Make profile switching more atomic #380759.

(Portage version: 2.2.0_alpha51/cvs/Linux x86_64)

2 files changed, 37 insertions, 14 deletions

diff --git a/sys-devel/binutils-config/ChangeLog b/sys-devel/binutils-config/ChangeLog
index 58e5d0b03297..6e07f87515e6 100644
--- a/sys-devel/binutils-config/ChangeLog
+++ b/sys-devel/binutils-config/ChangeLog
@@ -1,6 +1,9 @@
 # ChangeLog for sys-devel/binutils-config
 # Copyright 1999-2011 Gentoo Foundation; Distributed under the GPL v2
-# $Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/ChangeLog,v 1.48 2011/08/23 16:09:21 vapier Exp $
+# $Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/ChangeLog,v 1.49 2011/08/29 00:56:45 vapier Exp $
+
+  29 Aug 2011; Mike Frysinger <vapier@gentoo.org> files/binutils-config-3:
+  Make profile switching more atomic #380759.
 
   23 Aug 2011; Mike Frysinger <vapier@gentoo.org> files/binutils-config-3:
   Make sure all the profile specs still work after previous rework.
diff --git a/sys-devel/binutils-config/files/binutils-config-3 b/sys-devel/binutils-config/files/binutils-config-3
index 734b2d54e14e..725ae43aa6f3 100755
--- a/sys-devel/binutils-config/files/binutils-config-3
+++ b/sys-devel/binutils-config/files/binutils-config-3
@@ -1,7 +1,7 @@
 #!/bin/bash
 # Copyright 1999-2011 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
-# $Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/files/binutils-config-3,v 1.4 2011/08/23 16:09:21 vapier Exp $
+# $Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/files/binutils-config-3,v 1.5 2011/08/29 00:56:46 vapier Exp $
 
 # Format of /etc/env.d/binutils/:
 #  config-TARGET:	CURRENT=version for TARGET
@@ -59,6 +59,26 @@ mv_if_diff() {
 		mv -f "$1" "$2"
 	fi
 }
+atomic_ln() {
+	local target=$1 linkdir=$2 linkname=$3 linktmp linkfull
+	linktmp="${linkdir}/.binutils-config.tmp.${linkname}"
+	linkfull="${linkdir}/${linkname}"
+	if [[ -d ${linkfull} ]] ; then
+		# if linking to a dir, we need a little magic to
+		# make it atomic since `mv -T` is not portable
+		rm -rf "${linktmp}"
+		mkdir -p "${linktmp}"
+		ln -sf "${target}" "${linktmp}/${linkname}"
+		mv "${linktmp}/${linkname}" "${linktmp}/../"
+		rmdir "${linktmp}"
+	else
+		# `ln` will expand into unlink();symlink(); which
+		# is not atomic for a small amount of time, but
+		# `mv` is a single rename() call
+		ln -sf "${target}" "${linktmp}"
+		mv "${linktmp}" "${linkfull}"
+	fi
+}
 
 setup_env() {
 	unset TARGET VER LIBPATH FAKE_TARGETS
@@ -122,14 +142,14 @@ switch_profile() {
 	cd "${ROOT}/${BINPATH}" || exit 1
 	mkdir -p "${ROOT}/${BINPATH_LINKS}" "${ROOT}/usr/bin"
 	for x in * ; do
-		ln -sf "${BINPATH}/${x}" "${ROOT}/${BINPATH_LINKS}/${x}"
-		ln -sf "${BINPATH_LINKS}/${x}" "${ROOT}"/usr/bin/${TARGET}-${x}
+		atomic_ln "${BINPATH}/${x}" "${ROOT}/${BINPATH_LINKS}" "${x}"
+		atomic_ln "${BINPATH_LINKS}/${x}" "${ROOT}/usr/bin/" "${TARGET}-${x}"
 		for fake in ${FAKE_TARGETS} ; do
 			[[ -f ${ENV_D}/config-${fake} ]] && continue
-			ln -sf "${BINPATH_LINKS}/${x}" "${ROOT}"/usr/bin/${fake}-${x}
+			atomic_ln "${BINPATH_LINKS}/${x}" "${ROOT}/usr/bin" "${fake}-${x}"
 		done
 		if [[ ${TARGET} == ${HOST} ]] ; then
-			ln -sf ${TARGET}-${x} "${ROOT}"/usr/bin/${x}
+			atomic_ln "${TARGET}-${x}" "${ROOT}/usr/bin" "${x}"
 		fi
 	done
 
@@ -147,12 +167,12 @@ switch_profile() {
 		rmdir "${ROOT}"/usr/${TARGET}/lib >& /dev/null
 	fi
 	# When upgrading, we need to clean up ldscripts and libs
-	rm -rf "${dstlib}/ldscripts" "${ROOT}/${BINPATH_LINKS}"/ldscripts
 	mkdir -p "${dstlib}"
-	ln -sf "${LIBPATH}/ldscripts" "${dstlib}"/ldscripts
-	find -L "${dstlib}" -type l -exec rm {} +
+	rm -rf "${ROOT}/${BINPATH_LINKS}"/ldscripts
+	atomic_ln "${LIBPATH}/ldscripts" "${dstlib}" "ldscripts"
+	find -L "${dstlib}" -type l -exec rm -v {} +
 	for x in lib* ; do
-		ln -sf "${LIBPATH}/${x}" "${dstlib}/${x}"
+		atomic_ln "${LIBPATH}/${x}" "${dstlib}" "${x}"
 	done
 
 	#
@@ -164,7 +184,7 @@ switch_profile() {
 		if [[ ${HOST} == ${TARGET} ]] ; then
 			mkdir -p "${ROOT}/usr/include"
 			for x in * ; do
-				ln -sf "${INCPATH}/${x}" "${ROOT}/usr/include/${x}"
+				atomic_ln "${INCPATH}/${x}" "${ROOT}/usr/include" "${x}"
 			done
 		else
 			# Clean out old path -- cannot use '-exec {} +' syntax here
@@ -337,14 +357,14 @@ switch_linker() {
 	setup_env || return 1
 
 	# does this binutils even support the requested linker ?
-	if [[ ! -e ${BINPATH}/ld.${ld} ]] ; then
+	if [[ ! -e ${ROOT}/${BINPATH}/ld.${ld} ]] ; then
 		eerror "${argv0}: sorry, but ${PROFILE} doesn't support the ${ld} linker"
 		exit 1
 	fi
 
 	# switch it up
 	ebegin "Setting default linker to ${ld} for ${PROFILE}"
-	ln -sf ld.${ld} "${BINPATH}"/ld
+	atomic_ln ld.${ld} "${ROOT}/${BINPATH}" ld
 	eend $?
 }
 switch_linker_gold() { switch_linker gold ; }
@@ -389,7 +409,7 @@ while [[ $# -gt 0 ]] ; do
 		-h|--help)                 usage 0 ;;
 		-V|--version)
 			unset Header
-			cvsver="$Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/files/binutils-config-3,v 1.4 2011/08/23 16:09:21 vapier Exp $"
+			cvsver="$Header: /var/cvsroot/gentoo-x86/sys-devel/binutils-config/files/binutils-config-3,v 1.5 2011/08/29 00:56:46 vapier Exp $"
 			cvsver=${cvsver##*binutils-config-}
 			bver=${cvsver%%,v *}
 			cvsver=${cvsver#* }