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Re: [bug-gnulib] new modules chdir-long, openat; also, save-cwd improvem
From: |
Paul Eggert |
Subject: |
Re: [bug-gnulib] new modules chdir-long, openat; also, save-cwd improvements |
Date: |
Thu, 20 Jan 2005 14:23:13 -0800 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) |
Jim Meyering <address@hidden> writes:
> FYI, fchdir is used by fts.c, and hence by chmod, chgrp, chown, and du.
> It's been in use like that (at least for du) for over a year - since 5.1.0.
> No one has complained about link failures :-)
In that case let's just rip out the claimed support for non-fchdir
systems in save-cwd.c; its comments are a bit wrong now, it's possible
the fchdir code doesn't work, and we're probably better off not giving
people the warm feeling that it does work.
I installed this, into both gnulib and coreutils. (This also changes
the .m4 file's license to match RMS's suggestion.)
2005-01-20 Paul Eggert <address@hidden>
* lib/save-cwd.c (save_cwd): Remove code to support the case
where fchdir is missing or flaky.
* m4/save-cwd.m4 (gl_SAVE_CWD): Remove check for fcntl; we now
assume it.
Index: lib/save-cwd.c
===================================================================
RCS file: /fetish/cu/lib/save-cwd.c,v
retrieving revision 1.23
diff -p -c -r1.23 save-cwd.c
*** lib/save-cwd.c 3 Dec 2004 06:25:03 -0000 1.23
--- lib/save-cwd.c 20 Jan 2005 22:15:26 -0000
***************
*** 1,5 ****
/* save-cwd.c -- Save and restore current working directory.
! Copyright (C) 1995, 1997, 1998, 2003, 2004 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
--- 1,7 ----
/* save-cwd.c -- Save and restore current working directory.
!
! Copyright (C) 1995, 1997, 1998, 2003, 2004, 2005 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
***************
*** 51,118 ****
closed; return non-zero -- in that case, free_cwd need not be
called, but doing so is ok. Otherwise, return zero.
! The `raison d'etre' for this interface is that some systems lack
! support for fchdir, and getcwd is not robust or as efficient.
So, we prefer to use the open/fchdir approach, but fall back on
! getcwd if necessary. Some systems lack fchdir altogether: OS/2,
! Cygwin (as of March 2003), SCO Xenix. At least SunOS 4 and Irix 5.3
! provide the function, yet it doesn't work for partitions on which
! auditing is enabled. */
int
save_cwd (struct saved_cwd *cwd)
{
- #if !HAVE_FCHDIR
- # undef fchdir
- # define fchdir(x) (abort (), 0)
- bool have_working_fchdir = false;
- bool fchdir_needs_testing = false;
- #elif (__sgi || __sun)
- static bool have_working_fchdir = true;
- bool fchdir_needs_testing = true;
- #else
- bool have_working_fchdir = true;
- bool fchdir_needs_testing = false;
- #endif
-
- cwd->desc = -1;
cwd->name = NULL;
! if (have_working_fchdir)
{
! cwd->desc = open (".", O_RDONLY);
if (cwd->desc < 0)
{
! cwd->desc = open (".", O_WRONLY);
! if (cwd->desc < 0)
! {
! cwd->name = xgetcwd ();
! return cwd->name ? 0 : -1;
! }
! }
!
! /* On SunOS 4 and IRIX 5.3, fchdir returns EINVAL when auditing
! is enabled, so we have to fall back to chdir. */
! if (fchdir_needs_testing && fchdir (cwd->desc) != 0)
! {
! int saved_errno = errno;
! close (cwd->desc);
! cwd->desc = -1;
! if (saved_errno != EINVAL)
! {
! errno = saved_errno;
! return -1;
! }
! have_working_fchdir = false;
}
}
- if (!have_working_fchdir)
- {
- cwd->name = xgetcwd ();
- if (cwd->name == NULL)
- return -1;
- }
return 0;
}
--- 53,85 ----
closed; return non-zero -- in that case, free_cwd need not be
called, but doing so is ok. Otherwise, return zero.
! The `raison d'etre' for this interface is that the working directory
! is sometimes inaccessible, and getcwd is not robust or as efficient.
So, we prefer to use the open/fchdir approach, but fall back on
! getcwd if necessary.
!
! Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
! SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it
! doesn't work for partitions on which auditing is enabled. If
! you're still using an obsolete system with these problems, please
! send email to the maintainer of this code. */
int
save_cwd (struct saved_cwd *cwd)
{
cwd->name = NULL;
! cwd->desc = open (".", O_RDONLY);
! if (cwd->desc < 0)
{
! cwd->desc = open (".", O_WRONLY);
if (cwd->desc < 0)
{
! cwd->name = xgetcwd ();
! return cwd->name ? 0 : -1;
}
}
return 0;
}
Index: m4/save-cwd.m4
===================================================================
RCS file: /fetish/cu/m4/save-cwd.m4,v
retrieving revision 1.4
diff -p -c -r1.4 save-cwd.m4
*** m4/save-cwd.m4 6 Dec 2004 10:35:27 -0000 1.4
--- m4/save-cwd.m4 20 Jan 2005 22:15:26 -0000
***************
*** 1,10 ****
! # save-cwd.m4 serial 3
! dnl Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
! dnl This file is free software, distributed under the terms of the GNU
! dnl General Public License. As a special exception to the GNU General
! dnl Public License, this file may be distributed as part of a program
! dnl that contains a configuration script generated by Autoconf, under
! dnl the same distribution terms as the rest of that program.
AC_DEFUN([gl_SAVE_CWD],
[
--- 1,8 ----
! # save-cwd.m4 serial 4
! dnl Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
! dnl This file is free software; the Free Software Foundation
! dnl gives unlimited permission to copy and/or distribute it,
! dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_SAVE_CWD],
[
*************** AC_DEFUN([gl_SAVE_CWD],
*** 12,16 ****
AC_LIBOBJ([save-cwd])
dnl Prerequisites for lib/save-cwd.c.
AC_CHECK_HEADERS_ONCE(fcntl.h unistd.h)
- AC_CHECK_FUNCS(fchdir)
])
--- 10,13 ----
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