t/remake-timing-bug-pr8365.sh

   1 #! /bin/sh
   2 # Copyright (C) 2011-2024 Free Software Foundation, Inc.
   3 #
   4 # This program is free software; you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation; either version 2, or (at your option)
   7 # any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  16
  17 # Test for automake bug#8365, related to Makefile remake rules.
  18 # The bug is due to subtle timestamp issues and limitations in
  19 # make's behaviour, and is very unlikely to be triggered (we have
  20 # to resort to timestamp edit hacks to consistently expose it); in
  21 # any account, it is nigh to impossible to trigger it by running
  22 # make by hand.  Thus, fixing it would not be worth the hassle, but
  23 # we prefer to keep it exposed anyway.
  24
  25 . test-init.sh
  26
  27 # We'll use calls to stat to get debugging information.
  28 if stat /dev/null; then stat=stat; else stat=:; fi
  29
  30 cat >> configure.ac << 'END'
  31 FOOBAR=zardoz
  32 AC_OUTPUT
  33 END
  34
  35 : > Makefile.am
  36
  37 $ACLOCAL
  38 # Run automake *before* autoconf, because we want to ensure that
  39 # Makefile.in is not newer than configure.
  40 $AUTOMAKE
  41 $AUTOCONF
  42
  43 ./configure
  44 $MAKE Makefile
  45 # Sanity check.
  46 $EGREP 'FOOBAR|zardoz' Makefile && fatal_ 'unexpected AC_SUBST in Makefile'
  47
  48 echo 'AC_SUBST([FOOBAR])' >> configure.ac
  49
  50 # Modified configure dependencies must have the same timestamp of
  51 # config.status and Makefile in order to trigger the bug.
  52 # We also re-touch config.status, because "touch -r" can truncate
  53 # timestamps on file systems with sub-second resolutions (see the
  54 # autoconf manual).  Finally, we also sleep before touching, to ensure
  55 # that the (possibly truncated) timestamps of config.status etc. are
  56 # strictly newer than the non-truncated configure timestamp.
  57 $stat config.status Makefile configure.ac
  58 $sleep
  59 touch config.status
  60 touch -r config.status config.status Makefile configure.ac
  61 $stat config.status Makefile configure.ac
  62
  63 # Also, the race condition is triggered only when aclocal, automake
  64 # and aclocal run fast enough to keep the timestamp of the generated
  65 # aclocal.m4, Makefile.in and configure equal to the timestamp of
  66 # Makefile & config.status.  To reproduce this race consistently, we
  67 # need the following hackish wrappers.
  68
  69 cat > aclocal-wrap <<END
  70 #!/bin/sh
  71 set -ex
  72 # aclocal shouldn't use our autoconf wrapper when extracting
  73 # the races from configure.ac.
  74 AUTOCONF='$AUTOCONF'; export AUTOCONF
  75 $ACLOCAL "\$@"
  76 touch -r config.status aclocal.m4
  77 $stat aclocal.m4
  78 END
  79
  80 cat > automake-wrap <<END
  81 #!/bin/sh
  82 set -ex
  83 # automake shouldn't use our autoconf wrapper when extracting
  84 # the races from configure.ac.
  85 AUTOCONF='$AUTOCONF'; export AUTOCONF
  86 $AUTOMAKE "\$@"
  87 touch -r config.status Makefile.in
  88 $stat Makefile.in
  89 END
  90
  91 cat > autoconf-wrap <<END
  92 #!/bin/sh
  93 set -ex
  94 $AUTOCONF "\$@"
  95 touch -r config.status configure
  96 $stat configure
  97 END
  98
  99 chmod a+x aclocal-wrap automake-wrap autoconf-wrap
 100
 101 run_make Makefile \
 102   ACLOCAL=./aclocal-wrap AUTOMAKE=./automake-wrap AUTOCONF=./autoconf-wrap
 103 grep '^FOOBAR =' Makefile.in
 104 grep '^FOOBAR *= *zardoz *$' Makefile
 105
 106 :