JNI segfaults创建新对象 [英] JNI segfaults creating new object
问题描述
我是JNI(和Java)的新手,所以如果这只是一个愚蠢的错误,我事先表示歉意.但是经过大量搜索,我找不到解释或解决方案.
I'm new to JNI (and java), so I apologize in advance if this is just a stupid mistake. But after much searching I can't find an explanation or a solution.
我有一个名为 Tagged< T>
的参数Java类. Tagged< T>
的Java构造函数采用一个对象 T
和一个长的 ptr
.C代码具有一个值,并且应该使用 v
值和该值的内存地址创建一个Tagged对象.但是,当我调用NewObject时遇到段错误.不确定问题是否出在泛型Type构造函数(用整数调用),Java/C整数类型之间的不匹配(长对长,长对长),愚蠢的错误或我未曾考虑的东西.
I have a parametric Java class called Tagged<T>
. The Java constructor for Tagged<T>
takes an object T
and a long ptr
. The C code has a value and is supposed to create a Tagged object with the value v
and the memory address of that value. However, I get a segfault when I call NewObject. Not sure if the problem is the generic Type constructor (called with an integer), a mismatch between Java/C integer types (long vs long long vs long), a stupid mistake, or something I haven't considered.
Java类:
public class Tagged<T> {
private final T value;
private long ptr;
private TaggedValue(T value, long ptr){
this.value = value;
this.ptr = ptr;
}
}
JNI代码:
JNIEXPORT jobject JNICALL Java_package_Class_function (JNIEnv * env, jclass cls, ...){
// Find Java class
jclass c = (*env)->FindClass(env, "package/Tagged");
if (c == 0) {
printf("Find Class Failed.\n");
}else{
printf("Found class.\n");
}
// Find Tagged<T> constructor
jmethodID constructor = (*env)->GetMethodID(env,c, "<init>", "(Ljava/lang/Object;J)V");
if (constructor == 0) {
printf("Find method Failed.\n");
} else {
printf("Found method.\n");
}
// Get value
int * valptr = LibraryCall();
// check that constructor arguments are what we expect
int val = (int) *valptr;
printf("Value: %i\n",val);
long long addr = (long long) valptr;
printf("Address: %p = %lld = %p\n",valptr,addr,(void *)addr);
// Try to create Tagged object
jobject taggedval = (*env)->NewObject(env, c, constructor, val, addr);
printf("We never get here\n");
return taggedval;
}
控制台输出:
Found class.
Found method.
Value: 102583
Address: 0x7fdcc2d209b0 = 140586138077616 = 0x7fdcc2d209b0
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x0000000109ae9bcf, pid=42140, tid=3847
#
# JRE version: Java(TM) SE Runtime Environment (8.0_66-b17) (build 1.8.0_66-b17)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.66-b17 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# V [libjvm.dylib+0x2e9bcf] JavaCallArguments::parameters()+0x27
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /Users/eleanor/Documents/workspace/av-java/src/hs_err_pid42140.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#
Abort trap: 6
感谢任何/所有帮助!
推荐答案
您的构造函数使用 jobject
和 long
,然后将其传递给 int
和 long long
.
Your constructor takes an jobject
and a long
, and you are passing it an int
and a long long
.
也许您可能打算将 int
包装到Java Integer
中?而且,您也应该将long转换为 jlong
,以防 long long
和 jlong
相同类型.
Maybe you probably meant to wrap the int
into a java Integer
? And you should probably cast the long to a jlong
too, just in case long long
and jlong
arent the same type.
这篇关于JNI segfaults创建新对象的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!