Re: [PATCH] dpkg-base: mount git source folder into buildchroot

[Christian Storm <christian.storm@siemens.com>]

> > When building a Debian source package with source/format "3.0 (git)",
> > the git binary is used to bundle the source. For being able to do so,
> > <build>/tmp/downloads/git/<git_repo> needs to be mounted into the
> > buildchroot as .git/objects/info/alternates refers to it.
> 
> Could you please provide more details regarding where it should be mounted?

Please see below for an explanation.


> > Signed-off-by: Christian Storm <christian.storm@siemens.com>
> > ---
> >   meta/classes/dpkg-base.bbclass | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-base.bbclass
> > index 35af6d5..a98e690 100644
> > --- a/meta/classes/dpkg-base.bbclass
> > +++ b/meta/classes/dpkg-base.bbclass
> > @@ -20,14 +20,18 @@ dpkg_runbuild() {
> >   # Wrap the function dpkg_runbuild with the bind mount for buildroot
> >   do_build() {
> >       mkdir -p ${BUILDROOT}
> > -    sudo mount --bind ${WORKDIR} ${BUILDROOT}
> > +    [ ! -d ${BUILDCHROOT_DIR}/${GITDIR} ] && sudo install -d -m 755 ${BUILDCHROOT_DIR}/${GITDIR}
> 
> ${GITDIR} - will be expanded to absolute path of your build tree on the 
> host. Why this private path is needed in buildchroot? This doesn't look 
> correct for me if you need it for build.
> 
> Also git repository is already available in buildchroot:
> 
> 1. If package is fetched via git repository - it's stored in ${GITDIR}.
> 2. Then task "do_unpack" clones this to ${WORKDIR}/git folder
> 3. During build task, the folder ${WORKDIR} is mounted to ${BUILDROOT}
> 4. So your git repo is in: /home/builder/${PN}/git folder inside chroot.

Well, no. It contains the checkout of the source done by the fetcher.
You'll get a castrated .git/ in the buildchroot, i.e., try to run git
operations in the buildchroot when do_build'ing a particular package and
git complains:
  error: object directory /build/tmp/downloads/git/xxxxxx/objects does not exist; check .git/objects/info/alternates.
  fatal: bad object HEAD

It tries to resolve the repository "symlink" in
.git/objects/info/alternates which points to the directory the fetcher
has put it in, i.e., <build>/tmp/downloads/git/xxxxxx. This directory,
respectively, <build>/tmp/downloads/git/, however, isn't mounted in the
buildchroot and so git can't do operations.
Hence, source/format "3.0 (git)" fails as it wants to do git operations.

Does this explanation help?



Kind regards,
   Christian

-- 
Dr. Christian Storm
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Otto-Hahn-Ring 6, 81739 M�nchen, Germany