diff: Add ostree_diff_dirs_with_options(), expose via cmdline

The first options are owner_uid/owner_gid, which makes it possible to use diff
on local files where --owner-uid/gid have been passed to commit.

Closes: #740
Approved by: cgwalters

tests/basic-test.sh

@@ -19,7 +19,7 @@
 
 set -euo pipefail
 
-echo "1..63"
+echo "1..65"
 
 $CMD_PREFIX ostree --version > version.yaml
 python -c 'import yaml; yaml.safe_load(open("version.yaml"))'
@@ -171,6 +171,21 @@ cd ${test_tmpdir}
 assert_file_has_content diff-test2-2 'A *oh-look-a-file$'
 echo "ok diff cwd"
 
+cd ${test_tmpdir}/checkout-test2-4
+$OSTREE diff test2 ./ > ${test_tmpdir}/diff-test2
+assert_file_empty ${test_tmpdir}/diff-test2
+$OSTREE diff test2 --owner-uid=$((`id -u`+1)) ./ > ${test_tmpdir}/diff-test2
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet$'
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet/message$'
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet/another/tree/green$'
+echo "ok diff file with different uid"
+
+$OSTREE diff test2 --owner-gid=$((`id -g`+1)) ./ > ${test_tmpdir}/diff-test2
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet$'
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet/message$'
+assert_file_has_content ${test_tmpdir}/diff-test2 'M */yet/another/tree/green$'
+echo "ok diff file with different gid"
+
 cd ${test_tmpdir}/checkout-test2-4
 rm four
 mkdir four