2-安卓底层-java实现调用linux系统调用

java实现调用linux系统调用流程：

驱动：ibo.c

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#define     IBO_MAJOR   505
#define     IBO_MINOR   0
#define     IBO_NUM     1
#define     IBO_NAME    "ibo"
#define     CLS_NAME    "ibo_cls"
#define     DEV_NAME    "ibo"

dev_t devno;
struct cdev ibo_cdev;
struct class * cls;

static int ibo_open(struct inode *inode,struct file *filp){
printk("ibo_open success\n");
return 0;
}

static int ibo_release(struct inode *inode,struct file *filp){
printk("ibo_release success\n");
return 0;
}

static long ibo_ioctl(struct file *filp,unsigned int cmd,unsigned long arg){
printk("ibo_ioctl success %d\n",cmd);
return 0;
}

struct file_operations ibo_fops={
.owner          = THIS_MODULE,
.open           = ibo_open,
.release        = ibo_release,
.unlocked_ioctl = ibo_ioctl,
};

static int ibo_init(void){
int ret;
devno = MKDEV(IBO_MAJOR,IBO_MINOR);
ret = register_chrdev_region(devno,IBO_NUM,IBO_NAME);
if (ret < 0){
return -EFAULT;
}

cdev_init(&ibo_cdev,&ibo_fops);
ibo_cdev.owner = THIS_MODULE;

cdev_add(&ibo_cdev,devno,IBO_NUM);

cls = class_create(THIS_MODULE,CLS_NAME);
if (IS_ERR(cls)){
printk("class_create fail!!!\n");
return -EFAULT;
}

device_create(cls,NULL,devno,NULL,DEV_NAME);

printk("ibo_init success\n");
return 0;
}

static void ibo_exit(void){
device_destroy(cls,devno);
class_destroy(cls);
cdev_del(&ibo_cdev);
unregister_chrdev_region(devno,IBO_NUM);

printk("ibo_exit success\n");
return;
}

module_init(ibo_init);
module_exit(ibo_exit);

MODULE_LICENSE("GPL");

驱动:Makefile

ifeq ($(KERNELRELEASE),)

KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD)

clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions Module* modules*

.PHONY: modules clean

else
obj-m := ibo.o
endif

sudo insmod ibo.ko

ibo_init success

JAVA : Ibo.java

class Ibo{
static{
System.loadLibrary("native");
}
private native void open();
private native void ioctl(int cmd);
private native void release();

public static void main(String[] args) {

Ibo m=new Ibo();
m.open();
m.ioctl(525);
m.release();
}
}

javac Ibo.java

javah Ibo

JNI : native.c

#include <jni.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/ioctl.h>

int fd;

void Jopen(JNIEnv *env,jobject obj){
fd = open("/dev/ibo",O_RDWR);
return;
}
void Jioctl(JNIEnv *env,jobject obj,jint cmd){
ioctl(fd,cmd);
return;
}
void Jrelease(JNIEnv *env,jobject obj){
a690
close(fd);
return;
}

JNINativeMethod methods[]={
"open","()V",(void *)Jopen,
"ioctl","(I)V",(void *)Jioctl,
"release","()V",(void *)Jrelease,
};

JNIEXPORT jint JNICALL
JNI_OnLoad(JavaVM *vm, void *reserved){
JNIEnv *env;
jclass cls;

system("sudo chmod 777 /dev/ibo");

(*vm)->GetEnv(vm, (void **)&env, JNI_VERSION_1_2);
if(env == NULL) return JNI_ERR;

cls = (*env)->FindClass(env, "Ibo");
if(cls == NULL) return JNI_ERR;

(*env)->RegisterNatives(env, cls,methods, sizeof(methods)/sizeof(JNINativeMethod));

return JNI_VERSION_1_2;
}

gcc -shared -fPIC native.c -o libnative.so -I /usr/lib/jvm/java-7-openjdk-amd64/include/

export LD_LIBRARY_PATH=:

java Ibo