Re: [PATCH v3] dpkg-base: resolve DL_DIR in do_adjust_git

[Cedric Hombourger <Cedric_Hombourger@mentor.com>]

On Fri, 2022-02-04 at 12:04 +0100, Jan Kiszka wrote:
> On 04.02.22 11:54, Cedric Hombourger wrote:
> > From: Cedric Hombourger <cedric.hombourger@siemens.com>
> > 
> > git_link is resolved using os.path.realpath() but git_dl is not.
> > If DL_DIR points to a symbolic link, the comparison will always
> > fail and do_adjust_git() will attempt to re-create the symbolic
> > link. Resolve DL_DIR for a comparison between resolved paths.
> > In the event where paths do differ, the symbolic link needs to
> > be deleted first.
> > 
> > Signed-off-by: Cedric Hombourger <cedric.hombourger@siemens.com>
> > ---
> >  meta/classes/dpkg-base.bbclass | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> > 
> > diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-
> > base.bbclass
> > index 2add0b2..258e040 100644
> > --- a/meta/classes/dpkg-base.bbclass
> > +++ b/meta/classes/dpkg-base.bbclass
> > @@ -20,9 +20,13 @@ python do_adjust_git() {
> >      rootdir = d.getVar('WORKDIR', True)
> >  
> >      git_link = os.path.join(d.getVar('GIT_DL_LINK_DIR'), '.git-
> > downloads')
> > -    git_dl = os.path.join(d.getVar("DL_DIR"), "git")
> > +    dl_dir = os.path.realpath(d.getVar("DL_DIR"))
> > +    git_dl = os.path.join(dl_dir, "git")
> >  
> > -    if not os.path.exists(git_link) or os.path.realpath(git_link)
> > != git_dl:
> > +    if os.path.exists(git_link) and os.path.realpath(git_link) !=
> > git_dl:
> > +        os.unlink(git_link)
> > +
> > +    if not os.path.exists(git_link):
> >          os.symlink(git_dl, git_link)
> >  
> >      for src_uri in (d.getVar("SRC_URI", True) or "").split():
> > @@ -34,7 +38,7 @@ python do_adjust_git() {
> >  
> >              if os.path.islink(ud.localpath):
> >                  realpath = os.path.realpath(ud.localpath)
> > -                filter_out = os.path.join(d.getVar("DL_DIR"),
> > "git") + "/"
> > +                filter_out = git_dl + "/"
> >                  if realpath.startswith(filter_out):
> >                      # make the link relative
> >                      link = realpath.replace(filter_out, '', 1)
> 
> Looks good and was surely an untested case so far. It's actually two
> fixes in one (os.symlink != ln -sf...)
> 
> Does this explain your "race condition" from before?

Yes it certainly did. I had misinterpreted the symptoms / root-cause
(thanks again for pointing me to the lock around do_adjust_git)

> 
> Jan
>