Win long path

pkgs/io_file/constants.json

@@ -48,5 +48,8 @@
   "<fcntl.h>": [
     "AT_FDCWD",
     "AT_REMOVEDIR"
+  ],
+  "<limits.h>": [
+    "PATH_MAX"
   ]
 }

pkgs/io_file/dart_test.yaml

@@ -0,0 +1,3 @@
+concurrency: 1
+reporter: compact
+test-randomize-ordering-seed: random

pkgs/io_file/lib/src/constant_bindings.g.dart

@@ -49,6 +49,9 @@ external int get_AT_FDCWD();
 @ffi.Native<ffi.Int64 Function()>(symbol: 'libc_shim_get_AT_REMOVEDIR')
 external int get_AT_REMOVEDIR();
 
+@ffi.Native<ffi.Int64 Function()>(symbol: 'libc_shim_get_PATH_MAX')
+external int get_PATH_MAX();
+
 @ffi.Native<ffi.Int64 Function()>(symbol: 'libc_shim_get_S_IEXEC')
 external int get_S_IEXEC();
 

pkgs/io_file/lib/src/constants.g.dart

@@ -131,6 +131,15 @@ int get AT_REMOVEDIR {
   }
 }
 
+int get PATH_MAX {
+  final v = get_PATH_MAX();
+  if (v == libc_shim_UNDEFINED) {
+    throw UnsupportedError('PATH_MAX');
+  } else {
+    return v;
+  }
+}
+
 int get S_IEXEC {
   final v = get_S_IEXEC();
   if (v == libc_shim_UNDEFINED) {

pkgs/io_file/lib/src/file_system.dart

@@ -86,6 +86,24 @@ base class FileSystem {
     throw UnsupportedError('createTemporaryDirectory');
   }
 
+  /// The current
+  /// [working directory](https://en.wikipedia.org/wiki/Working_directory) of
+  /// the Dart process.
+  ///
+  /// Setting the value of this field will change the working directory for
+  /// *all* isolates.
+  ///
+  /// On Windows, unless
+  /// [long paths are enabled](https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation),
+  /// the maximum length of the [currentDirectory] path is 260 characters.
+  String get currentDirectory {
+    throw UnsupportedError('currentDirectory');
+  }
+
+  set currentDirectory(String path) {
+    throw UnsupportedError('currentDirectory');
+  }
+
   /// Deletes the directory at the given path.
   ///
   /// If `path` is a directory but the directory is not empty, then

pkgs/io_file/lib/src/libc_bindings.g.dart

@@ -78,9 +78,17 @@ external ffi.Pointer<ffi.Char> mkdtemp(ffi.Pointer<ffi.Char> template);
 external ffi.Pointer<ffi.Char> strerror(int errnum);
 
 /// <unistd.h>
+@ffi.Native<ffi.Int Function(ffi.Pointer<ffi.Char>)>(symbol: 'libc_shim_chdir')
+external int chdir(ffi.Pointer<ffi.Char> path);
+
 @ffi.Native<ffi.Int Function(ffi.Int)>(symbol: 'libc_shim_close')
 external int close(int fd);
 
+@ffi.Native<ffi.Pointer<ffi.Char> Function(ffi.Pointer<ffi.Char>, ffi.Int64)>(
+  symbol: 'libc_shim_getcwd',
+)
+external ffi.Pointer<ffi.Char> getcwd(ffi.Pointer<ffi.Char> buf, int size);
+
 @ffi.Native<ffi.Int Function(ffi.Int, ffi.Pointer<ffi.Char>, ffi.Int)>(
   symbol: 'libc_shim_unlinkat',
 )

pkgs/io_file/lib/src/vm_posix_file_system.dart

@@ -21,7 +21,7 @@ const _defaultMode = 438; // => 0666 => rw-rw-rw-
 /// The default `mode` to use when creating a directory.
 const _defaultDirectoryMode = 511; // => 0777 => rwxrwxrwx
 
-Exception _getError(int err, String message, String path) {
+Exception _getError(int err, String message, [String? path]) {
   //TODO(brianquinlan): In the long-term, do we need to avoid exceptions that
   // are part of `dart:io`? Can we move those exceptions into a different
   // namespace?
@@ -30,12 +30,16 @@ Exception _getError(int err, String message, String path) {
     err,
   );
 
