[io_file] Add the ability to get file metadata on Windows.

pkgs/io_file/example/io_file_example.dart

@@ -2,9 +2,23 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:io_file/posix_file_system.dart';
+import 'package:io_file/io_file.dart';
+import 'package:io_file/windows_file_system.dart';
+
+import 'package:path/path.dart' as p;
+
+bool isHidden(String path) {
+  if (fileSystem case final WindowsFileSystem fs) {
+    return fs.metadata(path).isHidden;
+  } else {
+    // On POSIX, convention is that files and directories starting with a period
+    // are hidden (except for the special files representing the current working
+    // directory and parent directory).
+    final name = p.basename(path);
+    return name.startsWith('.') && name != '.' && name != '..';
+  }
+}
 
 void main() {
-  // TODO(brianquinlan): Create a better example.
-  PosixFileSystem().rename('foo.txt', 'bar.txt');
+  isHidden('somefile');
 }

pkgs/io_file/lib/src/file_system.dart

@@ -2,6 +2,47 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+/// Information about a directory, link, etc. stored in the [FileSystem].
+base class Metadata {
+  // TODO(brianquinlan): Document all public fields.
+
+  final bool isFile;
+  final bool isDirectory;
+  final bool isLink;
+  final int size;
+
+  Metadata({
+    this.isDirectory = false,
+    this.isFile = false,
+    this.isLink = false,
+    this.size = 0,
+  }) {
+    final count = (isDirectory ? 1 : 0) + (isFile ? 1 : 0) + (isLink ? 1 : 0);
+    if (count > 1) {
+      // TODO(brianquinlan): Decide whether a path must be a a file, directory
+      // or link and whether it can be more than one of these at once.
+      // Rust requires that at most one of these is true. Python has no such
+      // restriction.
+
+      // TODO(bquinlan): if we keep this logic, use `ArgumentError.value`.
+      throw ArgumentError(
+        'only one of isDirectory, isFile, or isLink must be true',
+      );
+    }
+  }
+
+  @override
+  bool operator ==(Object other) =>
+      other is Metadata &&
+      isDirectory == other.isDirectory &&
+      isFile == other.isFile &&
+      isLink == other.isLink &&
+      size == other.size;
+
+  @override
+  int get hashCode => Object.hash(isDirectory, isFile, isLink, size).hashCode;
+}
+
 /// An abstract representation of a file system.
 base class FileSystem {
   /// Renames, and possibly moves a file system object from one path to another.
@@ -23,4 +64,12 @@ base class FileSystem {
   void rename(String oldPath, String newPath) {
     throw UnsupportedError('rename');
   }
+
+  /// Metadata for the file system object at [path].
+  ///
+  /// If `path` represents a symbolic link then metadata for the link is
+  /// returned.
+  Metadata metadata(String path) {
+    throw UnsupportedError('metadata');
+  }
 }

pkgs/io_file/lib/src/vm_windows_file_system.dart

@@ -10,6 +10,11 @@ import 'package:win32/win32.dart' as win32;
 
 import 'file_system.dart';
 
+DateTime _fileTimeToDateTime(int t) {
+  final microseconds = t ~/ 10;
+  return DateTime.utc(1601, 1, 1).add(Duration(microseconds: microseconds));
+}
+
 String _formatMessage(int errorCode) {
   final buffer = win32.wsalloc(1024);
   try {
@@ -62,14 +67,93 @@ Exception _getError(int errorCode, String message, String path) {
   }
 }
 
