errors: move error creation helpers to errors.js

This commit moves error creation helpers scattered around
under lib/ into lib/internal/errors.js in the hope of being clearer
about the differences of errors that we throw into the user land.

- Move util._errnoException and util._exceptionWithHostPort
  into internal/errors.js and simplify their logic so it's
  clearer what the properties these helpers create.
- Move the errnoException helper in dns.js to internal/errors.js
  into internal/errors.js and rename it to dnsException. Simplify
  it's logic so it no longer calls errnoException and skips
  the unnecessary argument checks.

PR-URL: #18546
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/dgram.js

@@ -45,8 +45,8 @@ const SEND_BUFFER = false;
 // Lazily loaded
 var cluster = null;
 
-const errnoException = util._errnoException;
-const exceptionWithHostPort = util._exceptionWithHostPort;
+const errnoException = errors.errnoException;
+const exceptionWithHostPort = errors.exceptionWithHostPort;
 
 
 function lookup4(lookup, address, callback) {

lib/dns.js

@@ -21,12 +21,10 @@
 
 'use strict';
 
-const util = require('util');
-
 const cares = process.binding('cares_wrap');
-const uv = process.binding('uv');
 const { isLegalPort } = require('internal/net');
 const { customPromisifyArgs } = require('internal/util');
+const errors = require('internal/errors');
 
 const {
   GetAddrInfoReqWrap,
@@ -36,30 +34,6 @@ const {
   isIP
 } = cares;
 
-function errnoException(err, syscall, hostname) {
-  // FIXME(bnoordhuis) Remove this backwards compatibility nonsense and pass
-  // the true error to the user. ENOTFOUND is not even a proper POSIX error!
-  if (err === uv.UV_EAI_MEMORY ||
-      err === uv.UV_EAI_NODATA ||
-      err === uv.UV_EAI_NONAME) {
-    err = 'ENOTFOUND';
-  }
-  var ex = null;
-  if (typeof err === 'string') {  // c-ares error code.
-    const errHost = hostname ? ` ${hostname}` : '';
-    ex = new Error(`${syscall} ${err}${errHost}`);
-    ex.code = err;
-    ex.errno = err;
-    ex.syscall = syscall;
-  } else {
-    ex = util._errnoException(err, syscall);
-  }
-  if (hostname) {
-    ex.hostname = hostname;
-  }
-  return ex;
-}
-
 const IANA_DNS_PORT = 53;
 const digits = [
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0-15
@@ -86,10 +60,11 @@ function isIPv4(str) {
   return (str.length > 3 && str.charCodeAt(3) === 46/*'.'*/);
 }
 
+const dnsException = errors.dnsException;
 
 function onlookup(err, addresses) {
   if (err) {
-    return this.callback(errnoException(err, 'getaddrinfo', this.hostname));
+    return this.callback(dnsException(err, 'getaddrinfo', this.hostname));
   }
   if (this.family) {
     this.callback(null, addresses[0], this.family);
@@ -101,7 +76,7 @@ function onlookup(err, addresses) {
 
 function onlookupall(err, addresses) {
   if (err) {
-    return this.callback(errnoException(err, 'getaddrinfo', this.hostname));
+    return this.callback(dnsException(err, 'getaddrinfo', this.hostname));
   }
 
   var family = this.family;
@@ -181,7 +156,7 @@ function lookup(hostname, options, callback) {
 
   var err = cares.getaddrinfo(req, hostname, family, hints, verbatim);
   if (err) {
-    process.nextTick(callback, errnoException(err, 'getaddrinfo', hostname));
+    process.nextTick(callback, dnsException(err, 'getaddrinfo', hostname));
     return {};
   }
   return req;
@@ -193,7 +168,7 @@ Object.defineProperty(lookup, customPromisifyArgs,
 
 function onlookupservice(err, host, service) {
   if (err)
-    return this.callback(errnoException(err, 'getnameinfo', this.host));
+    return this.callback(dnsException(err, 'getnameinfo', this.host));
 
   this.callback(null, host, service);
 }
@@ -222,7 +197,7 @@ function lookupService(host, port, callback) {
   req.oncomplete = onlookupservice;
 
   var err = cares.getnameinfo(req, host, port);
-  if (err) throw errnoException(err, 'getnameinfo', host);
+  if (err) throw dnsException(err, 'getnameinfo', host);
   return req;
 }
 
