From 45b1eebe6a4a4cf2487344e6467c92a18d972bb2 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Tue, 9 Jun 2015 17:59:42 -0700
Subject: [PATCH] [fix] Get `tailFile` function working on latest/all node
 versions

---
 lib/winston/common.js | 119 +++++++++++++++++++++++++++++-------------
 1 file changed, 84 insertions(+), 35 deletions(-)

diff --git a/lib/winston/common.js b/lib/winston/common.js
index e201c697c..7351b11cc 100644
--- a/lib/winston/common.js
+++ b/lib/winston/common.js
@@ -10,6 +10,8 @@ var util = require('util'),
     crypto = require('crypto'),
     cycle = require('cycle'),
     fs = require('fs'),
+    StringDecoder = require('string_decoder').StringDecoder,
+    Stream = require('stream').Stream,
     config = require('./config');
 
 //
@@ -337,60 +339,107 @@ exports.serialize = function (obj, key) {
   return msg;
 };
 
-
 //
 // ### function tailFile (options, callback)
 // #### @options {Object} Options for tail.
 // #### @callback {function} Callback to execute on every line.
 // `tail -f` a file. Options must include file.
 //
-exports.tailFile = function tail(options, callback) {
-  var stream = fs.createReadStream(options.file, { encoding: 'utf8' }),
-      buff = '',
-      destroy,
-      row = 0;
-
-  destroy = stream.destroy.bind(stream);
-  stream.destroy = function () {};
+exports.tailFile = function(options, callback) {
+  var buffer = new Buffer(64 * 1024)
+    , decode = new StringDecoder('utf8')
+    , stream = new Stream
+    , buff = ''
+    , pos = 0
+    , row = 0;
 
   if (options.start === -1) {
     delete options.start;
   }
 
-  stream.on('data', function (data) {
-    var data = (buff + data).split(/\n+/),
-        l = data.length - 1,
-        i = 0;
-
-    for (; i < l; i++) {
-      if (options.start == null || row > options.start) {
-        callback(null, data[i]);
+  stream.readable = true;
+  stream.destroy = function() {
+    stream.destroyed = true;
+    stream.emit('end');
+    stream.emit('close');
+  };
+
+  fs.open(options.file, 'a+', 0644, function(err, fd) {
+    if (err) {
+      if (!callback) {
+        stream.emit('error', err);
+      } else {
+        callback(err);
       }
-      row++;
+      stream.destroy();
+      return;
     }
 
-    buff = data[l];
-  });
+    (function read() {
+      if (stream.destroyed) {
+        fs.close(fd);
+        return;
+      }
 
-  stream.on('error', function (err) {
-    callback(err);
-    destroy();
-  });
+      return fs.read(fd, buffer, 0, buffer.length, pos, function(err, bytes) {
+        if (err) {
+          if (!callback) {
+            stream.emit('error', err);
+          } else {
+            callback(err);
+          }
+          stream.destroy();
+          return;
+        }
 
-  stream.on('end', function () {
-    if (buff) {
-      stream.emit('line', buff);
-      buff = '';
-    }
+        if (!bytes) {
+          if (buff) {
+            if (options.start == null || row > options.start) {
+              if (!callback) {
+                stream.emit('line', buff);
+              } else {
+                callback(null, buff);
+              }
+            }
+            row++;
+            buff = '';
+          }
+          return setTimeout(read, 1000);
+        }
+
+        var data = decode.write(buffer.slice(0, bytes));
+
+        if (!callback) {
+          stream.emit('data', data);
+        }
+
+        var data = (buff + data).split(/\n+/)
+          , l = data.length - 1
+          , i = 0;
+
+        for (; i < l; i++) {
+          if (options.start == null || row > options.start) {
+            if (!callback) {
+              stream.emit('line', data[i]);
+            } else {
+              callback(null, data[i]);
+            }
+          }
+          row++;
+        }
+
+        buff = data[l];
+
+        pos += bytes;
 
-    resume();
+        return read();
+      });
+    })();
   });
 
-  function resume() {
-    setTimeout(function () {
-      stream.resume();
-    }, 1000);
+  if (!callback) {
+    return stream;
   }
 
-  return destroy;
+  return stream.destroy;
 };