crosstool-ng/m4/ax_build_date_epoch.m4

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_build_date_epoch.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_BUILD_DATE_EPOCH(VARIABLE[, FORMAT[, ACTION-IF-FAIL]])
#
# DESCRIPTION
#
# Sets VARIABLE to a string representing the current time. It is
# formatted according to FORMAT if specified, otherwise it is formatted as
# the number of seconds (excluding leap seconds) since the UNIX epoch (01
# Jan 1970 00:00:00 UTC).
#
# If the SOURCE_DATE_EPOCH environment variable is set, it uses the value
# of that variable instead of the current time. See
# https://reproducible-builds.org/specs/source-date-epoch). If
# SOURCE_DATE_EPOCH is set but cannot be properly interpreted as a UNIX
# timestamp, then execute ACTION-IF-FAIL if specified, otherwise error.
#
# VARIABLE is AC_SUBST-ed.
#
# LICENSE
#
# Copyright (c) 2016 Eric Bavier <bavier@member.fsf.org>
#
# 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 the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program. If not, see <https://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
#serial 2
AC_DEFUN([AX_BUILD_DATE_EPOCH],
[dnl
AC_MSG_CHECKING([for build time])
ax_date_fmt="m4_default($2,%s)"
AS_IF([test x"$SOURCE_DATE_EPOCH" = x],
[$1=`date "+$ax_date_fmt"`],
[ax_build_date=`date -u -d "@$SOURCE_DATE_EPOCH" "+$ax_date_fmt" 2>/dev/null \
|| date -u -r "$SOURCE_DATE_EPOCH" "+$ax_date_fmt" 2>/dev/null`
AS_IF([test x"$ax_build_date" = x],
[m4_ifval([$3],
[$3],
[AC_MSG_ERROR([malformed SOURCE_DATE_EPOCH])])],
[$1=$ax_build_date])])
AC_MSG_RESULT([$$1])
])dnl AX_BUILD_DATE_EPOCH