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/* -*- indent-tabs-mode: nil; js-indent-level: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* jorendb - A toy command-line debugger for shell-js programs.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
*/
/*
* jorendb is a simple command-line debugger for shell-js programs. It is
* intended as a demo of the Debugger object (as there are no shell js programs
* to speak of).
*
* To run it: $JS -d path/to/this/file/jorendb.js
* To run some JS code under it, try:
* (jorendb) print load("my-script-to-debug.js")
* Execution will stop at debugger statements and you'll get a jorendb prompt.
*/
// Debugger state.
var focusedFrame = null;
var topFrame = null;
var debuggeeValues = {};
var nextDebuggeeValueIndex = 1;
var lastExc = null;
var todo = [];
var activeTask;
var options = { 'pretty': true,
'emacs': !!os.getenv('INSIDE_EMACS') };
var rerun = true;
// Cleanup functions to run when we next re-enter the repl.
var replCleanups = [];
// Redirect debugger printing functions to go to the original output
// destination, unaffected by any redirects done by the debugged script.
var initialOut = os.file.redirect();
var initialErr = os.file.redirectErr();
function wrap(global, name) {
var orig = global[name];
global[name] = function(...args) {
var oldOut = os.file.redirect(initialOut);
var oldErr = os.file.redirectErr(initialErr);
try {
return orig.apply(global, args);
} finally {
os.file.redirect(oldOut);
os.file.redirectErr(oldErr);
}
};
}
wrap(this, 'print');
wrap(this, 'printErr');
wrap(this, 'putstr');
// Convert a debuggee value v to a string.
function dvToString(v) {
if (typeof(v) === 'object' && v !== null) {
return `[object ${v.class}]`;
}
const s = uneval(v);
if (s.length > 400) {
return s.substr(0, 400) + "...<" + (s.length - 400) + " more bytes>...";
}
return s;
}
function summaryObject(dv) {
var obj = {};
for (var name of dv.getOwnPropertyNames()) {
var v = dv.getOwnPropertyDescriptor(name).value;
if (v instanceof Debugger.Object) {
v = "(...)";
}
obj[name] = v;
}
return obj;
}
function debuggeeValueToString(dv, style) {
var dvrepr = dvToString(dv);
if (!style.pretty || (typeof dv !== 'object') || (dv === null))
return [dvrepr, undefined];
const exec = debuggeeGlobalWrapper.executeInGlobalWithBindings.bind(debuggeeGlobalWrapper);
if (dv.class == "Error") {
let errval = exec("$$.toString()", debuggeeValues);
return [dvrepr, errval.return];
}
if (style.brief)
return [dvrepr, JSON.stringify(summaryObject(dv), null, 4)];
let str = exec("JSON.stringify(v, null, 4)", {v: dv});
if ('throw' in str) {
if (style.noerror)
return [dvrepr, undefined];
let substyle = {};
Object.assign(substyle, style);
substyle.noerror = true;
return [dvrepr, debuggeeValueToString(str.throw, substyle)];
}
return [dvrepr, str.return];
}
// Problem! Used to do [object Object] followed by details. Now just details?
function showDebuggeeValue(dv, style={pretty: options.pretty}) {
var i = nextDebuggeeValueIndex++;
debuggeeValues["$" + i] = dv;
debuggeeValues["$$"] = dv;
let [brief, full] = debuggeeValueToString(dv, style);
print("$" + i + " = " + brief);
if (full !== undefined)
print(full);
}
Object.defineProperty(Debugger.Frame.prototype, "num", {
configurable: true,
enumerable: false,
get: function () {
var i = 0;
for (var f = topFrame; f && f !== this; f = f.older)
i++;
return f === null ? undefined : i;
}
});
Debugger.Frame.prototype.frameDescription = function frameDescription() {
if (this.type == "call")
return ((this.callee.name || '<anonymous>') +
"(" + this.arguments.map(dvToString).join(", ") + ")");
else
return this.type + " code";
}
Debugger.Frame.prototype.positionDescription = function positionDescription() {
if (this.script) {
var line = this.script.getOffsetLocation(this.offset).lineNumber;
if (this.script.url)
return this.script.url + ":" + line;
return "line " + line;
}
return null;
}
Debugger.Frame.prototype.location = function () {
if (this.script) {
var { lineNumber, columnNumber, isEntryPoint } = this.script.getOffsetLocation(this.offset);
if (this.script.url)
return this.script.url + ":" + lineNumber;
return null;
}
return null;
}
Debugger.Frame.prototype.fullDescription = function fullDescription() {
var fr = this.frameDescription();
var pos = this.positionDescription();
if (pos)
return fr + ", " + pos;
return fr;
}
Object.defineProperty(Debugger.Frame.prototype, "line", {
configurable: true,
enumerable: false,
get: function() {
if (this.script)
return this.script.getOffsetLocation(this.offset).lineNumber;
else
return null;
}
});
function callDescription(f) {
return ((f.callee.name || '<anonymous>') +
"(" + f.arguments.map(dvToString).join(", ") + ")");
}
function showFrame(f, n) {
if (f === undefined || f === null) {
f = focusedFrame;
if (f === null) {
print("No stack.");
return;
}
}
if (n === undefined) {
n = f.num;
if (n === undefined)
throw new Error("Internal error: frame not on stack");
}
print('#' + n + " " + f.fullDescription());
}
function saveExcursion(fn) {
var tf = topFrame, ff = focusedFrame;
try {
return fn();
} finally {
topFrame = tf;
focusedFrame = ff;
}
}
function parseArgs(str) {
return str.split(" ");
}
function describedRv(r, desc) {
desc = "[" + desc + "] ";
if (r === undefined) {
print(desc + "Returning undefined");
} else if (r === null) {
print(desc + "Returning null");
} else if (r.length === undefined) {
print(desc + "Returning object " + JSON.stringify(r));
} else {
print(desc + "Returning length-" + r.length + " list");
if (r.length > 0) {
print(" " + r[0]);
}
}
return r;
}
// Rerun the program (reloading it from the file)
function runCommand(args) {
print(`Restarting program (${args})`);
if (args)
activeTask.scriptArgs = parseArgs(args);
else
activeTask.scriptArgs = [...actualScriptArgs];
rerun = true;
for (var f = topFrame; f; f = f.older) {
if (f.older) {
f.onPop = () => null;
} else {
f.onPop = () => ({ 'return': 0 });
}
}
//return describedRv([{ 'return': 0 }], "runCommand");
return null;
}
// Evaluate an expression in the Debugger global
function evalCommand(expr) {
eval(expr);
}
function quitCommand() {
dbg.removeAllDebuggees();
quit(0);
}
function backtraceCommand() {
if (topFrame === null)
print("No stack.");
for (var i = 0, f = topFrame; f; i++, f = f.older)
showFrame(f, i);
}
function setCommand(rest) {
var space = rest.indexOf(' ');
if (space == -1) {
print("Invalid set <option> <value> command");
} else {
var name = rest.substr(0, space);
var value = rest.substr(space + 1);
if (name == 'args') {
activeTask.scriptArgs = parseArgs(value);
} else {
var yes = ["1", "yes", "true", "on"];
var no = ["0", "no", "false", "off"];
if (yes.includes(value))
options[name] = true;
else if (no.includes(value))
options[name] = false;
else
options[name] = value;
}
}
}
function split_print_options(s, style) {
var m = /^\/(\w+)/.exec(s);
if (!m)
return [ s, style ];
if (m[1].includes("p"))
style.pretty = true;
if (m[1].includes("b"))
style.brief = true;
return [ s.substr(m[0].length).trimLeft(), style ];
}
function doPrint(expr, style) {
// This is the real deal.