+/// File system entity data available on Windows.
+final class WindowsMetadata extends Metadata {
+  // TODO(brianquinlan): Reoganize fields when the POSIX `metadata` is
+  // available.
+  // TODO(brianquinlan): Document the public fields.
+
+  final bool isReadOnly;
+  final bool isHidden;
+  final bool isSystem;
+  final bool isArchive;
+  final bool isTemporary;
+  final bool isOffline;
+  final bool isContentNotIndexed;
+
+  final int creationTime100Nanos;
+  final int lastAccessTime100Nanos;
+  final int lastWriteTime100Nanos;
+
+  DateTime get creation => _fileTimeToDateTime(creationTime100Nanos);
+  DateTime get access => _fileTimeToDateTime(lastAccessTime100Nanos);
+  DateTime get modification => _fileTimeToDateTime(lastWriteTime100Nanos);
+
+  /// TODO(bquinlan): Document this constructor.
+  WindowsMetadata({
+    super.isDirectory = false,
+    super.isFile = false,
+    super.isLink = false,
+
+    super.size = 0,
+
+    this.isReadOnly = false,
+    this.isHidden = false,
+    this.isSystem = false,
+    this.isArchive = false,
+    this.isTemporary = false,
+    this.isOffline = false,
+    this.isContentNotIndexed = false,
+
+    this.creationTime100Nanos = 0,
+    this.lastAccessTime100Nanos = 0,
+    this.lastWriteTime100Nanos = 0,
+  });
+
+  @override
+  bool operator ==(Object other) =>
+      other is WindowsMetadata &&
+      super == other &&
+      isReadOnly == other.isReadOnly &&
+      isHidden == other.isHidden &&
+      isSystem == other.isSystem &&
+      isArchive == other.isArchive &&
+      isTemporary == other.isTemporary &&
+      isOffline == other.isOffline &&
+      isContentNotIndexed == other.isContentNotIndexed &&
+      creationTime100Nanos == other.creationTime100Nanos &&
+      lastAccessTime100Nanos == other.lastAccessTime100Nanos &&
+      lastWriteTime100Nanos == other.lastWriteTime100Nanos;
+
+  @override
+  int get hashCode => Object.hash(
+    super.hashCode,
+    isReadOnly,
+    isHidden,
+    isSystem,
+    isArchive,
+    isTemporary,
+    isOffline,
+    isContentNotIndexed,
+    creationTime100Nanos,
+    lastAccessTime100Nanos,
+    lastWriteTime100Nanos,
+  );
+}
+
 /// A [FileSystem] implementation for Windows systems.
 base class WindowsFileSystem extends FileSystem {
-  @override
-  void rename(String oldPath, String newPath) => using((arena) {
+  WindowsFileSystem() {
     // Calling `GetLastError` for the first time causes the `GetLastError`
     // symbol to be loaded, which resets `GetLastError`. So make a harmless
     // call before the value is needed.
+    //
+    // TODO(brianquinlan): Remove this after it is fixed in the Dart SDK.
     win32.GetLastError();
+  }
+
+  @override
+  void rename(String oldPath, String newPath) => using((arena) {
     if (win32.MoveFileEx(
           oldPath.toNativeUtf16(allocator: arena),
           newPath.toNativeUtf16(allocator: arena),
@@ -80,4 +164,127 @@ base class WindowsFileSystem extends FileSystem {
       throw _getError(errorCode, 'rename failed', oldPath);
     }
   });
+
+  /// Sets metadata for the file system entity.
+  ///
+  /// TODO(brianquinlan): Document the arguments.
+  void setMetadata(
+    String path, {
+    bool? isReadOnly,
+    bool? isHidden,
+    bool? isSystem,
+    bool? isArchive,
+    bool? isTemporary,
+    bool? isContentNotIndexed,
+    bool? isOffline,
+  }) => using((arena) {
+    if ((isReadOnly ??
+            isHidden ??
+            isSystem ??
+            isArchive ??
+            isTemporary ??
+            isContentNotIndexed ??
+            isOffline) ==
+        null) {
+      return;
+    }
+    final fileInfo = arena<win32.WIN32_FILE_ATTRIBUTE_DATA>();
+    final nativePath = path.toNativeUtf16(allocator: arena);
+    if (win32.GetFileAttributesEx(
+          nativePath,
+          win32.GetFileExInfoStandard,
+          fileInfo,
+        ) ==
+        win32.FALSE) {
+      final errorCode = win32.GetLastError();
