Re: [PATCH] POSIX extended API set 2

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost> wrote:

> I don't think namei.h / vfs_lookup.c is the right place to be handling
> file descriptors.  Can you make these take vnodes, rather than file
> descriptors, or move them into vfs_syscalls.c?

I made the change, but it makes nameiat_simple_user() usage more
complicated, with code duplicated on each call (see example at the end)

> I think you'll leak pb here in the error branch above.  I haven't gone
> through the other error branches in the patch, but the proliferation
> of new resource acquisitions requiring clean-up makes me nervous.

The problem is that we need to hold a reference on the vnode we use 
in NDAT().


+static int
+do_sys_chmodat(struct lwp *l, int fdat, const char *path, int mode, int flags)
+{
        int error;
        struct vnode *vp;
+       namei_simple_flags_t nsflag;
+       file_t *dfp = NULL;
+       struct vnode *dvp = NULL;
 
-       error = namei_simple_user(SCARG(uap, path),
-                               NSM_FOLLOW_TRYEMULROOT, &vp);
+       if (flags & AT_SYMLINK_NOFOLLOW)
+               nsflag = NSM_NOFOLLOW_TRYEMULROOT;
+       else
+               nsflag = NSM_FOLLOW_TRYEMULROOT;
+
+       /* fd_getvnode() will use the descriptor for us */
+       if (fdat != AT_FDCWD) {
+               if ((error = fd_getvnode(fdat, &dfp)) != 0)
+                       return (error);
+               dvp = dfp->f_data;
+       }
+
+       error = nameiat_simple_user(dvp, path, nsflag, &vp);
        if (error != 0)
-               return (error);
+               goto out;
 
-       error = change_mode(vp, SCARG(uap, mode), l);
+       error = change_mode(vp, mode, l);
 
        vrele(vp);
+out:
+       if (dfp != NULL)
+               fd_putfile(fdat);
+
        return (error);
 }



-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost