Re: [PATCH] Automake-git testsuite failures: aclocal9, acloca10, nodef

[Peter Breitenlohner]

On Fri, 4 Dec 2009, Ralf Wildenhues wrote:

> One involved tool is perl:
>  perl -e 'use File::stat; print (stat("README")->mtime . "\n");'

Hi Ralf,

all my tests are for x86_64-linux (however, the utilities are 32Bit ones) on
a jfs partition (I think ext2 doesn't have subsecond time stamps).

 ~> ls -l --fu README
 -rw-r--r-- 1 peb THEORY 0 2009-12-07 14:15:16.791586449 +0100 README

 ~> perl -e 'use File::stat; print (stat("README")->mtime . "\n");'
 1260191716

 ~> date -r README +%s
 1260191716

This is perl, v5.10.0 built for ix86-linux-gnu
touch (GNU coreutils) 7.4

> Another is the shell/test, and ls: Create two files with same-second
> but different sub-second time stamps (try until this succeeds):
>
>  echo stamp > file1
>  echo stamp > file2
>  ls -l --full-time file?

 ~> echo stamp > file1;sleep 0.5; echo stamp > file2; ls -l --fu file?
 -rw-r--r-- 1 peb THEORY 6 2009-12-07 14:20:04.460965546 +0100 file1
 -rw-r--r-- 1 peb THEORY 6 2009-12-07 14:20:04.964956156 +0100 file2

> then test 'test' and 'ls':
>
>  if test file2 -nt file1; then echo "shell test uses sub-second"; fi
>  if /usr/bin/test file2 -nt file1; then echo "/usr/bin/test uses sub-second"; fi
>  set X `ls -Lt file1 file2`
>  if test $3 = file1; then echo "ls uses sub-second"; fi

 ~> if test file2 -nt file1; then echo "shell test uses sub-second"
 >  else echo "no"; fi
 no

 ~> if /bin/test file2 -nt file1; then
 >  echo "/bin/test uses sub-second"; else echo "no"; fi
 /bin/test uses sub-second

 ~> set X `ls -Lt file1 file2`
 ~> if test $3 = file1; then echo "ls uses sub-second"; else echo "no"; fi
 ls uses sub-second

> For completeness let's also test 'make':
>  echo 'file1: file2; echo "make uses sub-second"' > Makefile
>  make

 ~> echo 'file1: file2; echo "make uses sub-second"' > Makefile
 ~> make
 echo "make uses sub-second"
 make uses sub-second

> and whether 'touch -r' can generate sub-second stamps:
>  : > foo
>  touch -r foo bar
>  ls -l --full-time foo bar

 ~> touch -r file2 file3; cp -p file2 file4; ls -l --full-time file?
 >  -rw-r--r-- 1 peb THEORY 6 2009-12-07 14:20:04.460965546 +0100 file1
 >  -rw-r--r-- 1 peb THEORY 6 2009-12-07 14:20:04.964956156 +0100 file2
 >  -rw-r--r-- 1 peb THEORY 0 2009-12-07 14:20:05.000000000 +0100 file3
 >  -rw-r--r-- 1 peb THEORY 6 2009-12-07 14:20:05.000000000 +0100 file4
As I knew already from trying to understand a similar problem, 'cp -p' and
'touch -r' both round sub-seconds, whereas tar and rsync truncate them.

> This shows that the second "autoconf" did not update configure.  Can you
> post, for this same build, also
>  ls -lrt --fu autom4te.cache

 -rw-r--r-- 1 peb THEORY 66570 2009-12-04 11:57:00.858053547 +0100 output.0
 -rw-r--r-- 1 peb THEORY 66570 2009-12-04 11:57:01.062638375 +0100 output.1
 -rw-r--r-- 1 peb THEORY 66570 2009-12-04 11:57:01.505099509 +0100 output.2
 -rw-r--r-- 1 peb THEORY 11851 2009-12-04 11:57:01.650015678 +0100 requests
 -rw-r--r-- 1 peb THEORY 32184 2009-12-04 11:57:00.858053547 +0100 traces.0
 -rw-r--r-- 1 peb THEORY 14302 2009-12-04 11:57:01.062638375 +0100 traces.1
 -rw-r--r-- 1 peb THEORY 32257 2009-12-04 11:57:01.505099509 +0100 traces.2

> Let's see if your data confirms this.  I just tried out my Cygwin
> install:
>
> tool              sub-second?
> -----------------------------
> file system       yes
certainly depends on the file system (could this be vfat?)
> perl              no
> shell test        no
> /usr/bin/test     yes
> ls                yes
> make              yes
> touch -r          yes
here our coreutils 7.4 differ
> Ugh.  If Cygwin weren't so slow, it would fall prey to this issue, too.
>
>
> I think we either need to reintroduce the 'sleep 1' in the build sanity
> check, or some other way to ensure that a file newly created by
> configure has a time stamp with a strictly larger integer part than the
> time stamp of the configure script.  Any ideas of what the most portable
> way to achieve this could be?

In view of the fact demonstrated above that the sub-seconds could be
honored, truncated, or rounded, the actual requirement might be somewhat
more stringent, but of course 1sec difference should always suffice.

> We may be able to get by with something like spawning off a
>  ( sleep 1 ) &
>
> early in the configure script, and ensuring that it has completed before
> we get to config.status creation.  I'm a bit afraid of introducing
> 'kill' into configure scripts, however.  Any less dangerous ideas?

How about '( sleep 1; CREATE_A_FILE ) &' and later waiting until that file
exists?

Regards
Peter Breitenlohner <address@hidden>