tests: display system error for the special files test

tests/all.rs

@@ -1157,27 +1157,27 @@ fn tar_directory_containing_special_files() {
     use std::ffi::CString;
 
     let td = t!(TempBuilder::new().prefix("tar-rs").tempdir());
-    let cdev = td.path().join("chr");
     let fifo = td.path().join("fifo");
 
     unsafe {
-        let cdev_path = t!(CString::new(cdev.to_str().unwrap()));
-        let ret = libc::mknod(cdev_path.as_ptr(), libc::S_IFCHR | 0o644, 0);
-        assert_eq!(ret, 0);
         let fifo_path = t!(CString::new(fifo.to_str().unwrap()));
         let ret = libc::mknod(fifo_path.as_ptr(), libc::S_IFIFO | 0o644, 0);
-        assert_eq!(ret, 0);
+        if ret != 0 {
+            libc::perror(fifo_path.as_ptr());
+            panic!("Failed to create a FIFO file");
+        }
     }
 
     t!(env::set_current_dir(td.path()));
     let mut ar = Builder::new(Vec::new());
     // append_path has a different logic for processing files, so we need to test it as well
-    t!(ar.append_path("chr"));
     t!(ar.append_path("fifo"));
     t!(ar.append_dir_all("special", td.path()));
     // unfortunately, block device file cannot be created by non-root users
     // as a substitute, just test the file that exists on most Unix systems
     t!(env::set_current_dir("/dev/"));
     t!(ar.append_path("loop0"));
+    // CI systems seem to have issues with creating a chr device
+    t!(ar.append_path("null"));
     t!(ar.finish());
 }