From: H. Peter Anvin Date: Mon, 10 Oct 2005 19:26:16 GMT Subject: Re: First cut at git port to Cygwin Message-ID: <434AC058.60803@zytor.com> In-Reply-To: Johannes Schindelin wrote: > >>Junio C Hamano wrote: >> >>>PROT_WRITE is true, but we do MAP_PRIVATE, and if I recall >>>correctly we do not write file via mmap -- at least we do not >>>intend to. >>> >> >>Then PROT_READ probably makes more sense? > > Not necessarily. Sometimes you need to annotate the data from the index, > and this does not need to be written back to the index file. > In the above sentence, emphasis on "at least we do not intend to." If writes are done legitimately then that's fine, but we shouldn't have "accidental writes" -- those would be program bugs! > >>>Yes. It might have been overkill that you supported writing >>>changes back, though. >> >>Not just overkill; if we do MAP_PRIVATE it's actively WRONG. > > See above. > Eh? If we MAP_PRIVATE, *and* we (intentionally) write to it, we *BETTER* not write anything back. -hpa