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etcupdate: Always extract to a temporary tree.

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etcupdate has had a somewhat nasty race condition since its creation
in that its state machine can get very confused if it is interrupted
while building the tree to compare against.  This is exacerbated by
the fact that etcupdate doesn't emit any output while building the
tree which can take several seconds (especially in recent years with
the addition of the tree-wide buildconfig/installconfig passes).

To mitigate this, always install a new tree into a temporary directory
created via mktemp as was previously done only for dry-runs via -n.
The existing trees are only rotated and the new tree installed as
/var/db/etcupdate/current after the update command has completed.

Reported by:	dim, np (and many others)
Reviewed by:	imp
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D29843
This commit is contained in:
John Baldwin 2021-04-20 13:21:42 -07:00
parent dd559118ab
commit 0611aec3cf
1 changed files with 96 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

156
usr.sbin/etcupdate/etcupdate.sh
View File

@ -226,9 +226,11 @@ build_tree()
return 0
}
# Generate a new NEWTREE tree. If tarball is set, then the tree is
# Generate a new tree. If tarball is set, then the tree is
# extracted from the tarball. Otherwise the tree is built from a
# source tree.
#
# $1 - directory to store new tree in
extract_tree()
{
local files
@ -239,16 +241,16 @@ extract_tree()
if [ -n "$preworld" ]; then
files="$PREWORLD_FILES"
fi
if ! (mkdir -p $NEWTREE && tar xf $tarball -C $NEWTREE $files) \
if ! (mkdir -p $1 && tar xf $tarball -C $1 $files) \
>&3 2>&1; then
echo "Failed to extract new tree."
remove_tree $NEWTREE
remove_tree $1
exit 1
fi
else
if ! build_tree $NEWTREE; then
if ! build_tree $1; then
echo "Failed to build new tree."
remove_tree $NEWTREE
remove_tree $1
exit 1
fi
fi
@ -1353,14 +1355,28 @@ extract_cmd()
log "extract command: tarball=$tarball"
# Create a temporary directory to hold the tree
dir=`mktemp -d $WORKDIR/etcupdate-XXXXXXX`
if [ $? -ne 0 ]; then
echo "Unable to create temporary directory."
exit 1
fi
extract_tree $dir
if [ -d $NEWTREE ]; then
if ! remove_tree $NEWTREE; then
echo "Unable to remove current tree."
remove_tree $dir
exit 1
fi
fi
extract_tree
if ! mv $dir $NEWTREE >&3 2>&1; then
echo "Unable to rename temp tree to current tree."
remove_tree $dir
exit 1
fi
}
# Resolve conflicts left from an earlier merge.
@ -1420,7 +1436,7 @@ status_cmd()
# source tree.
update_cmd()
{
local dir
local dir new old
if [ $# -ne 0 ]; then
usage
@ -1449,60 +1465,44 @@ update_cmd()
exit 1
fi
# Save tree names to use for rotation later.
old=$OLDTREE
new=$NEWTREE
if [ -z "$rerun" ]; then
# For a dryrun that is not a rerun, do not rotate the existing
# stock tree. Instead, extract a tree to a temporary directory
# and use that for the comparison.
if [ -n "$dryrun" ]; then
dir=`mktemp -d $WORKDIR/etcupdate-XXXXXXX`
if [ $? -ne 0 ]; then
echo "Unable to create temporary directory."
exit 1
fi
# A pre-world dryrun has already set OLDTREE to
# point to the current stock tree.
if [ -z "$preworld" ]; then
OLDTREE=$NEWTREE
fi
NEWTREE=$dir
# For a pre-world update, blow away any pre-existing
# NEWTREE.
elif [ -n "$preworld" ]; then
if ! remove_tree $NEWTREE; then
echo "Unable to remove pre-world tree."
exit 1
fi
# Rotate the existing stock tree to the old tree.
elif [ -d $NEWTREE ]; then
# First, delete the previous old tree if it exists.
if ! remove_tree $OLDTREE; then
echo "Unable to remove old tree."
exit 1
fi
# Move the current stock tree.
if ! mv $NEWTREE $OLDTREE >&3 2>&1; then
echo "Unable to rename current stock tree."
exit 1
fi
fi
if ! [ -d $OLDTREE ]; then
cat <<EOF
No previous tree to compare against, a sane comparison is not possible.
EOF
log "No previous tree to compare against."
if [ -n "$dir" ]; then
rmdir $dir
fi
# Extract the new tree to a temporary directory. The
# trees are only rotated after a successful update to
# avoid races if an update command is interrupted
# before it completes.
dir=`mktemp -d $WORKDIR/etcupdate-XXXXXXX`
if [ $? -ne 0 ]; then
echo "Unable to create temporary directory."
exit 1
fi
# Populate the new tree.
extract_tree
extract_tree $dir
# Compare the new tree against the previous tree. For
# the preworld case OLDTREE already points to the
# current stock tree.
if [ -z "$preworld" ]; then
OLDTREE=$NEWTREE
fi
NEWTREE=$dir
fi
if ! [ -d $OLDTREE ]; then
cat <<EOF
No previous tree to compare against, a sane comparison is not possible.
EOF
log "No previous tree to compare against."
if [ -n "$dir" ]; then
if [ -n "$rerun" ]; then
panic "Should not have a temporary directory"
fi
remove_tree $dir
fi
exit 1
fi
# Build lists of nodes in the old and new trees.
@ -1568,12 +1568,48 @@ EOF
cat $WARNINGS
fi
if [ -n "$dir" ]; then
if [ -z "$dryrun" -o -n "$rerun" ]; then
# Finally, rotate any needed trees.
if [ "$new" != "$NEWTREE" ]; then
if [ -n "$rerun" ]; then
panic "Should not have a temporary directory"
fi
remove_tree $dir
if [ -z "$dir" ]; then
panic "Should have a temporary directory"
fi
# Rotate the old tree if needed
if [ "$old" != "$OLDTREE" ]; then
if [ -n "$preworld" ]; then
panic "Old tree should be unchanged"
fi
if ! remove_tree $old; then
echo "Unable to remove previous old tree."
exit 1
fi
if ! mv $OLDTREE $old >&3 2>&1; then
echo "Unable to rename old tree."
exit 1
fi
fi
# Rotate the new tree. Remove a previous pre-world
# tree if it exists.
if [ -d $new ]; then
if [ -z "$preworld" ]; then
panic "New tree should be rotated to old"
fi
if ! remove_tree $old; then
echo "Unable to remove previous pre-world tree."
exit 1
fi
fi
if ! mv $NEWTREE $new >&3 2>&1; then
echo "Unable to rename current tree."
exit 1
fi
fi
}