On Feb 15, 2014, at 5:50 AM, Corinna Vinschen wrote: > I grabbed all of this including your followup > change shamelessly and added it to the text.
Happy to provide it. >> It seems to me that we really only need a single Boolean setting: >> >> ignore_db=true > > No, that's not right. We have two mechanisms implemented you can > choose three out of four possible combinations: > > files only > db only > files, then db Yes, I realize that. While composing the previous email, I considered a 2-Boolean design: ignore_db=false ignore_files=false I rejected that design when I realized that ignore_files is redundant with respect to /etc/foo file existence. If the files are present, use them. If not, you have a DB-only configuration. I consider it an advantage of this design that it is not possible for the files to be present but ignored. It avoids confusion, both human and software. A person modifying /etc/passwd expects the change to take immediate effect. (Obviously SAM or AD could mask it, but…) Software that scans /etc/passwd expects that the data found within have relevance to system operation. The nonsense configuration — ignore files *and* ignore DB — is still possible to achieve with the 1-Boolean design. Set ignore_db=true and remove the /etc files. Cygwin should simply treat this as a “DB-only” configuration, since that’s the only place it *can* get answers. > It drops any check for existence, too, which > is one code point less which has to run for each getpwXXX/getgrXXX > invocation. Cygwin should check for file existence at the process tree start, where it reads /etc/nsswitch.conf. If the files are missing at that time, set the “ignore_files” flag. Cygwin should use that flag instead of explicit file existence tests for the same reason it doesn’t keep re-reading nsswitch.conf. If the files are missing at process tree start, then later created, you have to create a new process tree for the new files to be used. This is no sacrifice. If you use a 2-Boolean design, you only end up in the code fork where file checking is done if ignore_files == false. That means there is no point to checking for file existence explicitly. Just blindly try to read the files; if the file is missing, the open will fail, so your check is implicit in the attempt. -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
