reset-if-staging

#!/usr/bin/env python
#
# Remove all commits from a branch that have "redhat.staging"
# as a detached metadata key.
#
# Copyright 2015 Colin Walters <walters@verbum.org>
# Licensed under the new-BSD license (http://www.opensource.org/licenses/bsd-license.php)

import gi
gi.require_version('OSTree', '1.0')
from gi.repository import GLib, Gio, OSTree
import argparse

staging_key = 'redhat.staging'

def fatal(msg):
    print >>sys.stderr, msg
    sys.exit(1)

parser = argparse.ArgumentParser(prog="ostree-edit-detached")
parser.add_argument("--repo", help="Repo path",
                    action='store', required=True)
parser.add_argument("--ref", help="Branch or commit",
                    action='store', required=True)

arg = parser.parse_args()

r = OSTree.Repo.new(Gio.File.new_for_path(arg.repo))
r.open(None)

[_,rev] = r.resolve_rev(arg.ref, False)
print "%s => %s" % (arg.ref, rev)

# Loop across the history, stopping as soon as we find
# a commit without redhat.staging
commit = None
iter_rev = rev
while True:
    _,commit = r.load_variant(OSTree.ObjectType.COMMIT, iter_rev)
    _,metadata = r.read_commit_detached_metadata(iter_rev, None)
    if (metadata is not None and metadata.unpack().get(staging_key)):
        iter_rev = OSTree.commit_get_parent(commit)
        if iter_rev is None:
            fatal("Found a staging commit but no parent?")
        # skip this commit
        continue   
    else:
        break

if iter_rev != rev:
    # We have commits to delete

    print "Resetting {0} to {1}".format(arg.ref, iter_rev)
    r.set_ref_immediate(None, arg.ref, iter_rev, None)

    # Now do a prune
    _,nobjs,npruned,objsize = r.prune(OSTree.RepoPruneFlags.REFS_ONLY, -1, None)
    if npruned == 0:
        print "No unreachable objects"
    else:
        fmtsize = GLib.format_size_full(objsize, 0)
        print "Deleted {0} objects, {1} freed".format(npruned, fmtsize)

else:
    # Nothing to do!
    print "Latest commit {0} for {1} does not have {2} detached metadata key".format(rev, arg.ref, staging_key)