sdk/lib/io/link.dart - sdk.git - Git at Google

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // 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.

 part of dart.io;

 /**
  * [Link] objects are references to filesystem links.
  *
  */
 abstract class Link implements FileSystemEntity {
   /**
    * Creates a Link object.
    */
   factory Link(String path) => new _Link(path);

   /**
    * Creates a symbolic link. Returns a [:Future<Link>:] that completes with
    * the link when it has been created. If the link exists,
    * the future will complete with an error.
    *
    * On the Windows platform, this will only work with directories, and the
    * target directory must exist. The link will be created as a Junction.
    * Only absolute links will be created, and relative paths to the target
    * will be converted to absolute paths by joining them with the path of the
    * directory the link is contained in.
    *
    * On other platforms, the posix symlink() call is used to make a symbolic
    * link containing the string [target].  If [target] is a relative path,
    * it will be interpreted relative to the directory containing the link.
    */
   Future<Link> create(String target);

   /**
    * Synchronously create the link. Calling [createSync] on an existing link
    * will throw an exception.
    *
    * On the Windows platform, this will only work with directories, and the
    * target directory must exist. The link will be created as a Junction.
    * Only absolute links will be created, and relative paths to the target
    * will be converted to absolute paths.
    *
    * On other platforms, the posix symlink() call is used to make a symbolic
    * link containing the string [target].  If [target] is a relative path,
    * it will be interpreted relative to the directory containing the link.
    */
   void createSync(String target);

   /**
    * Synchronously updates the link. Calling [updateSync] on a non-existing link
    * will throw an exception.
    *
    * On the Windows platform, this will only work with directories, and the
    * target directory must exist.
    */
   void updateSync(String target);

   /**
    * Updates the link. Returns a [:Future<Link>:] that completes with the
    * link when it has been updated.  Calling [update] on a non-existing link
    * will complete its returned future with an exception.
    *
    * On the Windows platform, this will only work with directories, and the
    * target directory must exist.
    */
   Future<Link> update(String target);

   Future<String> resolveSymbolicLinks();

   String resolveSymbolicLinksSync();

   /**
    * Renames this link. Returns a `Future<Link>` that completes
    * with a [Link] instance for the renamed link.
    *
    * If [newPath] identifies an existing link, that link is
    * replaced. If [newPath] identifies an existing file or directory,
    * the operation fails and the future completes with an exception.
    */
   Future<Link> rename(String newPath);

    /**
    * Synchronously renames this link. Returns a [Link]
    * instance for the renamed link.
    *
    * If [newPath] identifies an existing link, that link is
    * replaced. If [newPath] identifies an existing file or directory
    * the operation fails and an exception is thrown.
    */
   Link renameSync(String newPath);

   /**
    * Returns a [Link] instance whose path is the absolute path to [this].
    *
    * The absolute path is computed by prefixing
    * a relative path with the current working directory, and returning
    * an absolute path unchanged.
    */
   Link get absolute;

   /**
    * Gets the target of the link. Returns a future that completes with
    * the path to the target.
    *
    * If the returned target is a relative path, it is relative to the
    * directory containing the link.
    *
    * If the link does not exist, or is not a link, the future completes with
    * a LinkException.
    */
   Future<String> target();

   /**
    * Synchronously gets the target of the link. Returns the path to the target.
    *
    * If the returned target is a relative path, it is relative to the
    * directory containing the link.
    *
    * If the link does not exist, or is not a link, throws a LinkException.
    */
   String targetSync();
 }


 class _Link extends FileSystemEntity implements Link {
   final String path;

   _Link(String this.path) {
     if (path is! String) {
       throw new ArgumentError('${Error.safeToString(path)} '
                               'is not a String');
     }
   }


   String toString() => "Link: '$path'";

   Future<bool> exists() => FileSystemEntity.isLink(path);

   bool existsSync() => FileSystemEntity.isLinkSync(path);

   Link get absolute => new Link(_absolutePath);

   Future<FileStat> stat() => FileStat.stat(path);

   FileStat statSync() => FileStat.statSync(path);

   Future<Link> create(String target) {
     if (Platform.operatingSystem == 'windows') {
       target = _makeWindowsLinkTarget(target);
     }
     return _IOService.dispatch(_FILE_CREATE_LINK, [path, target])
         .then((response) {
           if (_isErrorResponse(response)) {
             throw _exceptionFromResponse(
                 response, "Cannot create link to target '$target'", path);
           }
           return this;
         });
   }

   void createSync(String target) {
     if (Platform.operatingSystem == 'windows') {
       target = _makeWindowsLinkTarget(target);
     }
     var result = _File._createLink(path, target);
     throwIfError(result, "Cannot create link", path);
   }

