utils.cpp

//
// Created by swift on 2019/2/3.
//

#include <cstring>
#include "../includes/utils.h"

extern "C" {

Size getAddressFromJava(JNIEnv *env, const char *className, const char *fieldName) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return 0;
    }
    jfieldID id = env->GetStaticFieldID(clazz, fieldName, "J");
    if (id == NULL) {
        printf("find field error !");
        return 0;
    }
    return static_cast<Size>(env->GetStaticLongField(clazz, id));
}

Size callStaticMethodAddr(JNIEnv *env, const char *className, const char *method, const char *sig, ...) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return 0;
    }
    jmethodID id = env->GetStaticMethodID(clazz, method, sig);
    if (id == NULL) {
        printf("find field error !");
        return 0;
    }
    va_list vas;
    va_start(vas, sig);
    auto res = static_cast<Size>(env->CallStaticLongMethodV(clazz, id, vas));
    env->ExceptionClear();
    va_end(vas);
    return res;
}

jobject callStaticMethodObject(JNIEnv *env, const char *className, const char *method, const char *sig, ...) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return 0;
    }
    jmethodID id = env->GetStaticMethodID(clazz, method, sig);
    if (id == NULL) {
        printf("find field error !");
        return 0;
    }
    va_list vas;
    va_start(vas, sig);
    auto res = env->CallStaticObjectMethodV(clazz, id, vas);
    env->ExceptionClear();
    va_end(vas);
    return res;
}

jobject getMethodObject(JNIEnv *env, const char *clazz, const char *method) {
    auto methodStr = env->NewStringUTF(method);
    auto clazzStr = env->NewStringUTF(clazz);
    auto res = callStaticMethodObject(env, "com/swift/sandhook/SandHook", "getJavaMethod",
                         "(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;", clazzStr, methodStr);
    env->ExceptionClear();
    env->DeleteLocalRef(methodStr);
    env->DeleteLocalRef(clazzStr);
    return res;
}

Size getAddressFromJavaByCallMethod(JNIEnv *env, const char *className, const char *methodName) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return 0;
    }
    jmethodID id = env->GetStaticMethodID(clazz, methodName, "()J");
    if (id == NULL) {
        printf("find field error !");
        return 0;
    }
    auto res = env->CallStaticLongMethodA(clazz, id, nullptr);
    env->ExceptionClear();
    return static_cast<Size>(res);
}

jint getIntFromJava(JNIEnv *env, const char *className, const char *fieldName) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return 0;
    }
    jfieldID id = env->GetStaticFieldID(clazz, fieldName, "I");
    if (id == NULL) {
        printf("find field error !");
        return 0;
    }
    return env->GetStaticIntField(clazz, id);
}

bool getBooleanFromJava(JNIEnv *env, const char *className, const char *fieldName) {
    jclass clazz = env->FindClass(className);
    if (clazz == NULL) {
        printf("find class error !");
        return false;
    }
    jfieldID id = env->GetStaticFieldID(clazz, fieldName, "Z");
    if (id == NULL) {
        printf("find field error !");
        return false;
    }
    return env->GetStaticBooleanField(clazz, id);
}

bool munprotect(size_t addr, size_t len) {
    long pagesize = sysconf(_SC_PAGESIZE);
    unsigned alignment = (unsigned) ((unsigned long long) addr % pagesize);
    int i = mprotect((void *) (addr - alignment), (size_t) (alignment + len),
                     PROT_READ | PROT_WRITE | PROT_EXEC);
    if (i == -1) {
        return false;
    }
    return true;
}

bool flushCacheExt(Size addr, Size len) {
#if defined(__arm__)
    int i = cacheflush(addr, addr + len, 0);
    if (i == -1) {
        return false;
    }
    return true;
#elif defined(__aarch64__)
    char *begin = reinterpret_cast<char *>(addr);
    __builtin___clear_cache(begin, begin + len);
#endif
    return true;
}

}