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lib,src: refactor assert to load error source from memory #59751

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lib,src: refactor assert to load error source from memory #59751

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506cbcf
lib,src: refactor assert to load error source from memory
legendecas Sep 2, 2025
9e516a3
lib: add source map support for assert messages
legendecas Sep 3, 2025
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214 changes: 9 additions & 205 deletions lib/internal/assert/utils.js
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Original file line number Diff line number Diff line change
@@ -1,38 +1,21 @@
'use strict';

const {
ArrayPrototypeShift,
Error,
ErrorCaptureStackTrace,
FunctionPrototypeBind,
RegExpPrototypeSymbolReplace,
SafeMap,
StringPrototypeCharCodeAt,
StringPrototypeIncludes,
StringPrototypeReplace,
StringPrototypeSlice,
StringPrototypeSplit,
StringPrototypeStartsWith,
} = primordials;

const { Buffer } = require('buffer');
const {
isErrorStackTraceLimitWritable,
overrideStackTrace,
} = require('internal/errors');
const AssertionError = require('internal/assert/assertion_error');
const { openSync, closeSync, readSync } = require('fs');
const { EOL } = require('internal/constants');
const { BuiltinModule } = require('internal/bootstrap/realm');
const { isError } = require('internal/util');

const errorCache = new SafeMap();
const { fileURLToPath } = require('internal/url');

let parseExpressionAt;
let findNodeAround;
let tokenizer;
let decoder;
const {
getErrorSourceExpression,
} = require('internal/errors/error_source');

// Escape control characters but not \n and \t to keep the line breaks and
// indentation intact.
Expand All @@ -50,111 +33,7 @@ const meta = [

const escapeFn = (str) => meta[StringPrototypeCharCodeAt(str, 0)];

function findColumn(fd, column, code) {
if (code.length > column + 100) {
try {
return parseCode(code, column);
} catch {
// End recursion in case no code could be parsed. The expression should
// have been found after 2500 characters, so stop trying.
if (code.length - column > 2500) {
// eslint-disable-next-line no-throw-literal
throw null;
}
}
}
// Read up to 2500 bytes more than necessary in columns. That way we address
// multi byte characters and read enough data to parse the code.
const bytesToRead = column - code.length + 2500;
const buffer = Buffer.allocUnsafe(bytesToRead);
const bytesRead = readSync(fd, buffer, 0, bytesToRead);
code += decoder.write(buffer.slice(0, bytesRead));
// EOF: fast path.
if (bytesRead < bytesToRead) {
return parseCode(code, column);
}
// Read potentially missing code.
return findColumn(fd, column, code);
}

function getCode(fd, line, column) {
let bytesRead = 0;
if (line === 0) {
// Special handle line number one. This is more efficient and simplifies the
// rest of the algorithm. Read more than the regular column number in bytes
// to prevent multiple reads in case multi byte characters are used.
return findColumn(fd, column, '');
}
let lines = 0;
// Prevent blocking the event loop by limiting the maximum amount of
// data that may be read.
let maxReads = 32; // bytesPerRead * maxReads = 512 KiB
const bytesPerRead = 16384;
// Use a single buffer up front that is reused until the call site is found.
let buffer = Buffer.allocUnsafe(bytesPerRead);
while (maxReads-- !== 0) {
// Only allocate a new buffer in case the needed line is found. All data
// before that can be discarded.
buffer = lines < line ? buffer : Buffer.allocUnsafe(bytesPerRead);
bytesRead = readSync(fd, buffer, 0, bytesPerRead);
// Read the buffer until the required code line is found.
for (let i = 0; i < bytesRead; i++) {
if (buffer[i] === 10 && ++lines === line) {
// If the end of file is reached, directly parse the code and return.
if (bytesRead < bytesPerRead) {
return parseCode(buffer.toString('utf8', i + 1, bytesRead), column);
}
// Check if the read code is sufficient or read more until the whole
// expression is read. Make sure multi byte characters are preserved
// properly by using the decoder.
const code = decoder.write(buffer.slice(i + 1, bytesRead));
return findColumn(fd, column, code);
}
}
}
}

function parseCode(code, offset) {
// Lazy load acorn.
if (parseExpressionAt === undefined) {
const Parser = require('internal/deps/acorn/acorn/dist/acorn').Parser;
({ findNodeAround } = require('internal/deps/acorn/acorn-walk/dist/walk'));

