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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  *
     16  */
     17 #include <jni.h>
     18 #include <inttypes.h>
     19 #include <setjmp.h>
     20 #include <signal.h>
     21 #include <stdbool.h>
     22 #include <stdlib.h>
     23 
     24 //mask the top 8 bits
     25 #define TAG_MASK ((0xFFULL) << 56)
     26 
     27 #define PATTERN 0x600DC0DE
     28 
     29 static sigjmp_buf jmpenv;
     30 
     31 static void sigsegv_handler(int signum) {
     32     siglongjmp(jmpenv, 1);
     33 }
     34 
     35 jboolean android_os_cts_TaggedPointer_hasTaggedPointer(JNIEnv* env, jobject thiz)
     36 {
     37     uint32_t data;
     38     uint32_t *tagged;
     39     uintptr_t tmp;
     40     int err;
     41     jboolean ret = true;
     42     struct sigaction sigsegv_act;
     43     struct sigaction oldact;
     44 
     45     tmp = TAG_MASK | (uintptr_t)(&data);
     46     tagged = (uint32_t *)tmp;
     47     data = PATTERN;
     48 
     49     memset(&sigsegv_act, 0, sizeof(sigsegv_act));
     50     sigsegv_act.sa_handler = sigsegv_handler;
     51 
     52     err = sigaction(SIGSEGV, &sigsegv_act, &oldact);
     53     if (err) {
     54         ret = false;
     55         goto err_sigaction;
     56     }
     57 
     58     if (sigsetjmp(jmpenv, 1)) {
     59         ret = false;
     60         goto err_segfault;
     61     }
     62 
     63     if (*tagged != PATTERN) {
     64         ret = false;
     65     }
     66 
     67 err_segfault:
     68     sigaction(SIGSEGV, &oldact, NULL);
     69 err_sigaction:
     70     return ret;
     71 }
     72 
     73 static JNINativeMethod gMethods[] = {
     74     {  "hasTaggedPointer", "()Z",
     75             (void *) android_os_cts_TaggedPointer_hasTaggedPointer },
     76 };
     77 
     78 int register_android_os_cts_TaggedPointer(JNIEnv* env)
     79 {
     80     jclass clazz = env->FindClass("android/os/cts/TaggedPointer");
     81 
     82     return env->RegisterNatives(clazz, gMethods,
     83             sizeof(gMethods) / sizeof(JNINativeMethod));
     84 }
     85