我给出了一个奇怪的代码问题。任务很简单,我从本地代码调用一个java函数,它从prefs中获取一个参数,然后返回c++,该方法没有参数并返回一个字符串。
更奇怪的是,它在第一次运行时运行良好,但第二次我从 java 调用整个本机过程时,当 c++ 例程尝试联系它崩溃的 java 方法时。这告诉我这是内存损坏,但我不知道为什么会发生。
好的。因此,在 lib 的 onLoad 方法中,我对 javaVM 进行了引用,如下所示:
JNIEnv *env;
LOGI("JNI_OnLoad called");
if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
LOGE("Failed to get the environment using GetEnv()");
return -1;
}
MY_NAMESPACE::VMHandler::getInstance()->init(env);
Init 实际上只是将指针保存在正在运行的实例中,并且在以后的运行中不会给我带来任何问题,因为我多次调用它。
接下来,我调用 java 方法 getTime()
LOGE("get TIME called");
//getting a pointer to the VM
JNIEnv * env = VMHandler::getInstance()->getJava();
LOGE("1");
if (env==NULL) {
LOGE("1.0");
}else{
LOGE("1.0 OK");
}
if (dao==NULL) {
LOGE("1.1");
}else{
LOGE("1.1 OK");
}
if (jgetTime==NULL) {
LOGE("1.2");
}else{
LOGE("1.2 OK");
}
jstring time = (jstring) env->CallObjectMethod(dao,jgetTime);
LOGE("2");
有趣的是,我从第一次运行中得到以下日志:
E/app-cpp(7121): 1
E/app-cpp(7121): 1.0 OK
E/app-cpp(7121): 1.1 OK
E/app-cpp(7121): 1.2 OK
E/Settings(7121): Java received : getTime()
E/Settings(7121): Java returning : 1341250295
然后第二次运行...
E/app-cpp(1941): get TIME called
E/app-cpp(1941): 1
E/app-cpp(1941): 1.0 OK
E/app-cpp(1941): 1.1 OK
E/app-cpp(1941): 1.2 OK
A/libc(1941): Fatal signal 11 (SIGSEGV) at 0x0000008d (code=1)
完整的转储是:
07-02 17:08:20.948: E/my-cpp(1941): 1
07-02 17:08:20.958: E/my-cpp(1941): 1.0 OK
07-02 17:08:20.958: E/my-cpp(1941): 1.1 OK
07-02 17:08:20.958: E/my-cpp(1941): 1.2 OK
07-02 17:08:20.958: A/libc(1941): Fatal signal 11 (SIGSEGV) at 0x0000008d (code=1)
07-02 17:08:20.967: D/debug(1941): LoaderCalled!
07-02 17:08:21.298: D/dalvikvm(78): GC_CONCURRENT freed 296K, 13% free 11332K/12935K, paused 4ms+28ms
07-02 17:08:21.407: I/Process(78): Sending signal. PID: 1941 SIG: 3
07-02 17:08:21.407: I/dalvikvm(1941): threadid=3: reacting to signal 3
07-02 17:08:21.417: I/dalvikvm(1941): Wrote stack traces to '/data/anr/traces.txt'
07-02 17:08:21.477: D/debug(1941): mSwitcher:android.widget.TextSwitcher@41495318
07-02 17:08:21.487: I/DEBUG(3844): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
07-02 17:08:21.487: I/DEBUG(3844): Build fingerprint: 'generic/sdk/generic:4.0.4/MR1/302030:eng/test-keys'
07-02 17:08:21.487: I/DEBUG(3844): pid: 1941, tid: 2162 >>> com.myapp <<<
07-02 17:08:21.487: I/DEBUG(3844): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0000008d
07-02 17:08:21.487: I/DEBUG(3844): r0 00238040 r1 1d200222 r2 00000001 r3 0000008c
07-02 17:08:21.487: I/DEBUG(3844): r4 4a5db590 r5 004ea2e8 r6 4a5db590 r7 49cc1bc4
07-02 17:08:21.487: I/DEBUG(3844): r8 49cc1bc4 r9 49ab4f64 10 495f752c fp 49cc1bdc
07-02 17:08:21.487: I/DEBUG(3844): ip 40003108 sp 49cc17b8 lr 4a02a79b pc 4a029fb0 cpsr 00000030
07-02 17:08:21.487: I/DEBUG(3844): d0 42c8000042b6aa73 d1 3ff0000000b23680
07-02 17:08:21.487: I/DEBUG(3844): d2 3ff0000000000000 d3 4197d78400000000
07-02 17:08:21.487: I/DEBUG(3844): d4 3ff0000000000000 d5 4028000000000000
07-02 17:08:21.487: I/DEBUG(3844): d6 00c31fe000000000 d7 0000005b4e8b3a94
07-02 17:08:21.487: I/DEBUG(3844): d8 3f8000003f800000 d9 43d2000000000000
07-02 17:08:21.487: I/DEBUG(3844): d10 000000004479f062 d11 0000000000000000
07-02 17:08:21.487: I/DEBUG(3844): d12 0000000000000000 d13 0000000000000000
07-02 17:08:21.487: I/DEBUG(3844): d14 0000000000000000 d15 0000000000000000
07-02 17:08:21.487: I/DEBUG(3844): scr 20000012
07-02 17:08:21.717: I/ActivityManager(78): Displayed com.myapp/.ui.activities.Loader: +831ms
07-02 17:08:22.437: I/DEBUG(3844): #00 pc 00367fb0 /data/data/com.myapp/lib/libwrapper.so (_ZN7_JNIEnv16CallObjectMethodEP8_jobjectP10_jmethodIDz)
07-02 17:08:22.437: I/DEBUG(3844): #01 lr 4a02a79b /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.437: I/DEBUG(3844): code around pc:
07-02 17:08:22.437: I/DEBUG(3844): 4a029f90 1c0347a0 b0041c18 46c0bd10 b510b40c .G.........F....
