fs: replace duplicate conditions by function

PR-URL: #18717
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/fs.js

@@ -145,6 +145,12 @@ function isFd(path) {
 
 fs.Stats = Stats;
 
+function isFileType(fileType) {
+  // Use stats array directly to avoid creating an fs.Stats instance just for
+  // our internal use.
+  return (statValues[1/*mode*/] & S_IFMT) === fileType;
+}
+
 // Don't allow mode to accidentally be overwritten.
 Object.defineProperties(fs, {
   F_OK: { enumerable: true, value: constants.F_OK || 0 },
@@ -317,10 +323,8 @@ function readFileAfterStat(err) {
   if (err)
     return context.close(err);
 
-  // Use stats array directly to avoid creating an fs.Stats instance just for
-  // our internal use.
   var size;
-  if ((statValues[1/*mode*/] & S_IFMT) === S_IFREG)
+  if (isFileType(S_IFREG))
     size = context.size = statValues[8];
   else
     size = context.size = 0;
@@ -432,10 +436,8 @@ fs.readFileSync = function(path, options) {
   var fd = isUserFd ? path : fs.openSync(path, options.flag || 'r', 0o666);
 
   tryStatSync(fd, isUserFd);
-  // Use stats array directly to avoid creating an fs.Stats instance just for
-  // our internal use.
   var size;
-  if ((statValues[1/*mode*/] & S_IFMT) === S_IFREG)
+  if (isFileType(S_IFREG))
     size = statValues[8];
   else
     size = 0;
@@ -1604,8 +1606,7 @@ fs.realpathSync = function realpathSync(p, options) {
 
     // continue if not a symlink, break if a pipe/socket
     if (knownHard[base] || (cache && cache.get(base) === base)) {
-      if ((statValues[1/*mode*/] & S_IFMT) === S_IFIFO ||
-          (statValues[1/*mode*/] & S_IFMT) === S_IFSOCK) {
+      if (isFileType(S_IFIFO) || isFileType(S_IFSOCK)) {
         break;
       }
       continue;
@@ -1624,7 +1625,7 @@ fs.realpathSync = function realpathSync(p, options) {
       binding.lstat(baseLong, undefined, ctx);
       handleErrorFromBinding(ctx);
 
-      if ((statValues[1/*mode*/] & S_IFMT) !== S_IFLNK) {
+      if (!isFileType(S_IFLNK)) {
         knownHard[base] = true;
         if (cache) cache.set(base, base);
         continue;
@@ -1750,8 +1751,7 @@ fs.realpath = function realpath(p, options, callback) {
 
     // continue if not a symlink, break if a pipe/socket
     if (knownHard[base]) {
-      if ((statValues[1/*mode*/] & S_IFMT) === S_IFIFO ||
-          (statValues[1/*mode*/] & S_IFMT) === S_IFSOCK) {
+      if (isFileType(S_IFIFO) || isFileType(S_IFSOCK)) {
         return callback(null, encodeRealpathResult(p, options));
       }
       return process.nextTick(LOOP);
@@ -1767,7 +1767,7 @@ fs.realpath = function realpath(p, options, callback) {
     // our internal use.
 
     // if not a symlink, skip to the next path part
-    if ((statValues[1/*mode*/] & S_IFMT) !== S_IFLNK) {
+    if (!isFileType(S_IFLNK)) {
       knownHard[base] = true;
       return process.nextTick(LOOP);
     }