-  if (err == libc.EPERM || err == libc.EACCES) {
-    return io.PathAccessException(path, osError, message);
-  } else if (err == libc.EEXIST) {
-    return io.PathExistsException(path, osError, message);
-  } else if (err == libc.ENOENT) {
-    return io.PathNotFoundException(path, osError, message);
+  if (path != null) {
+    if (err == libc.EPERM || err == libc.EACCES) {
+      return io.PathAccessException(path, osError, message);
+    } else if (err == libc.EEXIST) {
+      return io.PathExistsException(path, osError, message);
+    } else if (err == libc.ENOENT) {
+      return io.PathNotFoundException(path, osError, message);
+    } else {
+      return io.FileSystemException(message, path, osError);
+    }
   } else {
     return io.FileSystemException(message, path, osError);
   }
@@ -95,6 +99,24 @@ base class PosixFileSystem extends FileSystem {
     }
   });
 
+  @override
+  set currentDirectory(String path) => ffi.using((arena) {
+    if (libc.chdir(path.toNativeUtf8(allocator: arena).cast()) == -1) {
+      final errno = libc.errno;
+      throw _getError(errno, 'chdir failed', path);
+    }
+  });
+
+  @override
+  String get currentDirectory => ffi.using((arena) {
+    final buffer = arena<Char>(libc.PATH_MAX);
+    if (libc.getcwd(buffer, libc.PATH_MAX) == nullptr) {
+      final errno = libc.errno;
+      throw _getError(errno, 'getcwd failed', null);
+    }
+    return buffer.cast<ffi.Utf8>().toDartString();
+  });
+
   @override
   String createTemporaryDirectory({String? parent, String? prefix}) =>
       ffi.using((arena) {

pkgs/io_file/lib/src/vm_windows_file_system.dart

@@ -23,6 +23,33 @@ void _primeGetLastError() {
   win32.GetLastError();
 }
 
+Pointer<Utf16> _apiPath(String path, Allocator a) =>
+    (r'\\?\' + p.canonicalize(path)).toNativeUtf16(allocator: a);
+
+/*
+Pointer<Utf16> _apiPath(String path, Allocator a) {
+  var length = 256;
+  var utf16Path = path.toNativeUtf16(allocator: a);
+  do {
+    final buffer = win32.wsalloc(length);
+    try {
+      final result = win32.GetFullPathName(utf16Path, length, buffer, nullptr);
+      if (result == 0) {
+        final errorCode = win32.GetLastError();
+        throw _getError(errorCode, 'GetFullPathName failed', path);
+      }
+      if (result < length) {
+        win32.PathAllocCanonicalize()
+      } else {
+        length = result;
+      }
+    } finally {
+      win32.free(buffer);
+    }
+  } while (true);
+}
+*/
+
 String _formatMessage(int errorCode) {
   final buffer = win32.wsalloc(1024);
   try {
@@ -130,8 +157,7 @@ base class WindowsFileSystem extends FileSystem {
   void createDirectory(String path) => using((arena) {
     _primeGetLastError();
 
-    if (win32.CreateDirectory(path.toNativeUtf16(allocator: arena), nullptr) ==
-        win32.FALSE) {
+    if (win32.CreateDirectory(_apiPath(path, arena), nullptr) == win32.FALSE) {
       final errorCode = win32.GetLastError();
       throw _getError(errorCode, 'create directory failed', path);
     }
@@ -148,6 +174,44 @@ base class WindowsFileSystem extends FileSystem {
     return path;
   }
 
+  @override
+  set currentDirectory(String path) => using((arena) {
+    // XXX
+    // SetCurrentDirectory does not actually support paths larger than MAX_PATH,
+    // this limitation is due to the size of the internal buffer used for
+    // storing
+    // current directory. In Windows 10, version 1607, changes have been made
+    // to the OS to lift MAX_PATH limitations from file and directory management
+    // APIs, but both application and OS need to opt-in into new behavior.
+    // See https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry#enable-long-paths-in-windows-10-version-1607-and-later
+
+    _primeGetLastError();
+    if (win32.SetCurrentDirectory(path.toNativeUtf16()) == win32.FALSE) {
+      final errorCode = win32.GetLastError();
+      throw _getError(errorCode, 'SetCurrentDirectory failed', path);
+    }
+  });
+
+  @override
+  String get currentDirectory => using((arena) {
+    _primeGetLastError();
+
+    var length = 256;
+    do {
+      final buffer = win32.wsalloc(length);
+      try {
+        final result = win32.GetCurrentDirectory(length, buffer);
+        if (result < length) {
+          return buffer.toDartString();
+        } else {
+          length = result;
+        }
+      } finally {
+        win32.free(buffer);
+      }
+    } while (true);
+  });
+
   @override
   void removeDirectory(String path) => using((arena) {
     _primeGetLastError();
@@ -247,7 +311,7 @@ base class WindowsFileSystem extends FileSystem {
     _primeGetLastError();
 
