c++ - Android -- get MEID from JNI

Question

I'm working in Android, writing some JNI code, and I'm looking for a way to query the Mobile Equipment Identifier (MEID) from the device.

http://en.wikipedia.org/wiki/Mobile_equipment_identifier

I'm trying to write C or C++ code that can run by itself on an Android device, so I don't think I can use Java (i.e., get MEID from TelephonyManager).

A search of StackOverflow finds: Is there an android shell or adb command that I could use to get a device's IMEI/MEID?

Okay great, dumpsys iphonesubinfo can get the info I need. And it works!

I couldn't find the source for dumpsys except as part of the source for Android. So I downloaded that... my hard disk filled up before the download finished, but I did get the source code to dumpsys. It is a surprisingly short C++ file. All it does is query Android's IBinder interface.

So, my questions:

0) Is there any way I can write a query against IBinder using just the stuff in the NDK? The include files used by dumpsys.cpp are not in the NDK, and grep in the NDK directory didn't find IBinder in any include files or code samples, so my guess is "no" (but I would like to be wrong).

1) Is there any other good way to get the MEID?

I'm seriously thinking I should just use system("dumpsys iphonesubinfo > /tmp/myprogname_dumpsys.tmp" and then open the resulting file and parse it. That should work, but I would hardly call it elegant... and I'm not sure if dumpsys is available on every Android device or not.

EDIT: The idea of using system() to run dumpsys will not work, because dumpsys needs android.permission.DUMP and Android no longer allows non-system apps to have that permission.

Dumpsys permission denial in java

Answer 1

I believe Dalvik implements all the same JNI interfaces that the JVM does, so while it's a bit fiddly, it's perfectly possible to make calls from native code through JNI to arbitrary Java classes and methods.

/* assuming you already have */
JNIEnv *env;
jobject context;
/* then call (with error-checking) */
jclass cls = (*env)->FindClass(env, "android/context/Context");
jmethodId mid = (*env)->GetMethodID(env, context_cls, "getSystemService",
    "(Ljava/lang/String;)Ljava/lang/Object;");
jfieldID fid = (*env)->GetStaticFieldID(env, cls, "TELEPHONY_SERVICE",
    "Ljava/lang/String;");
jstring str = (*env)->GetStaticObjectField(env, cls, fid);
jobject telephony = (*env)->CallObjectMethod(env, context, mid, str);
cls = (*env)->FindClass(env, "android/telephony/TelephonyManager");
mid =(*env)->GetMethodID(env, cls, "getDeviceId", "()Ljava/lang/String;");
str = (*env)->CallObjectMethod(env, telephony, mid);
jsize len = (*env)->GetStringUTFLength(env, str);
char* deviceId = calloc(len + 1, 1);
(*env)->GetStringUTFRegion(env, str, 0, len, deviceId);
(*env)->DeleteLocalRef(env, str);
/* to get a string in deviceId */