From 1803370cb24c0f78fdcea5a7cb4f00c1404422fc Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Tue, 17 Aug 2021 11:16:51 +0200
Subject: [PATCH] glib-aux: add nm_dedup_multi_iter_init_reverse() to iterate
 in reverse order

(cherry picked from commit 57a519cc035a55ed51c5e5fd1390eb387d342e8f)
---
 src/libnm-glib-aux/nm-dedup-multi.h | 40 +++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/libnm-glib-aux/nm-dedup-multi.h b/src/libnm-glib-aux/nm-dedup-multi.h
index 9a995ec5d4..75cc193363 100644
--- a/src/libnm-glib-aux/nm-dedup-multi.h
+++ b/src/libnm-glib-aux/nm-dedup-multi.h
@@ -309,8 +309,11 @@ guint nm_dedup_multi_index_dirty_remove_idx(NMDedupMultiIndex *  self,
 /*****************************************************************************/
 
 typedef struct _NMDedupMultiIter {
-    const CList *            _head;
-    const CList *            _next;
+    const CList *_head;
+    union {
+        const CList *_next;
+        const CList *_prev;
+    };
     const NMDedupMultiEntry *current;
 } NMDedupMultiIter;
 
@@ -329,6 +332,21 @@ nm_dedup_multi_iter_init(NMDedupMultiIter *iter, const NMDedupMultiHeadEntry *he
     iter->current = NULL;
 }
 
+static inline void
+nm_dedup_multi_iter_init_reverse(NMDedupMultiIter *iter, const NMDedupMultiHeadEntry *head)
+{
+    g_return_if_fail(iter);
+
+    if (head && !c_list_is_empty(&head->lst_entries_head)) {
+        iter->_head = &head->lst_entries_head;
+        iter->_prev = head->lst_entries_head.prev;
+    } else {
+        iter->_head = NULL;
+        iter->_prev = NULL;
+    }
+    iter->current = NULL;
+}
+
 static inline gboolean
 nm_dedup_multi_iter_next(NMDedupMultiIter *iter)
 {
@@ -347,6 +365,24 @@ nm_dedup_multi_iter_next(NMDedupMultiIter *iter)
     return TRUE;
 }
 
+static inline gboolean
+nm_dedup_multi_iter_prev(NMDedupMultiIter *iter)
+{
+    g_return_val_if_fail(iter, FALSE);
+
+    if (!iter->_prev)
+        return FALSE;
+
+    /* we always look ahead for the prev. This way, the user
+     * may delete the current entry (but no other entries). */
+    iter->current = c_list_entry(iter->_prev, NMDedupMultiEntry, lst_entries);
+    if (iter->_prev->prev == iter->_head)
+        iter->_prev = NULL;
+    else
+        iter->_prev = iter->_prev->prev;
+    return TRUE;
+}
+
 #define nm_dedup_multi_iter_for_each(iter, head_entry) \
     for (nm_dedup_multi_iter_init((iter), (head_entry)); nm_dedup_multi_iter_next((iter));)