use strict;
use warnings FATAL => 'all';
-use Exporter;
-use IO::File;
+BEGIN
+{
+ require Exporter;
+ our @ISA = qw (Exporter);
+ our @EXPORT = qw (&contents
+ &find_file &mtime
+ &update_file
+ &xsystem &xsystem_hint &xqx
+ &dir_has_case_matching_file &reset_dir_cache
+ &set_dir_cache_file);
+}
-# use sub-second resolution timestamps if available,
-# carry on with one-second resolution timestamps if that is all we have
-BEGIN { eval { require Time::HiRes; import Time::HiRes qw(stat) } }
+# Use sub-second resolution file timestamps if available, carry on
+# with one-second resolution timestamps if Time::HiRes is not available.
+#
+# Unfortunately, even if Time::HiRes is available, we don't get
+# timestamps to the full precision recorded by the operating system,
+# because Time::HiRes converts timestamps to floating-point, and the
+# rounding error is hundreds of nanoseconds for circa-2023 timestamps
+# in IEEE double precision. But this is the best we can do without
+# dropping down to C.
+#
+# $subsecond_mtime is not exported, but is intended for external
+# consumption, as $Automake::FileUtils::subsecond_mtime.
+BEGIN
+{
+ our $subsecond_mtime = 0;
+ eval
+ {
+ require Time::HiRes;
+ import Time::HiRes qw(stat);
+ $subsecond_mtime = 1;
+ }
+}
+use IO::File;
use Automake::Channels;
use Automake::ChannelDefs;
-our @ISA = qw (Exporter);
-our @EXPORT = qw (&contents
- &find_file &mtime
- &update_file
- &xsystem &xsystem_hint &xqx
- &dir_has_case_matching_file &reset_dir_cache
- &set_dir_cache_file);
-
=over 4
=item C<find_file ($file_name, @include)>
$atime,$mtime,$ctime,$blksize,$blocks) = stat ($file)
or fatal "cannot stat $file: $!";
- # Unfortunately Time::HiRes converts timestamps to floating-point, and the
- # rounding error can be hundreds of nanoseconds for circa-2023 timestamps.
- # Perhaps some day Perl will support accurate file timestamps.
- # For now, do the best we can without going outside Perl.
-
return $mtime;
}
=cut
1; # for require
+
+### Setup "GNU" style for perl-mode and cperl-mode.
+## Local Variables:
+## perl-indent-level: 2
+## perl-continued-statement-offset: 2
+## perl-continued-brace-offset: 0
+## perl-brace-offset: 0
+## perl-brace-imaginary-offset: 0
+## perl-label-offset: -2
+## cperl-indent-level: 2
+## cperl-brace-offset: 0
+## cperl-continued-brace-offset: 0
+## cperl-label-offset: -2
+## cperl-extra-newline-before-brace: t
+## cperl-merge-trailing-else: nil
+## cperl-continued-statement-offset: 2
+## End:
# _AM_FILESYSTEM_TIMESTAMP_RESOLUTION
# -----------------------------------
-# Determine the filesystem timestamp resolution. Modern systems are
-# nanosecond capable, but historical systems could have millisecond,
-# second, or even 2-second resolution.
+# Determine the filesystem's resolution for file modification
+# timestamps. The coarsest we know of is FAT, with a resolution
+# of only two seconds, even with the most recent "exFAT" extensions.
+# The finest (e.g. ext4 with large inodes, XFS, ZFS) is one
+# nanosecond, matching clock_gettime. However, it is probably not
+# possible to delay execution of a shell script for less than one
+# millisecond, due to process creation overhead and scheduling
+# granularity, so we don't check for anything finer than that.
AC_DEFUN([_AM_FILESYSTEM_TIMESTAMP_RESOLUTION], [dnl
AC_REQUIRE([_AM_SLEEP_FRACTIONAL_SECONDS])
-#
-# Check if Autom4te uses Time::HiRes. If not, we cannot use fractional sleep,
-# because this sanity test and automated tests will be unreliable due to
-# Autom4te's caching of results and comparing timestamps.
