[oe-commits] James Limbouris : initscripts: Modify 'populate-volatile.sh' to atomically update 'volatile.cache'

[git version control]

Module: openembedded.git
Branch: master
Commit: 9a799fb3464b61df51f5e772c693cd76ad948f28
URL:    http://git.openembedded.org/?p=openembedded.git&a=commit;h=9a799fb3464b61df51f5e772c693cd76ad948f28

Author: James Limbouris <james at digitalmatter.com.au>
Date:   Tue Jun  7 17:35:26 2011 +0800

initscripts: Modify 'populate-volatile.sh' to atomically update 'volatile.cache'

When power is lost before a new volatile.cache has been flushed to disk, it can
be corrupted, leaving the volatiles uncreated and causing software failure
during the next reboot.

Since only the existence of volative.cache is checked for using a temporary file
on the same volume and renaming it avoids this issue.

The file is sync'd before the rename to avoid problems with newer caching
filesystems, in which the rename is atomic, but the contents of the file may not
yet be flushed.

Signed-off-by: James Limbouris <james at digitalmatter.com.au>
Acked-by: Paul Menzel <paulepanter at users.sourceforge.net>

---

 .../initscripts-1.0/populate-volatile.sh           |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/recipes/initscripts/initscripts-1.0/populate-volatile.sh b/recipes/initscripts/initscripts-1.0/populate-volatile.sh
index 3bb3d94..f0a45ea 100755
--- a/recipes/initscripts/initscripts-1.0/populate-volatile.sh
+++ b/recipes/initscripts/initscripts-1.0/populate-volatile.sh
@@ -14,7 +14,7 @@ create_file() {
 	chown ${TUSER}.${TGROUP} $1 || echo \"Failed to set owner -${TUSER}- for -$1-.\" >/dev/tty0 2>&1; 
 	chmod ${TMODE} $1 || echo \"Failed to set mode -${TMODE}- for -$1-.\" >/dev/tty0 2>&1 " 
 
-	test "$VOLATILE_ENABLE_CACHE" = yes && echo "$EXEC" >> /etc/volatile.cache
+	test "$VOLATILE_ENABLE_CACHE" = yes && echo "$EXEC" >> /etc/volatile.cache.build
 
 	[ -e "$1" ] && {
 	  [ "${VERBOSE}" != "no" ] && echo "Target already exists. Skipping."
@@ -29,7 +29,7 @@ mk_dir() {
 	chown ${TUSER}.${TGROUP} $1 || echo \"Failed to set owner -${TUSER}- for -$1-.\" >/dev/tty0 2>&1; 
 	chmod ${TMODE} $1 || echo \"Failed to set mode -${TMODE}- for -$1-.\" >/dev/tty0 2>&1 "
 
-	test "$VOLATILE_ENABLE_CACHE" = yes && echo "$EXEC" >> /etc/volatile.cache
+	test "$VOLATILE_ENABLE_CACHE" = yes && echo "$EXEC" >> /etc/volatile.cache.build
 	
 	[ -e "$1" ] && {
 	  [ "${VERBOSE}" != "no" ] && echo "Target already exists. Skipping."
@@ -41,7 +41,7 @@ mk_dir() {
 link_file() {
 	EXEC="test -e \"$2\" -o -L $2 || ln -s \"$1\" \"$2\" >/dev/tty0 2>&1" 
 
-	test "$VOLATILE_ENABLE_CACHE" = yes && echo "	$EXEC" >> /etc/volatile.cache
+	test "$VOLATILE_ENABLE_CACHE" = yes && echo "	$EXEC" >> /etc/volatile.cache.build
 	
 	[ -e "$2" ] && {
 	  echo "Cannot create link over existing -${TNAME}-." >&2
@@ -164,8 +164,10 @@ if test -e /etc/volatile.cache -a "$VOLATILE_ENABLE_CACHE" = "yes" -a "x$1" != "
 then
 	sh /etc/volatile.cache
 else	
-	rm -f /etc/volatile.cache
+	rm -f /etc/volatile.cache /etc/volatile.cache.build
 	for file in `ls -1 "${CFGDIR}" | sort`; do
 		apply_cfgfile "${CFGDIR}/${file}"
 	done
+
+	[ -e /etc/volatile.cache.build ] && sync && mv /etc/volatile.cache.build /etc/volatile.cache
 fi