131 lines
4.2 KiB
JavaScript
131 lines
4.2 KiB
JavaScript
// this entire module is depressing. i should have spent my time learning
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// how to patch v8 so that these options would just be available on the
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// process object.
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const os = require('os');
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const fs = require('fs');
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const path = require('path');
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const execFile = require('child_process').execFile;
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const env = process.env;
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const user = env.LOGNAME || env.USER || env.LNAME || env.USERNAME;
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const configfile = '.v8flags.'+process.versions.v8+'.'+user+'.json';
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const exclusions = ['--help'];
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const failureMessage = [
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'Unable to cache a config file for v8flags to a your home directory',
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'or a temporary folder. To fix this problem, please correct your',
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'environment by setting HOME=/path/to/home or TEMP=/path/to/temp.',
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'NOTE: the user running this must be able to access provided path.',
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'If all else fails, please open an issue here:',
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'http://github.com/tkellen/js-v8flags'
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].join('\n');
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function fail (err) {
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err.message += '\n\n' + failureMessage;
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return err;
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}
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function openConfig (cb) {
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var userHome = require('user-home');
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if (!userHome) {
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return tryOpenConfig(path.join(os.tmpdir(), configfile), cb);
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}
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tryOpenConfig(path.join(userHome, configfile), function (err, fd) {
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if (err) return tryOpenConfig(path.join(os.tmpdir(), configfile), cb);
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return cb(null, fd);
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});
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}
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function tryOpenConfig (configpath, cb) {
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try {
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// if the config file is valid, it should be json and therefore
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// node should be able to require it directly. if this doesn't
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// throw, we're done!
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content = require(configpath);
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process.nextTick(function () {
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cb(null, content);
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});
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} catch (e) {
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// if requiring the config file failed, maybe it doesn't exist, or
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// perhaps it has become corrupted. instead of calling back with the
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// content of the file, call back with a file descriptor that we can
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// write the cached data to
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fs.open(configpath, 'w+', function (err, fd) {
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if (err) {
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return cb(err);
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}
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return cb(null, fd);
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});
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}
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}
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// i can't wait for the day this whole module is obsolete because these
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// options are available on the process object. this executes node with
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// `--v8-options` and parses the result, returning an array of command
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// line flags.
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function getFlags (cb) {
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execFile(process.execPath, ['--v8-options'], function (execErr, result) {
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if (execErr) {
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return cb(execErr);
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}
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var flags = result.match(/\s\s--(\w+)/gm).map(function (match) {
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return match.substring(2);
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}).filter(function (name) {
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return exclusions.indexOf(name) === -1;
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});
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return cb(null, flags);
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});
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}
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// write some json to a file descriptor. if this fails, call back
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// with both the error and the data that was meant to be written.
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function writeConfig (fd, flags, cb) {
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var buf = new Buffer(JSON.stringify(flags));
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return fs.write(fd, buf, 0, buf.length, 0 , function (writeErr) {
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fs.close(fd, function (closeErr) {
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var err = writeErr || closeErr;
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if (err) {
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return cb(fail(err), flags);
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}
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return cb(null, flags);
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});
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});
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}
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module.exports = function (cb) {
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// bail early if this is not node
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var isElectron = process.versions && process.versions.electron;
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if (isElectron) {
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return process.nextTick(function () {
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cb(null, []);
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});
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}
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// attempt to open/read cache file
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openConfig(function (openErr, result) {
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if (!openErr && typeof result !== 'number') {
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return cb(null, result);
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}
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// if the result is not an array, we need to go fetch
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// the flags by invoking node with `--v8-options`
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getFlags(function (flagsErr, flags) {
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// if there was an error fetching the flags, bail immediately
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if (flagsErr) {
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return cb(flagsErr);
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}
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// if there was a problem opening the config file for writing
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// throw an error but include the flags anyway so that users
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// can continue to execute (at the expense of having to fetch
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// flags on every run until they fix the underyling problem).
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if (openErr) {
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return cb(fail(openErr), flags);
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}
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// write the config file to disk so subsequent runs can read
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// flags out of a cache file.
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return writeConfig(result, flags, cb);
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});
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});
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};
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module.exports.configfile = configfile;
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