Passing string array to linux kernel module as parameter

Question

is there any way to pass array of strings to kernel-module? I would like to pass it like this:

insmod mod.ko array="string1","string2","string3"

There is my code but it is not compiling:

#include<linux/module.h>
#include<linux/moduleparam.h>

static int number_of_elements = 0;
static char array[5][10];
module_param_array(array,charp,&number_of_elements,0644);



static int __init mod_init(void)
{

    int i;
    for(i=0; i<number_of_elements;i++)
    {
        pr_notice("%s\n",array[i]);
    }

    return 0;
}

static void __exit mod_exit(void)
{
    pr_notice("End\n");
}

module_init(mod_init);
module_exit(mod_exit);

MODULE_AUTHOR("...");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.0");

Not sure if there is a way, but of course you can always do insmod mod.ko array="string1,string2,string3" and split the string in your module code — Ctx
– Ctx, Commented Mar 21, 2019 at 15:04
@Ctx That's effectively what happens in the kernel's array parameter parser anyway. It simply splits the parameter value into comma-separated chunks. (This means you cannot include a comma within one of the comma-separated strings, because there is no "escape" mechanism.) — Ian Abbott
– Ian Abbott, Commented Mar 21, 2019 at 19:04

Ian Abbott · Accepted Answer · 2019-03-21 19:14:48Z

1

module_param_array(array,charp,&number_of_elements,0644); expects array to be an array of char *. You simply need to replace static char array[5][10]; with static char *array[5];

A normal command shell such as /bin/sh will treat "string1","string2","string3" as a single parameter (assuming you haven't been messing around with the shell's IFS variable). The kernel's module parameter parser will see it as a single parameter: string1,string2,string3 and use the commas to split it into three null-terminated strings. Your char *array[5] contents will be filled in with the pointers to these null-terminated strings and your number_of_elements will be set to the number of comma-separated strings.

answered Mar 21, 2019 at 19:14

Ian Abbott

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