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process: add lineLength to source-map-cache

Without the line lengths of in-memory transpiled source, it's not
possible to convert from byte ofsets to line/column offsets.

PR-URL: #29863
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
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bcoe authored and targos committed Oct 6, 2019
1 parent 735ec1b commit 62bc80c906be8bd8ec02442c7a52e208b91a08a5
@@ -1199,8 +1199,9 @@ If found, Source Map data is appended to the top-level key `source-map-cache`
on the JSON coverage object.

`source-map-cache` is an object with keys representing the files source maps
were extracted from, and the values include the raw source-map URL
(in the key `url`) and the parsed Source Map V3 information (in the key `data`).
were extracted from, and values which include the raw source-map URL
(in the key `url`), the parsed Source Map V3 information (in the key `data`),
and the line lengths of the source file (in the key `lineLengths`).

```json
{
@@ -1226,7 +1227,13 @@ were extracted from, and the values include the raw source-map URL
],
"mappings": "MAAMA,IACJC,YAAaC",
"sourceRoot": "./"
}
},
"lineLengths": [
13,
62,
38,
27
]
}
}
}
@@ -25,7 +25,7 @@ function prepareMainThreadExecution(expandArgv1 = false) {
// prepareStackTrace method, replacing the default in errors.js.
if (getOptionValue('--enable-source-maps')) {
const { prepareStackTrace } =
require('internal/source_map/source_map_cache');
require('internal/source_map/prepare_stack_trace');
const { setPrepareStackTraceCallback } = internalBinding('errors');
setPrepareStackTraceCallback(prepareStackTrace);
}
@@ -0,0 +1,52 @@
'use strict';

const debug = require('internal/util/debuglog').debuglog('source_map');
const { findSourceMap } = require('internal/source_map/source_map_cache');
const { overrideStackTrace } = require('internal/errors');

// Create a prettified stacktrace, inserting context from source maps
// if possible.
const ErrorToString = Error.prototype.toString; // Capture original toString.
const prepareStackTrace = (globalThis, error, trace) => {
// API for node internals to override error stack formatting
// without interfering with userland code.
// TODO(bcoe): add support for source-maps to repl.
if (overrideStackTrace.has(error)) {
const f = overrideStackTrace.get(error);
overrideStackTrace.delete(error);
return f(error, trace);
}

const { SourceMap } = require('internal/source_map/source_map');
const errorString = ErrorToString.call(error);

if (trace.length === 0) {
return errorString;
}
const preparedTrace = trace.map((t, i) => {
let str = i !== 0 ? '\n at ' : '';
str = `${str}${t}`;
try {
const sourceMap = findSourceMap(t.getFileName(), error);
if (sourceMap && sourceMap.data) {
const sm = new SourceMap(sourceMap.data);
// Source Map V3 lines/columns use zero-based offsets whereas, in
// stack traces, they start at 1/1.
const [, , url, line, col] =
sm.findEntry(t.getLineNumber() - 1, t.getColumnNumber() - 1);
if (url && line !== undefined && col !== undefined) {
str +=
`\n -> ${url.replace('file://', '')}:${line + 1}:${col + 1}`;
}
}
} catch (err) {
debug(err.stack);
}
return str;
});
return `${errorString}\n at ${preparedTrace.join('')}`;
};

module.exports = {
prepareStackTrace,
};
@@ -17,7 +17,6 @@ const cjsSourceMapCache = new WeakMap();
// on filenames.
const esmSourceMapCache = new Map();
const { fileURLToPath, URL } = require('url');
const { overrideStackTrace } = require('internal/errors');

let experimentalSourceMaps;
function maybeCacheSourceMap(filename, content, cjsModuleInstance) {
@@ -38,18 +37,22 @@ function maybeCacheSourceMap(filename, content, cjsModuleInstance) {

const match = content.match(/\/[*/]#\s+sourceMappingURL=(?<sourceMappingURL>[^\s]+)/);
if (match) {
const data = dataFromUrl(basePath, match.groups.sourceMappingURL);
const url = data ? null : match.groups.sourceMappingURL;
if (cjsModuleInstance) {
cjsSourceMapCache.set(cjsModuleInstance, {
filename,
url: match.groups.sourceMappingURL,
data: dataFromUrl(basePath, match.groups.sourceMappingURL)
lineLengths: lineLengths(content),
data,
url
});
} else {
// If there is no cjsModuleInstance assume we are in a
