Add PathExistsException and PathAccessException FileSystemException subclasses.

Bug:https://github.com/dart-lang/sdk/issues/50436
Change-Id: Ie2954f162c01189cd0d817f58606529acdc13416
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/269240
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Brian Quinlan <bquinlan@google.com>

CHANGELOG.md

@@ -124,11 +124,15 @@
 
 [#49878]: https://github.com/dart-lang/sdk/issues/49878
 
-- When a `dart:io` operation fails because a file is not found, throw
-  `PathNotFoundException`, a `FileSystemException` subclass, to make it
-  easier to handle "file not found" errors.
+- Adds three new `FileSystemException` subclasses to handle common error
+  cases:
+
+  - `PathAccessException`: The necessary access rights are not available.
+  - `PathExistsException`: The path being created already exists.
+  - `PathNotFoundException`: The path being accessed does not exist.
 
 [#12461]: https://github.com/dart-lang/sdk/issues/12461
+[#50436]: https://github.com/dart-lang/sdk/issues/50436
 
 #### `dart:isolate`
 

sdk/lib/_internal/vm/bin/file_patch.dart

@@ -173,7 +173,7 @@ abstract class _FileSystemWatcher {
         _newWatcher();
       } on dynamic catch (e) {
         _broadcastController.addError(FileSystemException._fromOSError(
-            e, "Failed to initialize file system entity watcher", null));
+            e, "Failed to initialize file system entity watcher", _path));
         _broadcastController.close();
         return;
       }

sdk/lib/io/common.dart

@@ -17,17 +17,30 @@ const int _osErrorResponseMessage = 2;
 
 // POSIX error codes.
 // See https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
+const _ePerm = 1;
 const _eNoEnt = 2;
+const _eAccess = 13;
+const _eExist = 17;
 
 // Windows error codes.
 // See https://learn.microsoft.com/en-us/windows/win32/debug/system-error-codes--0-499-
 const _errorFileNotFound = 2;
 const _errorPathNotFound = 3;
+const _errorAccessDenied = 5;
 const _errorInvalidDrive = 15;
+const _errorCurrentDirectory = 16;
 const _errorNoMoreFiles = 18;
+const _errorWriteProtect = 19;
+const _errorBadLength = 24;
+const _errorSharingViolation = 32;
+const _errorLockViolation = 33;
 const _errorBadNetpath = 53;
+const _errorNetworkAccessDenied = 65;
 const _errorBadNetName = 67;
+const _errorFileExists = 80;
+const _errorDriveLocked = 108;
 const _errorBadPathName = 161;
+const _errorAlreadyExists = 183;
 const _errorFilenameExedRange = 206;
 
 /// If the [response] is an error, throws an [Exception] or an [Error].

sdk/lib/io/file.dart

@@ -222,7 +222,7 @@ abstract class File implements FileSystemEntity {
   /// non-existing parent paths are created first.
   ///
   /// If [exclusive] is `true` and to-be-created file already exists, this
-  /// operation completes the future with a [FileSystemException].
+  /// operation completes the future with a [PathExistsException].
   ///
   /// If [exclusive] is `false`, existing files are left untouched by [create].
   /// Calling [create] on an existing file still might fail if there are
@@ -900,9 +900,21 @@ class FileSystemException implements IOException {
   /// will be returned.
   @pragma("vm:entry-point")
   factory FileSystemException._fromOSError(
-      OSError err, String message, String? path) {
+      OSError err, String message, String path) {
     if (Platform.isWindows) {
       switch (err.errorCode) {
+        case _errorAccessDenied:
+        case _errorCurrentDirectory:
+        case _errorWriteProtect:
+        case _errorBadLength:
+        case _errorSharingViolation:
+        case _errorLockViolation:
+        case _errorNetworkAccessDenied:
+        case _errorDriveLocked:
+          return PathAccessException(path, err, message);
+        case _errorFileExists:
+        case _errorAlreadyExists:
+          return PathExistsException(path, err, message);
         case _errorFileNotFound:
         case _errorPathNotFound:
         case _errorInvalidDrive:
@@ -911,14 +923,19 @@ class FileSystemException implements IOException {
         case _errorBadNetName:
         case _errorBadPathName:
         case _errorFilenameExedRange:
-          return PathNotFoundException(path!, err, message);
+          return PathNotFoundException(path, err, message);
         default:
           return FileSystemException(message, path, err);
       }
     } else {
       switch (err.errorCode) {
+        case _ePerm:
+        case _eAccess:
+          return PathAccessException(path, err, message);
+        case _eExist:
+          return PathExistsException(path, err, message);
         case _eNoEnt:
-          return PathNotFoundException(path!, err, message);
+          return PathNotFoundException(path, err, message);
         default:
           return FileSystemException(message, path, err);
       }
@@ -952,6 +969,24 @@ class FileSystemException implements IOException {
   }
 }
 
