preferences.cpp

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#ifdef USE_ESP32
 
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
#include "esphome/core/preferences.h"
#include <nvs_flash.h>
#include <cstring>
#include <cinttypes>
#include <vector>
#include <string>
#include <memory>
 
namespace esphome {
namespace esp32 {
 
static const char *const TAG = "esp32.preferences";
 
struct NVSData {
  std::string key;
  std::unique_ptr<uint8_t[]> data;
  size_t len;
 
  void set_data(const uint8_t *src, size_t size) {
    data = std::make_unique<uint8_t[]>(size);
    memcpy(data.get(), src, size);
    len = size;
  }
};
 
static std::vector<NVSData> s_pending_save;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
class ESP32PreferenceBackend : public ESPPreferenceBackend {
 public:
  std::string key;
  uint32_t nvs_handle;
  bool save(const uint8_t *data, size_t len) override {
    // try find in pending saves and update that
    for (auto &obj : s_pending_save) {
      if (obj.key == key) {
        obj.set_data(data, len);
        return true;
      }
    }
    NVSData save{};
    save.key = key;
    save.set_data(data, len);
    s_pending_save.emplace_back(std::move(save));
    ESP_LOGVV(TAG, "s_pending_save: key: %s, len: %zu", key.c_str(), len);
    return true;
  }
  bool load(uint8_t *data, size_t len) override {
    // try find in pending saves and load from that
    for (auto &obj : s_pending_save) {
      if (obj.key == key) {
        if (obj.len != len) {
          // size mismatch
          return false;
        }
        memcpy(data, obj.data.get(), len);
        return true;
      }
    }
 
    size_t actual_len;
    esp_err_t err = nvs_get_blob(nvs_handle, key.c_str(), nullptr, &actual_len);
    if (err != 0) {
      ESP_LOGV(TAG, "nvs_get_blob('%s'): %s - the key might not be set yet", key.c_str(), esp_err_to_name(err));
      return false;
    }
    if (actual_len != len) {
      ESP_LOGVV(TAG, "NVS length does not match (%zu!=%zu)", actual_len, len);
      return false;
    }
    err = nvs_get_blob(nvs_handle, key.c_str(), data, &len);
    if (err != 0) {
      ESP_LOGV(TAG, "nvs_get_blob('%s') failed: %s", key.c_str(), esp_err_to_name(err));
      return false;
    } else {
      ESP_LOGVV(TAG, "nvs_get_blob: key: %s, len: %zu", key.c_str(), len);
    }
    return true;
  }
};
 
class ESP32Preferences : public ESPPreferences {
 public:
  uint32_t nvs_handle;
 
  void open() {
    nvs_flash_init();
    esp_err_t err = nvs_open("esphome", NVS_READWRITE, &nvs_handle);
    if (err == 0)
      return;
 
    ESP_LOGW(TAG, "nvs_open failed: %s - erasing NVS", esp_err_to_name(err));
    nvs_flash_deinit();
    nvs_flash_erase();
    nvs_flash_init();
 
    err = nvs_open("esphome", NVS_READWRITE, &nvs_handle);
    if (err != 0) {
      nvs_handle = 0;
    }
  }
  ESPPreferenceObject make_preference(size_t length, uint32_t type, bool in_flash) override {
    return make_preference(length, type);
  }
  ESPPreferenceObject make_preference(size_t length, uint32_t type) override {
    auto *pref = new ESP32PreferenceBackend();  // NOLINT(cppcoreguidelines-owning-memory)
    pref->nvs_handle = nvs_handle;
 
    uint32_t keyval = type;
    pref->key = str_sprintf("%" PRIu32, keyval);
 
    return ESPPreferenceObject(pref);
  }
 
  bool sync() override {
    if (s_pending_save.empty())
      return true;
 
    ESP_LOGV(TAG, "Saving %zu items...", s_pending_save.size());
    // goal try write all pending saves even if one fails
    int cached = 0, written = 0, failed = 0;
    esp_err_t last_err = ESP_OK;
    std::string last_key{};
 
    // go through vector from back to front (makes erase easier/more efficient)
    for (ssize_t i = s_pending_save.size() - 1; i >= 0; i--) {
      const auto &save = s_pending_save[i];
      ESP_LOGVV(TAG, "Checking if NVS data %s has changed", save.key.c_str());
      if (is_changed(nvs_handle, save)) {
        esp_err_t err = nvs_set_blob(nvs_handle, save.key.c_str(), save.data.get(), save.len);
        ESP_LOGV(TAG, "sync: key: %s, len: %zu", save.key.c_str(), save.len);
        if (err != 0) {
          ESP_LOGV(TAG, "nvs_set_blob('%s', len=%zu) failed: %s", save.key.c_str(), save.len, esp_err_to_name(err));
          failed++;
          last_err = err;
          last_key = save.key;
          continue;
        }
        written++;
      } else {
        ESP_LOGV(TAG, "NVS data not changed skipping %s  len=%zu", save.key.c_str(), save.len);
        cached++;
      }
      s_pending_save.erase(s_pending_save.begin() + i);
    }
    ESP_LOGD(TAG, "Writing %d items: %d cached, %d written, %d failed", cached + written + failed, cached, written,
             failed);
    if (failed > 0) {
      ESP_LOGE(TAG, "Writing %d items failed. Last error=%s for key=%s", failed, esp_err_to_name(last_err),
               last_key.c_str());
    }
 
    // note: commit on esp-idf currently is a no-op, nvs_set_blob always writes
    esp_err_t err = nvs_commit(nvs_handle);
    if (err != 0) {
      ESP_LOGV(TAG, "nvs_commit() failed: %s", esp_err_to_name(err));
      return false;
    }
 
    return failed == 0;
  }
  bool is_changed(const uint32_t nvs_handle, const NVSData &to_save) {
    size_t actual_len;
    esp_err_t err = nvs_get_blob(nvs_handle, to_save.key.c_str(), nullptr, &actual_len);
    if (err != 0) {
      ESP_LOGV(TAG, "nvs_get_blob('%s'): %s - the key might not be set yet", to_save.key.c_str(), esp_err_to_name(err));
      return true;
    }
    // Check size first before allocating memory
    if (actual_len != to_save.len) {
      return true;
    }
    auto stored_data = std::make_unique<uint8_t[]>(actual_len);
    err = nvs_get_blob(nvs_handle, to_save.key.c_str(), stored_data.get(), &actual_len);
    if (err != 0) {
      ESP_LOGV(TAG, "nvs_get_blob('%s') failed: %s", to_save.key.c_str(), esp_err_to_name(err));
      return true;
    }
    return memcmp(to_save.data.get(), stored_data.get(), to_save.len) != 0;
  }
 
  bool reset() override {
    ESP_LOGD(TAG, "Erasing storage");
    s_pending_save.clear();
 
    nvs_flash_deinit();
    nvs_flash_erase();
    // Make the handle invalid to prevent any saves until restart
    nvs_handle = 0;
    return true;
  }
};
 
void setup_preferences() {
  auto *prefs = new ESP32Preferences();  // NOLINT(cppcoreguidelines-owning-memory)
  prefs->open();
  global_preferences = prefs;
}
 
}  // namespace esp32
 
ESPPreferences *global_preferences;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
}  // namespace esphome
 
#endif  // USE_ESP32