src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java

/*
 * Copyright (c) 2008, 2024, 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
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package sun.nio.fs;

import java.io.IOException;
import java.nio.file.*;
import java.nio.file.attribute.*;
import java.util.*;
import java.util.concurrent.TimeUnit;

import static sun.nio.fs.UnixConstants.*;
import static sun.nio.fs.UnixNativeDispatcher.*;

class UnixFileAttributeViews {

    static class Basic extends AbstractBasicFileAttributeView {
        protected final UnixPath file;
        protected final boolean followLinks;

        Basic(UnixPath file, boolean followLinks) {
            this.file = file;
            this.followLinks = followLinks;
        }

        @Override
        public BasicFileAttributes readAttributes() throws IOException {
            try {
                 UnixFileAttributes attrs = UnixFileAttributes.get(file, followLinks);
                 return attrs.asBasicFileAttributes();
            } catch (UnixException x) {
                if (x.errno() == ENOTDIR) {
                    x.setError(ENOENT);
                }
                x.rethrowAsIOException(file);
                return null;    // keep compiler happy
            }
        }

        @Override
        public void setTimes(FileTime lastModifiedTime,
                             FileTime lastAccessTime,
                             FileTime createTime) throws IOException
        {
            // null => don't change
            if (lastModifiedTime == null && lastAccessTime == null) {
                // no effect
                return;
            }

            // use a file descriptor if possible to avoid a race due to
            // accessing a path more than once as the file at that path could
            // change.
            // if path is a symlink, then the open should fail with ELOOP and
            // the path will be used instead of the file descriptor.
            int fd = -1;
            try {
                fd = file.openForAttributeAccess(followLinks);
            } catch (UnixException x) {
                if (!(x.errno() == ENXIO || (x.errno() == ELOOP))) {
                    x.rethrowAsIOException(file);
                }
            }

            try {
                // if not changing both attributes then need existing attributes
                if (lastModifiedTime == null || lastAccessTime == null) {
                    try {
                        UnixFileAttributes attrs = fd >= 0 ?
                            UnixFileAttributes.get(fd) :
                            UnixFileAttributes.get(file, followLinks);
                        if (lastModifiedTime == null)
                            lastModifiedTime = attrs.lastModifiedTime();
                        if (lastAccessTime == null)
                            lastAccessTime = attrs.lastAccessTime();
                    } catch (UnixException x) {
                        x.rethrowAsIOException(file);
                    }
                }

                // update times
                long modValue = lastModifiedTime.to(TimeUnit.NANOSECONDS);
                long accessValue= lastAccessTime.to(TimeUnit.NANOSECONDS);

                boolean retry = false;
                try {
                    if (fd >= 0)
                        futimens(fd, accessValue, modValue);
                    else
                        utimensat(AT_FDCWD, file, accessValue, modValue,
                                  followLinks ? 0 : AT_SYMLINK_NOFOLLOW);
                } catch (UnixException x) {
                    // if utimensat fails with EINVAL and one/both of
                    // the times is negative then we adjust the value to the
                    // epoch and retry.
                    if (x.errno() == EINVAL &&
                        (modValue < 0L || accessValue < 0L)) {
                        retry = true;
                    } else {
                        x.rethrowAsIOException(file);
                    }
                }
                if (retry) {
                    if (modValue < 0L) modValue = 0L;
                    if (accessValue < 0L) accessValue= 0L;
                    try {
                        if (fd >= 0)
                            futimens(fd, accessValue, modValue);
                        else
                            utimensat(AT_FDCWD, file, accessValue, modValue,
                                      followLinks ? 0 : AT_SYMLINK_NOFOLLOW);
                    } catch (UnixException x) {
                        x.rethrowAsIOException(file);
                    }
                }
            } finally {
                close(fd, e -> null);
            }
        }
    }

    static class Posix extends Basic implements PosixFileAttributeView {
        private static final String PERMISSIONS_NAME = "permissions";
        private static final String OWNER_NAME = "owner";
        private static final String GROUP_NAME = "group";

        // the names of the posix attributes (includes basic)
        static final Set<String> posixAttributeNames =
            Util.newSet(basicAttributeNames, PERMISSIONS_NAME, OWNER_NAME, GROUP_NAME);

        Posix(UnixPath file, boolean followLinks) {
            super(file, followLinks);
        }

        @Override
        public String name() {
            return "posix";
        }

        @Override
        @SuppressWarnings("unchecked")
        public void setAttribute(String attribute, Object value)
            throws IOException
        {
            if (attribute.equals(PERMISSIONS_NAME)) {
                setPermissions((Set<PosixFilePermission>)value);
                return;
            }
            if (attribute.equals(OWNER_NAME)) {
                setOwner((UserPrincipal)value);
                return;
            }
            if (attribute.equals(GROUP_NAME)) {
                setGroup((GroupPrincipal)value);
                return;
            }
            super.setAttribute(attribute, value);
        }

