On June 8, 2020 3:08 PM, Brandon Casey wrote: > To: Junio C Hamano <gitster@xxxxxxxxx> > Cc: git <git@xxxxxxxxxxxxxxx>; Kyle Evans <kevans@xxxxxxxxxxx>; Jeff King > <peff@xxxxxxxx> > Subject: Re: fread reading directories > > On Mon, Jun 8, 2020 at 10:18 AM Junio C Hamano <gitster@xxxxxxxxx> > wrote: > > > > It may make sense to do one of the two things: > > > > - The lighter weight one is to rename the macro to the reflect the > > trait we are trying to capture more faithfully: "fopen opens > > directories" and leave the code and performance characteristics > > as-is. > > > > - Heavier weight one is to audit callers of fopen() and only let > > those that know they do not have a directory directly call > > fopen(). The other callers would call our wrapper under a > > different name. This way, the former won't have to pay the > > overhead of checking for "you gave me a directory but I only take > > a file" error twice. This is what Brandon proposed in the > > thread. > > > > Doing neither would leave this seed of confusion for later readers, > > which is not ideal. I am tempted to say that we for now should do an > > even lighter variant of the former, which is to give a comment. > > > > Thoughts? > > I'd suggest a medium weight approach which would be to introduce a new > function with an appropriate name (fopen_file_only()?) that behaves the way > we want it to, and replace every existing fopen() call with this new function. > We could introduce a new macro, which I think would only be used on > Windows, to say "fopen already fails to open directories" > (FOPEN_FAILS_ON_DIRECTORIES?) so that fopen_file_only could be > simplified to just a bare fopen there. That way it's clear to the reader, at the > callsite, that the call does not have the standard behavior of fopen. > > Then, FREAD_READS_DIRECTORIES could be removed from all but the 1 or 2 > platforms that it was originally set for. I'd imagine that we'd basically just > promote the git_fopen() function from compat to become the > implementation of the first tier fopen_file_only() function. On the > FREAD_READS_DIRECTORIES platforms, a bare fopen would also become > fopen_file_only(). The call to fopen() within fopen_file_only() would > obviously need to take this into account to ensure that it calls the real > fopen(). > > I think this would put the pieces in place for someone to audit all of the > existing uses of fopen_file_only() and potentially replace them with a straight > fopen() if appropriate. And it would allow future code to explicitly make the > choice between fopen_file_only() or just fopen(). > > None of this would produce any functional change on any of our platforms, > but I think it would make things more clear. Please keep me on the loop on this one. The NonStop platforms have FREAD_READS_DIRECTORIES UnfortunatelyYes. We will want to move to the new structure as soon as we can, so compat makes me comfortable. Thanks, Randall
