getutline (3) fails on a daemon process

getutline (3) fails on a daemon process

[vadiraj]

Hi List,

I'm trying to fetch userid using utmp.h API's. I'm able to get the
userid from the funciton getutline(3) on normal process. But the
same function while called by a daemon process it fails with perror
"no such process".

Any Idea why this is failing on a daemon process? 

here is the sudo code of the program I'm using.


    struct utmp *out_entry ;
    out_entry = calloc(1,sizeof(struct utmp));
    if(out_entry == NULL)
        return -1;

    strcpy (out_entry->ut_line,"pts/0") ;
    out_entry = getutline(out_entry) ;
    if(out_entry != NULL){
        strcpy(username,out_entry->ut_user) ;
        return 0;
    }
    

I have no alternate to get the username, other calls are of no fruit to
me. Only this call is of use to me and it does work on a normal process.
It fails only if the same code is run as a daemon process.


Thanks in advance


Regards,
Vadiraj

Re: getutline (3) fails on a daemon process

[Glynn Clements]

vadiraj wrote:

> I'm trying to fetch userid using utmp.h API's. I'm able to get the
> userid from the funciton getutline(3) on normal process. But the
> same function while called by a daemon process it fails with perror
> "no such process".
> 
> Any Idea why this is failing on a daemon process? 

Because the daemon hasn't logged itself to the utmp file.

The utmp file is intended for recording "logged-in users". daemon
processes don't normally register themselves.

-- 
Glynn Clements <glynn@gclements.plus.com>