[lxc-devel] call to setup_dev_symlinks with lxc.autodev

[Michael H. Warfield]

On Fri, 2014-04-25 at 16:50 +0200, William Dauchy wrote:
> On Thu, Apr 17, 2014 at 9:04 PM, Michael H. Warfield <mhw at wittsend.com> wrote:
> > -- diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> > index 06235fb..65f1f85 100644
> > --- a/src/lxc/conf.c
> > +++ b/src/lxc/conf.c
> > @@ -828,19 +828,38 @@ static int setup_dev_symlinks(const struct lxc_rootfs *rootfs)
> >  {
> >         char path[MAXPATHLEN];
> >         int ret,i;
> > +       struct stat s;
> >
> >
> > +       INFO("Entering setup_dev_symlinks");
> >         for (i = 0; i < sizeof(dev_symlinks) / sizeof(dev_symlinks[0]); i++) {
> >                 const struct dev_symlinks *d = &dev_symlinks[i];
> >                 ret = snprintf(path, sizeof(path), "%s/dev/%s", rootfs->mount, d->name);
> >                 if (ret < 0 || ret >= MAXPATHLEN)
> >                         return -1;
> > +
> > +               /*
> > +                * Stat the path first.  If we don't get an error
> > +                * accept it as is and don't try to create it
> > +                */
> > +               if (!stat(path, &s)) {
> > +                       INFO("Symlink to %s exists", path);
> > +                       continue;
> > +               }
> > +
> 
> When using stat, it obviously fixes the issue; my workaround was
> indeed to list the /dev directory before starting in order to make the
> `symlink` function return EEXIST.
> 
> > +               INFO("Creating symlink from %s to %s", d->oldpath, path);
> >                 ret = symlink(d->oldpath, path);
> > +
> >                 if (ret && errno != EEXIST) {
> > -                       SYSERROR("Error creating %s", path);
> > -                       return -1;
> > +                       if ( errno == EROFS ) {
> > +                               SYSERROR("Warning: Read Only file system while creating %s", path);
> > +                       } else {
> > +                               SYSERROR("Error creating %s", path);
> > +                               return -1;
> > +                       }

> If I remove the `stat`call, I'm getting EROFS. That explains the issue.

Bingo!  I guess my conjecture about it being a quirk in the kernel VFS
must be pretty close.

Ok...  I'll submit a formal patch shortly.

Thanks!

> Best regards,
> -- 
> William

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 978-7061 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!

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