test: copy out the necessary test data before we start overmounting stuff

Otherwise the get_testdata_dir() call fails if the source tree is under
/root (which is usually the case in CIs).

I got bitten by this after leaving the source tree under /root but moving the
$BUILD_DIR elsewhere. This used to work by accident, as load_testdata_env()
would try to read $BUILD_DIR/systemd-runtest.env, but would fail if the
$BUILD_DIR is also under /root and fall back to SYSTEMD_TEST_DATA
(/lib/systemd/tests/testdata), which usually exist as we install the just built
revision. However, if the $BUILD_DIR is outside of /root we'd read
$BUILD_DIR/systemd-runtest.env which contains
SYSTEMD_TEST_DATA=/path/to/source/tree/test and that source tree is not visible
once we overmount /root with tmpfs making the test fail:

/* test_run_tests_unprivileged */
Successfully forked off '(test-execute-unprivileged)' as PID 10672.
Changing mount flags / (MS_REMOUNT|MS_BIND "")...
Changing mount propagation / (MS_REC|MS_SHARED "")
Mounting tmpfs (tmpfs) on /dev/shm (MS_NOSUID|MS_NODEV "")...
Mounting tmpfs (tmpfs) on /root (MS_NOSUID|MS_NODEV "")...
Mounting tmpfs (tmpfs) on /tmp (MS_NOSUID|MS_NODEV "")...
Mounting tmpfs (tmpfs) on /var/tmp (MS_NOSUID|MS_NODEV "")...
Mounting tmpfs (tmpfs) on /var/lib (MS_NOSUID|MS_NODEV "")...
Mounting tmpfs (tmpfs) on /run/test-execute-unit-dir (MS_NOSUID|MS_NODEV "")...
ERROR: $SYSTEMD_TEST_DATA directory [/root/systemd/test] not accessible: No such file or directory
Assertion 'get_testdata_dir("test-execute/", &unit_dir) >= 0' failed at src/test/test-execute.c:1306, function prepare_ns(). Aborting.
(test-execute-unprivileged) terminated by signal ABRT.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/test/test-execute.c b/src/test/test-execute.c
index 9705cbce59..4d2eefc1b3 100644
--- a/src/test/test-execute.c
+++ b/src/test/test-execute.c
@@ -1297,15 +1297,16 @@ static int prepare_ns(const char *process_name) {
                 assert_se(mount_follow_verbose(LOG_DEBUG, NULL, "/", NULL, MS_SHARED|MS_REC, NULL) >= 0);
 
                 assert_se(mkdir_p(PRIVATE_UNIT_DIR, 0755) >= 0);
-
-                /* Mount tmpfs on the following directories to make not StateDirectory= or friends disturb the host. */
-                FOREACH_STRING(p, "/dev/shm", "/root", "/tmp", "/var/tmp", "/var/lib", PRIVATE_UNIT_DIR)
-                        assert_se(mount_nofollow_verbose(LOG_DEBUG, "tmpfs", p, "tmpfs", MS_NOSUID|MS_NODEV, NULL) >= 0);
+                assert_se(mount_nofollow_verbose(LOG_DEBUG, "tmpfs", PRIVATE_UNIT_DIR, "tmpfs", MS_NOSUID|MS_NODEV, NULL) >= 0);
 
                 /* Copy unit files to make them accessible even when unprivileged. */
                 assert_se(get_testdata_dir("test-execute/", &unit_dir) >= 0);
                 assert_se(copy_directory_at(AT_FDCWD, unit_dir, AT_FDCWD, PRIVATE_UNIT_DIR, COPY_MERGE_EMPTY) >= 0);
 
+                /* Mount tmpfs on the following directories to make not StateDirectory= or friends disturb the host. */
+                FOREACH_STRING(p, "/dev/shm", "/root", "/tmp", "/var/tmp", "/var/lib")
+                        assert_se(mount_nofollow_verbose(LOG_DEBUG, "tmpfs", p, "tmpfs", MS_NOSUID|MS_NODEV, NULL) >= 0);
+
                 /* Prepare credstore like tmpfiles.d/credstore.conf for LoadCredential= tests. */
                 FOREACH_STRING(p, "/run/credstore", "/run/credstore.encrypted") {
                         assert_se(mkdir_p(p, 0) >= 0);