Fix incorrect musl detection causing turbo to fail on some systems

src/Turbo/TurboExtensionSelector.php

@@ -3,13 +3,13 @@
 namespace PHPStan\Turbo;
 
 use Phar;
-use function count;
 use function dirname;
+use function file_get_contents;
 use function getenv;
-use function glob;
 use function is_file;
 use function php_uname;
 use function sprintf;
+use function str_contains;
 use const PHP_DEBUG;
 use const PHP_MAJOR_VERSION;
 use const PHP_MINOR_VERSION;
@@ -115,18 +115,25 @@ public static function resolvePlatformDirectory(string $osFamily, string $machin
 	}
 
 	/**
-	 * libc has no PHP constant; this is the same filesystem heuristic
-	 * datadog-setup.php uses.
+	 * libc has no PHP constant; this checks what loader is actually
+	 * mapped into the running process rather than whether a musl loader
+	 * merely exists somewhere on disk — a glibc host with musl-tools
+	 * installed has one too, and would otherwise be misdetected as musl.
 	 */
 	public static function isMusl(): bool
 	{
-		if (is_file('/etc/alpine-release')) {
-			return true;
-		}
+		return self::resolveIsMusl(@file_get_contents('/proc/self/maps'), is_file('/etc/alpine-release'));
+	}
 
-		$muslLoaders = glob('/lib/ld-musl-*');
+	public static function resolveIsMusl(string|false $selfMaps, bool $hasAlpineRelease): bool
+	{
+		if ($selfMaps !== false) {
+			return str_contains($selfMaps, '/ld-musl-');
+		}
 
-		return $muslLoaders !== false && count($muslLoaders) > 0;
+		// no procfs to inspect (non-Linux, or a sandboxed container without
+		// /proc) — Alpine's own musl PHP packages are still worth detecting
+		return $hasAlpineRelease;
 	}
 
 }

tests/PHPStan/Turbo/TurboExtensionSelectorTest.php

@@ -35,4 +35,44 @@ public function testResolvePlatformDirectory(string $osFamily, string $machine,
 		$this->assertSame($expected, TurboExtensionSelector::resolvePlatformDirectory($osFamily, $machine, $isMusl));
 	}
 
+	/**
+	 * @return iterable<array{string|false, bool, bool}>
+	 */
+	public static function dataResolveIsMusl(): iterable
+	{
+		// captured from `php -r 'echo file_get_contents("/proc/self/maps");'`
+		// running inside the official php:8.4-cli (glibc/Debian) image
+		$glibcMaps = <<<'MAPS'
+		58d76a000000-58d76a159000 r--p 00000000 00:67 14567852                   /usr/local/bin/php
+		58d76a200000-58d76a714000 r-xp 00200000 00:67 14567852                   /usr/local/bin/php
+		7da75ca7a000-7da75ca85000 r--p 00029000 00:67 14556924                   /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
+		7da75ca85000-7da75ca87000 r--p 00034000 00:67 14556924                   /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
+		7ffe37e20000-7ffe37e41000 rw-p 00000000 00:00 0                          [stack]
+		MAPS;
+
+		// same command, inside php:8.4-cli-alpine3.23 — /lib/ld-musl-x86_64.so.1
+		// is the musl dynamic loader mapped into the process
+		$muslMaps = <<<'MAPS'
+		58adcee00000-58adcef58000 r--p 00000000 00:67 14555462                   /usr/local/bin/php
+		58adcf000000-58adcf525000 r-xp 00200000 00:67 14555462                   /usr/local/bin/php
+		7934c7f6a000-7934c7f7e000 r--p 00000000 00:67 14554411                   /lib/ld-musl-x86_64.so.1
+		7934c7f7e000-7934c7fd6000 r-xp 00014000 00:67 14554411                   /lib/ld-musl-x86_64.so.1
+		7934c800c000-7934c8010000 rw-p 00000000 00:00 0
+		MAPS;
+
+		// glibc host with a musl loader present on disk (e.g. musl-tools
+		// installed) but not mapped into this process — the false positive
+		// the old glob-based heuristic produced
+		yield [$glibcMaps, false, false];
+		yield [$muslMaps, false, true];
+		yield [false, false, false];
+		yield [false, true, true];
+	}
+
+	#[DataProvider('dataResolveIsMusl')]
+	public function testResolveIsMusl(string|false $selfMaps, bool $hasAlpineRelease, bool $expected): void
+	{
+		$this->assertSame($expected, TurboExtensionSelector::resolveIsMusl($selfMaps, $hasAlpineRelease));
+	}
+
 }