Como read ESP32 NVS value into std::string

#include <nvs.h>
#include <string>

std::string ReadNVSValueAsStdString(nvs_handle_t nvs, const char* key) {
    /**
     * Strategy:
     *  1. Determine size de value en NVS
     *  2. Allocate temporary buffer de determined size
     *  3. Read value from NVS into temporary buffer
     *  4. Create std::string from value
     *  5. Cleanup
     */
    // Step 1: Get size de key
    esp_err_t err;
    size_t value_size = 0;
    if((err = nvs_get_str(nvs, _key.c_str(), nullptr, &value_size)) != ESP_OK) {
        if(err == ESP_ERR_NVS_NOT_FOUND) {
            // Not found, no error
            return "";
        } else {
            printf("Failed to get size of NVS key %s: %s\r\n", key, esp_err_to_name(err));
            return;
        }
    }
    // Step 2: Allocate temporary buffer para read from
    char* buf = (char*)malloc(value_size);
    // Step 3: Read value into temporary buffer.
    esp_err_t err;
    if((err = nvs_get_str(nvs, _key.c_str(), buf, &value_size)) != ESP_OK) {
        // "Doesn't exist" ha already sido handled before, asi que esto es un actual error.
        // Asumimos que el value no change between reading el size (step 1) y now.
        // In case que esa assumption es value, esto failara con ESP_ERR_NVS_INVALID_LENGTH.
        // Esto es extremely unlikely in all usage scenarios, however.
        printf("Failed to read NVS key %s: %s\r\n", key, esp_err_to_name(err));
        free(buf);
        return "";
    }
    // Step 4: Make string
    std::string value = std::string(buf, value_size);
    // Step 5: cleanup
    free(buf);

    return value;
}

std::string value = ReadNVSValueAsStdString(myNvs, "MyKey");