初学内核编程，写了一个makefile文件，使用VPATH全局变量设置头文件搜索路径可还是显示找不到
makefile文件内容如下：
ifneq ($(KERNELRELEASE),)
obj-m += http.o
else
PWD := $(shell pwd)
KVER := $(shell uname -r)
KDIR := /lib/modules/$(KVER)/build
VPATH = /usr/include:/usr/include/x86_64-linux-gnu:/usr/lib/gcc/x86_64-linux-gnu/4.8/include:/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed:/usr/local/include
default:
$(MAKE) -C $(KDIR) M=$(PWD) modules
all:
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf *.o *.mod.c *.ko *.symvers *.order *.makers
endif
代码如下：
#include <linux/netfilter.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/inet.h>
#include <stdlib.h>
/**
* Hook function to be called.
* We modify the packet's src IP.
*/
unsigned int my_hookfn(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct iphdr *iph;
iph = ip_hdr(skb);
int * temp = iph;
iph = realloc(iph,sizeof(iph)+4);
printk(KERN_INFO"%lu\n",sizeof(*iph));
return NF_ACCEPT;
}
/* A netfilter instance to use */
static struct nf_hook_ops nfho = {
.hook = my_hookfn,
.pf = PF_INET,
.hooknum = NF_INET_PRE_ROUTING,
.priority = NF_IP_PRI_FIRST,
.owner = THIS_MODULE,
};
static int __init http_init(void)
{
if (nf_register_hook(&nfho)) {
printk(KERN_ERR"nf_register_hook() failed\n");
return -1;
}
return 0;
}
static void __exit http_exit(void)
{
nf_unregister_hook(&nfho);
}
module_init(http_init);
module_exit(http_exit);
MODULE_AUTHOR("flyking");
MODULE_LICENSE("GPL");
错误提示如下：
make -C /lib/modules/3.13.0-113-generic/build M=/home/test/fk modules
make[1]: 正在进入目录 `/usr/src/linux-headers-3.13.0-113-generic'
CC [M] /home/test/fk/http.o
/home/test/fk/http.c:7:20: fatal error: stdlib.h: 没有那个文件或目录
#include <stdlib.h>
^
compilation terminated.
make[2]: *** [/home/test/fk/http.o] 错误 1
make[1]: *** [_module_/home/test/fk] 错误 2
make[1]:正在离开目录 `/usr/src/linux-headers-3.13.0-113-generic'
make: *** [default] 错误 2
##
