ESP32 Forum

Posted: **Thu Dec 17, 2020 1:45 pm**

Hi, I am able to write successfully but when I read from NVS it throws an error of "Error (ESP_ERR_NVS_INVALID_LENGTH) reading!"

Code: Select all

[Codebox=c file=Untitled.c]void set_nvs_string(char* data, char* key)
{
	nvs_handle my_handle;
	esp_err_t err = nvs_open("storage", NVS_READWRITE, &my_handle);
	if (err != ESP_OK) {
		printf("Error (%s) opening NVS handle!\n", esp_err_to_name(err));
	}				
	err = nvs_set_str(my_handle, key, data);
	printf((err != ESP_OK) ? "Failed! Setting String from NVS\n" : "Done Setting String from NVS\n");
	printf("Committing updates in NVS ... ");
	err = nvs_commit(my_handle);
	printf((err != ESP_OK) ? "Failed! Commiting\n" : "Done Commiting\n");
}

esp_err_t get_nvs_string(char* key, char* data)
{
	nvs_handle my_handle;
	esp_err_t err = nvs_open("storage", NVS_READWRITE, &my_handle);
	if (err != ESP_OK) {
		printf("Error (%s) opening NVS handle!\n", esp_err_to_name(err));
	}
	size_t size = strlen(data);
	err = nvs_get_str(my_handle, key, data, &size);
	switch (err) 
	{
	case ESP_OK:
		printf("Done Getting String from NVS\n");
		break;
	case ESP_ERR_NVS_NOT_FOUND:
		printf("The value is not initialized yet!\n");
		break;
	default :
		printf("Error (%s) reading!\n", esp_err_to_name(err));
	}
	return err;
}

ESP_LOGI(TAG_ap, "SSID Local: %s  PASSWORD Local: %s Inverter ID %s", ssidLocal, passwordLocal, InverterId);
	set_nvs_string(InverterId, "InverterId");
	
	
	if (strlen(ssidLocal) != 0 && strlen(passwordLocal) != 0)
	{

		set_nvs_string(ssidLocal, "ssid");
		set_nvs_string(passwordLocal, "password");
		wifi_config_t wifi_config;
		
		
		char* tempSsid = malloc(sizeof(char) * 32);
		char* tempPassword = malloc(sizeof(char) * 64);
	
	
		get_nvs_string("ssid", tempSsid);
		get_nvs_string("password", tempPassword);
	
	
		strcpy((char*)wifi_config.sta.ssid, tempSsid); 
		strcpy((char*)wifi_config.sta.password, tempPassword);

		ESP_LOGI("WIFI CHECK4", "Set SSID: %s", (char*)wifi_config.sta.ssid);
		ESP_LOGI("WIFI CHECK4", "Set Password: %s", (char*)wifi_config.sta.password);
	
		free(tempSsid);
		free(tempPassword);
			
		ESP_LOGI(TAG_ap, "=========== PARSED DATA ==========");
		ESP_LOGI(TAG_ap, "SSID: %s  PASSWORD: %s", wifi_config.sta.ssid, wifi_config.sta.password);
		ESP_LOGI(TAG_ap, "====================================");
		ESP_ERROR_CHECK(esp_wifi_stop());
		wifi_init_sta();
			
		
		s_retry_num = 0;
	}[/Codebox]

Output:

Code: [Select all] [Expand/Collapse]

I (146517) Hojaa Pls: SSID Local: ZongAltium1  PASSWORD Local: Xavor123 Inverter ID Schneider
Done Setting String from NVS
Committing updates in NVS ... Done Commiting
Done Setting String from NVS
Committing updates in NVS ... Done Commiting
Done Setting String from NVS
Committing updates in NVS ... Done Commiting
Done Getting String from NVS
Error (ESP_ERR_NVS_INVALID_LENGTH) reading!
I (146557) wifi: station: 9e:62:e3:2e:66:f5 leave, AID = 1, bss_flags is 134243
I (146567) WIFI CHECK4: Set SSID: ZongAltium1
I (146567) wifi: n:1 0, o:1 0, ap:1 1, sta:0 0, prof:1
I (146567) WIFI CHECK4: Set Password: ???
I (146577) Hojaa Pls: =========== PARSED DATA ==========
I (146587) Hojaa Pls: SSID: ZongAltium1  PASSWORD: ???
I (146587) Hojaa Pls: ====================================
I (146637) wifi: flush txq
I (146637) wifi: stop sw txq
I (146637) wifi: lmac stop hw txq
Error (ESP_ERR_NVS_INVALID_LENGTH) reading!

GeSHi © Codebox Plus Extension

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Posted: **Wed Jun 29, 2022 6:37 am**

Hello. I had a very similar problem. In my case the initialization of the size was wrong
You could try:

Code: Select all

size_t size = strlen(data)+1;

best regards
Dominik

Posted: **Wed Jun 29, 2022 1:48 pm**

Indeed, this part of the code leads to the issue:

Code: Select all

	size_t size = strlen(data);
	err = nvs_get_str(my_handle, key, data, &size);

The last argument of nvs_get_str has the following meaning (see docs):

as an input, it should contain the amount of space (number of bytes) available in "out_value" pointer.
as an output, if "out_value" is not NULL, it will be filled with the actual number of bytes written into "out_value", including the NULL terminator

So the code should look like this:

Code: Select all

// 1. add "out_data_size" argument to tell this function how much space is available in "out_data".
// 2. Also make "key" const, since it is not modified by this function.
esp_err_t get_nvs_string(const char* key, char* data, size_t data_size)
{
	nvs_handle my_handle;
	esp_err_t err = nvs_open("storage", NVS_READWRITE, &my_handle);
	if (err != ESP_OK) {
		printf("Error (%s) opening NVS handle!\n", esp_err_to_name(err));
	}
	// 3. as input, "size" should contain the amount of space available
	size_t size = out_data_size;
	err = nvs_get_str(my_handle, key, data, &size);
	// 4. after this call, if err == ESP_OK, "size" will contain the number of bytes written into "data"
...

Then the caller of this function should pass the "data_size" value based on the size of the storage allocated for "data" variable.
For example:

Code: Select all

char value[32];
err = get_nvs_string("some_key", value, sizeof(value));

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