rtw_android.c error: implicit declaration of function ‘strnicmp’ [-Werror=implicit-function-declaration]

Question

I am trying tin install my Alfa AWUS036ACH adapter for Kali linux 2.0

I have fixed the prior errors but now I am stuck here. This is the error I am receiving.

os_dep/linux/rtw_android.c:345:3: error: implicit declaration of function 'strnicmp' [-Werror=implicit-function-declaration] if(0 == strnicmp(cmdstr , android_wifi_cmd_str[cmd_num], strlen(android_wifi_cmd_str[cmd_num])) ) ^

My coding skills are not up to par and I am still learning so any help would be appreciated.

The code in specific is as follows:

int rtw_android_cmdstr_to_num(char *cmdstr)
{
    int cmd_num;
    for(cmd_num=0 ; cmd_num<ANDROID_WIFI_CMD_MAX; cmd_num++)
        if(0 == strnicmp(cmdstr , android_wifi_cmd_str[cmd_num], strlen(android_wifi_cmd_str[cmd_num])) )
        break;

return cmd_num;
}

I looked at other peoples answers to other questions and I am not sure how this code should be adjusted.

Answer 1

A partial answer to your question:

Kali Linux 2.0, based on Debian Jessie, comes with a Linux 4.x kernel.

In recent Linux versions, the system call strnicmp has been deprecated and replaced by a wrapper, to allow later removal, in favour of strncasecmp . See also this commit log .

One way to find out if your system supports these calls, is to look for their names in the kernel symbol table, a table with names and their memory locations. This symbol table is usually represented by a file named System.map , and located in /boot/ .

An example for Linux 2.6.32:

    $ grep -e strnicmp -e strncasecmp /boot/System.map-2.6.32
    ffffffff81298450 T strnicmp
    ffffffff81298540 T strncasecmp
    ffffffff8183a680 r __ksymtab_strncasecmp
    ffffffff8183a6a0 r __ksymtab_strnicmp
    ffffffff8184e0d0 r __kcrctab_strncasecmp
    ffffffff8184e0e0 r __kcrctab_strnicmp
    ffffffff81861153 r __kstrtab_strncasecmp
    ffffffff8186116a r __kstrtab_strnicmp

An example for Linux 4.4.6:

    $ grep -e strnicmp -e strncasecmp /boot/System.map-4.4.6
    ffffffff813aaee0 T strncasecmp
    ffffffff81b484a0 R __ksymtab_strncasecmp
    ffffffff81b608c8 r __kcrctab_strncasecmp
    ffffffff81b776e4 r __kstrtab_strncasecmp

To fix your problem, without regression, a clause that reflects the renaming will have to be added to the code, in this case rtw_android.c .

An example diff for Linux version 4.0.0:

    diff -urN os_dep.orig/linux/rtw_android.c os_dep/linux/rtw_android.c
    --- os_dep.orig/linux/rtw_android.c 2016-03-29 13:53:46.657398453 +0200
    +++ os_dep/linux/rtw_android.c  2016-03-29 13:26:13.871323615 +0200
    @@ -30,6 +30,10 @@
     #endif
     #endif /* defined(RTW_ENABLE_WIFI_CONTROL_FUNC) */

    +#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 0, 0))
    +#define strnicmp strncasecmp
    +#endif
    +

     const char *android_wifi_cmd_str[ANDROID_WIFI_CMD_MAX] = {
        "START",