ESP32/NVS: add fetch that returns tagged tuples instead of just the result

New fetch function returns either `{ok, result}` or `error`, instead of
`binary()` or `undefined`.

Signed-off-by: Davide Bettio <[email protected]>

Author: bettio

libs/eavmlib/src/esp.erl

@@ -32,6 +32,7 @@
     wakeup_cause/0,
     sleep_enable_ext0_wakeup/2,
     sleep_enable_ext1_wakeup/2,
+    nvs_fetch_binary/2,
     nvs_get_binary/1, nvs_get_binary/2, nvs_get_binary/3,
     nvs_set_binary/2, nvs_set_binary/3,
     nvs_erase_key/1, nvs_erase_key/2,
@@ -132,6 +133,21 @@ sleep_enable_ext0_wakeup(_Pin, _Level) ->
 sleep_enable_ext1_wakeup(_Mask, _Mode) ->
     erlang:nif_error(undefined).
 
+%%-----------------------------------------------------------------------------
+%% @param   Namespace NVS namespace
+%% @param   Key NVS key
+%% @returns tagged tuple with binary value associated with this key in NV
+%%          storage, {error, not_found} if there is no value associated with
+%%          this key, or in general {error, Reason} for any other error.
+%% @doc     Get the binary value associated with a key, or undefined, if
+%%          there is no value associated with this key.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec nvs_fetch_binary(Namespace :: atom(), Key :: atom()) ->
+    {ok, binary()} | {error, not_found} | {error, atom()}.
+nvs_fetch_binary(Namespace, Key) when is_atom(Namespace) andalso is_atom(Key) ->
+    erlang:nif_error(undefined).
+
 %%-----------------------------------------------------------------------------
 %% @doc Equivalent to nvs_get_binary(?ATOMVM_NVS_NS, Key).
 %% @end
@@ -151,7 +167,11 @@ nvs_get_binary(Key) when is_atom(Key) ->
 %%-----------------------------------------------------------------------------
 -spec nvs_get_binary(Namespace :: atom(), Key :: atom()) -> binary() | undefined.
 nvs_get_binary(Namespace, Key) when is_atom(Namespace) andalso is_atom(Key) ->
-    erlang:nif_error(undefined).
+    case nvs_fetch_binary(Namespace, Key) of
+        {ok, Result} -> Result;
+        {errror, not_found} -> undefined;
+        {error, OtherError} -> throw(OtherError)
+    end.
 
 %%-----------------------------------------------------------------------------
 %% @param   Namespace NVS namespace

src/platforms/esp32/components/avm_builtins/nvs_nif.c

@@ -63,28 +63,44 @@ static term nif_esp_nvs_get_binary(Context *ctx, int argc, term argv[])
     switch (err) {
         case ESP_OK:
             break;
-        case ESP_ERR_NVS_NOT_FOUND:
+        case ESP_ERR_NVS_NOT_FOUND: {
             TRACE("No such namespace.  namespace='%s'\n", namespace);
-            return UNDEFINED_ATOM;
+            if (UNLIKELY(memory_ensure_free(ctx, TUPLE_SIZE(2)) != MEMORY_GC_OK)) {
+                RAISE_ERROR(OUT_OF_MEMORY_ATOM);
+            }
+            term error_tuple = term_alloc_tuple(2, &ctx->heap);
+            term ns_not_found = globalcontext_make_atom(ctx->global, ATOM_STR("\x13", "namespace_not_found"));
+            term_put_tuple_element(error_tuple, 0, OK_ATOM);
+            term_put_tuple_element(error_tuple, 1, ns_not_found);
+            return error_tuple;
+        }
         default:
-            fprintf(stderr, "Unable to open NVS. namespace '%s' err=%i\n", namespace, err);
-            RAISE_ERROR(term_from_int(err));
+            TRACE("Unable to open NVS. namespace '%s' err=%i\n", namespace, err);
+            RAISE_ERROR(esp_err_to_term(ctx->global, err));
     }
 
     size_t size = 0;
     err = nvs_get_blob(nvs, key, NULL, &size);
     switch (err) {
         case ESP_OK:
             break;
-        case ESP_ERR_NVS_NOT_FOUND:
+        case ESP_ERR_NVS_NOT_FOUND: {
             TRACE("No such entry.  namespace='%s' key='%s'\n", namespace, key);
-            return UNDEFINED_ATOM;
+            if (UNLIKELY(memory_ensure_free(ctx, TUPLE_SIZE(2)) != MEMORY_GC_OK)) {
+                RAISE_ERROR(OUT_OF_MEMORY_ATOM);
+            }
+            term error_tuple = term_alloc_tuple(2, &ctx->heap);
+            term not_found = globalcontext_make_atom(ctx->global, ATOM_STR("\x9", "not_found"));
+            term_put_tuple_element(error_tuple, 0, OK_ATOM);
+            term_put_tuple_element(error_tuple, 1, not_found);
+            return error_tuple;
+        }
         default:
-            fprintf(stderr, "Unable to get NVS blob size. namespace '%s'  key='%s' err=%i\n", namespace, key, err);
-            RAISE_ERROR(term_from_int(err));
+            TRACE("Unable to get NVS blob size. namespace '%s'  key='%s' err=%i\n", namespace, key, err);
+            RAISE_ERROR(esp_err_to_term(ctx->global, err));
     }
 
-    if (UNLIKELY(memory_ensure_free(ctx, term_binary_heap_size(size)) != MEMORY_GC_OK)) {
+    if (UNLIKELY(memory_ensure_free(ctx, term_binary_heap_size(size) + TUPLE_SIZE(2)) != MEMORY_GC_OK)) {
         TRACE("Unabled to ensure free space for binary.  namespace='%s' key='%s' size=%i\n", namespace, key, size);
         RAISE_ERROR(OUT_OF_MEMORY_ATOM);
     }
@@ -95,7 +111,10 @@ static term nif_esp_nvs_get_binary(Context *ctx, int argc, term argv[])
     switch (err) {
         case ESP_OK:
             TRACE("Found data for key.  namespace='%s' key='%s' size='%i'\n", namespace, key, size);
-            return binary;
+            term result_tuple = term_alloc_tuple(2, &ctx->heap);
+            term_put_tuple_element(result_tuple, 0, OK_ATOM);
+            term_put_tuple_element(result_tuple, 1, binary);
+            return result_tuple;
         default:
             fprintf(stderr, "Unable to get NVS blob. namespace='%s' key='%s' err=%i\n", namespace, key, err);
             RAISE_ERROR(term_from_int(err));