   // Put target into the form "\??\C:\my\target\dir".
   String _makeWindowsLinkTarget(String target) {
     Uri base = new Uri.file('${Directory.current.path}\\');
     Uri link = new Uri.file(path);
     Uri destination = new Uri.file(target);
     String result = base.resolveUri(link).resolveUri(destination).toFilePath();
     if (result.length > 3 && result[1] == ':' && result[2] == '\\') {
       return '\\??\\$result';
     } else {
       throw new LinkException(
           'Target $result of Link.create on Windows cannot be converted' +
           ' to start with a drive letter.  Unexpected error.');
     }
   }

   void updateSync(String target) {
     // TODO(12414): Replace with atomic update, where supported by platform.
     // Atomically changing a link can be done by creating the new link, with
     // a different name, and using the rename() posix call to move it to
     // the old name atomically.
     deleteSync();
     createSync(target);
   }

   Future<Link> update(String target) {
     // TODO(12414): Replace with atomic update, where supported by platform.
     // Atomically changing a link can be done by creating the new link, with
     // a different name, and using the rename() posix call to move it to
     // the old name atomically.
     return delete().then((_) => create(target));
   }

   Future<Link> _delete({bool recursive: false}) {
     if (recursive) {
       return new Directory(path).delete(recursive: true).then((_) => this);
     }
     return _IOService.dispatch(_FILE_DELETE_LINK, [path]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "Cannot delete link", path);
       }
       return this;
     });
   }

   void _deleteSync({bool recursive: false}) {
     if (recursive) {
       return new Directory(path).deleteSync(recursive: true);
     }
     var result = _File._deleteLinkNative(path);
     throwIfError(result, "Cannot delete link", path);
   }

   Future<Link> rename(String newPath) {
     return _IOService.dispatch(_FILE_RENAME_LINK, [path, newPath])
         .then((response) {
           if (_isErrorResponse(response)) {
             throw _exceptionFromResponse(
                 response, "Cannot rename link to '$newPath'", path);
           }
           return new Link(newPath);
         });
   }

   Link renameSync(String newPath) {
     var result = _File._renameLink(path, newPath);
     throwIfError(result, "Cannot rename link '$path' to '$newPath'");
     return new Link(newPath);
   }

   Future<String> target() {
     return _IOService.dispatch(_FILE_LINK_TARGET, [path]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(
             response, "Cannot get target of link", path);
       }
       return response;
     });
   }

   String targetSync() {
     var result = _File._linkTarget(path);
     throwIfError(result, "Cannot read link", path);
     return result;
   }

   static throwIfError(Object result, String msg, [String path = ""]) {
     if (result is OSError) {
       throw new LinkException(msg, path, result);
     }
   }

   bool _isErrorResponse(response) {
     return response is List && response[0] != _SUCCESS_RESPONSE;
   }

   _exceptionFromResponse(response, String message, String path) {
     assert(_isErrorResponse(response));
     switch (response[_ERROR_RESPONSE_ERROR_TYPE]) {
       case _ILLEGAL_ARGUMENT_RESPONSE:
         return new ArgumentError();
       case _OSERROR_RESPONSE:
         var err = new OSError(response[_OSERROR_RESPONSE_MESSAGE],
                               response[_OSERROR_RESPONSE_ERROR_CODE]);
         return new LinkException(message, path, err);
       default:
         return new Exception("Unknown error");
     }
   }
 }


 class LinkException implements IOException {
   const LinkException([String this.message = "",
                        String this.path = "",
                        OSError this.osError = null]);
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.write("LinkException");
     if (!message.isEmpty) {
       sb.write(": $message");
       if (path != null) {
         sb.write(", path = $path");
       }
       if (osError != null) {
         sb.write(" ($osError)");
       }
     } else if (osError != null) {
       sb.write(": $osError");
       if (path != null) {
         sb.write(", path = $path");
       }
     }
     return sb.toString();
   }
   final String message;
   final String path;
   final OSError osError;
 }
	// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
	// 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.

	part of dart.io;

