build-snapshot: Remove only unreferenced old files

Make sure that no symlink points to an old snapshot before cleaning it
up.  Also, don't check for dangling symlinks, as they should not occur
anymore.

1 files changed, 24 insertions, 2 deletions

diff --git a/bin/build-snapshot b/bin/build-snapshot
index 43c6293..5633abd 100755
--- a/bin/build-snapshot
+++ b/bin/build-snapshot
@@ -59,6 +59,29 @@ create_snapshot()
         cd "$OLDPWD"
 }
 
+rm_old_snapshots()
+{
+        snapshot_dir=$1
+        keep_days=$2
+        link_targets=$(find "$snapshot_dir" -type l -exec readlink '{}' ';')
+
+        find "$snapshot_dir" -type f -mtime "+$((keep_days - 1))" -print \
+            | while read file
+        do
+                referenced=0
+
+                for link_target in $link_targets
+                do
+                        if [ "$link_target" = "$file" ]
+                        then
+                                referenced=1
+                                break
+                        fi
+                done
+                test $referenced -eq 1 || rm -f "$file"
+        done
+}
+
 if [ $# -eq 1 ] && [ "x$1" = 'x-h' -o "x$1" = 'x--help' ]
 then
         echo "Usage: $myself [branch ...]"
@@ -82,7 +105,6 @@ do
 done
 
 cd "$OLDPWD"
-find "$snapshot_dir" -type f -mtime "+$((keep_days - 1))" -exec rm -f '{}' '+'
-find "$snapshot_dir" -type l '!' -exec test -e '{}' ';' -exec rm -f '{}' '+'
+rm_old_snapshots "$snapshot_dir" "$keep_days"
 trap - EXIT
 rm -rf "$temp_dir"