From 37285a20190ad5e871c5e141d574a4eb80c466a8 Mon Sep 17 00:00:00 2001
From: loma-one <loma-one@noreply.git.friendi.ca>
Date: Sat, 3 May 2025 13:26:23 +0200
Subject: [PATCH] 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 | 91 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 85 insertions(+), 6 deletions(-)

diff --git a/tesseract/tesseract.php b/tesseract/tesseract.php
index b3e1feb6..62ff4d18 100644
--- a/tesseract/tesseract.php
+++ b/tesseract/tesseract.php
@@ -1,9 +1,10 @@
 <?php
 /**
  * Name: Tesseract OCR
- * Description: Use OCR to get text from images
- * Version: 0.1
+ * Description: Use OCR to get text from images (with timeout, resource limits, format check)
+ * Version: 0.2
  * Author: Michael Vogel <http://pirati.ca/profile/heluecht>
+ * Modified by: Matthias Ebers <http://loma.ml/profile/feb>
  */
 
 use Friendica\Core\Hook;
@@ -13,25 +14,103 @@ use thiagoalessio\TesseractOCR\TesseractOCR;
 
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
 
+/**
+ * Is called up when the add-on is activated
+ */
 function tesseract_install()
 {
 	Hook::register('ocr-detection', __FILE__, 'tesseract_ocr_detection');
 
-	Logger::notice('installed tesseract');
+	$wrapperPath = __DIR__ . '/tesseract-limited.sh';
+
+	// Create wrapper script with timeout and CPU/I/O priority
+	if (!file_exists($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);
+
+		Logger::notice('Tesseract wrapper script created', ['path' => $wrapperPath]);
+	} else {
+		Logger::info('Tesseract wrapper script already exists', ['path' => $wrapperPath]);
+	}
+
+	Logger::notice('Tesseract OCR addon installed');
 }
 
+/**
+ * Is called up when the add-on is deactivated
+ */
+function tesseract_uninstall()
+{
+	$wrapperPath = __DIR__ . '/tesseract-limited.sh';
+
+	if (file_exists($wrapperPath)) {
+		unlink($wrapperPath);
+		Logger::notice('Tesseract wrapper script removed', ['path' => $wrapperPath]);
+	}
+
+	Hook::unregister('ocr-detection', __FILE__, 'tesseract_ocr_detection');
+	Logger::notice('Tesseract OCR addon uninstalled');
+}
+
+/**
+ * Main function for OCR recognition
+ */
 function tesseract_ocr_detection(&$media)
 {
+	// ➤ Alt text available? → Skip OCR
+	if (!empty($media['description'])) {
+		Logger::debug('Image already has description, skipping OCR');
+		return;
+	}
+
+	// Format check: Only process certain image types
+	$allowedTypes = ['image/jpeg', 'image/png', 'image/bmp', 'image/tiff'];
+	if (!empty($media['type']) && !in_array($media['type'], $allowedTypes)) {
+		Logger::debug('Unsupported image type for OCR', ['type' => $media['type']]);
+		return;
+	}
+
+	// Alternatively: Check file extension (if MIME type is missing)
+	if (empty($media['type']) && !empty($media['filename']) && preg_match('/\.gif$/i', $media['filename'])) {
+		Logger::debug('GIF image detected via filename, skipping OCR');
+		return;
+	}
+
 	$ocr = new TesseractOCR();
+
 	try {
+		// Bash wrapper with resource limit
+		$wrapperPath = __DIR__ . '/tesseract-limited.sh';
+		$ocr->executable($wrapperPath);
+
+		// Load all available languages
 		$languages = $ocr->availableLanguages();
 		if ($languages) {
 			$ocr->lang(implode('+', $languages));
 		}
+
+		// Set temporary directory
 		$ocr->tempDir(System::getTempPath());
+
+		// Set image data
 		$ocr->imageData($media['img_str'], strlen($media['img_str']));
-		$media['description'] = $ocr->run();
+
+		// Start OCR
+		$text = trim($ocr->run());
+
+		if (!empty($text)) {
+			$media['description'] = $text;
+			Logger::debug('OCR text detected', ['text' => $text]);
+		} else {
+			Logger::debug('No text detected in image');
+		}
 	} catch (\Throwable $th) {
 		Logger::info('Error calling TesseractOCR', ['message' => $th->getMessage()]);
-	}			
-}
+	}
+}
\ No newline at end of file