NoexecVolumeDetector Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java lines 514–544

    private static final class NoexecVolumeDetector {

        private static boolean canExecuteExecutable(File file) throws IOException {
            // If we can already execute, there is nothing to do.
            if (file.canExecute()) {
                return true;
            }

            // On volumes, with noexec set, even files with the executable POSIX permissions will fail to execute.
            // The File#canExecute() method honors this behavior, probaby via parsing the noexec flag when initializing
            // the UnixFileStore, though the flag is not exposed via a public API.  To find out if library is being
            // loaded off a volume with noexec, confirm or add executalbe permissions, then check File#canExecute().
            Set<PosixFilePermission> existingFilePermissions = Files.getPosixFilePermissions(file.toPath());
            Set<PosixFilePermission> executePermissions =
                    EnumSet.of(PosixFilePermission.OWNER_EXECUTE,
                            PosixFilePermission.GROUP_EXECUTE,
                            PosixFilePermission.OTHERS_EXECUTE);
            if (existingFilePermissions.containsAll(executePermissions)) {
                return false;
            }

            Set<PosixFilePermission> newPermissions = EnumSet.copyOf(existingFilePermissions);
            newPermissions.addAll(executePermissions);
            Files.setPosixFilePermissions(file.toPath(), newPermissions);
            return file.canExecute();
        }

        private NoexecVolumeDetector() {
            // Utility
        }
    }