07-02 17:08:22.437: I/DEBUG(3844): 4a029fa0 9001b084 ab079100 9b019302 238c681a .............h.#
07-02 17:08:22.437: I/DEBUG(3844): 4a029fb0 980158d4 9a069900 47a09b02 93031c03 .X.........G....
07-02 17:08:22.437: I/DEBUG(3844): 4a029fc0 1c189b03 bc10b004 b002bc08 46c04718 .............G.F
07-02 17:08:22.437: I/DEBUG(3844): 4a029fd0 b510b40c 9001b084 ab079100 9b019302 ................
07-02 17:08:22.437: I/DEBUG(3844): code around lr:
07-02 17:08:22.437: I/DEBUG(3844): 4a02a778 1c112006 f3e91c1a 4b40fbe7 681a58e3 . ........@K.X.h
07-02 17:08:22.437: I/DEBUG(3844): 4a02a788 58e34b43 9904681b 1c111c08 f7ff1c1a CK.X.h..........
07-02 17:08:22.437: I/DEBUG(3844): 4a02a798 1c03fc01 4b439305 1c1a447b 447b4b42 ......CK{D..BK{D
07-02 17:08:22.437: I/DEBUG(3844): 4a02a7a8 1c112006 f3e91c1a 9a04fbcf 1c109b05 . ..............
07-02 17:08:22.437: I/DEBUG(3844): 4a02a7b8 22001c19 fbaaf7f5 93061c03 447b4b3b ..."........;K{D
07-02 17:08:22.437: I/DEBUG(3844): stack:
07-02 17:08:22.437: I/DEBUG(3844): 49cc1778 00000000
07-02 17:08:22.437: I/DEBUG(3844): 49cc177c 0038d96c [heap]
07-02 17:08:22.437: I/DEBUG(3844): 49cc1780 0023c108 [heap]
07-02 17:08:22.437: I/DEBUG(3844): 49cc1784 49cc1884
07-02 17:08:22.437: I/DEBUG(3844): 49cc1788 4a5d28d0 /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.437: I/DEBUG(3844): 49cc178c 001a1f20 [heap]
07-02 17:08:22.437: I/DEBUG(3844): 49cc1790 001a1f28 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc1794 001a1f28 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc1798 001c7580 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc179c 001c7588 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc17a0 001c7588 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc17a4 00483ccc [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc17a8 0023c540 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc17ac 4004c4b0
07-02 17:08:22.457: I/DEBUG(3844): 49cc17b0 df0027ad
07-02 17:08:22.457: I/DEBUG(3844): 49cc17b4 00000000
07-02 17:08:22.457: I/DEBUG(3844): #00 49cc17b8 1d200222
07-02 17:08:22.457: I/DEBUG(3844): 49cc17bc 00238040 [heap]
07-02 17:08:22.457: I/DEBUG(3844): 49cc17c0 49cc17d4
07-02 17:08:22.457: I/DEBUG(3844): 49cc17c4 4a5db590 /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.457: I/DEBUG(3844): 49cc17c8 4a5db590 /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.457: I/DEBUG(3844): 49cc17cc 4a02a79b /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.457: I/DEBUG(3844): 49cc17d0 44e313c0 /dev/ashmem/dalvik-LinearAlloc (deleted)
07-02 17:08:22.467: I/DEBUG(3844): 49cc17d4 44e313c0 /dev/ashmem/dalvik-LinearAlloc (deleted)
07-02 17:08:22.467: I/DEBUG(3844): 49cc17d8 49cc1bc4
07-02 17:08:22.467: I/DEBUG(3844): 49cc17dc 0023c710 [heap]
07-02 17:08:22.467: I/DEBUG(3844): 49cc17e0 495f752c /data/dalvik-cache/data@app@com.myapp-1.apk@classes.dex
07-02 17:08:22.467: I/DEBUG(3844): 49cc17e4 0023c108 [heap]
07-02 17:08:22.467: I/DEBUG(3844): 49cc17e8 00238040 [heap]
07-02 17:08:22.467: I/DEBUG(3844): 49cc17ec 4a5db590 /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:22.467: I/DEBUG(3844): 49cc17f0 49cc1bc4
07-02 17:08:22.467: I/DEBUG(3844): 49cc17f4 0023c108 [heap]
07-02 17:08:22.467: I/DEBUG(3844): 49cc17f8 0023c108 [heap]
07-02 17:08:22.467: I/DEBUG(3844): 49cc17fc 4a3c579f /data/data/com.myapp/lib/libwrapper.so
07-02 17:08:27.908: I/BootReceiver(78): Copying /data/tombstones/tombstone_07 to DropBox (SYSTEM_TOMBSTONE)