     final f = win32.CreateFile(
-      path.toNativeUtf16(),
+      _apiPath(path, arena),
       win32.GENERIC_READ | win32.FILE_SHARE_READ,
       win32.FILE_SHARE_READ | win32.FILE_SHARE_WRITE,
       nullptr,
@@ -383,7 +447,7 @@ base class WindowsFileSystem extends FileSystem {
     };
 
     final f = win32.CreateFile(
-      path.toNativeUtf16(allocator: arena),
+      _apiPath(path, arena),
       mode == WriteMode.appendExisting
           ? win32.FILE_APPEND_DATA
           : win32.FILE_GENERIC_WRITE,

pkgs/io_file/pubspec.yaml

@@ -14,7 +14,7 @@ dependencies:
   logging: ^1.3.0
   native_toolchain_c: ^0.16.0
   path: ^1.9.1
-  win32: ^5.11.0
+  win32: ^5.13.0
 
 dev_dependencies:
   args: ^2.7.0

pkgs/io_file/src/constants.g.c

@@ -7,6 +7,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <sys/stat.h>
 int64_t libc_shim_get_EACCES(void) {
 #ifdef EACCES
@@ -106,6 +107,13 @@ int64_t libc_shim_get_AT_REMOVEDIR(void) {
 #endif
   return libc_shim_UNDEFINED;
 }
+int64_t libc_shim_get_PATH_MAX(void) {
+#ifdef PATH_MAX
+  assert(PATH_MAX != libc_shim_UNDEFINED);
+  return PATH_MAX;
+#endif
+  return libc_shim_UNDEFINED;
+}
 int64_t libc_shim_get_S_IEXEC(void) {
 #ifdef S_IEXEC
   assert(S_IEXEC != libc_shim_UNDEFINED);

pkgs/io_file/src/constants.g.h

@@ -38,6 +38,8 @@ int64_t libc_shim_get_AT_FDCWD(void);
 __attribute__((visibility("default"))) __attribute__((used))
 int64_t libc_shim_get_AT_REMOVEDIR(void);
 __attribute__((visibility("default"))) __attribute__((used))
+int64_t libc_shim_get_PATH_MAX(void);
+__attribute__((visibility("default"))) __attribute__((used))
 int64_t libc_shim_get_S_IEXEC(void);
 __attribute__((visibility("default"))) __attribute__((used))
 int64_t libc_shim_get_S_IFBLK(void);

pkgs/io_file/src/libc_shim.c

@@ -142,8 +142,12 @@ char *libc_shim_strerror(int errnum) { return strerror(errnum); }
 
 // <unistd.h>
 
+int libc_shim_chdir(const char *path) { return chdir(path); }
+
 int libc_shim_close(int fd) { return close(fd); }
 
+char *libc_shim_getcwd(char *buf, int64_t size) { return getcwd(buf, size); }
+
 int libc_shim_unlinkat(int dirfd, const char *pathname, int flags) {
   return unlinkat(dirfd, pathname, flags);
 }

pkgs/io_file/src/libc_shim.h

@@ -106,6 +106,8 @@ LIBC_SHIM_EXPORT char *libc_shim_strerror(int errnum);
 
 // <unistd.h>
 
+LIBC_SHIM_EXPORT int libc_shim_chdir(const char *path);
 LIBC_SHIM_EXPORT int libc_shim_close(int fd);
+LIBC_SHIM_EXPORT char *libc_shim_getcwd(char *buf, int64_t size);
 LIBC_SHIM_EXPORT int libc_shim_unlinkat(int dirfd, const char *pathname,
                                         int flags);