s:%i: %s\n", filename_string, linenum, exception_string);
// Print line of source code.
isolate, message->GetSourceLine(context).ToLocalChecked());
const char* sourceline_string = ToCString(sourceline);
fprintf(stderr, "%s\n", 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() &&
stack_trace_string.As<v8::String>()->Length() > 0) {
v8::String::Utf8Value stack_trace(isolate, stack_trace_string);
const char* err = ToCString(stack_trace);
fprintf(stderr, "%s\n", err);
}
}
}
static Allocator * NewDefaultAllocator()
Definition: v8-context.h:383
static Local< Context > New(Isolate *isolate, ExtensionConfiguration *extensions=nullptr, MaybeLocal< ObjectTemplate > global_template=MaybeLocal< ObjectTemplate >(), MaybeLocal< Value > global_object=MaybeLocal< Value >(), DeserializeInternalFieldsCallback internal_fields_deserializer=DeserializeInternalFieldsCallback(), MicrotaskQueue *microtask_queue=nullptr, DeserializeContextDataCallback context_data_deserializer=DeserializeContextDataCallback(), DeserializeAPIWrapperCallback api_wrapper_deserializer=DeserializeAPIWrapperCallback())
Definition: v8-function-callback.h:118
ReturnValue< T > GetReturnValue() const
Definition: v8-function-callback.h:679
Isolate * GetIsolate() const
Definition: v8-function-callback.h:674
int Length() const
Definition: v8-function-callback.h:689
static Local< FunctionTemplate > New(Isolate *isolate, FunctionCallback callback=nullptr, Local< Value > data=Local< Value >(), Local< Signature > signature=Local< Signature >(), int length=0, ConstructorBehavior behavior=ConstructorBehavior::kAllow, SideEffectType side_effect_type=SideEffectType::kHasSideEffect, const CFunction *c_function=nullptr, uint16_t instance_type=0, uint16_t allowed_receiver_instance_type_range_start=0, uint16_t allowed_receiver_instance_type_range_end=0)
Definition: v8-persistent-handle.h:347
Definition: v8-local-handle.h:97
Definition: v8-isolate.h:284
Definition: v8-isolate.h:190
void Dispose()
static Isolate * New(const CreateParams &params)
Local< Value > ThrowError(const char(&message)[N])
Definition: v8-isolate.h:958
Local< Context > GetCurrentContext()
Definition: v8-local-handle.h:266
Local< S > As() const
Definition: v8-local-handle.h:337
Definition: v8-local-handle.h:632
static Local< ObjectTemplate > New(Isolate *isolate, Local< FunctionTemplate > constructor=Local< FunctionTemplate >())
Local< T > Get(Isolate *isolate) const
Definition: v8-persistent-handle.h:111
Definition: v8-platform.h:1058
Definition: v8-message.h:62
static MaybeLocal< Script > Compile(Local< Context > context, Local< String > source, ScriptOrigin *origin=nullptr)
Definition: v8-primitive.h:614
Definition: v8-primitive.h:124
static MaybeLocal< String > NewFromUtf8(Isolate *isolate, const char *data, NewStringType type=NewStringType::kNormal, int length=-1)
static Local< String > NewFromUtf8Literal(Isolate *isolate, const char(&literal)[N], NewStringType type=NewStringType::kNormal)
Definition: v8-primitive.h:492
int Length() const
Definition: v8-exception.h:138
Local< v8::Message > Message() const
static MaybeLocal< Value > StackTrace(Local< Context > context, Local< Value > exception)
Local< Value > Exception() const
static void InitializePlatform(Platform *platform)
static const char * GetVersion()
static bool InitializeICUDefaultLocation(const char *exec_path, const char *icu_data_file=nullptr)
static bool Initialize()
Definition: v8-initialization.h:108
static bool Dispose()
static void SetFlagsFromCommandLine(int *argc, char **argv, bool remove_flags)
static void DisposePlatform()
static void InitializeExternalStartupData(const char *directory_path)
bool IsEmpty() const
Definition: v8-handle-base.h:60
std::unique_ptr< v8::Platform > NewDefaultPlatform(int thread_pool_size=0, IdleTaskSupport idle_task_support=IdleTaskSupport::kDisabled, InProcessStackDumping in_process_stack_dumping=InProcessStackDumping::kDisabled, std::unique_ptr< v8::TracingController > tracing_controller={}, PriorityMode priority_mode=PriorityMode::kDontApply)
bool PumpMessageLoop(v8::Platform *platform, v8::Isolate *isolate, MessageLoopBehavior behavior=MessageLoopBehavior::kDoNotWait)
Definition: v8-isolate.h:195
ArrayBuffer::Allocator * array_buffer_allocator
Definition: v8-isolate.h:242