// "modules/esm" context.
esmSourceMapCache.set(filename, {
url: match.groups.sourceMappingURL,
data: dataFromUrl(basePath, match.groups.sourceMappingURL)
lineLengths: lineLengths(content),
data,
url
});
}
}
@@ -73,6 +76,18 @@ function dataFromUrl(basePath, sourceMappingURL) {
}
}

// Cache the length of each line in the file that a source map was extracted
// from. This allows translation from byte offset V8 coverage reports,
// to line/column offset Source Map V3.
function lineLengths(content) {
// We purposefully keep \r as part of the line-length calculation, in
// cases where there is a \r\n separator, so that this can be taken into
// account in coverage calculations.
return content.split(/\n|\u2028|\u2029/).map((line) => {
return line.length;
});
}

function sourceMapFromFile(sourceMapFile) {
try {
const content = fs.readFileSync(sourceMapFile, 'utf8');
@@ -161,56 +176,14 @@ function appendCJSCache(obj) {
const value = cjsSourceMapCache.get(Module._cache[key]);
if (value) {
obj[`file://${key}`] = {
url: value.url,
data: value.data
lineLengths: value.lineLengths,
data: value.data,
url: value.url
};
}
});
}

// Create a prettified stacktrace, inserting context from source maps
// if possible.
const ErrorToString = Error.prototype.toString; // Capture original toString.
const prepareStackTrace = (globalThis, error, trace) => {
// API for node internals to override error stack formatting
// without interfering with userland code.
// TODO(bcoe): add support for source-maps to repl.
if (overrideStackTrace.has(error)) {
const f = overrideStackTrace.get(error);
overrideStackTrace.delete(error);
return f(error, trace);
}

const { SourceMap } = require('internal/source_map/source_map');
const errorString = ErrorToString.call(error);

if (trace.length === 0) {
return errorString;
}
const preparedTrace = trace.map((t, i) => {
let str = i !== 0 ? '\n at ' : '';
str = `${str}${t}`;
try {
const sourceMap = findSourceMap(t.getFileName(), error);
if (sourceMap && sourceMap.data) {
const sm = new SourceMap(sourceMap.data);
// Source Map V3 lines/columns use zero-based offsets whereas, in
// stack traces, they start at 1/1.
const [, , url, line, col] =
sm.findEntry(t.getLineNumber() - 1, t.getColumnNumber() - 1);
if (url && line !== undefined && col !== undefined) {
str +=
`\n -> ${url.replace('file://', '')}:${line + 1}:${col + 1}`;
}
}
} catch (err) {
debug(err.stack);
}
return str;
});
return `${errorString}\n at ${preparedTrace.join('')}`;
};

// Attempt to lookup a source map, which is either attached to a file URI, or
// keyed on an error instance.
function findSourceMap(uri, error) {
@@ -230,8 +203,8 @@ function findSourceMap(uri, error) {
}

module.exports = {
findSourceMap,
maybeCacheSourceMap,
prepareStackTrace,
rekeySourceMap,
sourceMapCacheToObject,
};
@@ -176,6 +176,7 @@
'lib/internal/repl/history.js',
'lib/internal/repl/utils.js',
'lib/internal/socket_list.js',
'lib/internal/source_map/prepare_stack_trace.js',
'lib/internal/source_map/source_map.js',
'lib/internal/source_map/source_map_cache.js',
'lib/internal/test/binding.js',
@@ -193,6 +193,36 @@ function nextdir() {
);
}

// Does not persist url parameter if source-map has been parsed.
{
const coverageDirectory = nextdir();
spawnSync(process.execPath, [
require.resolve('../fixtures/source-map/inline-base64.js')
], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
const sourceMap = getSourceMapFromCache(
'inline-base64.js',
coverageDirectory
);
assert.strictEqual(sourceMap.url, null);
}

// Persists line lengths for in-memory representation of source file.
{
const coverageDirectory = nextdir();
spawnSync(process.execPath, [
require.resolve('../fixtures/source-map/istanbul-throw.js')
], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
const sourceMap = getSourceMapFromCache(
'istanbul-throw.js',
coverageDirectory
);
if (common.isWindows) {
assert.deepStrictEqual(sourceMap.lineLengths, [1086, 31, 185, 649, 0]);
} else {
assert.deepStrictEqual(sourceMap.lineLengths, [1085, 30, 184, 648, 0]);
}
}

function getSourceMapFromCache(fixtureFile, coverageDirectory) {
const jsonFiles = fs.readdirSync(coverageDirectory);
for (const jsonFile of jsonFiles) {

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