Fix #16208: Fix yii\log\FileTarget to not export empty messages

Author: terabytesoftw

framework/CHANGELOG.md

@@ -4,6 +4,7 @@ Yii Framework 2 Change Log
 2.0.49 under development
 ------------------------
 
+- Bug #16208: Fix `yii\log\FileTarget` to not export empty messages (terabytesoftw)
 - Bug #19857: Fix AttributeTypecastBehavior::resetOldAttributes() causes "class has no attribute named" InvalidArgumentException (uaoleg)
 - Bug #18859: Fix `yii\web\Controller::bindInjectedParams()` to not throw error when argument of `ReflectionUnionType` type is passed (bizley)
 - Enh #19841: Allow jQuery 3.7 to be installed (wouter90)

framework/log/FileTarget.php

@@ -106,12 +106,18 @@ public function init()
      */
     public function export()
     {
+        $text = implode("\n", array_map([$this, 'formatMessage'], $this->messages)) . "\n";
+        $trimmedText = trim($text);
+
+        if (empty($trimmedText)) {
+            return; // No messages to export, so we exit the function early
+        }
+
         if (strpos($this->logFile, '://') === false || strncmp($this->logFile, 'file://', 7) === 0) {
             $logPath = dirname($this->logFile);
             FileHelper::createDirectory($logPath, $this->dirMode, true);
         }
 
-        $text = implode("\n", array_map([$this, 'formatMessage'], $this->messages)) . "\n";
         if (($fp = @fopen($this->logFile, 'a')) === false) {
             throw new InvalidConfigException("Unable to append to log file: {$this->logFile}");
         }
@@ -124,12 +130,12 @@ public function export()
         if ($this->enableRotation && @filesize($this->logFile) > $this->maxFileSize * 1024) {
             $this->rotateFiles();
         }
-        $writeResult = @fwrite($fp, $text);
+        $writeResult = @fwrite($fp, $trimmedText);
         if ($writeResult === false) {
             $error = error_get_last();
             throw new LogRuntimeException("Unable to export log through file ({$this->logFile})!: {$error['message']}");
         }
-        $textSize = strlen($text);
+        $textSize = strlen($trimmedText);
         if ($writeResult < $textSize) {
             throw new LogRuntimeException("Unable to export whole log through file ({$this->logFile})! Wrote $writeResult out of $textSize bytes.");
         }

tests/framework/log/FileTargetTest.php

@@ -12,6 +12,7 @@
 use yii\log\Dispatcher;
 use yii\log\FileTarget;
 use yii\log\Logger;
+use yiiunit\framework\log\mocks\CustomLogger;
 use yiiunit\TestCase;
 
 /**
@@ -110,4 +111,41 @@ public function testRotate()
         $this->assertFileNotExists($logFile . '.3');
         $this->assertFileNotExists($logFile . '.4');
     }
+
+    public function testLogEmptyStrings()
+    {
+        $logFile = Yii::getAlias('@yiiunit/runtime/log/filetargettest.log');
+        $this->clearLogFile($logFile);
+
+        $logger = new CustomLogger();
+        $logger->logFile = $logFile;
+        $logger->messages = array_fill(0, 1, 'xxx');
+        $logger->export();
+
+        $test = file($logFile);
+        $this->assertEquals("xxx", $test[0]);
+
+        $this->clearLogFile($logFile);
+
+        $logger->messages = array_fill(0, 1, 'yyy');
+        $logger->export();
+
+        $this->assertFileNotExists($logFile);
+
+        $logger->messages = array_fill(0, 10, '');
+        $logger->export();
+
+        $this->assertFileNotExists($logFile);
+
+        $logger->messages = array_fill(0, 10, null);
+        $logger->export();
+
+        $this->assertFileNotExists($logFile);
+    }
+
+    private function clearLogFile($logFile)
+    {
+        FileHelper::removeDirectory(dirname($logFile));
+        mkdir(dirname($logFile), 0777, true);
+    }
 }

tests/framework/log/mocks/CustomLogger.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace yiiunit\framework\log\mocks;
+
+use yii\log\FileTarget;
+
+class CustomLogger extends FileTarget
+{
+    /**
+     * @param array $message
+     *
+     * @return null|string|array
+     */
+    public function formatMessage($message)
+    {
+        if ($message == 'yyy') {
+            return null;
+        }
+
+        return $message;
+    }
+}