var cv = saveExcursion(
() => focusedFrame == null
? debuggeeGlobalWrapper.executeInGlobalWithBindings(expr, debuggeeValues)
: focusedFrame.evalWithBindings(expr, debuggeeValues));
if (cv === null) {
print("Debuggee died.");
} else if ('return' in cv) {
showDebuggeeValue(cv.return, style);
} else {
print("Exception caught. (To rethrow it, type 'throw'.)");
lastExc = cv.throw;
showDebuggeeValue(lastExc, style);
}
}
function printCommand(rest) {
var [expr, style] = split_print_options(rest, {pretty: options.pretty});
return doPrint(expr, style);
}
function keysCommand(rest) { return doPrint("Object.keys(" + rest + ")"); }
function detachCommand() {
dbg.removeAllDebuggees();
return [undefined];
}
function continueCommand(rest) {
if (focusedFrame === null) {
print("No stack.");
return;
}
var match = rest.match(/^(\d+)$/);
if (match) {
return doStepOrNext({upto:true, stopLine:match[1]});
}
return [undefined];
}
function throwCommand(rest) {
var v;
if (focusedFrame !== topFrame) {
print("To throw, you must select the newest frame (use 'frame 0').");
return;
} else if (focusedFrame === null) {
print("No stack.");
return;
} else if (rest === '') {
return [{throw: lastExc}];
} else {
var cv = saveExcursion(function () { return focusedFrame.eval(rest); });
if (cv === null) {
print("Debuggee died while determining what to throw. Stopped.");
} else if ('return' in cv) {
return [{throw: cv.return}];
} else {
print("Exception determining what to throw. Stopped.");
showDebuggeeValue(cv.throw);
}
return;
}
}
function frameCommand(rest) {
var n, f;
if (rest.match(/[0-9]+/)) {
n = +rest;
f = topFrame;
if (f === null) {
print("No stack.");
return;
}
for (var i = 0; i < n && f; i++) {
if (!f.older) {
print("There is no frame " + rest + ".");
return;
}
f.older.younger = f;
f = f.older;
}
focusedFrame = f;
updateLocation(focusedFrame);
showFrame(f, n);
} else if (rest === '') {
if (topFrame === null) {
print("No stack.");
} else {
updateLocation(focusedFrame);
showFrame();
}
} else {
print("do what now?");
}
}
function upCommand() {
if (focusedFrame === null)
print("No stack.");
else if (focusedFrame.older === null)
print("Initial frame selected; you cannot go up.");
else {
focusedFrame.older.younger = focusedFrame;
focusedFrame = focusedFrame.older;
updateLocation(focusedFrame);
showFrame();
}
}
function downCommand() {
if (focusedFrame === null)
print("No stack.");
else if (!focusedFrame.younger)
print("Youngest frame selected; you cannot go down.");
else {
focusedFrame = focusedFrame.younger;
updateLocation(focusedFrame);
showFrame();
}
}
function forcereturnCommand(rest) {
var v;
var f = focusedFrame;
if (f !== topFrame) {
print("To forcereturn, you must select the newest frame (use 'frame 0').");
} else if (f === null) {
print("Nothing on the stack.");
} else if (rest === '') {
return [{return: undefined}];
} else {
var cv = saveExcursion(function () { return f.eval(rest); });
if (cv === null) {
print("Debuggee died while determining what to forcereturn. Stopped.");
} else if ('return' in cv) {
return [{return: cv.return}];
} else {
print("Error determining what to forcereturn. Stopped.");
showDebuggeeValue(cv.throw);
}
}
}
function printPop(f, c) {
var fdesc = f.fullDescription();
if (c.return) {
print("frame returning (still selected): " + fdesc);
showDebuggeeValue(c.return, {brief: true});
} else if (c.throw) {
print("frame threw exception: " + fdesc);
showDebuggeeValue(c.throw);
print("(To rethrow it, type 'throw'.)");
lastExc = c.throw;
} else {
print("frame was terminated: " + fdesc);
}
}
// Set |prop| on |obj| to |value|, but then restore its current value
// when we next enter the repl.
