examples: check return value of nvs_flash_init

nvs_flash_init may return an error code in some cases, and applications
should check this error code (or at least assert on it being ESP_OK, to
make potential issues more immediately obvious).

This change modifies all the examples which use NVS to check the error
code. Most examples get a simple ESP_ERROR_CHECK assert, while NVS
examples, OTA example, and NVS unit tests get a more verbose check which
may be used in real applications.

components/nvs_flash/test/test_nvs.c

@@ -6,14 +6,26 @@
 #include "unity.h"
 #include "nvs.h"
 #include "nvs_flash.h"
-#include "esp_spi_flash.h"
+#include "esp_partition.h"
+#include "esp_log.h"
 #include <string.h>
 
+static const char* TAG = "test_nvs";
 
 TEST_CASE("various nvs tests", "[nvs]")
 {
     nvs_handle handle_1;
-    TEST_ESP_OK(nvs_flash_init());
+    esp_err_t err = nvs_flash_init();
+    if (err == ESP_ERR_NVS_NO_FREE_PAGES) {
+        ESP_LOGW(TAG, "nvs_flash_init failed (0x%x), erasing partition and retrying", err);
+        const esp_partition_t* nvs_partition = esp_partition_find_first(
+                ESP_PARTITION_TYPE_DATA, ESP_PARTITION_SUBTYPE_DATA_NVS, NULL);
+        assert(nvs_partition && "partition table must have an NVS partition");
+        ESP_ERROR_CHECK( esp_partition_erase_range(nvs_partition, 0, nvs_partition->size) );
+        err = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK( err );
+
     TEST_ESP_ERR(nvs_open("test_namespace1", NVS_READONLY, &handle_1), ESP_ERR_NVS_NOT_FOUND);
 
     TEST_ESP_ERR(nvs_set_i32(handle_1, "foo", 0x12345678), ESP_ERR_NVS_INVALID_HANDLE);

examples/bluetooth/blufi/main/blufi_main.c

@@ -312,7 +312,7 @@ void app_main()
 {
     esp_err_t ret;
 
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
 
     esp_bt_controller_init();

examples/protocols/coap_client/main/coap_client.c

@@ -199,7 +199,7 @@ static void wifi_conn_init(void)
 
 void app_main(void)
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     wifi_conn_init();
     xTaskCreate(coap_demo_thread, "coap", 2048, NULL, 5, NULL);
 }

examples/protocols/coap_server/main/coap_server.c

@@ -185,7 +185,7 @@ static void wifi_conn_init(void)
 
 void app_main(void)
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     wifi_conn_init();
 
     xTaskCreate(coap_demo_thread, "coap", 2048, NULL, 5, NULL);

examples/protocols/http_request/main/http_request_main.c

@@ -174,7 +174,7 @@ static void http_get_task(void *pvParameters)
 
 void app_main()
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
     xTaskCreate(&http_get_task, "http_get_task", 2048, NULL, 5, NULL);
 }

examples/protocols/https_request/main/https_request_main.c

@@ -325,7 +325,7 @@ static void https_get_task(void *pvParameters)
 
 void app_main()
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
     xTaskCreate(&https_get_task, "https_get_task", 8192, NULL, 5, NULL);
 }

examples/protocols/mdns/main/mdns_example_main.c

@@ -178,7 +178,7 @@ static void mdns_task(void *pvParameters)
 
 void app_main()
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
     xTaskCreate(&mdns_task, "mdns_task", 2048, NULL, 5, NULL);
 }

examples/protocols/openssl_client/main/openssl_client.c

@@ -220,6 +220,6 @@ static void wifi_conn_init(void)
 
 void app_main(void)
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     wifi_conn_init();
 }

examples/protocols/openssl_server/main/openssl_server.c

@@ -255,6 +255,6 @@ static void wifi_conn_init(void)
 
 void app_main(void)
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     wifi_conn_init();
 }

examples/protocols/sntp/main/sntp_main.c

@@ -93,7 +93,7 @@ void app_main()
 
 static void obtain_time(void)
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
     xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT,
                         false, true, portMAX_DELAY);

examples/storage/nvs_rw_blob/main/nvs_rw_blob.c

@@ -13,6 +13,7 @@
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "esp_system.h"
+#include "esp_partition.h"
 #include "nvs_flash.h"
 #include "nvs.h"
 #include "driver/gpio.h"
@@ -146,9 +147,17 @@ esp_err_t print_what_saved(void)
 