@@ -235,7 +210,7 @@ function onresolve(err, result, ttls) {
     result = result.map((address, index) => ({ address, ttl: ttls[index] }));
 
   if (err)
-    this.callback(errnoException(err, this.bindingName, this.hostname));
+    this.callback(dnsException(err, this.bindingName, this.hostname));
   else
     this.callback(null, result);
 }
@@ -272,7 +247,7 @@ function resolver(bindingName) {
     req.oncomplete = onresolve;
     req.ttl = !!(options && options.ttl);
     var err = this._handle[bindingName](req, name);
-    if (err) throw errnoException(err, bindingName);
+    if (err) throw dnsException(err, bindingName);
     return req;
   }
   Object.defineProperty(query, 'name', { value: bindingName });

lib/fs.js

@@ -59,7 +59,7 @@ const { kMaxLength } = require('buffer');
 const isWindows = process.platform === 'win32';
 
 const DEBUG = process.env.NODE_DEBUG && /fs/.test(process.env.NODE_DEBUG);
-const errnoException = util._errnoException;
+const errnoException = errors.errnoException;
 
 function getOptions(options, defaultOptions) {
   if (options === null || options === undefined ||

lib/internal/child_process.js

@@ -18,7 +18,7 @@ const SocketList = require('internal/socket_list');
 const { convertToValidSignal } = require('internal/util');
 const { isUint8Array } = require('internal/util/types');
 
-const errnoException = util._errnoException;
+const errnoException = errors.errnoException;
 const { SocketListSend, SocketListReceive } = SocketList;
 
 const MAX_HANDLE_RETRANSMISSIONS = 3;

lib/internal/errors.js

@@ -11,6 +11,11 @@
 const kCode = Symbol('code');
 const messages = new Map();
 
+const {
+  UV_EAI_MEMORY,
+  UV_EAI_NODATA,
+  UV_EAI_NONAME
+} = process.binding('uv');
 const { defineProperty } = Object;
 
 // Lazily loaded
@@ -22,6 +27,14 @@ function lazyUtil() {
   return util_;
 }
 
+var internalUtil = null;
+function lazyInternalUtil() {
+  if (!internalUtil) {
+    internalUtil = require('internal/util');
+  }
+  return internalUtil;
+}
+
 function makeNodeError(Base) {
   return class NodeError extends Base {
     constructor(key, ...args) {
@@ -125,7 +138,110 @@ function E(sym, val) {
   messages.set(sym, typeof val === 'function' ? val : String(val));
 }
 
+/**
+ * This used to be util._errnoException().
+ *
+ * @param {number} err - A libuv error number
+ * @param {string} syscall
+ * @param {string} [original]
+ * @returns {Error}
+ */
+function errnoException(err, syscall, original) {
+  // TODO(joyeecheung): We have to use the type-checked
+  // getSystemErrorName(err) to guard against invalid arguments from users.
+  // This can be replaced with [ code ] = errmap.get(err) when this method
+  // is no longer exposed to user land.
+  const code = lazyUtil().getSystemErrorName(err);
+  const message = original ?
+    `${syscall} ${code} ${original}` : `${syscall} ${code}`;
+
+  const ex = new Error(message);
+  // TODO(joyeecheung): errno is supposed to err, like in uvException
+  ex.code = ex.errno = code;
+  ex.syscall = syscall;
+
+  Error.captureStackTrace(ex, errnoException);
+  return ex;
+}
+
+/**
+ * This used to be util._exceptionWithHostPort().
+ *
+ * @param {number} err - A libuv error number
+ * @param {string} syscall
+ * @param {string} address
+ * @param {number} [port]
+ * @param {string} [additional]
+ * @returns {Error}
+ */
+function exceptionWithHostPort(err, syscall, address, port, additional) {
+  // TODO(joyeecheung): We have to use the type-checked
+  // getSystemErrorName(err) to guard against invalid arguments from users.
+  // This can be replaced with [ code ] = errmap.get(err) when this method
+  // is no longer exposed to user land.
+  const code = lazyUtil().getSystemErrorName(err);
+  let details = '';
+  if (port && port > 0) {
+    details = ` ${address}:${port}`;
+  } else if (address) {
+    details = ` ${address}`;
+  }
+  if (additional) {
+    details += ` - Local (${additional})`;
+  }
+
+  const ex = new Error(`${syscall} ${code}${details}`);
+  // TODO(joyeecheung): errno is supposed to err, like in uvException
+  ex.code = ex.errno = code;
+  ex.syscall = syscall;
+  ex.address = address;
+  if (port) {
+    ex.port = port;
+  }
+
+  Error.captureStackTrace(ex, exceptionWithHostPort);
+  return ex;
+}
+
+/**
+ * @param {number|string} err - A libuv error number or a c-ares error code
+ * @param {string} syscall
+ * @param {string} [hostname]
+ * @returns {Error}
+ */
+function dnsException(err, syscall, hostname) {
+  const ex = new Error();
+  // FIXME(bnoordhuis) Remove this backwards compatibility nonsense and pass
+  // the true error to the user. ENOTFOUND is not even a proper POSIX error!
+  if (err === UV_EAI_MEMORY ||
+      err === UV_EAI_NODATA ||
+      err === UV_EAI_NONAME) {
+    err = 'ENOTFOUND';  // Fabricated error name.
+  }
+  if (typeof err === 'string') {  // c-ares error code.
+    const errHost = hostname ? ` ${hostname}` : '';
+    ex.message = `${syscall} ${err}${errHost}`;
+    // TODO(joyeecheung): errno is supposed to be a number, like in uvException
+    ex.code = ex.errno = err;
+    ex.syscall = syscall;
+  } else {  // libuv error number
+    const code = lazyInternalUtil().getSystemErrorName(err);
+    ex.message = `${syscall} ${code}`;
+    // TODO(joyeecheung): errno is supposed to be err, like in uvException
+    ex.code = ex.errno = code;
+    ex.syscall = syscall;
+  }
+  if (hostname) {
+    ex.hostname = hostname;
+  }
+  Error.captureStackTrace(ex, dnsException);
+  return ex;
+}
+
 module.exports = exports = {
+  dnsException,
+  errnoException,
+  exceptionWithHostPort,
   message,
   Error: makeNodeError(Error),
   TypeError: makeNodeError(TypeError),