+      throw _getError(errorCode, 'set metadata failed', path);
+    }
+
+    var attributes = fileInfo.ref.dwFileAttributes;
+    if (attributes == win32.FILE_ATTRIBUTE_NORMAL) {
+      // `FILE_ATTRIBUTE_NORMAL` indicates that no other attributes are set and
+      // is valid only when used alone.
+      attributes = 0;
+    }
+
+    int updateBit(int base, int value, bool? bit) => switch (bit) {
+      null => base,
+      true => base | value,
+      false => base & ~value,
+    };
+
+    attributes = updateBit(
+      attributes,
+      win32.FILE_ATTRIBUTE_READONLY,
+      isReadOnly,
+    );
+    attributes = updateBit(attributes, win32.FILE_ATTRIBUTE_HIDDEN, isHidden);
+    attributes = updateBit(attributes, win32.FILE_ATTRIBUTE_SYSTEM, isSystem);
+    attributes = updateBit(attributes, win32.FILE_ATTRIBUTE_ARCHIVE, isArchive);
+    attributes = updateBit(
+      attributes,
+      win32.FILE_ATTRIBUTE_TEMPORARY,
+      isTemporary,
+    );
+    attributes = updateBit(
+      attributes,
+      win32.FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,
+      isContentNotIndexed,
+    );
+    attributes = updateBit(attributes, win32.FILE_ATTRIBUTE_OFFLINE, isOffline);
+    if (attributes == 0) {
+      // `FILE_ATTRIBUTE_NORMAL` indicates that no other attributes are set and
+      // is valid only when used alone.
+      attributes = win32.FILE_ATTRIBUTE_NORMAL;
+    }
+    if (win32.SetFileAttributes(nativePath, attributes) == win32.FALSE) {
+      final errorCode = win32.GetLastError();
+      throw _getError(errorCode, 'set metadata failed', path);
+    }
+  });
+
+  @override
+  WindowsMetadata metadata(String path) => using((arena) {
+    final fileInfo = arena<win32.WIN32_FILE_ATTRIBUTE_DATA>();
+    if (win32.GetFileAttributesEx(
+          path.toNativeUtf16(allocator: arena),
+          win32.GetFileExInfoStandard,
+          fileInfo,
+        ) ==
+        win32.FALSE) {
+      final errorCode = win32.GetLastError();
+      throw _getError(errorCode, 'metadata failed', path);
+    }
+    final info = fileInfo.ref;
+    final attributes = info.dwFileAttributes;
+
+    final isDirectory = attributes & win32.FILE_ATTRIBUTE_DIRECTORY > 0;
+    final isLink = attributes & win32.FILE_ATTRIBUTE_REPARSE_POINT > 0;
+    final isFile = !(isDirectory || isLink);
+
+    return WindowsMetadata(
+      isReadOnly: attributes & win32.FILE_ATTRIBUTE_READONLY > 0,
+      isHidden: attributes & win32.FILE_ATTRIBUTE_HIDDEN > 0,
+      isSystem: attributes & win32.FILE_ATTRIBUTE_SYSTEM > 0,
+      isDirectory: isDirectory,
+      isArchive: attributes & win32.FILE_ATTRIBUTE_ARCHIVE > 0,
+      isTemporary: attributes & win32.FILE_ATTRIBUTE_TEMPORARY > 0,
+      isLink: isLink,
+      isFile: isFile,
+      isOffline: attributes & win32.FILE_ATTRIBUTE_OFFLINE > 0,
+      isContentNotIndexed:
+          attributes & win32.FILE_ATTRIBUTE_NOT_CONTENT_INDEXED > 0,
+
+      size: info.nFileSizeHigh << 32 | info.nFileSizeLow,
+      creationTime100Nanos:
+          info.ftCreationTime.dwHighDateTime << 32 |
+          info.ftCreationTime.dwLowDateTime,
+      lastAccessTime100Nanos:
+          info.ftLastAccessTime.dwHighDateTime << 32 |
+          info.ftLastAccessTime.dwLowDateTime,
+      lastWriteTime100Nanos:
+          info.ftLastWriteTime.dwHighDateTime << 32 |
+          info.ftLastWriteTime.dwLowDateTime,
+    );
+  });
 }

pkgs/io_file/pubspec.yaml

@@ -11,10 +11,15 @@ dependencies:
   ffi: ^2.1.4
   stdlibc:
     git:
-      # Change this to a released version.
+      # TODO(brianquinlan): Change this to a released version.
       url: https://github.com/canonical/stdlibc.dart.git
-  win32: ^5.11.0
+  win32:
+    git:
+      # TODO(brianquinlan): Change this to a released version.
+      url: https://github.com/halildurmus/win32.git
+      path: packages/win32
 
 dev_dependencies:
   dart_flutter_team_lints: ^3.4.0
+  path: ^1.9.1
   test: ^1.24.0