Can someone with knowledge of pseudo and fakeroot please shed some light on
this issue? Is there a reason that system calls are not being intercepted
correctly by pseudo/fakeroot to look up appropriate UIDs and GIDs to apply
to the migrated files? Is this due to Python shutil.chown?
On Mon, Jun 13, 2022 at 7:44 PM Sean via lists.yoctoproject.org wrote:
> I wrote a class, call it MYCLASS, whose purpose is to migrate certain
> files installed by standard recipes into a different directory and create
> symlinks to those files.
>
> The reason for this is to have a disk partition layout with a read-only,
> replaceable rootfs partition and a persistent storage partition. The idea
> is to move certain configuration files installed by a recipe into
> persistent storage and replace the rootfs version with a symlink.
>
> The user inherits this class in a .bbappend file in another layer and
> specifies the list of files that should have this treatment inside a
> MYCLASS_CONFFILES variable.
>
> I implemented this logic in a Python function and added it as a task as
> follows. I abstracted away some details and used "example.conf" as a
> hardcoded example configuration file being moved to a partition mounted at
> "/persistent".
>
> fakeroot python myclass_copy_and_symlink_conffiles() {
> ...
> sysconfdir_absfile = os.path.join(d.getVar('D'),
> d.getVar('sysconfdir'), 'example.conf')
> destdir_absfile = os.path.join(d.getVar('D', 'persistent/example.conf')
>
> st = os.stat(sysconfdir_absfile)
> shutil.copy(sysconfdir_absfile, destdir_absfile)
> shutil.chown(destdir_absfile, user=st.st_uid, group=st.st_gid)
>
> # omitted: replace original file with symlink to copied file
>
> ...
>
> }
>
> myclass_copy_and_symlink_conffiles[depends] +=
> "virtual/fakeroot-native:do_populate_sysroot"
>
> do_install[postfuncs] += "${MYCLASSINSTALLFUNCS}"
>
> MYCLASSINSTALLFUNCS_class-target = "myclass_copy_and_symlink_conffiles"
> MYCLASSINSTALLFUNCS = ""
>
>
> The problem I'm having is that UID and GID don't seem to be available to
> the shutil.chown function or they're not read correctly from the pseudo
> database when os.stat is called. Using the function as shown above, MYCLASS
> doesn't preserve the UID/GID of the original file (as known to
> fakeroot/pseudo) and falls back to setting UID:GID=root:root on the copied
> file instead.
>
> Any hints on how I can improve this approach? Is the problem that the
> system calls made by shutil/os functions aren't handled by pseudo? Should I
> replace this Python function with a shell function that can use fakeroot?
>
>
>
>
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