 void app_main()
 {
-    nvs_flash_init();
-
-    esp_err_t err;
+    esp_err_t err = nvs_flash_init();
+    if (err == ESP_ERR_NVS_NO_FREE_PAGES) {
+        // NVS partition was truncated and needs to be erased
+        const esp_partition_t* nvs_partition = esp_partition_find_first(
+                ESP_PARTITION_TYPE_DATA, ESP_PARTITION_SUBTYPE_DATA_NVS, NULL);
+        assert(nvs_partition && "partition table must have an NVS partition");
+        ESP_ERROR_CHECK( esp_partition_erase_range(nvs_partition, 0, nvs_partition->size) );
+        // Retry nvs_flash_init
+        err = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK( err );
 
     err = print_what_saved();
     if (err != ESP_OK) printf("Error (%d) reading data from NVS!\n", err);

examples/storage/nvs_rw_value/main/nvs_rw_value.c

@@ -13,23 +13,32 @@
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "esp_system.h"
+#include "esp_partition.h"
 #include "nvs_flash.h"
 #include "nvs.h"
 
 void app_main()
 {
-    nvs_flash_init();
-
-    nvs_handle my_handle;
-    esp_err_t err;
-
-    printf("\n");
+    // Initialize NVS
+    esp_err_t err = nvs_flash_init();
+    if (err == ESP_ERR_NVS_NO_FREE_PAGES) {
+        // NVS partition was truncated and needs to be erased
+        const esp_partition_t* nvs_partition = esp_partition_find_first(
+                ESP_PARTITION_TYPE_DATA, ESP_PARTITION_SUBTYPE_DATA_NVS, NULL);
+        assert(nvs_partition && "partition table must have an NVS partition");
+        ESP_ERROR_CHECK( esp_partition_erase_range(nvs_partition, 0, nvs_partition->size) );
+        // Retry nvs_flash_init
+        err = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK( err );
 
     // Open
-    printf("Opening Non-Volatile Storage (NVS) ... ");
+    printf("\n");
+    printf("Opening Non-Volatile Storage (NVS) handle... ");
+    nvs_handle my_handle;
     err = nvs_open("storage", NVS_READWRITE, &my_handle);
     if (err != ESP_OK) {
-        printf("Error (%d) opening NVS!\n", err);
+        printf("Error (%d) opening NVS handle!\n", err);
     } else {
         printf("Done\n");
 

examples/system/ota/main/ota_example.c

@@ -21,6 +21,7 @@
 #include "esp_ota_ops.h"
 #include "esp_partition.h"
 
+#include "nvs.h"
 #include "nvs_flash.h"
 
 #define EXAMPLE_WIFI_SSID CONFIG_WIFI_SSID
@@ -279,7 +280,20 @@ void main_task(void *pvParameter)
 
 void app_main()
 {
-    nvs_flash_init();
+    // Initialize NVS.
+    esp_err_t err = nvs_flash_init();
+    if (err == ESP_ERR_NVS_NO_FREE_PAGES) {
+        // OTA app partition table has a smaller NVS partition size than the non-OTA
+        // partition table. This size mismatch may cause NVS initialization to fail.
+        // If this happens, we erase NVS partition and initialize NVS again.
+        const esp_partition_t* nvs_partition = esp_partition_find_first(
+                ESP_PARTITION_TYPE_DATA, ESP_PARTITION_SUBTYPE_DATA_NVS, NULL);
+        assert(nvs_partition && "partition table must have an NVS partition");
+        ESP_ERROR_CHECK( esp_partition_erase_range(nvs_partition, 0, nvs_partition->size) );
+        err = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK( err );
+
     initialise_wifi();
     xTaskCreate(&main_task, "main_task", 8192, NULL, 5, NULL);
 }

examples/wifi/wpa2_enterprise/main/wpa2_enterprise_main.c

@@ -148,7 +148,7 @@ static void wpa2_enterprise_task(void *pvParameters)
 
 void app_main()
 {
-    nvs_flash_init();
+    ESP_ERROR_CHECK( nvs_flash_init() );
     initialise_wifi();
     xTaskCreate(&wpa2_enterprise_task, "wpa2_enterprise_task", 4096, NULL, 5, NULL);
 }