chase: make chaseat() provides absolute path also when dir_fd points to the root directory

Usually, we pass the file descriptor of the root directory to chaseat()
when `--root=` is not specified. Previously, even in such case, the
result was relative, and we need to prefix the path with "/" when we
want to pass the path to other functions that do not support dir_fd, or
log or show the path. That's inconvenient.

1 files changed, 28 insertions, 0 deletions

diff --git a/src/test/test-chase.c b/src/test/test-chase.c
index 1e98f5c6ed..52ea21a54c 100644
--- a/src/test/test-chase.c
+++ b/src/test/test-chase.c
@@ -442,6 +442,34 @@ TEST(chaseat) {
         assert_se(streq(result, "/usr"));
         result = mfree(result);
 
+        /* If the file descriptor points to the root directory, the result will be absolute. */
+
+        fd = open("/", O_CLOEXEC | O_DIRECTORY | O_PATH);
+        assert_se(fd >= 0);
+
+        assert_se(chaseat(fd, p, 0, &result, NULL) >= 0);
+        assert_se(streq(result, "/usr"));
+        result = mfree(result);
+
+        assert_se(chaseat(fd, p, CHASE_AT_RESOLVE_IN_ROOT, &result, NULL) >= 0);
+        assert_se(streq(result, "/usr"));
+        result = mfree(result);
+
+        fd = safe_close(fd);
+
+        /* If the file descriptor does not point to the root directory, the result will be relative. */
+
+        assert_se(chaseat(tfd, "abc", CHASE_AT_RESOLVE_IN_ROOT, NULL, NULL) == -ENOENT);
+        assert_se(chaseat(tfd, "/abc", CHASE_AT_RESOLVE_IN_ROOT, NULL, NULL) == -ENOENT);
+
+        assert_se(chaseat(tfd, "abc", CHASE_AT_RESOLVE_IN_ROOT | CHASE_NONEXISTENT, &result, NULL) >= 0);
+        assert_se(streq(result, "usr"));
+        result = mfree(result);
+
+        assert_se(chaseat(tfd, "/abc", CHASE_AT_RESOLVE_IN_ROOT | CHASE_NONEXISTENT, &result, NULL) >= 0);
+        assert_se(streq(result, "usr"));
+        result = mfree(result);
+
         /* Test that absolute path or not are the same when resolving relative to a directory file
          * descriptor and that we always get a relative path back. */