How to find what symlink points to?

[Unga]

--- On Tue, 7/28/09, Mel Flynn <mel.flynn+fbsd.questions at mailing.thruhere.net> wrote:

> From: Mel Flynn <mel.flynn+fbsd.questions at mailing.thruhere.net>
> Subject: Re: How to find what symlink points to?
> To: freebsd-questions at freebsd.org
> Date: Tuesday, July 28, 2009, 1:25 AM
> On Monday 27 July 2009 05:45:13 Unga
> wrote:
> 
> > > > Hi all
> > > >
> > > > I need to remove some unwanted symlinks on
> /dev using
> > >
> > > a C program.
> > >
> > > > The "struct dirent" only shows the symlink
> name, how
> > >
> > > do I find what that
> > >
> > > > symlink points to for verification purpose?
> > >
> > > By using the readlink(2) system call.
> >
> > But readlink(2) fails with errno set to 2. Can
> readlink(2) use with dev
> > nodes?
> 
> Works for me. errno 2 is ENOENT ("No such file or
> directory"). I would inspect 
> if your request path points to the right location.
> 
> % ./rl /dev/stderr
> /dev/stderr => fd/2
> 
> % cat rl.c
> #include <sys/types.h>
> #include <sys/param.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> 
> #include <err.h>
> 
> int main(int argc, char **argv)
> {
>         char path[MAXPATHLEN],
> buf[MAXPATHLEN+1];
>         ssize_t res;
> 
>         if( argc != 2 )
>                
> exit(67);
> 
>         (void)strlcpy(path, argv[1],
> sizeof(path));
>         res = readlink(path, buf,
> sizeof(buf));
>         if( res < 0 )
>                
> err(EXIT_FAILURE, "readlink()");
>         buf[MAXPATHLEN] = '\0';
>         printf("%s => %s\n", path,
> buf);
> 
>         return (0);
> }
> 

Thanks everybody for valuable replies. In fact, I also used readlink(2) but fed the symlink path directly from dirent, which was partial, readlink(2) requires full path.

Unga