tesseract/tesseract.php aktualisiert

Modified addon.
The addon used to generate a large system load and led to the server being unavailable. The changes help to make better use of system resources.

- Creates and removes tesseract-limited.sh to limit the system resources for tesseract (timeout/resource limits).
- Checks permitted formats to avoid wasting resources.

tesseract/tesseract.php

@@ -1,9 +1,10 @@
 <?php
 /**
  * Name: Tesseract OCR
- * Description: Use OCR to get text from images
+ * Description: Use OCR to extract text from images (with timeout, resource limits, alt-text & format checks)
- * Version: 0.1
+ * Version: 0.2
  * Author: Michael Vogel <http://pirati.ca/profile/heluecht>
+ *  * Modified by: Matthias Ebers <http://loma.ml/profile/feb>
  */
 
 use Friendica\Core\Hook;
@@ -13,26 +14,102 @@ use thiagoalessio\TesseractOCR\TesseractOCR;
 
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
 
+/**
+ * Called when the addon is enabled
+ */
 function tesseract_install()
 {
 	Hook::register('ocr-detection', __FILE__, 'tesseract_ocr_detection');
 
-	DI::logger()->notice('installed tesseract');
+	$wrapperPath = __DIR__ . '/tesseract-limited.sh';
+
+	// Create a wrapper script with timeout and resource constraints
+	if (!file_exists($wrapperPath)) {
+		$script = <<<BASH
+#!/bin/bash
+# Wrapper for tesseract with timeout and resource limits
+timeout 5s nice -n 10 ionice -c3 /usr/bin/tesseract "\$@"
+BASH;
+
+		file_put_contents($wrapperPath, $script);
+		chmod($wrapperPath, 0755);
+
+		DI::logger()->notice('Tesseract wrapper script created', ['path' => $wrapperPath]);
+	} else {
+		DI::logger()->info('Tesseract wrapper script already exists', ['path' => $wrapperPath]);
+	}
+
+	DI::logger()->notice('Tesseract OCR addon installed');
 }
 
+/**
+ * Called when the addon is disabled
+ */
+function tesseract_uninstall()
+{
+	$wrapperPath = __DIR__ . '/tesseract-limited.sh';
+
+	if (file_exists($wrapperPath)) {
+		unlink($wrapperPath);
+		DI::logger()->notice('Tesseract wrapper script removed', ['path' => $wrapperPath]);
+	}
+
+	Hook::unregister('ocr-detection', __FILE__, 'tesseract_ocr_detection');
+	DI::logger()->notice('Tesseract OCR addon uninstalled');
+}
+
+/**
+ * Main OCR processing hook for incoming images
+ */
 function tesseract_ocr_detection(&$media)
 {
+	// Skip OCR if image already contains an alt-text
+	if (!empty($media['description'])) {
+		DI::logger()->debug('Image already has description, skipping OCR');
+		return;
+	}
+
+	// Only allow specific MIME types for OCR
+	$allowedTypes = ['image/jpeg', 'image/png', 'image/bmp', 'image/tiff'];
+	if (!empty($media['type']) && !in_array($media['type'], $allowedTypes)) {
+		DI::logger()->debug('Unsupported image type for OCR', ['type' => $media['type']]);
+		return;
+	}
+
+	// Alternatively skip GIF files based on filename
+	if (empty($media['type']) && !empty($media['filename']) && preg_match('/\.gif$/i', $media['filename'])) {
+		DI::logger()->debug('GIF image detected via filename, skipping OCR');
+		return;
+	}
+
 	$ocr = new TesseractOCR();
+
 	try {
+		// Use wrapper script with timeout and niceness
+		$ocr->executable(__DIR__ . '/tesseract-limited.sh');
+
+		// Detect and set available languages
 		$languages = $ocr->availableLanguages();
 		if ($languages) {
-			/** @phpstan-ignore-next-line ignore call of \thiagoalessio\TesseractOCR\Option::lang() */
 			$ocr->lang(implode('+', $languages));
 		}
+
+		// Use Friendica's temporary path
 		$ocr->tempDir(System::getTempPath());
+
+		// Provide raw image data to Tesseract
 		$ocr->imageData($media['img_str'], strlen($media['img_str']));
-		$media['description'] = $ocr->run();
+
+		// Run OCR and assign description if text is found
+		$text = trim($ocr->run());
+
+		if (!empty($text)) {
+			$media['description'] = $text;
+			DI::logger()->debug('OCR text detected', ['text' => $text]);
+		} else {
+			DI::logger()->debug('No text detected in image');
+		}
 	} catch (\Throwable $th) {
 		DI::logger()->info('Error calling TesseractOCR', ['message' => $th->getMessage()]);
 	}
-}
+}