lib/internal/http2/core.js

@@ -1647,7 +1647,7 @@ class Http2Stream extends Duplex {
     req.async = false;
     const err = createWriteReq(req, handle, data, encoding);
     if (err)
-      return this.destroy(util._errnoException(err, 'write', req.error), cb);
+      return this.destroy(errors.errnoException(err, 'write', req.error), cb);
     trackWriteState(this, req.bytes);
   }
 
@@ -1690,7 +1690,7 @@ class Http2Stream extends Duplex {
     }
     const err = handle.writev(req, chunks);
     if (err)
-      return this.destroy(util._errnoException(err, 'write', req.error), cb);
+      return this.destroy(errors.errnoException(err, 'write', req.error), cb);
     trackWriteState(this, req.bytes);
   }
 

lib/internal/process.js

@@ -1,5 +1,6 @@
 'use strict';
 
+const errors = require('internal/errors');
 const util = require('util');
 const constants = process.binding('constants').os.signals;
 
@@ -180,7 +181,7 @@ function setupKillAndExit() {
     }
 
     if (err)
-      throw util._errnoException(err, 'kill');
+      throw errors.errnoException(err, 'kill');
 
     return true;
   };
@@ -211,7 +212,7 @@ function setupSignalHandlers() {
       const err = wrap.start(signum);
       if (err) {
         wrap.close();
-        throw util._errnoException(err, 'uv_signal_start');
+        throw errors.errnoException(err, 'uv_signal_start');
       }
 
       signalWraps[type] = wrap;

lib/net.js

@@ -48,8 +48,8 @@ const dns = require('dns');
 // reasons it's lazy loaded.
 var cluster = null;
 
-const errnoException = util._errnoException;
-const exceptionWithHostPort = util._exceptionWithHostPort;
+const errnoException = errors.errnoException;
+const exceptionWithHostPort = errors.exceptionWithHostPort;
 
 function noop() {}
 

lib/tty.js

@@ -21,11 +21,9 @@
 
 'use strict';
 
-const util = require('util');
+const { inherits, _extend } = require('util');
 const net = require('net');
 const { TTY, isTTY } = process.binding('tty_wrap');
-const { inherits } = util;
-const errnoException = util._errnoException;
 const errors = require('internal/errors');
 const readline = require('readline');
 
@@ -40,7 +38,7 @@ function ReadStream(fd, options) {
   if (fd >> 0 !== fd || fd < 0)
     throw new errors.RangeError('ERR_INVALID_FD', fd);
 
-  options = util._extend({
+  options = _extend({
     highWaterMark: 0,
     readable: true,
     writable: false,
@@ -99,7 +97,7 @@ WriteStream.prototype._refreshSize = function() {
   var winSize = new Array(2);
   var err = this._handle.getWindowSize(winSize);
   if (err) {
-    this.emit('error', errnoException(err, 'getWindowSize'));
+    this.emit('error', errors.errnoException(err, 'getWindowSize'));
     return;
   }
   var newCols = winSize[0];