[ESP32] Return the required length if buf is NULL when reading (#21413)

string/blob from NVS
project-chip · Jul 29, 2022 · 1e3b289 · 1e3b289
1 parent 40ef264
commit 1e3b289
Show file tree

Hide file tree

Showing 2 changed files with 21 additions and 9 deletions.
diff --git a/src/platform/ESP32/ESP32Config.cpp b/src/platform/ESP32/ESP32Config.cpp
@@ -185,19 +185,24 @@ CHIP_ERROR ESP32Config::ReadConfigValueStr(Key key, char * buf, size_t bufSize,
 
     ReturnErrorOnFailure(handle.Open(key.Namespace, NVS_READONLY, GetPartitionLabelByNamespace(key.Namespace)));
 
-    outLen        = bufSize;
+    outLen = bufSize;
+
+    // If buf is null, nvs_get_str() sets the outLen to required length to fit the string
     esp_err_t err = nvs_get_str(handle, key.Name, buf, &outLen);
     if (err == ESP_ERR_NVS_NOT_FOUND)
     {
         outLen = 0;
         return CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND;
     }
-    if (err == ESP_ERR_NVS_INVALID_LENGTH && buf != NULL)
+    if (buf != NULL)
     {
-        return CHIP_ERROR_BUFFER_TOO_SMALL;
+        if (err == ESP_ERR_NVS_INVALID_LENGTH)
+        {
+            return CHIP_ERROR_BUFFER_TOO_SMALL;
+        }
+        ReturnErrorCodeIf(buf[outLen - 1] != 0, CHIP_ERROR_INVALID_STRING_LENGTH);
+        ReturnMappedErrorOnFailure(err);
     }
-    ReturnErrorCodeIf(buf[outLen - 1] != 0, CHIP_ERROR_INVALID_STRING_LENGTH);
-    ReturnMappedErrorOnFailure(err);
 
     outLen -= 1; // Don't count trailing nul.
 
@@ -210,18 +215,22 @@ CHIP_ERROR ESP32Config::ReadConfigValueBin(Key key, uint8_t * buf, size_t bufSiz
 
     ReturnErrorOnFailure(handle.Open(key.Namespace, NVS_READONLY, GetPartitionLabelByNamespace(key.Namespace)));
 
-    outLen        = bufSize;
+    outLen = bufSize;
+    // If buf is null, nvs_get_blob() sets the outLen to required length to fit the blob
     esp_err_t err = nvs_get_blob(handle, key.Name, buf, &outLen);
     if (err == ESP_ERR_NVS_NOT_FOUND)
     {
         outLen = 0;
         return CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND;
     }
-    else if (err == ESP_ERR_NVS_INVALID_LENGTH && buf != NULL)
+    if (buf != NULL)
     {
-        return CHIP_ERROR_BUFFER_TOO_SMALL;
+        if (err == ESP_ERR_NVS_INVALID_LENGTH)
+        {
+            return CHIP_ERROR_BUFFER_TOO_SMALL;
+        }
+        ReturnMappedErrorOnFailure(err);
     }
-    ReturnMappedErrorOnFailure(err);
 
     return CHIP_NO_ERROR;
 }

diff --git a/src/platform/ESP32/ESP32Config.h b/src/platform/ESP32/ESP32Config.h
@@ -92,8 +92,11 @@ class ESP32Config
     static CHIP_ERROR ReadConfigValue(Key key, bool & val);
     static CHIP_ERROR ReadConfigValue(Key key, uint32_t & val);
     static CHIP_ERROR ReadConfigValue(Key key, uint64_t & val);
+
+    // If buf is NULL then outLen is set to the required length to fit the string/blob
     static CHIP_ERROR ReadConfigValueStr(Key key, char * buf, size_t bufSize, size_t & outLen);
     static CHIP_ERROR ReadConfigValueBin(Key key, uint8_t * buf, size_t bufSize, size_t & outLen);
+
     static CHIP_ERROR WriteConfigValue(Key key, bool val);
     static CHIP_ERROR WriteConfigValue(Key key, uint32_t val);
     static CHIP_ERROR WriteConfigValue(Key key, uint64_t val);