From 505204addc02831f248a5aae9fe71f611125c611 Mon Sep 17 00:00:00 2001
From: Lam Wei Li <peteriman@mail.com>
Date: Sun, 22 May 2022 15:47:00 +0800
Subject: [PATCH 1/3] style: white-space

---
 lib/appenders/fileSync.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/appenders/fileSync.js b/lib/appenders/fileSync.js
index 16dc538..763da33 100755
--- a/lib/appenders/fileSync.js
+++ b/lib/appenders/fileSync.js
@@ -14,7 +14,7 @@ function touchFile(file, options) {
   // attempt to create the directory
   const mkdir = (dir) => {
     try {
-      return fs.mkdirSync(dir, {recursive: true});
+      return fs.mkdirSync(dir, { recursive: true });
     }
     // backward-compatible fs.mkdirSync for nodejs pre-10.12.0 (without recursive option)
     catch (e) {

From 6de1da298e7745fe036a523181a278d0ad66184a Mon Sep 17 00:00:00 2001
From: Lam Wei Li <peteriman@mail.com>
Date: Sun, 22 May 2022 15:49:51 +0800
Subject: [PATCH 2/3] refactor: code flow and readability

---
 lib/appenders/fileSync.js | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/lib/appenders/fileSync.js b/lib/appenders/fileSync.js
index 763da33..7519de5 100755
--- a/lib/appenders/fileSync.js
+++ b/lib/appenders/fileSync.js
@@ -6,11 +6,6 @@ const os = require('os');
 const eol = os.EOL;
 
 function touchFile(file, options) {
-  // if the file exists, nothing to do
-  if (fs.existsSync(file)) {
-    return;
-  }
-
   // attempt to create the directory
   const mkdir = (dir) => {
     try {
@@ -45,9 +40,8 @@ function touchFile(file, options) {
   };
   mkdir(path.dirname(file));
 
-  // touch the file to apply flags (like w to truncate the file)
-  const id = fs.openSync(file, options.flags, options.mode);
-  fs.closeSync(id);
+  // try to throw EISDIR, EROFS, EACCES
+  fs.appendFileSync(file, "", { mode: options.mode, flags: options.flag });
 }
 
 class RollingFileSync {

From d182204079eaa7ef8df8965c5b8045b559eb1a55 Mon Sep 17 00:00:00 2001
From: Lam Wei Li <peteriman@mail.com>
Date: Sun, 22 May 2022 15:48:09 +0800
Subject: [PATCH 3/3] fix: filename validation (cannot be directory)

---
 lib/appenders/file.js             |  2 ++
 lib/appenders/fileSync.js         |  2 ++
 test/tap/fileAppender-test.js     | 19 +++++++++++++++++--
 test/tap/fileSyncAppender-test.js | 19 +++++++++++++++++--
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index 73dad71..673e348 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -29,6 +29,8 @@ function mainSighupHandler() {
 function fileAppender(file, layout, logSize, numBackups, options, timezoneOffset) {
   if (typeof file !== "string" || file.length === 0) {
     throw new Error(`Invalid filename: ${file}`);
+  } else if (file.endsWith(path.sep)) {
+    throw new Error(`Filename is a directory: ${file}`);
   }
   file = path.normalize(file);
   numBackups = (!numBackups && numBackups !== 0) ? 5 : numBackups;
diff --git a/lib/appenders/fileSync.js b/lib/appenders/fileSync.js
index 7519de5..24b3f9a 100755
--- a/lib/appenders/fileSync.js
+++ b/lib/appenders/fileSync.js
@@ -164,6 +164,8 @@ class RollingFileSync {
 function fileAppender(file, layout, logSize, numBackups, options, timezoneOffset) {
   if (typeof file !== "string" || file.length === 0) {
     throw new Error(`Invalid filename: ${file}`);
+  } else if (file.endsWith(path.sep)) {
+    throw new Error(`Filename is a directory: ${file}`);
   }
   file = path.normalize(file);
   numBackups = (!numBackups && numBackups !== 0) ? 5 : numBackups;
diff --git a/test/tap/fileAppender-test.js b/test/tap/fileAppender-test.js
index 5ca1f6a..ebc298b 100644
--- a/test/tap/fileAppender-test.js
+++ b/test/tap/fileAppender-test.js
@@ -50,7 +50,6 @@ test("log4js fileAppender", batch => {
 
   batch.test("should give error if invalid filename", async t => {
     const file = "";
-    const expectedError = new Error(`Invalid filename: ${file}`);
     t.throws(
       () => 
         log4js.configure({
@@ -64,7 +63,23 @@ test("log4js fileAppender", batch => {
             default: { appenders: ["file"], level: "debug" }
           }
         }),
-      expectedError
+      new Error(`Invalid filename: ${file}`)
+    );
+    const dir = `.${path.sep}`;
+    t.throws(
+      () => 
+        log4js.configure({
+          appenders: {
+            file: {
+              type: "file",
+              filename: dir
+            }
+          },
+          categories: {
+            default: { appenders: ["file"], level: "debug" }
+          }
+        }),
+      new Error(`Filename is a directory: ${dir}`)
     );
     t.end();
   });
diff --git a/test/tap/fileSyncAppender-test.js b/test/tap/fileSyncAppender-test.js
index b36e3b0..4ea96ac 100644
--- a/test/tap/fileSyncAppender-test.js
+++ b/test/tap/fileSyncAppender-test.js
@@ -78,7 +78,6 @@ test("log4js fileSyncAppender", batch => {
 
   batch.test("should give error if invalid filename", async t => {
     const file = "";
-    const expectedError = new Error(`Invalid filename: ${file}`);
     t.throws(
       () => 
         log4js.configure({
@@ -92,7 +91,23 @@ test("log4js fileSyncAppender", batch => {
             default: { appenders: ["file"], level: "debug" }
           }
         }),
-      expectedError
+      new Error(`Invalid filename: ${file}`)
+    );
+    const dir = `.${path.sep}`;
+    t.throws(
+      () => 
+        log4js.configure({
+          appenders: {
+            file: {
+              type: "fileSync",
+              filename: dir
+            }
+          },
+          categories: {
+            default: { appenders: ["file"], level: "debug" }
+          }
+        }),
+      new Error(`Filename is a directory: ${dir}`)
     );
     t.end();
   });