From d73050abc267082b41b7380d7b7083cab273e96b Mon Sep 17 00:00:00 2001
From: Mita Lapo <mitalapo@gmail.com>
Date: Tue, 18 May 2021 13:14:40 +0300
Subject: [PATCH 1/3] support reading from a pipe, such as stdin

---
 example.js   | 11 ++++++++---
 readlines.js | 19 +++++++++++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/example.js b/example.js
index 8df4045..2c38624 100644
--- a/example.js
+++ b/example.js
@@ -1,14 +1,19 @@
 'use strict';
 
 const lineByLine = require('./readlines.js');
-const liner = new lineByLine('./test/fixtures/normalFile.txt');
+
+const fname = process.argv.length > 2 ? process.argv[2] : './test/fixtures/normalFile.txt';
+const enc   = process.argv.length > 3 ? process.argv[3] : 'ascii';
+console.log('Reading', enc, 'encoded file', fname);
+
+const liner = new lineByLine(fname === '-' ? 0 : fname);
 
 let line;
 let lineNumber = 0;
 
 while (line = liner.next()) {
-    console.log('Line ' + lineNumber + ': ' + line.toString('ascii'));
+    console.log('Line ' + lineNumber + ': ' + line.toString(enc));
     lineNumber++;
 }
 
-console.log('end of line reached');
+console.log('end of file reached');
diff --git a/readlines.js b/readlines.js
index 6b8bdc1..1b420f5 100644
--- a/readlines.js
+++ b/readlines.js
@@ -47,6 +47,7 @@ class LineByLine {
     reset() {
         this.eofReached = false;
         this.linesCache = [];
+        this.seekable = true;
         this.fdPosition = 0;
     }
 
@@ -87,9 +88,18 @@ class LineByLine {
         let bytesRead;
         const buffers = [];
         do {
-            const readBuffer = new Buffer(this.options.readChunk);
+            const readBuffer = Buffer.alloc(this.options.readChunk);
 
-            bytesRead = fs.readSync(this.fd, readBuffer, 0, this.options.readChunk, this.fdPosition);
+            if (this.seekable) {
+                try {
+                    bytesRead = fs.readSync(this.fd, readBuffer, 0, this.options.readChunk, this.fdPosition);
+                } catch {
+                    this.seekable = false;
+                }
+            }
+            if (!this.seekable) {
+                bytesRead = fs.readSync(this.fd, readBuffer, 0, this.options.readChunk);
+            }
             totalBytesRead = totalBytesRead + bytesRead;
 
             this.fdPosition = this.fdPosition + bytesRead;
@@ -100,10 +110,11 @@ class LineByLine {
         let bufferData = Buffer.concat(buffers);
 
         if (bytesRead < this.options.readChunk) {
-            this.eofReached = true;
             bufferData = bufferData.slice(0, totalBytesRead);
         }
 
+        this.eofReached = bytesRead === 0;
+
         if (totalBytesRead) {
             this.linesCache = this._extractLines(bufferData);
 
@@ -116,7 +127,7 @@ class LineByLine {
     }
 
     next() {
-        if (!this.fd) return false;
+        if (this.fd === null) return false;
 
         let line = false;
 

From ad336305872da1fbefec98b5251808a9094ab266 Mon Sep 17 00:00:00 2001
From: Mita Lapo <mitalapo@gmail.com>
Date: Tue, 18 May 2021 13:39:58 +0300
Subject: [PATCH 2/3] fix catch

---
 readlines.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/readlines.js b/readlines.js
index 1b420f5..58fa2a5 100644
--- a/readlines.js
+++ b/readlines.js
@@ -93,7 +93,7 @@ class LineByLine {
             if (this.seekable) {
                 try {
                     bytesRead = fs.readSync(this.fd, readBuffer, 0, this.options.readChunk, this.fdPosition);
-                } catch {
+                } catch (e) {
                     this.seekable = false;
                 }
             }

From d43732dde0e3c0d9662fd87be8ecb8d611de189b Mon Sep 17 00:00:00 2001
From: Mita Lapo <mitalapo@gmail.com>
Date: Fri, 21 May 2021 18:50:53 +0300
Subject: [PATCH 3/3] fix eof and test conditions

---
 readlines.js           | 1 +
 test/readlines.test.js | 1 +
 2 files changed, 2 insertions(+)

diff --git a/readlines.js b/readlines.js
index 58fa2a5..893eb0c 100644
--- a/readlines.js
+++ b/readlines.js
@@ -132,6 +132,7 @@ class LineByLine {
         let line = false;
 
         if (this.eofReached && this.linesCache.length === 0) {
+            this.close();
             return line;
         }
 
diff --git a/test/readlines.test.js b/test/readlines.test.js
index 970836f..2a1b499 100644
--- a/test/readlines.test.js
+++ b/test/readlines.test.js
@@ -127,6 +127,7 @@ test('should correctly processes NULL character in lines', (t) => {
     t.equals(liner.next().toString(), 'line wi'+String.fromCharCode(0)+'th null', 'line 1: line with null');
     t.equals(liner.next().toString(), 'another line without null', 'line 2: another line without null');
 
+    t.equals(liner.next(), false, 'line 3: false');
     t.equals(liner.fd, null, 'fd is null');
     t.end();
 })