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Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell
From: |
Bruno Haible |
Subject: |
Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell |
Date: |
Tue, 16 Aug 2022 15:35:17 +0200 |
Eli Zaretskii wrote:
> 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.
You are making incorrect assumptions or hypotheses. I am adding the unit
test below. It proves that (at least) on Linux, FreeBSD 11, NetBSD 7,
OpenBSD 6.0, macOS, AIX 7.1, Solaris 10, Cygwin, and native Windows,
gen_tempname *does* return a new file name on each call, with a very high
probability.
So, gen_tempname does *not* repeat the same "random characters" upon each call.
2022-08-16 Bruno Haible <bruno@clisp.org>
tempname: Add tests.
* tests/test-tempname.c: New file.
* modules/tempname-tests: New file.
=========================== tests/test-tempname.c ==========================
/* Test of creating a temporary file.
Copyright (C) 2022 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2022. */
#include <config.h>
#include "tempname.h"
#include <string.h>
#include <unistd.h>
#include "macros.h"
int
main ()
{
/* Verify that two consecutive calls to gen_tempname return two different
file names, with a high probability. */
const char *templ18 = "gl-temp-XXXXXX.xyz";
char filename1[18 + 1];
char filename2[18 + 1];
strcpy (filename1, templ18);
int fd1 = gen_tempname (filename1, strlen (".xyz"), 0, GT_FILE);
ASSERT (fd1 >= 0);
strcpy (filename2, templ18);
int fd2 = gen_tempname (filename2, strlen (".xyz"), 0, GT_FILE);
ASSERT (fd2 >= 0);
/* With 6 'X' and a good pseudo-random number generator behind the scenes,
the probability of getting the same file name twice in a row should be
1/62^6 < 1/10^10. */
ASSERT (strcmp (filename1, filename2) != 0);
/* Clean up. */
close (fd1);
close (fd2);
unlink (filename1);
unlink (filename2);
return 0;
}
=========================== modules/tempname-tests =========================
Files:
tests/test-tempname.c
tests/macros.h
Depends-on:
unlink
configure.ac:
Makefile.am:
TESTS += test-tempname
check_PROGRAMS += test-tempname
test_tempname_LDADD = $(LDADD) $(LIB_GETRANDOM) $(LIB_CLOCK_GETTIME)
============================================================================
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Paul Eggert, 2022/08/15
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Bruno Haible, 2022/08/15
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell,
Bruno Haible <=
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Bruno Haible, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Paul Eggert, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Paul Eggert, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Paul Eggert, 2022/08/16
- Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell, Eli Zaretskii, 2022/08/16