| /* |
| * Copyright (c) 2007, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
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| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
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| */ |
| |
| package java.nio.file.attribute; |
| |
| import java.nio.file.*; |
| import java.util.Set; |
| import java.io.IOException; |
| |
| /** |
| * A file attribute view that provides a view of the file attributes commonly |
| * associated with files on file systems used by operating systems that implement |
| * the Portable Operating System Interface (POSIX) family of standards. |
| * |
| * <p> Operating systems that implement the <a href="http://www.opengroup.org"> |
| * POSIX</a> family of standards commonly use file systems that have a |
| * file <em>owner</em>, <em>group-owner</em>, and related <em>access |
| * permissions</em>. This file attribute view provides read and write access |
| * to these attributes. |
| * |
| * <p> The {@link #readAttributes() readAttributes} method is used to read the |
| * file's attributes. The file {@link PosixFileAttributes#owner() owner} is |
| * represented by a {@link UserPrincipal} that is the identity of the file owner |
| * for the purposes of access control. The {@link PosixFileAttributes#group() |
| * group-owner}, represented by a {@link GroupPrincipal}, is the identity of the |
| * group owner, where a group is an identity created for administrative purposes |
| * so as to determine the access rights for the members of the group. |
| * |
| * <p> The {@link PosixFileAttributes#permissions() permissions} attribute is a |
| * set of access permissions. This file attribute view provides access to the nine |
| * permission defined by the {@link PosixFilePermission} class. |
| * These nine permission bits determine the <em>read</em>, <em>write</em>, and |
| * <em>execute</em> access for the file owner, group, and others (others |
| * meaning identities other than the owner and members of the group). Some |
| * operating systems and file systems may provide additional permission bits |
| * but access to these other bits is not defined by this class in this release. |
| * |
| * <p> <b>Usage Example:</b> |
| * Suppose we need to print out the owner and access permissions of a file: |
| * <pre> |
| * Path file = ... |
| * PosixFileAttributes attrs = Files.getFileAttributeView(file, PosixFileAttributeView.class) |
| * .readAttributes(); |
| * System.out.format("%s %s%n", |
| * attrs.owner().getName(), |
| * PosixFilePermissions.toString(attrs.permissions())); |
| * </pre> |
| * |
| * <h2> Dynamic Access </h2> |
| * <p> Where dynamic access to file attributes is required, the attributes |
| * supported by this attribute view are as defined by {@link |
| * BasicFileAttributeView} and {@link FileOwnerAttributeView}, and in addition, |
| * the following attributes are supported: |
| * <blockquote> |
| * <table class="striped"> |
| * <caption style="display:none">Supported attributes</caption> |
| * <thead> |
| * <tr> |
| * <th> Name </th> |
| * <th> Type </th> |
| * </tr> |
| * </thead> |
| * <tbody> |
| * <tr> |
| * <td> "permissions" </td> |
| * <td> {@link Set}<{@link PosixFilePermission}> </td> |
| * </tr> |
| * <tr> |
| * <td> "group" </td> |
| * <td> {@link GroupPrincipal} </td> |
| * </tr> |
| * </tbody> |
| * </table> |
| * </blockquote> |
| * |
| * <p> The {@link Files#getAttribute getAttribute} method may be used to read |
| * any of these attributes, or any of the attributes defined by {@link |
| * BasicFileAttributeView} as if by invoking the {@link #readAttributes |
| * readAttributes()} method. |
| * |
| * <p> The {@link Files#setAttribute setAttribute} method may be used to update |
| * the file's last modified time, last access time or create time attributes as |
| * defined by {@link BasicFileAttributeView}. It may also be used to update |
| * the permissions, owner, or group-owner as if by invoking the {@link |
| * #setPermissions setPermissions}, {@link #setOwner setOwner}, and {@link |
| * #setGroup setGroup} methods respectively. |
| * |
| * <h2> Setting Initial Permissions </h2> |
| * <p> Implementations supporting this attribute view may also support setting |
| * the initial permissions when creating a file or directory. The |
| * initial permissions are provided to the {@link Files#createFile createFile} |
| * or {@link Files#createDirectory createDirectory} methods as a {@link |
| * FileAttribute} with {@link FileAttribute#name name} {@code "posix:permissions"} |
| * and a {@link FileAttribute#value value} that is the set of permissions. The |
| * following example uses the {@link PosixFilePermissions#asFileAttribute |
| * asFileAttribute} method to construct a {@code FileAttribute} when creating a |
| * file: |
| * |
| * <pre> |
| * Path path = ... |
| * Set<PosixFilePermission> perms = |
| * EnumSet.of(OWNER_READ, OWNER_WRITE, OWNER_EXECUTE, GROUP_READ); |
| * Files.createFile(path, PosixFilePermissions.asFileAttribute(perms)); |
| * </pre> |
| * |
| * <p> When the access permissions are set at file creation time then the actual |
| * value of the permissions may differ that the value of the attribute object. |
| * The reasons for this are implementation specific. On UNIX systems, for |
| * example, a process has a <em>umask</em> that impacts the permission bits |
| * of newly created files. Where an implementation supports the setting of |
| * the access permissions, and the underlying file system supports access |
| * permissions, then it is required that the value of the actual access |
| * permissions will be equal or less than the value of the attribute |
| * provided to the {@link Files#createFile createFile} or {@link |
| * Files#createDirectory createDirectory} methods. In other words, the file may |
| * be more secure than requested. |
| * |
| * @since 1.7 |
| */ |
| |
| public interface PosixFileAttributeView |
| extends BasicFileAttributeView, FileOwnerAttributeView |
| { |
| /** |
| * Returns the name of the attribute view. Attribute views of this type |
| * have the name {@code "posix"}. |
| */ |
| @Override |
| String name(); |
| |
| /** |
| * @throws IOException {@inheritDoc} |
| * @throws SecurityException |
| * In the case of the default provider, a security manager is |
| * installed, and it denies |
| * {@link RuntimePermission}{@code ("accessUserInformation")} |
| * or its {@link SecurityManager#checkRead(String) checkRead} method |
| * denies read access to the file. |
| */ |
| @Override |
| PosixFileAttributes readAttributes() throws IOException; |
| |
| /** |
| * Updates the file permissions. |
| * |
| * @param perms |
| * the new set of permissions |
| * |
| * @throws ClassCastException |
| * if the sets contains elements that are not of type {@code |
| * PosixFilePermission} |
| * @throws IOException |
| * if an I/O error occurs |
| * @throws SecurityException |
| * In the case of the default provider, a security manager is |
| * installed, and it denies |
| * {@link RuntimePermission}{@code ("accessUserInformation")} |
| * or its {@link SecurityManager#checkWrite(String) checkWrite} |
| * method denies write access to the file. |
| */ |
| void setPermissions(Set<PosixFilePermission> perms) throws IOException; |
| |
| /** |
| * Updates the file group-owner. |
| * |
| * @param group |
| * the new file group-owner |
| * |
| * @throws IOException |
| * if an I/O error occurs |
| * @throws SecurityException |
| * In the case of the default provider, and a security manager is |
| * installed, it denies |
| * {@link RuntimePermission}{@code ("accessUserInformation")} |
| * or its {@link SecurityManager#checkWrite(String) checkWrite} |
| * method denies write access to the file. |
| */ |
| void setGroup(GroupPrincipal group) throws IOException; |
| } |
