JNI将字符串从C传递给Java

Question

I'm trying to pass a string from C to java and I'm hitting a reboot with the following trace, can someone help me understand how to fix this?

PC: 2cf57c7c (__GI_strlen+0xc glibc-2.4/string/strlen.c:42) RA: 2cf202a0 (vfprintf+0x42c0 glibc-2.4/stdio-common/vfprintf.c:1549)

My JNI code looks like this:

JNIEXPORT jstring JNICALL xxx_nativeGetParentName
  (JNIEnv *env, jobject obj, jstring childName)
{
    log("nativeGetParentName entered\n");
    char *name; 
    Node* parentName = NULL;
    jstring jstr = NULL;

    name = (char *)(*env)->GetStringUTFChars(env, childName, NULL);
    if (name == NULL)
        return NULL;
    log("about to call mpe_hnGetParentName\n");
    int retCode = mpe_GetParentName(name,&parentName);  // Call to the C function which holds the implementation 
    (*env)->ReleaseStringUTFChars(env,childName,name);

    if (retCode != 0 ) {
       log("mpe_GetParentName called with return code=%d\n", retCode);
       return NULL;
    }

    if(parentName[0] != NULL) {
        jstr= (*env)->NewStringUTF(env, parentName[0]); // Hitting the reboot exactly here!
        log("getting ParentName Succeded=%s\n", jstr);
        free(parentUuid);
    }

    return jstr;
}

The prototype of the C function calling looks like this:

i32 GetParentName(Node childName, Node **parentName);

The node is essentially a character array:

typedef char[] Node;

I'm successfully getting the parentName from the C method, but when I'm trying to map to JString I am hitting a reboot.

Thanks in advance!

Answer 1

Your second log message is most likely the problem:

log("getting ParentName Succeded=%s\n", jstr);

jstr is of type jstring , which is a pointer to a struct. It's not a string that you can pass as a valid argument for the %s format expression.