https://bugs.gentoo.org/508708

From e9171f28f4437a8aa3e8e085f85c0c2bd7c5c05e Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Fri, 25 Apr 2014 13:37:03 -0400
Subject: [PATCH 1/4] update env.d entry atomically

---
 opengl.eselect | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/opengl.eselect b/opengl.eselect
index 3f59a19..90ac51e 100644
--- a/opengl.eselect
+++ b/opengl.eselect
@@ -196,9 +196,6 @@ set_new_implementation() {
 	fi
 
 	echo -n "Switching to ${gl_implem} OpenGL interface..."
-	if [[ -f ${ENV_FILE} ]] ; then
-		rm -f "${ENV_FILE}" || die -q "Failed to remove ${ENV_FILE}"
-	fi
 
 	for libdir in $(list_libdirs); do
 		# Set libdir correctly to EROOT
@@ -269,8 +266,10 @@ set_new_implementation() {
 		fi
 	done
 
-	store_config ${ENV_FILE} LDPATH "${ldpath}"
-	store_config ${ENV_FILE} OPENGL_PROFILE "${gl_implem}"
+	# Update the file atomically. #508708
+	store_config "${ENV_FILE}~" LDPATH "${ldpath}"
+	store_config "${ENV_FILE}~" OPENGL_PROFILE "${gl_implem}"
+	mv -f "${ENV_FILE}~" "${ENV_FILE}" || die -q "could not update ${ENV_FILE}"
 
 	do_action env update &> /dev/null
 
-- 
1.9.2