diff -r babdf40dd22c -r 8e1948eebef5 dav/sync.c
--- a/dav/sync.c	Fri Jun 01 09:23:51 2018 +0200
+++ b/dav/sync.c	Fri Jun 01 19:05:08 2018 +0200
@@ -258,11 +258,7 @@
 }
 
 static int res_matches_tags(DavResource *res, SyncTagFilter *tagfilter) {
-    if(!tagfilter) {
-        return 1;
-    }
-    
-    if(tagfilter->mode == DAV_SYNC_TAGFILTER_OFF) {
+    if(!tagfilter || tagfilter->mode == DAV_SYNC_TAGFILTER_OFF) {
         return 1;
     }
     
@@ -277,13 +273,25 @@
     return ret;
 }
 
-static int localres_matches_tags(LocalResource *res, SyncTagFilter *tagfilter) {
-    if(!tagfilter) {
+static int localres_matches_tags(
+        SyncDirectory *dir,
+        LocalResource *res,
+        SyncTagFilter *tagfilter)
+{
+    if(!tagfilter || tagfilter->mode == DAV_SYNC_TAGFILTER_OFF) {
         return 1;
     }
+
+    DavBool changed = 0;
+    UcxList *res_tags = sync_get_file_tags(dir, res, &changed);
     
-    // TODO: implement
-    return 1;
+    int ret = matches_tagfilter(res_tags, tagfilter);
+    UCX_FOREACH(elm, res_tags) {
+        DavTag *t = elm->data;
+        free_dav_tag(t);
+    }
+    ucx_list_free(res_tags);
+    return ret;
 }
 
 static DavSession* create_session(DavContext *ctx, Repository *repo, char *url) {
@@ -909,6 +917,13 @@
         return -1;
     }
     
+    // if there are syntax errors in the command line, fail asap.
+    SyncTagFilter* tagfilter = parse_tagfilter_string(cmd_getoption(a, "tags"));
+    if (!tagfilter) {
+        fprintf(stderr, "Malformed tag filter\n");
+        return -1;
+    }
+    
     SyncDirectory *dir = scfg_get_dir(a->argv[0]);
     if(!dir) {
         fprintf(stderr, "Unknown sync dir: %s\n", a->argv[0]);
@@ -980,6 +995,8 @@
         locktokenfile = create_locktoken_file(dir->name, lock->token);
     }
     
+    DavBool remove_file = cmd_getoption(a, "remove") ? 1 : 0;
+    
     int sync_success = 0;
     int sync_delete = 0;
     int sync_skipped = 0;
@@ -994,7 +1011,17 @@
     int ret = 0;
     UCX_FOREACH(elm, resources) {
         LocalResource *local_res = elm->data;
-        if (!res_matches_filter(dir, local_res->path+1)) {
+        int error = 0;
+        
+        if (   res_matches_filter(dir, local_res->path+1)
+            || !localres_matches_tags(dir, local_res, dir->tagfilter))
+        {
+            local_res->keep = TRUE;
+        } else if (!localres_matches_tags(dir, local_res, tagfilter)) {
+            if(!remove_file) {
+                local_res->keep = TRUE;
+            }
+        } else {
             if(sync_shutdown) {
                 LocalResource *lr = ucx_map_cstr_remove(db->resources, local_res->path);
                 if(lr) {
@@ -1016,7 +1043,6 @@
             }
                        
             // upload every changed file
-            int error = 0;
             int is_changed = local_resource_is_changed(dir, db, local_res);
             if (is_changed || local_res->tags_updated) {
                 DavResource *res = dav_resource_new(sn, local_res->path);
@@ -1078,18 +1104,18 @@
                 }
                 dav_resource_free(res);
             }
-            
-            // remove every locally available resource from db->resource
-            // the remaining elements are all deleted files
-            elm->data = NULL;
-            if(!error) {
-                ucx_map_cstr_put(lclres, local_res->path, local_res);
-            }
-            
-            LocalResource *lr = ucx_map_cstr_remove(db->resources, local_res->path);
-            if(lr) {
-                local_resource_free(lr);
-            }
+        }
+        
+        // remove every locally available resource from db->resource
+        // the remaining elements are all deleted files
+        elm->data = NULL;
+        if(!error) {
+            ucx_map_cstr_put(lclres, local_res->path, local_res);
+        }
+
+        LocalResource *lr = ucx_map_cstr_remove(db->resources, local_res->path);
+        if(lr) {
+            local_resource_free(lr);
         }
     }
     
@@ -1098,7 +1124,7 @@
         UcxMapIterator i = ucx_map_iterator(db->resources);
         LocalResource *local;
         UCX_MAP_FOREACH(key, local, i) {
-            if (!res_matches_filter(dir, local->path+1)) {
+            if (!local->keep) {
                 if(sync_shutdown) {
                     ucx_map_cstr_put(lclres, local->path, local_resource_copy(local));
                 } else if(sync_delete_remote_resource(sn, local, &sync_delete)) {