-# More info: long thread around
-# https://lists.gnu.org/archive/html/automake/2023-04/msg00002.html
-# and https://debbugs.gnu.org/cgi/bugreport.cgi?bug=64756.
-# By the way, we cannot use Perl to see if %INC{q[Time/HiRes.pm]} is
-# defined, because Time::HiRes might get pulled in from other system
-# modules even when not used directly. (An idea suggested in that thread.)
-AC_PATH_PROG([AUTOM4TE], [autom4te])
-if test x"$autom4te_perllibdir" = x; then
- autom4te_perllibdir=`sed -n \
- '/autom4te_perllibdir/{s/^.*|| //;s/;$//;s/^.//;s/.$//;p;q}' <$AUTOM4TE`
+AC_CACHE_CHECK([the filesystem timestamp resolution], am_cv_filesystem_timestamp_resolution, [dnl
+# Default to the worst case.
+am_cv_filesystem_timestamp_resolution=2
+
+# Only try to go finer than 1s if sleep can do it.
+am_try_resolutions=1
+if $am_cv_sleep_fractional_seconds; then
+ am_try_resolutions="0.001 0.01 0.1 $am_try_resolutions"
fi
-if grep HiRes "$autom4te_perllibdir"/Autom4te/FileUtils.pm >/dev/null; then
- :
-else
- am_cv_sleep_fractional_seconds=false
+
+# In order to catch current-generation FAT out, we must *modify* files
+# that already exist; the *creation* timestamp is finer. Use names
+# that make ls -t sort them differently when they have equal
+# timestamps than when they have distinct timestamps, keeping
+# in mind that ls -t prints the *newest* file first.
+rm -f conftest.ts?
+: > conftest.ts1
+: > conftest.ts2
+: > conftest.ts3
+
+# Make sure ls -t actually works. Do 'set' in a subshell so we don't
+# clobber the current shell's arguments.
+if (
+ set X `[ls -t conftest.ts[12]]` &&
+ {
+ test "$[*]" != "X conftest.ts1 conftest.ts2" ||
+ test "$[*]" != "X conftest.ts2 conftest.ts1";
+ }
+); then :; else
+ # 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".
+ _AS_ECHO_UNQUOTED(
+ ["Bad output from ls -t: \"`[ls -t conftest.ts[12]]`\""],
+ [AS_MESSAGE_LOG_FD])
+ AC_MSG_FAILURE([ls -t produces unexpected output.
+Make sure there is not a broken alias in your environment.])
fi
-AC_CACHE_CHECK([the filesystem timestamp resolution], am_cv_filesystem_timestamp_resolution, [dnl
-# Use names that lexically sort older-first when the timestamps are equal.
-rm -f conftest.file.a conftest.file.b
-: > conftest.file.a
-AS_IF([$am_cv_sleep_fractional_seconds], [dnl
- am_try_sleep=0.1 am_try_loops=20
-], [dnl
- am_try_sleep=1 am_try_loops=2
-])
-am_try=0
-while :; do
- AS_VAR_ARITH([am_try], [$am_try + 1])
- echo "timestamp $am_try" > conftest.file.b
- set X `ls -t conftest.file.a conftest.file.b`
- if test "$[2]" = conftest.file.b || test $am_try -eq $am_try_loops; then
+for am_try_res in $am_try_resolutions; do
+ # Any one fine-grained sleep might happen to cross the boundary
+ # between two values of a coarser actual resolution, but if we do
+ # two fine-grained sleeps in a row, at least one of them will fall
+ # entirely within a coarse interval.
+ echo alpha > conftest.ts1
+ sleep $am_try_res
+ echo beta > conftest.ts2
+ sleep $am_try_res
+ echo gamma > conftest.ts3
+
+ # We assume that 'ls -t' will make use of high-resolution
+ # timestamps if the operating system supports them at all.
