From b32cda92305cc8010953b2395adddd730c24a6c8 Mon Sep 17 00:00:00 2001
From: Michal Vasko <mvasko@cesnet.cz>
Date: Wed, 8 Jan 2025 09:43:11 +0100
Subject: [PATCH] tree data UPDATE error on invalid new_path position

Refs #2333
---
 src/tree_data_new.c          | 29 ++++++++++++++++++++++++++---
 tests/utests/data/test_new.c |  8 ++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/src/tree_data_new.c b/src/tree_data_new.c
index 647e266dd..76f9a6200 100644
--- a/src/tree_data_new.c
+++ b/src/tree_data_new.c
@@ -1658,14 +1658,14 @@ lyd_new_path_(struct lyd_node *parent, const struct ly_ctx *ctx, const struct ly
     LY_ERR ret = LY_SUCCESS, r;
     struct lyxp_expr *exp = NULL;
     struct ly_path *p = NULL;
-    struct lyd_node *nparent = NULL, *nnode = NULL, *node = NULL, *cur_parent;
+    struct lyd_node *nparent = NULL, *nnode = NULL, *node = NULL, *cur_parent, *iter;
     const struct lysc_node *schema;
     const struct lyd_value *val = NULL;
     ly_bool store_only = (options & LYD_NEW_VAL_STORE_ONLY) ? 1 : 0;
     ly_bool any_use_value = (options & LYD_NEW_ANY_USE_VALUE) ? 1 : 0;
     LY_ARRAY_COUNT_TYPE path_idx = 0, orig_count = 0;
     LY_VALUE_FORMAT format;
-    uint32_t hints;
+    uint32_t hints, count;
 
     assert(parent || ctx);
     assert(path && ((path[0] == '/') || parent));
@@ -1712,7 +1712,7 @@ lyd_new_path_(struct lyd_node *parent, const struct ly_ctx *ctx, const struct ly
                 goto cleanup;
             } /* else we were not searching for the whole path */
         } else if (r == LY_EINCOMPLETE) {
-            /* some nodes were found, adjust the iterator to the next segment */
+            /* some nodes were found, adjust the iterator to the next segment to be created */
             ++path_idx;
         } else if (r == LY_ENOTFOUND) {
             /* we will create the nodes from top-level, default behavior (absolute path), or from the parent (relative path) */
@@ -1731,6 +1731,29 @@ lyd_new_path_(struct lyd_node *parent, const struct ly_ctx *ctx, const struct ly
         LY_ARRAY_INCREMENT(p);
     }
 
+    if ((path_idx < LY_ARRAY_COUNT(p)) && lysc_is_dup_inst_list(p[path_idx].node) && p[path_idx].predicates &&
+            (p[path_idx].predicates[0].type == LY_PATH_PREDTYPE_POSITION)) {
+        /* check the used position of a key-less list or state leaf-list */
+        count = 0;
+        LYD_LIST_FOR_INST(node ? lyd_child(node) : parent, p[path_idx].node, iter) {
+            ++count;
+        }
+
+        if (count + 1 < p[path_idx].predicates[0].position) {
+            if (count) {
+                LOGVAL(ctx, LYVE_REFERENCE,
+                        "Cannot create \"%s\" on position %" PRIu64 ", only %" PRIu32 " instance%s exist%s.",
+                        p[path_idx].node->name, p[path_idx].predicates[0].position, count, (count > 1) ? "s" : "",
+                        (count > 1) ? "" : "s");
+            } else {
+                LOGVAL(ctx, LYVE_REFERENCE, "Cannot create \"%s\" on position %" PRIu64 ", no instances exist.",
+                        p[path_idx].node->name, p[path_idx].predicates[0].position);
+            }
+            ret = LY_EINVAL;
+            goto cleanup;
+        }
+    }
+
     /* create all the non-existing nodes in a loop */
     for ( ; path_idx < LY_ARRAY_COUNT(p); ++path_idx) {
         cur_parent = node;
diff --git a/tests/utests/data/test_new.c b/tests/utests/data/test_new.c
index 7194893e1..47ecc1907 100644
--- a/tests/utests/data/test_new.c
+++ b/tests/utests/data/test_new.c
@@ -353,6 +353,14 @@ test_path(void **state)
     assert_int_equal(ret, LY_SUCCESS);
     assert_non_null(node);
 
+    /* too high index */
+    ret = lyd_new_path2(root, NULL, "/a:c2/l3[8]", NULL, 0, 0, 0, NULL, &node);
+    assert_int_equal(ret, LY_EINVAL);
+    CHECK_LOG_CTX("Cannot create \"l3\" on position 8, only 6 instances exist.", NULL, 0);
+    ret = lyd_new_path2(root, NULL, "/a:l2[2]", NULL, 0, 0, 0, NULL, &node);
+    assert_int_equal(ret, LY_EINVAL);
+    CHECK_LOG_CTX("Cannot create \"l2\" on position 2, no instances exist.", NULL, 0);
+
     lyd_print_mem(&str, root, LYD_XML, LYD_PRINT_WITHSIBLINGS);
     assert_string_equal(str,
             "<c2 xmlns=\"urn:tests:a\">\n"