	/**
	* [Link] objects are references to filesystem links.
	*
	*/
	abstract class Link implements FileSystemEntity {
	/**
	* Creates a Link object.
	*/
	factory Link(String path) => new _Link(path);

	/**
	* Creates a symbolic link. Returns a [:Future<Link>:] that completes with
	* the link when it has been created. If the link exists,
	* the future will complete with an error.
	*
	* On the Windows platform, this will only work with directories, and the
	* target directory must exist. The link will be created as a Junction.
	* Only absolute links will be created, and relative paths to the target
	* will be converted to absolute paths by joining them with the path of the
	* directory the link is contained in.
	*
	* On other platforms, the posix symlink() call is used to make a symbolic
	* link containing the string [target]. If [target] is a relative path,
	* it will be interpreted relative to the directory containing the link.
	*/
	Future<Link> create(String target);

	/**
	* Synchronously create the link. Calling [createSync] on an existing link
	* will throw an exception.
	*
	* On the Windows platform, this will only work with directories, and the
	* target directory must exist. The link will be created as a Junction.
	* Only absolute links will be created, and relative paths to the target
	* will be converted to absolute paths.
	*
	* On other platforms, the posix symlink() call is used to make a symbolic
	* link containing the string [target]. If [target] is a relative path,
	* it will be interpreted relative to the directory containing the link.
	*/
	void createSync(String target);

	/**
	* Synchronously updates the link. Calling [updateSync] on a non-existing link
	* will throw an exception.
	*
	* On the Windows platform, this will only work with directories, and the
	* target directory must exist.
	*/
	void updateSync(String target);

	/**
	* Updates the link. Returns a [:Future<Link>:] that completes with the
	* link when it has been updated. Calling [update] on a non-existing link
	* will complete its returned future with an exception.
	*
	* On the Windows platform, this will only work with directories, and the
	* target directory must exist.
	*/
	Future<Link> update(String target);

	Future<String> resolveSymbolicLinks();

	String resolveSymbolicLinksSync();

	/**
	* Renames this link. Returns a `Future<Link>` that completes
	* with a [Link] instance for the renamed link.
	*
	* If [newPath] identifies an existing link, that link is
	* replaced. If [newPath] identifies an existing file or directory,
	* the operation fails and the future completes with an exception.
	*/
	Future<Link> rename(String newPath);

	/**
	* Synchronously renames this link. Returns a [Link]
	* instance for the renamed link.
	*
	* If [newPath] identifies an existing link, that link is
	* replaced. If [newPath] identifies an existing file or directory
	* the operation fails and an exception is thrown.
	*/
	Link renameSync(String newPath);

	/**
	* Returns a [Link] instance whose path is the absolute path to [this].
	*
	* The absolute path is computed by prefixing
	* a relative path with the current working directory, and returning
	* an absolute path unchanged.
	*/
	Link get absolute;

	/**
	* Gets the target of the link. Returns a future that completes with
	* the path to the target.
	*
	* If the returned target is a relative path, it is relative to the
	* directory containing the link.
	*
	* If the link does not exist, or is not a link, the future completes with
	* a LinkException.
	*/
	Future<String> target();

	/**
	* Synchronously gets the target of the link. Returns the path to the target.
	*
	* If the returned target is a relative path, it is relative to the
	* directory containing the link.
	*
	* If the link does not exist, or is not a link, throws a LinkException.
	*/
	String targetSync();
	}


	class _Link extends FileSystemEntity implements Link {
	final String path;

	_Link(String this.path) {
	if (path is! String) {
	throw new ArgumentError('${Error.safeToString(path)} '
	'is not a String');
	}
	}


	String toString() => "Link: '$path'";

	Future<bool> exists() => FileSystemEntity.isLink(path);

	bool existsSync() => FileSystemEntity.isLinkSync(path);

	Link get absolute => new Link(_absolutePath);

	Future<FileStat> stat() => FileStat.stat(path);

	FileStat statSync() => FileStat.statSync(path);

	Future<Link> create(String target) {
	if (Platform.operatingSystem == 'windows') {
	target = _makeWindowsLinkTarget(target);
	}
	return _IOService.dispatch(_FILE_CREATE_LINK, [path, target])
	.then((response) {
	if (_isErrorResponse(response)) {
	throw _exceptionFromResponse(
	response, "Cannot create link to target '$target'", path);
	}
	return this;
	});
	}

	void createSync(String target) {
	if (Platform.operatingSystem == 'windows') {
	target = _makeWindowsLinkTarget(target);
	}
	var result = _File._createLink(path, target);
	throwIfError(result, "Cannot create link", path);
	}

