When storing old versions of files for use in generating new files via

patching and for rolling back updates, don't copy a file if it has already
been stored.  This provides a significant speedup to the "Preparing to
download files" stage of "freebsd-update fetch" if many updates have already
been applied or if a file being updated is linked many times (such as
/rescue/*).

Reported by:	Paul Dekkers
MFC after:	1 week
Approved by:	re (bmah)

1 files changed, 20 insertions, 5 deletions

diff --git a/usr.sbin/freebsd-update/freebsd-update.sh b/usr.sbin/freebsd-update/freebsd-update.sh
index 552057e..a08517c 100644
--- a/usr.sbin/freebsd-update/freebsd-update.sh
+++ b/usr.sbin/freebsd-update/freebsd-update.sh
@@ -1365,12 +1365,27 @@ fetch_files_prepare () {
 	# Copy all files into /files/.  We only need the unmodified files
 	# for use in patching; but we'll want all of them if the user asks
 	# to rollback the updates later.
-	cut -f 1 -d '|' < $2.hashes |
-	    while read F; do
+	while read LINE; do
+		F=`echo "${LINE}" | cut -f 1 -d '|'`
+		HASH=`echo "${LINE}" | cut -f 2 -d '|'`
+
+		# Skip files we already have.
+		if [ -f files/${HASH}.gz ]; then
+			continue
+		fi
+
+		# Make sure the file hasn't changed.
 		cp "${BASEDIR}/${F}" tmpfile
-		gzip -c < tmpfile > files/`sha256 -q tmpfile`.gz
+		if [ `sha256 -q tmpfile` != ${HASH} ]; then
+			echo
+			echo "File changed while FreeBSD Update running: ${F}"
+			return 1
+		fi
+
+		# Place the file into storage.
+		gzip -c < tmpfile > files/${HASH}.gz
 		rm tmpfile
-	    done
+	done < $2.hashes
 
 	# Produce a list of patches to download
 	sort -k 1,1 -t '|' $3.hashes |
@@ -1665,7 +1680,7 @@ fetch_run () {
 	# Prepare to fetch files: Generate a list of the files we need,
 	# copy the unmodified files we have into /files/, and generate
 	# a list of patches to download.
-	fetch_files_prepare INDEX-OLD INDEX-PRESENT INDEX-NEW
+	fetch_files_prepare INDEX-OLD INDEX-PRESENT INDEX-NEW || return 1
 
 	# Fetch files.
 	fetch_files || return 1