From ac599e42c6762cd0cc6ee3a34873c6f839dd196f Mon Sep 17 00:00:00 2001
From: Lam Wei Li <peteriman@mail.com>
Date: Thu, 20 Jan 2022 01:37:12 +0800
Subject: [PATCH] allow for zero backup - in sync with
 https://github.com/log4js-node/streamroller/pull/74

**Important**
It is also to note the file does not roll within itself (truncate its older entry for newer entry).
It truncates all and appends only the new entry.

```javascript
var rollers = require('streamroller');
var stream = new rollers.RollingFileStream('myfile', 6, 0);
stream.write("abc"); // add as first row
stream.write("def"); // add as second row
stream.write("ghi"); // truncate all and add as first row
stream.end();
```

Output:
```
myfile   - ghi
```
---
 lib/appenders/file.js             |  4 +---
 lib/appenders/fileSync.js         | 10 +++++-----
 test/tap/fileAppender-test.js     |  8 ++++----
 test/tap/fileSyncAppender-test.js | 10 ++++------
 4 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index 824a4700..e976a29f 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -45,9 +45,7 @@ function openTheStream(file, fileSize, numFiles, options) {
  */
 function fileAppender(file, layout, logSize, numBackups, options, timezoneOffset) {
   file = path.normalize(file);
-  numBackups = numBackups === undefined ? 5 : numBackups;
-  // there has to be at least one backup if logSize has been specified
-  numBackups = numBackups === 0 ? 1 : numBackups;
+  numBackups = (!numBackups && numBackups !== 0) ? 5 : numBackups;
 
   debug(
     'Creating file appender (',
diff --git a/lib/appenders/fileSync.js b/lib/appenders/fileSync.js
index 3b920eef..4b6109c1 100755
--- a/lib/appenders/fileSync.js
+++ b/lib/appenders/fileSync.js
@@ -30,7 +30,7 @@ class RollingFileSync {
 
     this.filename = filename;
     this.size = size;
-    this.backups = backups || 1;
+    this.backups = backups;
     this.options = options;
     this.currentSize = 0;
 
@@ -80,7 +80,9 @@ class RollingFileSync {
     function increaseFileIndex(fileToRename) {
       const idx = index(fileToRename);
       debug(`Index of ${fileToRename} is ${idx}`);
-      if (idx < that.backups) {
+      if (that.backups === 0) {
+        fs.truncateSync(filename, 0);
+      } else if (idx < that.backups) {
         // on windows, you can get a EEXIST error if you rename a file to an existing file
         // so, we'll try to delete the file we're renaming to first
         try {
@@ -146,9 +148,7 @@ class RollingFileSync {
 function fileAppender(file, layout, logSize, numBackups, timezoneOffset, options) {
   debug('fileSync appender created');
   file = path.normalize(file);
-  numBackups = numBackups === undefined ? 5 : numBackups;
-  // there has to be at least one backup if logSize has been specified
-  numBackups = numBackups === 0 ? 1 : numBackups;
+  numBackups = (!numBackups && numBackups !== 0) ? 5 : numBackups;
 
   function openTheStream(filePath, fileSize, numFiles) {
     let stream;
diff --git a/test/tap/fileAppender-test.js b/test/tap/fileAppender-test.js
index 0abe3515..44d48b22 100644
--- a/test/tap/fileAppender-test.js
+++ b/test/tap/fileAppender-test.js
@@ -82,9 +82,9 @@ test("log4js fileAppender", batch => {
 
     t.tearDown(async () => {
       await new Promise(resolve => log4js.shutdown(resolve));
-      await Promise.all([removeFile(testFile), removeFile(`${testFile}.1`)]);
+      await removeFile(testFile);
     });
-    await Promise.all([removeFile(testFile), removeFile(`${testFile}.1`)]);
+    await removeFile(testFile);
 
     // log file of 100 bytes maximum, no backups
     log4js.configure({
@@ -113,7 +113,7 @@ test("log4js fileAppender", batch => {
     const logFiles = files.filter(file =>
       file.includes("fa-maxFileSize-test.log")
     );
-    t.equal(logFiles.length, 2, "should be 2 files");
+    t.equal(logFiles.length, 1, "should be 1 file");
     t.end();
   });
 
@@ -158,7 +158,7 @@ test("log4js fileAppender", batch => {
     const logFiles = files.filter(file =>
       file.includes("fa-maxFileSize-unit-test.log")
     );
-    t.equal(logFiles.length, 2, "should be 2 files");
+    t.equal(logFiles.length, 1, "should be 1 file");
     t.end();
   });
 
diff --git a/test/tap/fileSyncAppender-test.js b/test/tap/fileSyncAppender-test.js
index a69d08f1..b1c01886 100644
--- a/test/tap/fileSyncAppender-test.js
+++ b/test/tap/fileSyncAppender-test.js
@@ -43,11 +43,9 @@ test("log4js fileSyncAppender", batch => {
     const testFile = path.join(__dirname, "/fa-maxFileSize-sync-test.log");
     const logger = log4js.getLogger("max-file-size");
     remove(testFile);
-    remove(`${testFile}.1`);
 
     t.tearDown(() => {
       remove(testFile);
-      remove(`${testFile}.1`);
     });
 
     // log file of 100 bytes maximum, no backups
@@ -77,12 +75,12 @@ test("log4js fileSyncAppender", batch => {
       });
     });
 
-    t.test("there should be two test files", assert => {
+    t.test("there should be one test files", assert => {
       fs.readdir(__dirname, (err, files) => {
         const logFiles = files.filter(file =>
           file.includes("fa-maxFileSize-sync-test.log")
         );
-        assert.equal(logFiles.length, 2);
+        assert.equal(logFiles.length, 1);
         assert.end();
       });
     });
@@ -128,12 +126,12 @@ test("log4js fileSyncAppender", batch => {
       });
     });
 
-    t.test("there should be two test files", assert => {
+    t.test("there should be one test file", assert => {
       fs.readdir(__dirname, (err, files) => {
         const logFiles = files.filter(file =>
           file.includes("fa-maxFileSize-unit-sync-test.log")
         );
-        assert.equal(logFiles.length, 2);
+        assert.equal(logFiles.length, 1);
         assert.end();
       });
     });