test: make test-fd-util more lenient when using fd_move_above_stdio()

On s390x this test fails when the SUT uses the z90crypt kernel module,
as it's an another FD the test doesn't account for:

/* test_rearrange_stdio */
Successfully forked off 'rearrange' as PID 57293.
test_rearrange_stdio: r=0
/proc/57293/fd:
total 0
lrwx------. 1 root root 64 Apr  5 06:18 0 -> /dev/pts/0
lrwx------. 1 root root 64 Apr  5 06:18 1 -> /dev/pts/0
lrwx------. 1 root root 64 Apr  5 06:18 2 -> /dev/pts/0
lrwx------. 1 root root 64 Apr  5 06:18 3 -> /dev/z90crypt
rearrange terminated by signal ABRT.

Debugging this was pain, since the child process didn't log anything
once we closed stdout/stderr (for obvious reasons). Let's fix both
issues by switching logging to kmsg once we close stdin/stdout/stderr,
and also by making the test work fine when there are some extra FDs in
the child's environment.

diff --git a/src/test/test-fd-util.c b/src/test/test-fd-util.c
index cd4ce8359739dc2ac14664dc1b62030935e7eaad..f05cbbee6ee75a52b313d1a0fbae5f037ea91592 100644 (file)
--- a/src/test/test-fd-util.c
+++ b/src/test/test-fd-util.c
@@ -138,6 +138,7 @@ TEST(rearrange_stdio) {
 
         if (r == 0) {
                 _cleanup_free_ char *path = NULL;
+                int pipe_read_fd, pair[2];
                 char buffer[10];
 
                 /* Child */
@@ -145,6 +146,10 @@ TEST(rearrange_stdio) {
                 safe_close(STDERR_FILENO); /* Let's close an fd < 2, to make it more interesting */
 
                 assert_se(rearrange_stdio(-EBADF, -EBADF, -EBADF) >= 0);
+                /* Reconfigure logging after rearranging stdout/stderr, so we still log to somewhere if the
+                 * following tests fail, making it slightly less annoying to debug */
+                log_set_target(LOG_TARGET_KMSG);
+                log_open();
 
                 assert_se(fd_get_path(STDIN_FILENO, &path) >= 0);
                 assert_se(path_equal(path, "/dev/null"));
@@ -162,13 +167,12 @@ TEST(rearrange_stdio) {
                 safe_close(STDOUT_FILENO);
                 safe_close(STDERR_FILENO);
 
-                {
-                        int pair[2];
-                        assert_se(pipe(pair) >= 0);
-                        assert_se(pair[0] == 0);
-                        assert_se(pair[1] == 1);
-                        assert_se(fd_move_above_stdio(0) == 3);
-                }
+                assert_se(pipe(pair) >= 0);
+                assert_se(pair[0] == 0);
+                assert_se(pair[1] == 1);
+                pipe_read_fd = fd_move_above_stdio(0);
+                assert_se(pipe_read_fd >= 3);
+
                 assert_se(open("/dev/full", O_WRONLY|O_CLOEXEC) == 0);
                 assert_se(acquire_data_fd("foobar") == 2);
 
@@ -176,7 +180,7 @@ TEST(rearrange_stdio) {
 
                 assert_se(write(1, "x", 1) < 0 && errno == ENOSPC);
                 assert_se(write(2, "z", 1) == 1);
-                assert_se(read(3, buffer, sizeof(buffer)) == 1);
+                assert_se(read(pipe_read_fd, buffer, sizeof(buffer)) == 1);
                 assert_se(buffer[0] == 'z');
                 assert_se(read(0, buffer, sizeof(buffer)) == 6);
                 assert_se(memcmp(buffer, "foobar", 6) == 0);
@@ -184,7 +188,7 @@ TEST(rearrange_stdio) {
                 assert_se(rearrange_stdio(-EBADF, 1, 2) >= 0);
                 assert_se(write(1, "a", 1) < 0 && errno == ENOSPC);
                 assert_se(write(2, "y", 1) == 1);
-                assert_se(read(3, buffer, sizeof(buffer)) == 1);
+                assert_se(read(pipe_read_fd, buffer, sizeof(buffer)) == 1);
                 assert_se(buffer[0] == 'y');
 
                 assert_se(fd_get_path(0, &path) >= 0);