function setUntilRepl(obj, prop, value) {
var saved = obj[prop];
obj[prop] = value;
replCleanups.push(function () { obj[prop] = saved; });
}
function updateLocation(frame) {
if (options.emacs) {
var loc = frame.location();
if (loc)
print("\032\032" + loc + ":1");
}
}
function doStepOrNext(kind) {
var startFrame = topFrame;
var startLine = startFrame.line;
// print("stepping in: " + startFrame.fullDescription());
// print("starting line: " + uneval(startLine));
function stepPopped(completion) {
// Note that we're popping this frame; we need to watch for
// subsequent step events on its caller.
this.reportedPop = true;
printPop(this, completion);
topFrame = focusedFrame = this;
if (kind.finish) {
// We want to continue, but this frame is going to be invalid as
// soon as this function returns, which will make the replCleanups
// assert when it tries to access the dead frame's 'onPop'
// property. So clear it out now while the frame is still valid,
// and trade it for an 'onStep' callback on the frame we're popping to.
preReplCleanups();
setUntilRepl(this.older, 'onStep', stepStepped);
return undefined;
}
updateLocation(this);
return repl();
}
function stepEntered(newFrame) {
print("entered frame: " + newFrame.fullDescription());
updateLocation(newFrame);
topFrame = focusedFrame = newFrame;
return repl();
}
function stepStepped() {
// print("stepStepped: " + this.fullDescription());
updateLocation(this);
var stop = false;
if (kind.finish) {
// 'finish' set a one-time onStep for stopping at the frame it
// wants to return to
stop = true;
} else if (kind.upto) {
// running until a given line is reached
if (this.line == kind.stopLine)
stop = true;
} else {
// regular step; stop whenever the line number changes
if ((this.line != startLine) || (this != startFrame))
stop = true;
}
if (stop) {
topFrame = focusedFrame = this;
if (focusedFrame != startFrame)
print(focusedFrame.fullDescription());
return repl();
}
// Otherwise, let execution continue.
return undefined;
}
if (kind.step)
setUntilRepl(dbg, 'onEnterFrame', stepEntered);
// If we're stepping after an onPop, watch for steps and pops in the
// next-older frame; this one is done.
var stepFrame = startFrame.reportedPop ? startFrame.older : startFrame;
if (!stepFrame || !stepFrame.script)
stepFrame = null;
if (stepFrame) {
if (!kind.finish)
setUntilRepl(stepFrame, 'onStep', stepStepped);
setUntilRepl(stepFrame, 'onPop', stepPopped);
}
// Let the program continue!
return [undefined];
}
function stepCommand() { return doStepOrNext({step:true}); }
function nextCommand() { return doStepOrNext({next:true}); }
function finishCommand() { return doStepOrNext({finish:true}); }
// FIXME: DOES NOT WORK YET
function breakpointCommand(where) {
print("Sorry, breakpoints don't work yet.");
var script = focusedFrame.script;
var offsets = script.getLineOffsets(Number(where));
if (offsets.length == 0) {
print("Unable to break at line " + where);
return;
}
for (var offset of offsets) {
script.setBreakpoint(offset, { hit: handleBreakpoint });
}
print("Set breakpoint in " + script.url + ":" + script.startLine + " at line " + where + ", " + offsets.length);
}
// Build the table of commands.
