From e30e0aedb36bdb048b8feff7738c20e265fbac8d Mon Sep 17 00:00:00 2001
From: Lucio Andrés Illanes Albornoz <lucio@lucioillanes.de>
Date: Feb 14 2020 17:15:07 +0000
Subject: subr/build_init.subr:buildp_init_env(): default to -P jobs count to ${DEFAULT_BUILD_CPUS}/2 or 1.

subr/build_init.subr:buildp_init_env(): reject invalid -P job counts.
etc/build.usage: updated.

---

diff --git a/etc/build.usage b/etc/build.usage
index 7401608..226c66d 100644
--- a/etc/build.usage
+++ b/etc/build.usage
@@ -1,5 +1,5 @@
 usage: ./build.sh [-a nt32|nt64] [-b debug|release] [-C dir[,..]] [-D kind[,..]]
-                  [-F ipv4|ipv6|offline] [-h] [-P [jobs]] [-r [*[*]]ALL|LAST|name[,..][:step,..]]
+                  [-F ipv4|ipv6|offline] [-h] [-P[jobs]] [-r [*[*]]ALL|LAST|name[,..][:step,..]]
                   [-R] [-v[v[v[v]]]] [--as-needed] [--debug-minipix] [<group>[ ..]]
         -a nt32|nt64      Selects 32-bit or 64-bit architecture; defaults to nt64.
         -b debug|release  Selects debug or release build; defaults to debug.
@@ -15,7 +15,7 @@ usage: ./build.sh [-a nt32|nt64] [-b debug|release] [-C dir[,..]] [-D kind[,..]]
                           Force IPv4 (ipv4) or IPv6 (ipv6) when downloading package archives
                           and/or Git repositories or don't download either at all (offline.)
         -h                Show this screen.
-        -P [jobs]         Enables parallelisation at group-level, whenever applicable.
+        -P[jobs]          Enables parallelisation at group-level, whenever applicable.
                           The maximum count of jobs defaults to the number of logical
                           processors on the host system.
                           If -R is not specified and at least one (1) package fails to build,
diff --git a/subr/build_init.subr b/subr/build_init.subr
index c204c9b..97db31e 100644
--- a/subr/build_init.subr
+++ b/subr/build_init.subr
@@ -74,14 +74,23 @@ buildp_init_env() {
 			DEFAULT_BUILD_CPUS=1;
 		fi;
 	fi;
-	if [ "${ARG_PARALLEL}" = auto ]; then
-		ARG_PARALLEL="${DEFAULT_BUILD_CPUS}";
-	fi;
-	ex_rtl_clean_env "${DEFAULT_CLEAR_ENV_VARS_EXCEPT}";
-	if ex_rtl_check_path_vars "${DEFAULT_CHECK_PATH_VARS}"; then
-		export PATH="${PREFIX}/bin${PATH:+:${PATH}}";
-	else
-		: $((_rc+=(9-1)));
+	case "${ARG_PARALLEL}" in
+	auto)
+		if [ "${DEFAULT_BUILD_CPUS}" -gt 1 ]; then
+			ARG_PARALLEL=$((${DEFAULT_BUILD_CPUS}/2));
+		else
+			ARG_PARALLEL="${DEFAULT_BUILD_CPUS}";
+		fi; ;;
+	*[^0-9]*)
+		_rc=9; _status="Error: invalid jobs count \`${ARG_PARALLEL}'."; ;;
+	esac;
+	if [ "${_rc}" -eq 0 ]; then
+		ex_rtl_clean_env "${DEFAULT_CLEAR_ENV_VARS_EXCEPT}";
+		if ex_rtl_check_path_vars "${DEFAULT_CHECK_PATH_VARS}"; then
+			export PATH="${PREFIX}/bin${PATH:+:${PATH}}";
+		else
+			: $((_rc+=(10-1)));
+		fi;
 	fi;
 	return "${_rc}";
 };
@@ -99,7 +108,7 @@ buildp_init_files() {
 		ex_rtl_fileop mkdir "${PREFIX_RPM}";
 	fi;
 	if [ -e "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}" ]; then
-		_rc=11; _status="Error: another build targeting this architecture and build type is currently in progress.";
+		_rc=12; _status="Error: another build targeting this architecture and build type is currently in progress.";
 	else
 		touch "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}";
 		if [ -e "${DEFAULT_BUILD_LOG_FNAME}" ]; then
@@ -135,7 +144,7 @@ buildp_init_getopts() {
 			D)	ARG_DIST="${OPTARG}"; ;;
 			F)	ARG_FETCH_FORCE=1; ;;
 			h)	cat etc/build.usage; exit 0; ;;
-			P)	ARG_PARALLEL="${OPTARG:-auto}"; ;;
+			P)	ARG_PARALLEL="${1#-P}"; ARG_PARALLEL="${ARG_PARALLEL:-auto}"; ;;
 			r)	ARG_RESTART="${OPTARG}"; ;;
 			R)	ARG_RELAXED=1; ;;
 			*)	cat etc/build.usage; exit 1; ;;