parseExpressionAt = FunctionPrototypeBind(Parser.parseExpressionAt, Parser);
tokenizer = FunctionPrototypeBind(Parser.tokenizer, Parser);
}
let node;
let start;
// Parse the read code until the correct expression is found.
for (const token of tokenizer(code, { ecmaVersion: 'latest' })) {
start = token.start;
if (start > offset) {
// No matching expression found. This could happen if the assert
// expression is bigger than the provided buffer.
break;
}
try {
node = parseExpressionAt(code, start, { ecmaVersion: 'latest' });
// Find the CallExpression in the tree.
node = findNodeAround(node, offset, 'CallExpression');
if (node?.node.end >= offset) {
return [
node.node.start,
StringPrototypeReplace(StringPrototypeSlice(code,
node.node.start, node.node.end),
escapeSequencesRegExp, escapeFn),
];
}
// eslint-disable-next-line no-unused-vars
} catch (err) {
continue;
}
}
// eslint-disable-next-line no-throw-literal
throw null;
}

function getErrMessage(message, fn) {
function getErrMessage(fn) {
const tmpLimit = Error.stackTraceLimit;
const errorStackTraceLimitIsWritable = isErrorStackTraceLimitWritable();
// Make sure the limit is set to 1. Otherwise it could fail (<= 0) or it
Expand All @@ -166,85 +45,10 @@ function getErrMessage(message, fn) {
ErrorCaptureStackTrace(err, fn);
if (errorStackTraceLimitIsWritable) Error.stackTraceLimit = tmpLimit;

overrideStackTrace.set(err, (_, stack) => stack);
const call = err.stack[0];

let filename = call.getFileName();
const line = call.getLineNumber() - 1;
let column = call.getColumnNumber() - 1;
let identifier;

if (filename) {
identifier = `${filename}${line}${column}`;

// Skip Node.js modules!
if (StringPrototypeStartsWith(filename, 'node:') &&
BuiltinModule.exists(StringPrototypeSlice(filename, 5))) {
errorCache.set(identifier, undefined);
return;
}
} else {
return message;
}

if (errorCache.has(identifier)) {
return errorCache.get(identifier);
}

let fd;
try {
// Set the stack trace limit to zero. This makes sure unexpected token
// errors are handled faster.
if (errorStackTraceLimitIsWritable) Error.stackTraceLimit = 0;

if (decoder === undefined) {
const { StringDecoder } = require('string_decoder');
decoder = new StringDecoder('utf8');
}

// ESM file prop is a file proto. Convert that to path.
// This ensure opensync will not throw ENOENT for ESM files.
const fileProtoPrefix = 'file://';
if (StringPrototypeStartsWith(filename, fileProtoPrefix)) {
filename = fileURLToPath(filename);
}

fd = openSync(filename, 'r', 0o666);
// Reset column and message.
({ 0: column, 1: message } = getCode(fd, line, column));
// Flush unfinished multi byte characters.
decoder.end();

// Always normalize indentation, otherwise the message could look weird.
if (StringPrototypeIncludes(message, '\n')) {
if (EOL === '\r\n') {
message = RegExpPrototypeSymbolReplace(/\r\n/g, message, '\n');
}
const frames = StringPrototypeSplit(message, '\n');
message = ArrayPrototypeShift(frames);
for (let i = 0; i < frames.length; i++) {
const frame = frames[i];
let pos = 0;
while (pos < column && (frame[pos] === ' ' || frame[pos] === '\t')) {
pos++;
}
message += `\n ${StringPrototypeSlice(frame, pos)}`;
}
}
message = `The expression evaluated to a falsy value:\n\n ${message}\n`;
// Make sure to always set the cache! No matter if the message is
// undefined or not
errorCache.set(identifier, message);

return message;
} catch {
// Invalidate cache to prevent trying to read this part again.
errorCache.set(identifier, undefined);
} finally {
// Reset limit.
if (errorStackTraceLimitIsWritable) Error.stackTraceLimit = tmpLimit;
if (fd !== undefined)
closeSync(fd);
let source = getErrorSourceExpression(err);
if (source) {
source = StringPrototypeReplace(source, escapeSequencesRegExp, escapeFn);
return `The expression evaluated to a falsy value:\n\n ${source}\n`;
}
}

Expand All @@ -257,7 +61,7 @@ function innerOk(fn, argLen, value, message) {
message = 'No value argument passed to `assert.ok()`';
} else if (message == null) {
generatedMessage = true;
message = getErrMessage(message, fn);
message = getErrMessage(fn);
} else if (isError(message)) {
throw message;
}
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