var commands = {};
var commandArray = [
backtraceCommand, "bt", "where",
breakpointCommand, "b", "break",
continueCommand, "c",
detachCommand,
downCommand, "d",
evalCommand, "!",
forcereturnCommand,
frameCommand, "f",
finishCommand, "fin",
nextCommand, "n",
printCommand, "p",
keysCommand, "k",
quitCommand, "q",
runCommand, "run",
stepCommand, "s",
setCommand,
throwCommand, "t",
upCommand, "u",
helpCommand, "h",
];
var currentCmd = null;
for (var i = 0; i < commandArray.length; i++) {
var cmd = commandArray[i];
if (typeof cmd === "string")
commands[cmd] = currentCmd;
else
currentCmd = commands[cmd.name.replace(/Command$/, '')] = cmd;
}
function helpCommand(rest) {
print("Available commands:");
var printcmd = function(group) {
print(" " + group.join(", "));
}
var group = [];
for (var cmd of commandArray) {
if (typeof cmd === "string") {
group.push(cmd);
} else {
if (group.length) printcmd(group);
group = [ cmd.name.replace(/Command$/, '') ];
}
}
printcmd(group);
}
// Break cmd into two parts: its first word and everything else. If it begins
// with punctuation, treat that as a separate word. The first word is
// terminated with whitespace or the '/' character. So:
//
// print x => ['print', 'x']
// print => ['print', '']
// !print x => ['!', 'print x']
// ?!wtf!? => ['?', '!wtf!?']
// print/b x => ['print', '/b x']
//
function breakcmd(cmd) {
cmd = cmd.trimLeft();
if ("!@#$%^&*_+=/?.,<>:;'\"".includes(cmd.substr(0, 1)))
return [cmd.substr(0, 1), cmd.substr(1).trimLeft()];
var m = /\s+|(?=\/)/.exec(cmd);
if (m === null)
return [cmd, ''];
return [cmd.slice(0, m.index), cmd.slice(m.index + m[0].length)];
}
function runcmd(cmd) {
var pieces = breakcmd(cmd);
if (pieces[0] === "")
return undefined;
var first = pieces[0], rest = pieces[1];
if (!commands.hasOwnProperty(first)) {
print("unrecognized command '" + first + "'");
return undefined;
}
var cmd = commands[first];
if (cmd.length === 0 && rest !== '') {
print("this command cannot take an argument");
return undefined;
}
return cmd(rest);
}
function preReplCleanups() {
while (replCleanups.length > 0)
replCleanups.pop()();
}
var prevcmd = undefined;
function repl() {
preReplCleanups();
var cmd;
for (;;) {
putstr("\n" + prompt);
cmd = readline();
if (cmd === null)
return null;
else if (cmd === "")
cmd = prevcmd;
try {
prevcmd = cmd;
var result = runcmd(cmd);
if (result === undefined)
; // do nothing, return to prompt
else if (Array.isArray(result))
return result[0];
else if (result === null)
return null;
else
throw new Error("Internal error: result of runcmd wasn't array or undefined: " + result);
} catch (exc) {
print("*** Internal error: exception in the debugger code.");
print(" " + exc);
print(exc.stack);
}
}
}
var dbg = new Debugger();
dbg.onDebuggerStatement = function (frame) {
return saveExcursion(function () {
topFrame = focusedFrame = frame;
print("'debugger' statement hit.");
showFrame();
updateLocation(focusedFrame);
backtrace();
return describedRv(repl(), "debugger.saveExc");
});
};
dbg.onThrow = function (frame, exc) {
return saveExcursion(function () {
topFrame = focusedFrame = frame;
print("Unwinding due to exception. (Type 'c' to continue unwinding.)");
showFrame();
print("Exception value is:");
showDebuggeeValue(exc);
return repl();
});
};
function handleBreakpoint (frame) {
print("Breakpoint hit!");
return saveExcursion(() => {
topFrame = focusedFrame = frame;
print("breakpoint hit.");
showFrame();
updateLocation(focusedFrame);
return repl();
});
};
// The depth of jorendb nesting.
var jorendbDepth;
if (typeof jorendbDepth == 'undefined') jorendbDepth = 0;
var debuggeeGlobal = newGlobal({newCompartment: true});
debuggeeGlobal.jorendbDepth = jorendbDepth + 1;
var debuggeeGlobalWrapper = dbg.addDebuggee(debuggeeGlobal);
print("jorendb version -0.0");
prompt = '(' + Array(jorendbDepth+1).join('meta-') + 'jorendb) ';
var args = scriptArgs.slice(0);
print("INITIAL ARGS: " + args);
// Find the script to run and its arguments. The script may have been given as
// a plain script name, in which case all remaining arguments belong to the
// script. Or there may have been any number of arguments to the JS shell,
// followed by -f scriptName, followed by additional arguments to the JS shell,
// followed by the script arguments. There may be multiple -e or -f options in
// the JS shell arguments, and we want to treat each one as a debuggable
// script.
