lib/time.sh: New file

2 files changed, 164 insertions, 1 deletions

diff --git a/lib/local.mk b/lib/local.mk
index 845905a..dc5b5e8 100644
--- a/lib/local.mk
+++ b/lib/local.mk
@@ -24,7 +24,8 @@ libopkbuild_sources = \
 	%reldir%/metadata.sh \
 	%reldir%/control.sh \
 	%reldir%/changelog.sh \
-	%reldir%/deps.sh
+	%reldir%/deps.sh \
+	%reldir%/time.sh
 EXTRA_libopkbuild_sources =
 libopkbuild_ldadd = $(libopkbuild_sources:.sh=.sho)
 libopkbuild_dependencies = $(libopkbuild_ldadd)
diff --git a/lib/time.sh b/lib/time.sh
new file mode 100644
index 0000000..b65bbba
--- /dev/null
+++ b/lib/time.sh
@@ -0,0 +1,162 @@
+# Functions for converting date and time
+#
+# Copyright (C) 2019 Patrick McDermott
+#
+# This file is part of opkbuild.
+#
+# opkbuild is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# opkbuild is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with opkbuild.  If not, see <http://www.gnu.org/licenses/>.
+
+_ob_is_leap_year()
+{
+	local year="${1}"
+	shift 1 || _ob_abort
+
+	return $((!(!(${year} % 4) && ${year} % 100 || !(${year} % 400))))
+}
+
+_ob_year_to_days()
+{
+	local year="${1}"
+	shift 1 || _ob_abort
+	local y=1970
+	local d=0
+
+	# Simple but iterative.
+	while [ ${y} -ne ${year} ]; do
+		_ob_is_leap_year ${y} && : $((d += 366)) || : $((d += 365))
+		: $((y += 1))
+	done
+	printf '%d' ${d}
+	return 0
+}
+
+_ob_month_to_days()
+{
+	local month="${1}"
+	local year="${2}"
+	shift 2 || _ob_abort
+	local d=
+
+	case ${month} in
+		1)   d=0;;  2)  d=31;;  3)  d=59;;  4)  d=90;;
+		5) d=120;;  6) d=151;;  7) d=181;;  8) d=212;;
+		9) d=243;; 10) d=273;; 11) d=304;; 12) d=334;;
+	esac
+	[ ${month} -ge 2 ] && _ob_is_leap_year ${year} && : $((++d))
+	printf '%d' ${d}
+	return 0
+}
+
+_ob_mktime()
+{
+	local year="${1}"
+	local mon="${2}"
+	local mday="${3}"
+	local hour="${4}"
+	local min="${5}"
+	local sec="${6}"
+	local timezone="${7}"
+	shift 7 || _ob_abort
+	local d=
+	local t=
+
+	d=$(($(_ob_year_to_days ${year}) + $(_ob_month_to_days ${mon} ${year})))
+	d=$((${d} + ${mday} - 1))
+	t=$(( ( (${d} * 24 + ${hour}) * 60 + ${min}) * 60 + ${sec} ))
+	t=$((${t} - ${timezone}))
+	printf '%d' ${t}
+	return 0
+}
+
+## @brief Convert a date and time into seconds since the Epoch
+## @details \fBob_rfc822_mktime\fP() converts date and time formatted according
+##          to RFCs 822, 2822, and 5322 into non-leap seconds elapsed since the
+##          Epoch.  It is similar to the C function \fBmktime\fP() except that
+##          it accepts a formatted string instead of a structure as its
+##          argument.  It is intended to parse \fIchangelog\fP dates into a time
+##          value usable in the \fISOURCE_DATE_EPOCH\fP environment variable.
+## @operand rfc822_tm req A date and time string formatted according to the
+##                        \fIdate-time\fP symbol of RFC 5322 section 3.3.
+## @return Returns 0.
+## @stdout Prints the number of non-leap seconds elapsed since the Epoch.
+## @pure yes This function has no side effects.
+ob_rfc822_mktime()
+{
+	local rfc822_tm="${1}"
+	shift 1 || _ob_abort
+	local wday=
+	local mday=
+	local mon=
+	local year=
+	local hour=
+	local min=
+	local sec=
+	local tz=
+	local tzsgn=
+	local tzhour=
+	local tzmin=
+
+	read wday mday mon year hour min sec tz <<-EOF
+		${rfc822_tm}
+		EOF
+	tzsgn="${tz%%[0-9]*}"; tz=${tz#[+-]}; tz=${tz#0}; tz=${tz#0}
+	tzhour=$((${tz} / 100))
+	tzmin=$(( ${tz} % 100))
+	_ob_mktime ${year} ${mon#0} ${mday#0} ${hour#0} ${min#0} ${sec#0} \
+		$((${tzsgn}1 * (${tzhour} * 60 + ${tzmin}) * 60))
+	return 0
+}
+
+## @brief Convert seconds since the Epoch into a date and time
+## @details \fBob_iso8601_gmtime\fP() converts the number of non-leap seconds
+##          elapsed since the Epoch into date and time in UTC formatted
+##          according to ISO 8601.  It is similar to the C function \fBgmtime\fP
+##          except that it returns a formatted string instead of a structure. 
+##          It is intended to generate a date and time usable with a
+##          POSIX-conformant \fBtouch\fP utility.
+## @operand timep req The number of non-leap seconds elapsed since the Epoch.
+## @return Returns 0.
+## @stdout Prints the date and time in UTC formatted according to ISO 8601.
+## @pure yes This function has no side effects.
+ob_iso8601_gmtime()
+{
+	local timep="${1}"
+	shift 1 || _ob_abort
+	local sec=
+	local min=
+	local hour=
+	local days_in_year=
+	local year=1970
+	local mon=1
+	local mday=
+
+	 sec=$((${timep} % 60)); : $((timep /= 60))
+	 min=$((${timep} % 60)); : $((timep /= 60))
+	hour=$((${timep} % 24)); : $((timep /= 24))
+
+	while :; do
+		_ob_is_leap_year ${year} && days_in_year=366 || days_in_year=365
+		[ ${timep} -le ${days_in_year} ] && break
+		: $((timep -= ${days_in_year}))
+		: $((year += 1))
+	done
+	while [ ${timep} -gt $(_ob_month_to_days $((${mon} + 1)) ${year}) ]; do
+		: $((mon += 1))
+	done
+	mday=$((${timep} - $(_ob_month_to_days ${mon} ${year}) + 1))
+
+	printf '%04d-%02d-%02dT%02d:%02d:%02dZ' \
+		${year} ${mon} ${mday} ${hour} ${min} ${sec}
+	return 0
+}