	// Put target into the form "\??\C:\my\target\dir".
	String _makeWindowsLinkTarget(String target) {
	Uri base = new Uri.file('${Directory.current.path}\\');
	Uri link = new Uri.file(path);
	Uri destination = new Uri.file(target);
	String result = base.resolveUri(link).resolveUri(destination).toFilePath();
	if (result.length > 3 && result[1] == ':' && result[2] == '\\') {
	return '\\??\\$result';
	} else {
	throw new LinkException(
	'Target $result of Link.create on Windows cannot be converted' +
	' to start with a drive letter. Unexpected error.');
	}
	}

	void updateSync(String target) {
	// TODO(12414): Replace with atomic update, where supported by platform.
	// Atomically changing a link can be done by creating the new link, with
	// a different name, and using the rename() posix call to move it to
	// the old name atomically.
	deleteSync();
	createSync(target);
	}

	Future<Link> update(String target) {
	// TODO(12414): Replace with atomic update, where supported by platform.
	// Atomically changing a link can be done by creating the new link, with
	// a different name, and using the rename() posix call to move it to
	// the old name atomically.
	return delete().then((_) => create(target));
	}

	Future<Link> _delete({bool recursive: false}) {
	if (recursive) {
	return new Directory(path).delete(recursive: true).then((_) => this);
	}
	return _IOService.dispatch(_FILE_DELETE_LINK, [path]).then((response) {
	if (_isErrorResponse(response)) {
	throw _exceptionFromResponse(response, "Cannot delete link", path);
	}
	return this;
	});
	}

	void _deleteSync({bool recursive: false}) {
	if (recursive) {
	return new Directory(path).deleteSync(recursive: true);
	}
	var result = _File._deleteLinkNative(path);
	throwIfError(result, "Cannot delete link", path);
	}

	Future<Link> rename(String newPath) {
	return _IOService.dispatch(_FILE_RENAME_LINK, [path, newPath])
	.then((response) {
	if (_isErrorResponse(response)) {
	throw _exceptionFromResponse(
	response, "Cannot rename link to '$newPath'", path);
	}
	return new Link(newPath);
	});
	}

	Link renameSync(String newPath) {
	var result = _File._renameLink(path, newPath);
	throwIfError(result, "Cannot rename link '$path' to '$newPath'");
	return new Link(newPath);
	}

	Future<String> target() {
	return _IOService.dispatch(_FILE_LINK_TARGET, [path]).then((response) {
	if (_isErrorResponse(response)) {
	throw _exceptionFromResponse(
	response, "Cannot get target of link", path);
	}
	return response;
	});
	}

	String targetSync() {
	var result = _File._linkTarget(path);
	throwIfError(result, "Cannot read link", path);
	return result;
	}

	static throwIfError(Object result, String msg, [String path = ""]) {
	if (result is OSError) {
	throw new LinkException(msg, path, result);
	}
	}

	bool _isErrorResponse(response) {
	return response is List && response[0] != _SUCCESS_RESPONSE;
	}

	_exceptionFromResponse(response, String message, String path) {
	assert(_isErrorResponse(response));
	switch (response[_ERROR_RESPONSE_ERROR_TYPE]) {
	case _ILLEGAL_ARGUMENT_RESPONSE:
	return new ArgumentError();
	case _OSERROR_RESPONSE:
	var err = new OSError(response[_OSERROR_RESPONSE_MESSAGE],
	response[_OSERROR_RESPONSE_ERROR_CODE]);
	return new LinkException(message, path, err);
	default:
	return new Exception("Unknown error");
	}
	}
	}


	class LinkException implements IOException {
	const LinkException([String this.message = "",
	String this.path = "",
	OSError this.osError = null]);
	String toString() {
	StringBuffer sb = new StringBuffer();
	sb.write("LinkException");
	if (!message.isEmpty) {
	sb.write(": $message");
	if (path != null) {
	sb.write(", path = $path");
	}
	if (osError != null) {
	sb.write(" ($osError)");
	}
	} else if (osError != null) {
	sb.write(": $osError");
	if (path != null) {
	sb.write(", path = $path");
	}
	}
	return sb.toString();
	}
	final String message;
	final String path;
	final OSError osError;
	}