On Fri, Apr 9, 2021 at 4:50 AM Andrey Repin <anrdae...@yandex.ru> wrote: > > Greetings, Orgad Shaneh! > > > On Wed, Apr 7, 2021 at 11:47 PM Orgad Shaneh <org...@gmail.com> wrote: > >> > >> Hi, > >> > >> If a filesystem is mounted with noacl, calling chmod to add write > >> permissions after umasking this permission doesn't work. Demonstrated > >> with command-line and C++. > >> > >> Did I miss something or is this a real bug? According to umask man, it > >> should only affect newly created files and directories, but I didn't > >> find anything that relates to chmod. > >> > >> Command-line: > >> touch foo > >> ls -l foo > >> # -rw-r--r-- ... foo > >> umask 200 > >> chmod 0 foo > >> ls -l foo > >> # -r--r--r-- ... foo > >> chmod 200 foo > >> ls -l foo > >> # -r--r--r-- ... foo > >> # Expected to have rw > > > Marco Atzeri replied to the mailing list but did not CC me, so I > > didn't receive it: > > The expectation is that you subscribe to the list of interest.
Why? If I report a bug, I'm interested in this bug, and I don't want to receive dozens of emails every day about other issues. Every time you report a bug to a project on github/jira/whatever, you subscribe to everything in this project? > >> without ACL you can not expect the POSIX scheme to properly work. > >> see > >> https://cygwin.com/cygwin-ug-net/ntsec.html > >> to understand how Cygwin uses ACL to mimic POSIX permissions > > > Thanks Marco! > > > I'm well aware of that. I don't expect it to work properly. From what > > I know, it can only set/unset user write bit. Read bits are always > > enabled, even on chmod 0. > > > What I do expect is that the write bit will not be affected by umask. > > umask should only affect newly created files, not direct chmod > > commands. > > Yet again: using chmod on noacl filesystem is likely to cause more harm than > good. You may very well end up with an unusable filesystem until you fix > permissions by hands. With noacl, chmod is capable of setting and unsetting the user write bit, and I expect it to do that. I actually found this issue because CMake unit tests failed for me on MSYS which sets noacl. Anyway, I found the curprit. The problem is not with chmod, but with stat. fhandler_base::fstat_helper has this line: /* This fakes the permissions of all files to match the current umask. */ buf->st_mode &= ~(cygheap->umask); So chmod does set the write bit correctly, but stat doesn't report it. I can see why this is needed, so I'll adapt the CMake tests to workaround this. Thank you! - Orgad -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
