fixes

esphome/dashboard/util/file.py

@@ -6,10 +6,22 @@ from pathlib import Path
 _LOGGER = logging.getLogger(__name__)
 
 
-# from https://github.com/home-assistant/core/blob/dev/homeassistant/util/file.py
 def write_utf8_file(
     filename: Path,
-    utf8_data: str,
+    utf8_str: str,
+    private: bool = False,
+) -> None:
+    """Write a file and rename it into place.
+
+    Writes all or nothing.
+    """
+    write_file(filename, utf8_str.encode("utf-8"), private)
+
+
+# from https://github.com/home-assistant/core/blob/dev/homeassistant/util/file.py
+def write_file(
+    filename: Path,
+    utf8_data: bytes,
     private: bool = False,
 ) -> None:
     """Write a file and rename it into place.
@@ -21,7 +33,7 @@ def write_utf8_file(
     try:
         # Modern versions of Python tempfile create this file with mode 0o600
         with tempfile.NamedTemporaryFile(
-            mode="w", encoding="utf-8", dir=os.path.dirname(filename), delete=False
+            mode="wb", dir=os.path.dirname(filename), delete=False
         ) as fdesc:
             fdesc.write(utf8_data)
             tmp_filename = fdesc.name

esphome/dashboard/web_server.py

@@ -38,6 +38,7 @@ from esphome.yaml_util import FastestAvailableSafeLoader
 
 from .core import DASHBOARD
 from .entries import EntryState, entry_state_to_bool
+from .util.file import write_file
 from .util.subprocess import async_run_system_command
 from .util.text import friendly_name_slugify
 
@@ -746,22 +747,34 @@ class InfoRequestHandler(BaseHandler):
 class EditRequestHandler(BaseHandler):
     @authenticated
     @bind_config
-    def get(self, configuration=None):
+    async def get(self, configuration: str | None = None):
+        loop = asyncio.get_running_loop()
         filename = settings.rel_path(configuration)
-        content = ""
-        if os.path.isfile(filename):
-            with open(file=filename, encoding="utf-8") as f:
-                content = f.read()
+        try:
+            content = await loop.run_in_executor(None, self._read_file, filename)
+        except OSError:
+            self.send_error(404)
+            return
         self.write(content)
 
+    def _read_file(self, filename: str) -> bytes:
+        """Read a file and return the content as bytes."""
+        with open(file=filename, encoding="utf-8") as f:
+            return f.read()
+
+    def _write_file(self, filename: str, content: bytes) -> None:
+        """Write a file with the given content."""
+        write_file(filename, content)
+
     @authenticated
     @bind_config
-    async def post(self, configuration=None):
-        # Atomic write
+    async def post(self, configuration: str | None = None):
+        loop = asyncio.get_running_loop()
         config_file = settings.rel_path(configuration)
-        with open(file=config_file, mode="wb") as f:
-            f.write(self.request.body)
-
+        await loop.run_in_executor(
+            None, self._write_file, config_file, self.request.body
+        )
+        # Ensure the StorageJSON is updated as well
         await async_run_system_command(
             [*DASHBOARD_COMMAND, "compile", "--only-generate", config_file]
         )

tests/dashboard/util/test_file.py

@@ -5,7 +5,7 @@ from unittest.mock import patch
 import py
 import pytest
 
-from esphome.dashboard.util.file import write_utf8_file
+from esphome.dashboard.util.file import write_file, write_utf8_file
 
 
 def test_write_utf8_file(tmp_path: Path) -> None:
@@ -16,6 +16,11 @@ def test_write_utf8_file(tmp_path: Path) -> None:
         write_utf8_file(Path("/not-writable"), "bar")
 
 
+def test_write_file(tmp_path: Path) -> None:
+    write_file(tmp_path.joinpath("foo.txt"), b"foo")
+    assert tmp_path.joinpath("foo.txt").read_text() == "foo"
+
+
 def test_write_utf8_file_fails_at_rename(
     tmpdir: py.path.local, caplog: pytest.LogCaptureFixture
 ) -> None: