内核运行一个用户程序

使用call_usermodehelper即可。

函数原型

/**
 * call_usermodehelper() - prepare and start a usermode application
 * @path: path to usermode executable
 * @argv: arg vector for process
 * @envp: environment for process
 * @wait: wait for the application to finish and return status.
 *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
 *        when the program couldn't be exec'ed. This makes it safe to call
 *        from interrupt context.
 *
 * This function is the equivalent to use call_usermodehelper_setup() and
 * call_usermodehelper_exec().
 */
int call_usermodehelper(const char *path, char **argv, char **envp, int wait)

第4个参数wait取值如下：

#define UMH_NO_WAIT	0	/* don't wait at all */
#define UMH_WAIT_EXEC	1	/* wait for the exec, but not the process */
#define UMH_WAIT_PROC	2	/* wait for the process to complete */
#define UMH_KILLABLE	4	/* wait for EXEC/PROC killable */

例子

void run_users_proc(void)
{
    char *argv[] = {"/bin/sh", "-c", "/etc/test.sh > /dev/console", NULL};
    char *envp[] = {"PATH=/sbin:/bin:/usr/sbin:/usr/bin", "HOME=/", NULL};
    int ret = 0;

    printk(" run .... \n\n");
    ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
    printk("ret = %d\n", ret);
}

因为从内核打开的程序，并没有人为其准备标准输入输出，所以上面例子重定向console，才能有输出。

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人生苦短，远离bug Leon, 2024-04-17