call_usermodehelper使用实例

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#define UMH_WAIT_PROC 1

char * argv[3];

argv[0] = "/sbin/mdev";
argv[1] = "-s";
argv[2] = 0;
if (CallUserApp(argv)< 0)
{
printk("mdev -s failed\n");
break;

}

int CallUserApp(char * argv[])
{
int ret;
char *envp[3];

/* minimal command environment taken from cpu_run_sbin_hotplug */
envp[0] = "HOME=/";
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
envp[2] = NULL;

if (!argv || !argv[0])
{
printk( "%s argument is incorrect\n", __func__);
return -1;
}
ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);

if (ret < 0) {
printk("running user helper \"%s \" failed %d\n", argv[0], ret);
}
return ret;
}

static inline int call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait);
path --- 用户空间所要启用的应用程序路径,如:"/sbin/hotplug",那么hotplug应用程序就会被内核加载启用
argv --- 传递给启用了的用户空间应用程序的参数argv
envp --- 传递给启用了的用户空间应用程序的环境变量envp,类似int main(int argc, char *_argv[])模式
wait --- 调用call_usermodehelper的内核程序是否等到被exec的用户空间应用程序,

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