//
// The difficulty is that the JS shell has a mixture of
//
// --boolean
//
// and
//
// --value VAL
//
// parameters, and there's no way to know whether --option takes an argument or
// not. We will assume that VAL will never end in .js, or rather that the first
// argument that does not start with "-" but does end in ".js" is the name of
// the script.
//
// If you need to pass other options and not have them given to the script,
// pass them before the -f jorendb.js argument. Thus, the safe ways to pass
// arguments are:
//
// js [JS shell options] -f jorendb.js (-e SCRIPT | -f FILE)+ -- [script args]
// js [JS shell options] -f jorendb.js (-e SCRIPT | -f FILE)* script.js [script args]
//
// Additionally, if you want to run a script that is *NOT* debugged, put it in
// as part of the leading [JS shell options].
// Compute actualScriptArgs by finding the script to be run and grabbing every
// non-script argument. The script may be given by -f scriptname or just plain
// scriptname. In the latter case, it will be in the global variable
// 'scriptPath' (and NOT in scriptArgs.)
var actualScriptArgs = [];
var scriptSeen;
if (scriptPath !== undefined) {
todo.push({
'action': 'load',
'script': scriptPath,
});
scriptSeen = true;
}
while(args.length > 0) {
var arg = args.shift();
print("arg: " + arg);
if (arg == '-e') {
print(" eval");
todo.push({
'action': 'eval',
'code': args.shift()
});
} else if (arg == '-f') {
var script = args.shift();
print(" load -f " + script);
scriptSeen = true;
todo.push({
'action': 'load',
'script': script,
});
} else if (arg.indexOf("-") == 0) {
if (arg == '--') {
print(" pass remaining args to script");
actualScriptArgs.push(...args);
break;
} else if ((args.length > 0) && (args[0].indexOf(".js") + 3 == args[0].length)) {
// Ends with .js, assume we are looking at --boolean script.js
print(" load script.js after --boolean");
todo.push({
'action': 'load',
'script': args.shift(),
});
scriptSeen = true;
} else {
// Does not end with .js, assume we are looking at JS shell arg
// --value VAL
print(" ignore");
args.shift();
}
} else {
if (!scriptSeen) {
print(" load general");
actualScriptArgs.push(...args);
todo.push({
'action': 'load',
'script': arg,
});
break;
} else {
print(" arg " + arg);
actualScriptArgs.push(arg);
}
}
}
print("jorendb: scriptPath = " + scriptPath);
print("jorendb: scriptArgs = " + scriptArgs);
print("jorendb: actualScriptArgs = " + actualScriptArgs);
for (var task of todo) {
task['scriptArgs'] = [...actualScriptArgs];
}
// Always drop into a repl at the end. Especially if the main script throws an
// exception.
todo.push({ 'action': 'repl' });
while (rerun) {
print("Top of run loop");
rerun = false;
for (var task of todo) {
activeTask = task;
if (task.action == 'eval') {
debuggeeGlobal.eval(task.code);
} else if (task.action == 'load') {
debuggeeGlobal['scriptArgs'] = task.scriptArgs;
debuggeeGlobal['scriptPath'] = task.script;
print("Loading JavaScript file " + task.script);
try {
debuggeeGlobal.evaluate(read(task.script), { 'fileName': task.script, 'lineNumber': 1 });
} catch (exc) {
print("Caught exception " + exc);
print(exc.stack);
break;
}
} else if (task.action == 'repl') {
repl();
}
if (rerun)
break;
}
}
quit(0);