> Date: Mon, 15 Aug 2022 13:55:35 -0700 > Cc: la...@gnus.org, 57...@debbugs.gnu.org, Jim Porter > <jporterb...@gmail.com>, Gnulib bugs <bug-gnulib@gnu.org> > From: Paul Eggert <egg...@cs.ucla.edu> > > On 8/15/22 11:58, Eli Zaretskii wrote: > > > Ah, okay. It's a (mis)feature of Gnulib's gen_tempname function > > (which is the guts of make-temp-file) in its implementation for > > MS-Windows (and maybe other platforms?): it always begins from the > > same "random" characters in the file name, and only generates other > > random characters if there's already a file by that name. > > Not sure I'd call it a misfeature
I didn't say "misfeature". Evidently, for you and perhaps others it's a feature. > as gen_tempname is generating a uniquely-named file that is > exclusive to Emacs, which is all it's supposed to do. Then perhaps calling it from make-temp-file in Emacs is a mistake, because that function's doc string says Create a temporary file. The returned file name (created by appending some random characters at the end of PREFIX, and expanding against ‘temporary-file-directory’ if necessary), is guaranteed to point to a newly created file. When you tell someone that the file name will include "some random characters", they don't expect that they will be the same "random characters" every call, just like saying that some function generates random numbers doesn't imply it will be the same number every call. > I'm not sure I'm entirely understanding the Emacs problem, but it > appears to be that Emacs has its own set of filenames that it thinks it > knows about, and Emacs wants the new temporary file's name to not be a > member of that set. If I'm right, does the second attached patch (this > patch is to Emacs) address the problem? I haven't tested or installed it. I don't think that's the problem, no. The problem is that callers of make-temp-file reasonably expect it to return a new name every call. And evidently, it does that on GNU/Linux (not sure how, given that the tempname.c code is supposed to be in glibc?). So if there's no intention to change gen_tempname on non-glibc platforms so that it doesn't repeat the same "random characters" upon each call, I think Emacs should call a different function to generate "random" names of temporary files, for consistency across platforms if not for other reasons.