+/// Exception thrown when a file operation fails because the necessary access
+/// rights are not available.
+class PathAccessException extends FileSystemException {
+  const PathAccessException(String path, OSError osError, [String message = ""])
+      : super(message, path, osError);
+
+  String toString() => _toStringHelper("PathAccessException");
+}
+
+/// Exception thrown when a file operation fails because the target path
+/// already exists.
+class PathExistsException extends FileSystemException {
+  const PathExistsException(String path, OSError osError, [String message = ""])
+      : super(message, path, osError);
+
+  String toString() => _toStringHelper("PathExistsException");
+}
+
 /// Exception thrown when a file operation fails because a file or
 /// directory does not exist.
 class PathNotFoundException extends FileSystemException {
@@ -959,9 +994,7 @@ class PathNotFoundException extends FileSystemException {
       [String message = ""])
       : super(message, path, osError);
 
-  String toString() {
-    return _toStringHelper("PathNotFoundException");
-  }
+  String toString() => _toStringHelper("PathNotFoundException");
 }
 
 /// The "read" end of an [Pipe] created by [Pipe.create].

tests/standalone/io/file_error_test.dart

@@ -436,6 +436,31 @@ testReadSyncClosedFile() {
   });
 }
 
+void testCreateExistingFile() {
+  createTestFile((file, done) {
+    Expect.throws<PathExistsException>(() => file.createSync(exclusive: true));
+    done();
+  });
+}
+
+void testDeleteDirectoryWithoutPermissions() {
+  if (Platform.isMacOS) {
+    createTestFile((file, done) async {
+      Process.runSync('chflags', ['uchg', file.path]);
+      Expect.throws<PathAccessException>(file.deleteSync);
+      Process.runSync('chflags', ['nouchg', file.path]);
+      done();
+    });
+  }
+  if (Platform.isWindows) {
+    final oldCurrent = Directory.current;
+    Directory.current = tempDir();
+    // Cannot delete the current working directory in Windows.
+    Expect.throws<PathAccessException>(Directory.current.deleteSync);
+    Directory.current = oldCurrent;
+  }
+}
+
 main() {
   testOpenBlankFilename();
   testOpenNonExistent();
@@ -453,4 +478,6 @@ main() {
   testRepeatedlyCloseFile();
   testRepeatedlyCloseFileSync();
   testReadSyncClosedFile();
+  testCreateExistingFile();
+  testDeleteDirectoryWithoutPermissions();
 }

tests/standalone_2/io/file_error_test.dart

@@ -438,6 +438,31 @@ testReadSyncClosedFile() {
   });
 }
 
+void testCreateExistingFile() {
+  createTestFile((file, done) {
+    Expect.throws<PathExistsException>(() => file.createSync(exclusive: true));
+    done();
+  });
+}
+
+void testDeleteDirectoryWithoutPermissions() {
+  if (Platform.isMacOS) {
+    createTestFile((file, done) async {
+      Process.runSync('chflags', ['uchg', file.path]);
+      Expect.throws<PathAccessException>(file.deleteSync);
+      Process.runSync('chflags', ['nouchg', file.path]);
+      done();
+    });
+  }
+  if (Platform.isWindows) {
+    final oldCurrent = Directory.current;
+    Directory.current = tempDir();
+    // Cannot delete the current working directory in Windows.
+    Expect.throws<PathAccessException>(Directory.current.deleteSync);
+    Directory.current = oldCurrent;
+  }
+}
+
 main() {
   testOpenBlankFilename();
   testOpenNonExistent();
@@ -455,4 +480,6 @@ main() {
   testRepeatedlyCloseFile();
   testRepeatedlyCloseFileSync();
   testReadSyncClosedFile();
+  testCreateExistingFile();
+  testDeleteDirectoryWithoutPermissions();
 }