How to get app package name or applicationId using JNI android

Question

For the protection issue of the shared library I will try to get package name using JNI but it will give errors. So, is it possible to get package name or applicationId usin

Answer 1

This works for me:

  static jstring get_package_name(
      JNIEnv *env,
      jobject jActivity
  ) {
    jclass jActivity_class = env->GetObjectClass(jActivity);

    jmethodID jMethod_id_pn = env->GetMethodID(
        jActivity_class,
        "getPackageName",
        "()Ljava/lang/String;");
    jstring package_name = (jstring) env->CallObjectMethod(
        jActivity,
        jMethod_id_pn);

    return package_name;
  }

Answer 2

Yes, it's possible. Android is based on Linux, we can obtain a lot of information in user space provided by kernel.

In your example, the information stored here /proc/${process_id}/cmdline

We can read this file, and get the application id.

See a simple example

#include <jni.h>
#include <unistd.h>
#include <android/log.h>
#include <stdio.h>

#define TAG "YOURAPPTAG"

extern "C"
JNIEXPORT void JNICALL
Java_com_x_y_MyNative_showApplicationId(JNIEnv *env, jclass type) {

    pid_t pid = getpid();
    __android_log_print(ANDROID_LOG_DEBUG, TAG, "process id %d\n", pid);
    char path[64] = { 0 };
    sprintf(path, "/proc/%d/cmdline", pid);
    FILE *cmdline = fopen(path, "r");
    if (cmdline) {
        char application_id[64] = { 0 };
        fread(application_id, sizeof(application_id), 1, cmdline);
        __android_log_print(ANDROID_LOG_DEBUG, TAG, "application id %s\n", application_id);
        fclose(cmdline);
    }
}