[gentoo-dev] [PATCH] Use bash redirection to run 'tee' rather than simple pipes.

["Michał Górny" <mgorny@gentoo.org>]

This allows us to spawn 'tee' as separate process while keeping
the function code executed in the main shell.
---
 gx86/eclass/multibuild.eclass | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/gx86/eclass/multibuild.eclass b/gx86/eclass/multibuild.eclass
index 716d34f..d66d069 100644
--- a/gx86/eclass/multibuild.eclass
+++ b/gx86/eclass/multibuild.eclass
@@ -108,18 +108,20 @@ multibuild_foreach() {
 		local MULTIBUILD_VARIANT=${v}
 		local MULTIBUILD_ID=${prev_id}${v}
 		local BUILD_DIR=${bdir%%/}-${v}
-
-		einfo "${v}: running ${@}" \
-			| tee -a "${T}/build-${MULTIBUILD_ID}.log"
-
-		# _multibuild_parallel() does redirection internally.
-		# this is a hidden API to avoid writing multilib_foreach twice.
-		if [[ ${1} == _multibuild_parallel ]]; then
-			"${@}"
-		else
-			"${@}" 2>&1 | tee -a "${T}/build-${MULTIBUILD_ID}.log"
-		fi
-		lret=${?}
+		local log_fd
+
+		# redirect_alloc_fd accepts files only. so we need to open
+		# a random file and then reuse the fd for logger process.
+		redirect_alloc_fd log_fd /dev/null
+		# bash can't handle ${log_fd} in redirections,
+		# we need to use eval to pass fd numbers directly.
+		eval "
+			exec ${log_fd}> >(exec tee -a \"\${T}/build-\${MULTIBUILD_ID}.log\")
+			einfo \"\${v}: running \${@}\" >&${log_fd} 2>&1
+			\"\${@}\" >&${log_fd} 2>&1
+			lret=\${?}
+			exec ${log_fd}>&-
+		"
 	done
 	[[ ${ret} -eq 0 && ${lret} -ne 0 ]] && ret=${lret}
 
@@ -145,8 +147,7 @@ multibuild_parallel_foreach() {
 	_multibuild_parallel() {
 		(
 			multijob_child_init
-			"${@}" 2>&1 | tee -a "${T}/build-${MULTIBUILD_ID}.log"
-			exit ${PIPESTATUS[0]}
+			"${@}"
 		) &
 		multijob_post_fork
 	}
-- 
1.8.1.4