Merge branch 'contrib/github_pr_12460' into 'master'

fixing OTA write up to SPI_FLASH_SEC_SIZE margins (GitHub PR)

Closes IDFGH-11311

See merge request espressif/esp-idf!26897

components/app_update/esp_ota_ops.c

@@ -199,13 +199,18 @@ esp_err_t esp_ota_write(esp_ota_handle_t handle, const void *data, size_t size)
         return ESP_ERR_INVALID_ARG;
     }
 
+    if (size == 0) {
+        ESP_LOGD(TAG, "write data size is 0");
+        return ESP_OK;
+    }
+
     // find ota handle in linked list
     for (it = LIST_FIRST(&s_ota_ops_entries_head); it != NULL; it = LIST_NEXT(it, entries)) {
         if (it->handle == handle) {
             if (it->need_erase) {
                 // must erase the partition before writing to it
-                uint32_t first_sector = it->wrote_size / SPI_FLASH_SEC_SIZE;
-                uint32_t last_sector = (it->wrote_size + size) / SPI_FLASH_SEC_SIZE;
+                uint32_t first_sector = it->wrote_size / SPI_FLASH_SEC_SIZE; // first affected sector
+                uint32_t last_sector = (it->wrote_size + size - 1) / SPI_FLASH_SEC_SIZE; // last affected sector
 
                 ret = ESP_OK;
                 if ((it->wrote_size % SPI_FLASH_SEC_SIZE) == 0) {

components/app_update/include/esp_ota_ops.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2023 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -111,7 +111,7 @@ esp_err_t esp_ota_begin(const esp_partition_t* partition, size_t image_size, esp
  * @param size    Size of data buffer in bytes.
  *
  * @return
- *    - ESP_OK: Data was written to flash successfully.
+ *    - ESP_OK: Data was written to flash successfully, or size = 0
  *    - ESP_ERR_INVALID_ARG: handle is invalid.
  *    - ESP_ERR_OTA_VALIDATE_FAILED: First byte of image contains invalid app image magic byte.
  *    - ESP_ERR_FLASH_OP_TIMEOUT or ESP_ERR_FLASH_OP_FAIL: Flash write failed.