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 #43922

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

config/config.sample.php

@@ -2533,4 +2533,20 @@
  * 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

@@ -11,15 +11,28 @@
 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');
 	}
 
@@ -37,18 +50,10 @@ 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',
-			]);
-			if ($result === null) {
-				$result = false;
-			}
+			$result = $exeSniffer->find(
+				$program,
+				false,
+				$this->config->getSystemValue('binary_search_paths', self::DEFAULT_BINARY_SEARCH_PATHS));
 		}
 		// store the value for 5 minutes
 		$this->cache->set($program, $result, 300);

tests/lib/BinaryFinderTest.php

@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types = 1);
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+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->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'));
+	}
+}