feat: make search path for BinaryFinder customizable.

This feature is important for nextcloud running on
distributions like NixOS, where all the standard
search paths do not exist.

Also added tests.

This fixes issue nextcloud#43922

Signed-off-by: Reno Reckling <e-github@wthack.de>

config/config.sample.php

@@ -1962,7 +1962,7 @@
 /**
  * Blacklist characters from being used in filenames. This is useful if you
  * have a filesystem or OS which does not support certain characters like windows.
- * 
+ *
  * The '/' and '\' characters are always forbidden.
  *
  * Example for windows systems: ``array('?', '<', '>', ':', '*', '|', '"', chr(0), "\n", "\r")``
@@ -2431,4 +2431,20 @@
  * Defaults to ``true``
  */
 'enable_non-accessible_features' => true,
+
+/**
+ * Directories where nextcloud looks for binaries.
+ * This is used to find external binaries like libreoffice, sendmail, ffmpeg and more.
+ *
+ * Defaults to ``['/usr/local/sbin','/usr/local/bin','/usr/sbin','/usr/bin','/sbin','/bin','/opt/bin']``
+ */
+'binary_search_paths' => [
+	'/usr/local/sbin',
+	'/usr/local/bin',
+	'/usr/sbin',
+	'/usr/bin',
+	'/sbin',
+	'/bin',
+	'/opt/bin',
+],
 ];

lib/private/BinaryFinder.php

@@ -3,6 +3,7 @@
 declare(strict_types = 1);
 /**
  * @copyright 2022 Carl Schwan <carl@carlschwan.eu>
+ * @copyright 2024 Reno Reckling <e-github@wthack.de>
  * @license GNU AGPL version 3 or any later version
  *
  * This program is free software: you can redistribute it and/or modify
@@ -25,15 +26,28 @@
 use OCP\IBinaryFinder;
 use OCP\ICache;
 use OCP\ICacheFactory;
+use OCP\IConfig;
 use Symfony\Component\Process\ExecutableFinder;
 
 /**
  * Service that find the binary path for a program
  */
 class BinaryFinder implements IBinaryFinder {
+	public const DEFAULT_BINARY_SEARCH_PATHS = [
+		'/usr/local/sbin',
+		'/usr/local/bin',
+		'/usr/sbin',
+		'/usr/bin',
+		'/sbin',
+		'/bin',
+		'/opt/bin',
+	];
 	private ICache $cache;
 
-	public function __construct(ICacheFactory $cacheFactory) {
+	public function __construct(
+		ICacheFactory   $cacheFactory,
+		private IConfig $config
+	) {
 		$this->cache = $cacheFactory->createLocal('findBinaryPath');
 	}
 
@@ -51,15 +65,10 @@ public function findBinaryPath(string $program) {
 		if (\OCP\Util::isFunctionEnabled('exec')) {
 			$exeSniffer = new ExecutableFinder();
 			// Returns null if nothing is found
-			$result = $exeSniffer->find($program, null, [
-				'/usr/local/sbin',
-				'/usr/local/bin',
-				'/usr/sbin',
-				'/usr/bin',
-				'/sbin',
-				'/bin',
-				'/opt/bin',
-			]);
+			$result = $exeSniffer->find(
+				$program,
+				null,
+				$this->config->getSystemValue('binary_search_paths', self::DEFAULT_BINARY_SEARCH_PATHS));
 			if ($result === null) {
 				$result = false;
 			}

tests/lib/BinaryFinderTest.php

@@ -0,0 +1,99 @@
+<?php
+
+declare(strict_types = 1);
+/**
+ * @copyright 2024 Reno Reckling <e-github@wthack.de>
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Test;
+
+use OC\BinaryFinder;
+use OC\Memcache\ArrayCache;
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\IConfig;
+
+class BinaryFinderTest extends TestCase {
+	private ICache $cache;
+	private ICacheFactory $cacheFactory;
+	private $oldEnv;
+
+	protected function setUp(): void {
+		$this->oldEnv = getenv("PATH");
+		// BinaryFinder always includes the "PATH" environment variable into the search path,
+		// which we want to avoid in this test because they are not usually found in webserver
+		// deployments.
+		putenv('PATH=""');
+		$this->cacheMap = [];
+		$this->cacheFactory = $this->createMock(ICacheFactory::class);
+		$this->cache = new ArrayCache();
+		$this->cacheFactory->method('createLocal')->with('findBinaryPath')->willReturn($this->cache);
+	}
+
+	protected function tearDown(): void {
+		putenv('PATH='.$this->oldEnv);
+	}
+
+	public function testDefaultFindsCat() {
+		$config = $this->createMock(IConfig::class);
+		$config
+			->method('getSystemValue')
+			->with('binary_search_paths', $this->anything())
+			->will($this->returnCallback(function ($key, $default) {
+				return $default;
+			}));
+		$finder = new BinaryFinder($this->cacheFactory, $config);
+		$this->assertEquals($finder->findBinaryPath('cat'), '/usr/bin/cat');
+		$this->assertEquals($this->cache->get('cat'), '/usr/bin/cat');
+	}
+
+	public function testDefaultDoesNotFindCata() {
+		$config = $this->createMock(IConfig::class);
+		$config
+			->method('getSystemValue')
+			->with('binary_search_paths', $this->anything())
+			->will($this->returnCallback(function ($key, $default) {
+				return $default;
+			}));
+		$finder = new BinaryFinder($this->cacheFactory, $config);
+		$this->assertFalse($finder->findBinaryPath('cata'));
+		$this->assertFalse($this->cache->get('cata'));
+	}
+
+	public function testCustomPathFindsCat() {
+		$config = $this->createMock(IConfig::class);
+		$config
+			->method('getSystemValue')
+			->with('binary_search_paths', $this->anything())
+			->willReturn(['/usr/bin']);
+		$finder = new BinaryFinder($this->cacheFactory, $config);
+		$this->assertEquals($finder->findBinaryPath('cat'), '/usr/bin/cat');
+		$this->assertEquals($this->cache->get('cat'), '/usr/bin/cat');
+	}
+
+	public function testWrongCustomPathDoesNotFindCat() {
+		$config = $this->createMock(IConfig::class);
+		$config
+			->method('getSystemValue')
+			->with('binary_search_paths')
+			->willReturn(['/wrong']);
+		$finder = new BinaryFinder($this->cacheFactory, $config);
+		$this->assertFalse($finder->findBinaryPath('cat'));
+		$this->assertFalse($this->cache->get('cat'));
+	}
+}