Fix GH-18281: making flock flags mutually exclusive.

proposing a standard way to detect bitwise values through a new Zend
entry.

Author: devnexen

Zend/zend_portability.h

@@ -403,6 +403,22 @@ char *alloca();
 # define JMP_BUF jmp_buf
 #endif
 
+#ifdef ZEND_ENABLE_ZVAL_LONG64
+# ifdef _MSC_VER
+# define ZEND_POPCOUNT(x) __popcnt64(x)
+# else
+# define ZEND_POPCOUNT(x) __builtin_popcountll(x)
+# endif
+#else
+# ifdef _MSC_VER
+# define ZEND_POPCOUNT(x) __popcnt(x)
+# else
+# define ZEND_POPCOUNT(x) __builtin_popcount(x)
+# endif
+#endif
+
+#define ZEND_ISBITWISE(x) (ZEND_POPCOUNT(x) > 1)
+
 #if ZEND_DEBUG
 # define ZEND_FILE_LINE_D				const char *__zend_filename, const uint32_t __zend_lineno
 # define ZEND_FILE_LINE_DC				, ZEND_FILE_LINE_D

ext/standard/file.c

@@ -188,7 +188,7 @@ PHPAPI void php_flock_common(php_stream *stream, zend_long operation,
 	int act;
 
 	act = operation & PHP_LOCK_UN;
-	if (act < 1 || act > 3) {
+	if (act < 1 || act > 3 || ZEND_ISBITWISE(act)) {
 		zend_argument_value_error(operation_arg_num, "must be one of LOCK_SH, LOCK_EX, or LOCK_UN");
 		RETURN_THROWS();
 	}