+ if (set X `ls -t conftest.ts?` &&
+ test "$[]2" = conftest.ts3 &&
+ test "$[]3" = conftest.ts2 &&
+ test "$[]4" = conftest.ts1); then
+ am_cv_filesystem_timestamp_resolution=$am_try_res
break
fi
- sleep $am_try_sleep
done
-rm -f conftest.file.a conftest.file.b
-am_cv_filesystem_timestamp_resolution=$am_try
-AS_IF([$am_cv_sleep_fractional_seconds], [dnl
- AS_VAR_ARITH([am_cv_filesystem_timestamp_resolution], [$am_try / 10])
- AS_VAR_ARITH([am_fraction], [$am_try % 10])
- AS_VAR_APPEND([am_cv_filesystem_timestamp_resolution], [.$am_fraction])
-])
+rm -f conftest.ts?
])])
# AM_SANITY_CHECK
# ---------------
AC_DEFUN([AM_SANITY_CHECK],
[AC_REQUIRE([_AM_FILESYSTEM_TIMESTAMP_RESOLUTION])
-rm -f conftest.file
-AC_CACHE_CHECK([whether build environment is sane], am_cv_build_env_is_sane, [dnl
+# This check should not be cached, as it may vary across builds of
+# different projects.
+AC_MSG_CHECKING([whether build environment is sane])
# Reject unsafe characters in $srcdir or the absolute working directory
# name. Accept space and tab only in the latter.
am_lf='
# symlink; some systems play weird games with the mod time of symlinks
# (eg FreeBSD returns the mod time of the symlink's containing
# directory).
-if (
- am_has_slept=no
- for am_try in 1 2; do
- echo "timestamp, slept: $am_has_slept" > conftest.file
- set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
- if test "$[*]" = "X"; then
- # -L didn't work.
- set X `ls -t "$srcdir/configure" conftest.file`
- fi
- if test "$[*]" != "X $srcdir/configure conftest.file" \
- && test "$[*]" != "X conftest.file $srcdir/configure"; then
+am_build_env_is_sane=no
+am_has_slept=no
+rm -f conftest.file
+for am_try in 1 2; do
+ echo "timestamp, slept: $am_has_slept" > conftest.file
+ if (
+ set X `ls -Lt "$srcdir/configure" conftest.file 2> /dev/null`
+ if test "$[*]" = "X"; then
+ # -L didn't work.
+ set X `ls -t "$srcdir/configure" conftest.file`
+ fi
+ test "$[2]" = conftest.file
+ ); then
+ am_build_env_is_sane=yes
+ break
+ fi
+ # Just in case.
+ sleep $am_cv_filesystem_timestamp_resolution
+ am_has_slept=yes
+done
- # If neither matched, then we have a broken ls. This can happen
- # if, for instance, CONFIG_SHELL is bash and it inherits a
- # broken ls alias from the environment. This has actually
- # happened. Such a system could not be considered "sane".
- AC_MSG_ERROR([ls -t appears to fail. Make sure there is not a broken
- alias in your environment])
- fi
- if test "$[2]" = conftest.file || test $am_try -eq 2; then
- break
- fi
- # Just in case.
- sleep $am_cv_filesystem_timestamp_resolution
- am_has_slept=yes
- done
- test "$[2]" = conftest.file
- )
-then
- am_cv_build_env_is_sane=yes
-else
- AC_MSG_ERROR([newly created file is older than distributed files!
+AC_MSG_RESULT([$am_build_env_is_sane])
+if test $am_build_env_is_sane = no; then
+ AC_MSG_ERROR([newly created file is older than distributed files!
Check your system clock])
fi
-])
+
# If we didn't sleep, we still need to ensure time stamps of config.status and
# generated files are strictly newer.
am_sleep_pid=
projects / thirdparty / automake.git / commitdiff
