Java JNA和JNI-尝试引用未分配的内存
我正在使用JNI(现在使用JNA来查看问题是否发生了变化)将Java连接到C代码。这段代码有两个方法,我正在尝试使用,它们应该多次从Java代码中调用,但是,当我执行本机调用时,我得到了它:Java JNA和JNI-尝试引用未分配的内存,java,c,java-native-interface,jna,gnucobol,Java,C,Java Native Interface,Jna,Gnucobol,我正在使用JNI(现在使用JNA来查看问题是否发生了变化)将Java连接到C代码。这段代码有两个方法,我正在尝试使用,它们应该多次从Java代码中调用,但是,当我执行本机调用时,我得到了它: Call method one=我得到了一个响应 调用方法二=我得到了一个响应 再次调用方法1=尝试引用未分配的内存 (信号SIGSEGV) 此故障导致执行停止。 我试图单独调用第一个和第二个方法(而不是一个接一个地调用它们),但问题没有出现。当我一个接一个地打电话给他们的时候,这就发生了,就像他们应该
- Call method one=我得到了一个响应
- 调用方法二=我得到了一个响应
- 再次调用方法1=尝试引用未分配的内存
(信号SIGSEGV) - 此故障导致执行停止。
有人有同样的问题吗?在JNI版本中,您正在弹出一个本地参考框架,afaik也包含结果,而不保存结果。-JNA版本中的最后一个
memset
/memcpy
使用了一个未初始化的指针,它是UB。@Jorn Vernee关于弹出的本地引用,即使在这之后,我也可以在Java中获得结果。而且,如果我把它摘下来,反应是一样的(问题也是一样)。最后一个memset/memcpy,它们不是必需的吗?我正在准备响应,以使用char*值(结尾为\0)。是的,但实际上需要初始化指针(例如char*result=malloc(sizeof(struct3))
),现在它只是指向或多或少的随机内存位置。-如果删除PopLocalFrame
,我看不出该代码有任何错误。老实说,只需返回response
,而不释放它。gnu cobol的引用在哪里?
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "struct1.h"
#include "struct2.h"
#include "struct3.h"
#include "CALLExternMethod1s.h" //Interface External method
#include "CALLExternMethod2s.h" //Interface External method
#include "com_Method1Java.h" //Interface to Java Class
#include "com_Method2Java.h" //Interface to Java Class
void printStruct(void * structPar, int structSize) {
char buffer[structSize + 1];
memcpy(buffer, structPar, structSize);
buffer[structSize] = 0x00;
printf("{'%s'}\n", buffer);
}
JNIEXPORT jstring JNICALL Java_com_Method1Java_method1(JNIEnv *env, jobject obj, jstring input){
jboolean isCopy;
const char *request = (*env)->GetStringUTFChars(env, input, &isCopy);
struct1 struct1rec;
struct2 struct2rec;
char* response;
int reqLen = strlen(request);
reqLen = (reqLen <= sizeof(struct1)) ? reqLen : sizeof(struct1);
memcpy(&struct1rec, request, reqLen );
printf(" \n------ Struct1 Request ------\n ");
printStruct(&struct1rec, sizeof(struct1));
cob_init(0,NULL);
CALLExternMethod1(&struct1rec,&struct2rec); //Method overrides struct2rec with the response
response = malloc(sizeof(struct2) + 1);
memset(response, 0x20, sizeof(struct2) );
memcpy(response, &struct2rec, sizeof(struct2));
response[sizeof(struct2)] = '\0';
printf(" \n------ Struct2 Response ------\n ");
printStruct(response, sizeof(struct2));
(*env)->ReleaseStringUTFChars(env, input, request);
jstring result = (*env)->NewStringUTF(env, response);
free(response);
(*env)->PopLocalFrame(env,NULL);
printf("--- end of method1 JNI ---\n");
return result;
}
JNIEXPORT jstring JNICALL Java_com_Method2Java__struct3(JNIEnv *env, jobject obj, jstring input){
jboolean isCopy;
const char *request = (*env)->GetStringUTFChars(env, input, &isCopy);
struct3 struct3rec;
char* response;
int reqLen = strlen(request);
reqLen = (reqLen <= sizeof(struct3)) ? reqLen : sizeof(struct3);
memcpy(&struct3rec, request, reqLen );
printf("\n------ Struct3 Request ------\n");
printStruct(&struct3rec, sizeof(struct3));
cob_init(0,NULL);
CALLExternMethod2(&struct3rec); //Method overrides struct3Rec with the response
response = malloc(sizeof(struct3) + 1);
memset(response, 0x20, sizeof(struct3) );
memcpy(response, &struct3rec, sizeof(struct3));
response[sizeof(struct3)] = '\0';
printf("\n------ Struct3 Response ------\n");
printStruct(response, sizeof(struct3));
(*env)->ReleaseStringUTFChars(env, input, request);
jstring result = (*env)->NewStringUTF(env, response);
free(response);
printf("--- end of method2 JNI ---\n");
(*env)->PopLocalFrame(env,NULL);
return result;
}
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "struct1.h"
#include "struct2.h"
#include "struct3.h"
#include "CALLExternMethod1s.h" //Interface External method
#include "CALLExternMethod2s.h" //Interface External method
void printStruct(void * structPar, int structSize) {
char buffer[structSize + 1];
memcpy(buffer, structPar, structSize);
buffer[structSize] = 0x00;
printf("{'%s'}\n", buffer);
}
char* method1(char *request){
struct1 struct1rec;
struct2 struct2rec;
char* response;
int reqLen = strlen(request);
reqLen = (reqLen <= sizeof(struct1)) ? reqLen : sizeof(struct1);
memcpy(&struct1rec, request, reqLen);
printf("\n------ Struct1 Request -------- \n");
printStruct(&struct1rec, sizeof(struct1));
CALLExternMethod1(&struct1rec, &struct2rec); //Method overrides struct2rec with the response
printf("\n------ Struct2 Response -------- \n");
printStruct(&struct2rec, sizeof(struct2));
response = malloc(sizeof(struct2) + 1);
memset(response, 0x20, sizeof(struct2) );
memcpy(response, &struct2rec, sizeof(struct2));
response[sizeof(struct2)] = '\0';
char* result;
memset(result, 0x20, sizeof(struct2));
result = response;
free(response);
return result;
}
char* method2(char *request){
struct3 struct3Rec;
char* response;
memcpy(&struct3Rec,request, sizeof(struct3));
printf("\n------ Struct3 Request -------- \n");
printStruct(&struct3Rec, sizeof(struct3));
CALLExternMethod2(&struct3Rec); //Method overrides struct3Rec with the response
printf("\n------ Struct3 Response -------- \n");
printStruct(&struct3Rec,sizeof(struct3));
response = malloc(sizeof(struct3) + 1);
memset(response, 0x20, sizeof(struct3) );
memcpy(response, &struct3Rec, sizeof(struct3));
response[sizeof(struct3)] = '\0';
char* result;
memcpy(result, response, sizeof(struct3));
return result;
}
int main(int argc, char** args){
return 0;
}
(...)
static {
System.loadLibrary("libstuff");
}
public static synchronized native String method1(String struct);
(...)