errname.js

'use strict';
// Older verions of Node.js might not have `util.getSystemErrorName()`.
// In that case, fall back to a deprecated internal.
const util = require('util');

let uv;

if (typeof util.getSystemErrorName === 'function') {
	module.exports = util.getSystemErrorName;
} else {
	try {
		uv = process.binding('uv');

		if (typeof uv.errname !== 'function') {
			throw new TypeError('uv.errname is not a function');
		}
	} catch (err) {
		console.error('execa/lib/errname: unable to establish process.binding(\'uv\')', err);
		uv = null;
	}

	module.exports = code => errname(uv, code);
}

// Used for testing the fallback behavior
module.exports.__test__ = errname;

function errname(uv, code) {
	if (uv) {
		return uv.errname(code);
	}

	if (!(code < 0)) {
		throw new Error('err >= 0');
	}

	return `Unknown system error ${code}`;
}