lib/checkout: add filter API to skip over files

This is analogous to the filtering support for the commit API: we allow
library users to skip over checking out specific files. This is useful
in some tricky situations where we *know* that the files to be checked
out will conflict with existing files in subtle ways.

One such example is in rpm-ostree support for multilib. There, we want
to allow checking out a package onto an existing tree, but skipping over
files that are not coloured to our preferred value (e.g. not overwriting
an i686 version of `ldconfig` if we already have the `x86_64` version).
See https://github.com/projectatomic/rpm-ostree/pull/1227 for details.

Closes: #1441
Approved by: cgwalters

tests/basic-test.sh

@@ -21,7 +21,7 @@
 
 set -euo pipefail
 
-echo "1..$((79 + ${extra_basic_tests:-0}))"
+echo "1..$((81 + ${extra_basic_tests:-0}))"
 
 CHECKOUT_U_ARG=""
 CHECKOUT_H_ARGS="-H"
@@ -518,6 +518,35 @@ assert_file_has_content saucer alien
 rm t -rf
 echo "ok checkout subpath"
 
+cd ${test_tmpdir}
+rm -rf checkout-test2-skiplist
+cat > test-skiplist.txt <<EOF
+/baz/saucer
+/yet/another/tree
+EOF
+$OSTREE checkout --skip-list test-skiplist.txt test2 checkout-test2-skiplist
+cd checkout-test2-skiplist
+! test -f baz/saucer
+! test -d yet/another/tree
+test -f baz/cow
+test -d baz/deeper
+echo "ok checkout skip-list"
+
+cd ${test_tmpdir}
+rm -rf checkout-test2-skiplist
+cat > test-skiplist.txt <<EOF
+/saucer
+/deeper
+EOF
+$OSTREE checkout --skip-list test-skiplist.txt --subpath /baz \
+  test2 checkout-test2-skiplist
+cd checkout-test2-skiplist
+! test -f saucer
+! test -d deeper
+test -f cow
+test -d another
+echo "ok checkout skip-list with subpath"
+
 cd ${test_tmpdir}
 $OSTREE checkout  --union test2 checkout-test2-union
 find checkout-test2-union | wc -l > union-files-count

tests/installed/itest-label-selinux.sh

@@ -69,7 +69,19 @@ ostree checkout testbranch --selinux-policy / \
   --subpath subdir --selinux-prefix / co
 newcon=$(getfattr --only-values -m security.selinux co/usr/bin/bash)
 assert_streq "${oldcon}" "${newcon}"
-
-ostree refs --delete testbranch
 rm co -rf
 echo "ok checkout with sepolicy and selinux-prefix"
+
+# Now check that combining --selinux-policy with --skip-list doesn't blow up
+echo > skip-list.txt << EOF
+/usr/bin/true
+EOF
+ostree checkout testbranch --selinux-policy / --skip-list skip-list.txt \
+  --subpath subdir --selinux-prefix / co
+! test -f co/usr/bin/true
+test -f co/usr/bin/bash
+newcon=$(getfattr --only-values -m security.selinux co/usr/bin/bash)
+assert_streq "${oldcon}" "${newcon}"
+rm co -rf
+ostree refs --delete testbranch
+echo "ok checkout selinux and skip-list"