osutil: more cleanups
- eliminate a level of nesting
- untab targets of gotos
adding helloabort: '\n' and '\r' disallowed in filenamesadding helloabort: '\n' and '\r' disallowed in filenamesadding helloabort: '\n' and '\r' disallowed in filenamesadding helloabort: '\n' and '\r' disallowed in filenamesf hello hellof hello hello