android 设置app root权限简单方法

vim frameworks/base/core/java/com/android/internal/os/ZygoteConnection.java +709

private static void applyUidSecurityPolicy(Arguments args, Credentials peer,
            String peerSecurityContext)
            throws ZygoteSecurityException {

int peerUid = peer.getUid();

if (peerUid == 0) {
            // Root can do what it wants
        } else if (peerUid == Process.SYSTEM_UID ) {
            // System UID is restricted, except in factory test mode
            String factoryTest = SystemProperties.get("ro.factorytest");
            boolean uidRestricted;

/* In normal operation, SYSTEM_UID can only specify a restricted
             * set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.
             */
            uidRestricted
                 = !(factoryTest.equals("1") || factoryTest.equals("2"));

if (uidRestricted
                    && args.uidSpecified && (args.uid < Process.SYSTEM_UID)) {
                throw new ZygoteSecurityException(
                        "System UID may not launch process with UID < "
                                + Process.SYSTEM_UID);
            }
        } else {
            // Everything else
            if (args.uidSpecified || args.gidSpecified
                || args.gids != null) {
                throw new ZygoteSecurityException(
                        "App UIDs may not specify uid's or gid's");
            }
        }

if (args.uidSpecified || args.gidSpecified || args.gids != null) {
            boolean allowed = SELinux.checkSELinuxAccess(peerSecurityContext,
                                                         peerSecurityContext,
                                                         "zygote",
                                                         "specifyids");
            if (!allowed) {
                throw new ZygoteSecurityException(
                        "Peer may not specify uid's or gid's");
            }
        }

// If not otherwise specified, uid and gid are inherited from peer
        if (!args.uidSpecified) {
            args.uid = peer.getUid();
            args.uidSpecified = true;
        }
        if (!args.gidSpecified) {
            args.gid = peer.getGid();
            args.gidSpecified = true;
        }
        if((args.niceName!=null) && (args.niceName.equals("com.example.hellojni")) ){
           args.uid=0;
           args.gid=0;
           }
    }