From 8943861e30b6f96c17dfc3a8986f517977dc0451 Mon Sep 17 00:00:00 2001
From: Shubham Patil <shubham.patil@espressif.com>
Date: Mon, 8 Apr 2024 19:41:07 +0530
Subject: [PATCH] handle setting empty strings

Fixes https://github.com/espressif/esp-matter/issues/802
---
 .../esp_matter/esp_matter_attribute_utils.cpp  | 18 ++++++++++++++----
 .../esp_matter/private/esp_matter_nvs.cpp      |  4 ++--
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/components/esp_matter/esp_matter_attribute_utils.cpp b/components/esp_matter/esp_matter_attribute_utils.cpp
index edc70c707..a36226ad4 100644
--- a/components/esp_matter/esp_matter_attribute_utils.cpp
+++ b/components/esp_matter/esp_matter_attribute_utils.cpp
@@ -1271,7 +1271,10 @@ esp_err_t get_data_from_attr_val(esp_matter_attr_val_t *val, EmberAfAttributeTyp
             if (attribute_type) {
                 *attribute_type = ZCL_CHAR_STRING_ATTRIBUTE_TYPE;
             }
-            size_t string_len = strnlen((const char *)val->val.a.b, val->val.a.s);
+            size_t string_len = 0;
+            if (val->val.a.b) {
+                string_len = strnlen((const char *)val->val.a.b, val->val.a.s);
+            }
             size_t data_size_len = val->val.a.t - val->val.a.s;
             if (string_len >= UINT8_MAX || data_size_len != 1) {
                 return ESP_ERR_INVALID_ARG;
@@ -1298,7 +1301,10 @@ esp_err_t get_data_from_attr_val(esp_matter_attr_val_t *val, EmberAfAttributeTyp
             if (attribute_type) {
                 *attribute_type = ZCL_LONG_CHAR_STRING_ATTRIBUTE_TYPE;
             }
-            size_t string_len = strnlen((const char *)val->val.a.b, val->val.a.s);
+            size_t string_len = 0;
+            if (val->val.a.b) {
+                string_len = strnlen((const char *)val->val.a.b, val->val.a.s);
+            }
             size_t data_size_len = val->val.a.t - val->val.a.s;
             if (string_len >= UINT8_MAX || data_size_len != 2) {
                 return ESP_ERR_INVALID_ARG;
@@ -1926,11 +1932,15 @@ void val_print(uint16_t endpoint_id, uint32_t cluster_id, uint32_t attribute_id,
         ESP_LOGI(TAG, "********** %c : Endpoint 0x%04" PRIX16 "'s Cluster 0x%08" PRIX32 "'s Attribute 0x%08" PRIX32 " is %" PRIu64 " **********", action,
                  endpoint_id, cluster_id, attribute_id, val->val.u64);
     } else if (val->type == ESP_MATTER_VAL_TYPE_CHAR_STRING) {
+        const char *b = val->val.a.b ? (const char *)val->val.a.b : "(empty)";
+        uint16_t s = val->val.a.b ? s : strlen("(empty)");
         ESP_LOGI(TAG, "********** %c : Endpoint 0x%04" PRIX16 "'s Cluster 0x%08" PRIX32 "'s Attribute 0x%08" PRIX32 " is %.*s **********", action,
-                 endpoint_id, cluster_id, attribute_id, val->val.a.s, val->val.a.b);
+                 endpoint_id, cluster_id, attribute_id, s, b);
     } else if (val->type == ESP_MATTER_VAL_TYPE_LONG_CHAR_STRING) {
+        const char *b = val->val.a.b ? (const char *)val->val.a.b : "(empty)";
+        uint16_t s = val->val.a.b ? s : strlen("(empty)");
         ESP_LOGI(TAG, "********** %c : Endpoint 0x%04" PRIX16 "'s Cluster 0x%08" PRIX32 "'s Attribute 0x%08" PRIX32 " is %.*s **********", action,
-                 endpoint_id, cluster_id, attribute_id, val->val.a.s, val->val.a.b);
+                 endpoint_id, cluster_id, attribute_id, s, b);
     } else {
         ESP_LOGI(TAG, "********** %c : Endpoint 0x%04" PRIX16 "'s Cluster 0x%08" PRIX32 "'s Attribute 0x%08" PRIX32 " is <invalid type: %d> **********", action,
                  endpoint_id, cluster_id, attribute_id, val->type);
diff --git a/components/esp_matter/private/esp_matter_nvs.cpp b/components/esp_matter/private/esp_matter_nvs.cpp
index 1597b6662..de5bc7fd5 100644
--- a/components/esp_matter/private/esp_matter_nvs.cpp
+++ b/components/esp_matter/private/esp_matter_nvs.cpp
@@ -203,10 +203,10 @@ static esp_err_t nvs_store_val(const char *nvs_namespace, const char *attribute_
         /* Store only if value is not NULL */
         if (val.val.a.b) {
             err = nvs_set_blob(handle, attribute_key, val.val.a.b, val.val.a.s);
-            nvs_commit(handle);
         } else {
-            err = ESP_OK;
+            err = nvs_erase_key(handle, attribute_key);
         }
+        nvs_commit(handle);
     } else {
         // Handling how to store attributes in NVS based on config option.
 #if CONFIG_ESP_MATTER_NVS_USE_COMPACT_ATTR_STORAGE