Thanks for this fix. But, I think the the code I originally I wrote here is broken in a way that's not completely fixed by your patch. The case is where the type of a file changes between directory and non-directory. The code as it is now will issue an error whose message corresponds to ENOTDIR. If a directory is replaced by an empty file, I think there'a an argument for returning true without issuing a diagnostic (and hence without having find return with a nonzero exit status).
On the assumption that you also think this race should be handled silently, how about this approach? Instead of keeping the pre-existing race introduced by the iniail S_ISDIR check, we could begin by open()ing the file, without O_DIRECTORY. If the open fails, issue an error and return. Otherwise, perform fstat on the fd. If the fstat fails, issue an error message and return false. Otherwise, if the file is a regular file (S_ISREG, as current code) and it is zero bytes long, return true. Otherwise, if it is a non-directory, return false (as now). Last, handle the directory case. Perform fdopendir (which, now, we know cannot fail with ENOTDIR) and attempt readdir on it. If any readdir returns non-NULL, return false. If readdir returns NULL with errno != 0, I think it is probably safest to issue an error and return false, as now. Except EOVERFLOW: for this, we should issue no diagnostic and simply return false (since we know there is something in the directory, even though it cannot be correctly represented). Otherwise (that is, readdir returns NULL with errno == 0 and we didn't previously get a non-NULL result) return true. What do you think? James.
