git-repack: Be careful when updating the same pack as an existing one.

diff --git a/git-repack.sh b/git-repack.sh
index e0c9f323c3ba8a4f42ec5a4a4fa53a8bddb36b34..640ad8d90b9a9afd00506a9697af1d3e560e1255 100755 (executable)
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -48,15 +48,31 @@ name=$(git-rev-list --objects --all $rev_list 2>&1 |
        exit 1
 if [ -z "$name" ]; then
        echo Nothing new to pack.
-       exit 0
-fi
-echo "Pack pack-$name created."
-
-mkdir -p "$PACKDIR" || exit
+else
+       if test "$quiet" != '-q'; then
+           echo "Pack pack-$name created."
+       fi
+       mkdir -p "$PACKDIR" || exit
 
-mv .tmp-pack-$name.pack "$PACKDIR/pack-$name.pack" &&
-mv .tmp-pack-$name.idx  "$PACKDIR/pack-$name.idx" ||
-exit
+       for sfx in pack idx
+       do
+               if test -f "$PACKDIR/pack-$name.$sfx"
+               then
+                       mv -f "$PACKDIR/pack-$name.$sfx" \
+                               "$PACKDIR/old-pack-$name.$sfx"
+               fi
+       done &&
+       mv -f .tmp-pack-$name.pack "$PACKDIR/pack-$name.pack" &&
+       mv -f .tmp-pack-$name.idx  "$PACKDIR/pack-$name.idx" &&
+       test -f "$PACKDIR/pack-$name.pack" &&
+       test -f "$PACKDIR/pack-$name.idx" || {
+               echo >&2 "Couldn't replace the existing pack with updated one."
+               echo >&2 "The original set of packs have been saved as"
+               echo >&2 "old-pack-$name.{pack,idx} in $PACKDIR."
+               exit 1
+       }
+       rm -f "$PACKDIR/old-pack-$name.pack" "$PACKDIR/old-pack-$name.idx"
+fi
 
 if test "$remove_redundant" = t
 then