* Jim Meyering wrote on Sat, Aug 29, 2009 at 10:14:19PM CEST:
> Ralf Wildenhues wrote:
> > I think we can fix most instances of this wait portably, without looking
> > at subsecond time stamps: let's just try without sleeping first, and
> > only if that fails, try again after sleeping. What do you think about
> > the patch below (diff -w shown only, due to large reindentation)?
> >
> > Only missing bit still is a good testsuite addition to ensure that it
> > still catches messed-up time stamps.
> That looks like a fine approach.
> I tested it simply by inserting this line
>
> test $am_try = 1 && touch --ref="$srcdir/configure" conftest.file
>
> right after the echo timestamp... one, and verified (with inserted
> set -x ... set +x) that the sleep 1 was run.
>
> That's no good for a test-suite addition, I know, but better than nothing.
> I suppose a test could set the time of $srcdir/configure
> to a second in the future, just before running ./configure,
> but even then it'd be a race.
Yeah. Let's defer the test to later. (I tested it by touching the
configure script with a time 1 hour in the future.)
I've committed the patch now, to be merged in branch-1.11 and master,
with the only additional change to avoid a second sleep in the error
path.
Cheers, and thanks again, (and sorry for the multi-second delay ;-)
Ralf
Avoid sleeping for one second most of the time in sanity check.
* m4/sanity.m4 (AM_SANITY_CHECK): Try sanity check first without
sleeping for a second, and only if that failed, sleep and try
again, to avoid the delay in the common case of a configure
script that is older than a second, or a system with sub-second
time stamp granularity.
Report and different patch by Jim Meyering.
diff --git a/m4/sanity.m4 b/m4/sanity.m4
index 3d2f304..db87c8b 100644
--- a/m4/sanity.m4
+++ b/m4/sanity.m4
@@ -1,21 +1,18 @@
# Check to make sure that the build environment is sane. -*- Autoconf -*-
-# Copyright (C) 1996, 1997, 2000, 2001, 2003, 2005, 2008
+# Copyright (C) 1996, 1997, 2000, 2001, 2003, 2005, 2008, 2009
# Free Software Foundation, Inc.
#
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
-# serial 5
+# serial 6
# AM_SANITY_CHECK
# ---------------
AC_DEFUN([AM_SANITY_CHECK],
[AC_MSG_CHECKING([whether build environment is sane])
-# Just in case
-sleep 1
-echo timestamp > conftest.file
# Reject unsafe characters in $srcdir or the absolute working directory
# name. Accept space and tab only in the latter.
am_lf='
@@ -35,23 +32,30 @@ esac
# (eg FreeBSD returns the mod time of the symlink's containing
# directory).
if (
- set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
- if test "$[*]" = "X"; then
- # -L didn't work.
- set X `ls -t "$srcdir/configure" conftest.file`
- fi
- rm -f conftest.file
- if test "$[*]" != "X $srcdir/configure conftest.file" \
- && test "$[*]" != "X conftest.file $srcdir/configure"; then
-
- # If neither matched, then we have a broken ls. This can happen
- # if, for instance, CONFIG_SHELL is bash and it inherits a
- # broken ls alias from the environment. This has actually
- # happened. Such a system could not be considered "sane".
- AC_MSG_ERROR([ls -t appears to fail. Make sure there is not a broken
-alias in your environment])
- fi
+ for am_try in 1 2; do
+ echo timestamp > conftest.file
+ set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
+ if test "$[*]" = "X"; then
+ # -L didn't work.
+ set X `ls -t "$srcdir/configure" conftest.file`
+ fi
+ rm -f conftest.file
+ if test "$[*]" != "X $srcdir/configure conftest.file" \
+ && test "$[*]" != "X conftest.file $srcdir/configure"; then
+ # If neither matched, then we have a broken ls. This can happen
+ # if, for instance, CONFIG_SHELL is bash and it inherits a
+ # broken ls alias from the environment. This has actually
+ # happened. Such a system could not be considered "sane".
+ AC_MSG_ERROR([ls -t appears to fail. Make sure there is not a broken
+ alias in your environment])
+ fi
+ if test "$[2]" = conftest.file || test $am_try -eq 2; then
+ break
+ fi
+ # Just in case.
+ sleep 1
+ done
test "$[2]" = conftest.file
)
then