        /**
         * Invoked by readAttributes or sub-classes to add all matching posix
         * attributes to the builder
         */
        final void addRequestedPosixAttributes(PosixFileAttributes attrs,
                                               AttributesBuilder builder)
        {
            addRequestedBasicAttributes(attrs, builder);
            if (builder.match(PERMISSIONS_NAME))
                builder.add(PERMISSIONS_NAME, attrs.permissions());
            if (builder.match(OWNER_NAME))
                 builder.add(OWNER_NAME, attrs.owner());
            if (builder.match(GROUP_NAME))
                builder.add(GROUP_NAME, attrs.group());
        }

        @Override
        public Map<String,Object> readAttributes(String[] requested)
            throws IOException
        {
            AttributesBuilder builder =
                AttributesBuilder.create(posixAttributeNames, requested);
            PosixFileAttributes attrs = readAttributes();
            addRequestedPosixAttributes(attrs, builder);
            return builder.unmodifiableMap();
        }

        @Override
        public UnixFileAttributes readAttributes() throws IOException {
            try {
                 return UnixFileAttributes.get(file, followLinks);
            } catch (UnixException x) {
                if (x.errno() == ENOTDIR) {
                    x.setError(ENOENT);
                }
                x.rethrowAsIOException(file);
                return null;    // keep compiler happy
            }
        }

        // chmod
        final void setMode(int mode) throws IOException {
            if (followLinks) {
                try {
                    chmod(file, mode);
                } catch (UnixException e) {
                    e.rethrowAsIOException(file);
                }
                return;
            }

            if (O_NOFOLLOW == 0) {
                throw new IOException("NOFOLLOW_LINKS is not supported on this platform");
            }

            int fd = -1;
            try {
                fd = open(file, O_RDONLY, O_NOFOLLOW);
            } catch (UnixException e1) {
                if (e1.errno() == EACCES) {
                    // retry with write access if there is no read permission
                    try {
                        fd = open(file, O_WRONLY, O_NOFOLLOW);
                    } catch (UnixException e2) {
                        e2.rethrowAsIOException(file);
                    }
                } else {
                    e1.rethrowAsIOException(file);
                }
            }

            try {
                try {
                    fchmod(fd, mode);
                } finally {
                    close(fd);
                }
            } catch (UnixException e) {
                e.rethrowAsIOException(file);
            }
        }

        // chown
        final void setOwners(int uid, int gid) throws IOException {
            try {
                if (followLinks) {
                    chown(file, uid, gid);
                } else {
                    lchown(file, uid, gid);
                }
            } catch (UnixException x) {
                x.rethrowAsIOException(file);
            }
        }

        @Override
        public void setPermissions(Set<PosixFilePermission> perms)
            throws IOException
        {
            setMode(UnixFileModeAttribute.toUnixMode(perms));
        }

        @Override
        public void setOwner(UserPrincipal owner)
            throws IOException
        {
            if (owner == null)
                throw new NullPointerException("'owner' is null");
            if (!(owner instanceof UnixUserPrincipals.User))
                throw new ProviderMismatchException();
            if (owner instanceof UnixUserPrincipals.Group)
                throw new IOException("'owner' parameter can't be a group");
            int uid = ((UnixUserPrincipals.User)owner).uid();
            setOwners(uid, -1);
        }

        @Override
        public UserPrincipal getOwner() throws IOException {
            return readAttributes().owner();
        }

        @Override
        public void setGroup(GroupPrincipal group)
            throws IOException
        {
            if (group == null)
                throw new NullPointerException("'owner' is null");
            if (!(group instanceof UnixUserPrincipals.Group))
                throw new ProviderMismatchException();
            int gid = ((UnixUserPrincipals.Group)group).gid();
            setOwners(-1, gid);
        }
    }

    static class Unix extends Posix {
        private static final String MODE_NAME = "mode";
        private static final String INO_NAME = "ino";
        private static final String DEV_NAME = "dev";
        private static final String RDEV_NAME = "rdev";
        private static final String NLINK_NAME = "nlink";
        private static final String UID_NAME = "uid";
        private static final String GID_NAME = "gid";
        private static final String CTIME_NAME = "ctime";

        // the names of the unix attributes (including posix)
        static final Set<String> unixAttributeNames =
            Util.newSet(posixAttributeNames,
                        MODE_NAME, INO_NAME, DEV_NAME, RDEV_NAME,
                        NLINK_NAME, UID_NAME, GID_NAME, CTIME_NAME);

        Unix(UnixPath file, boolean followLinks) {
            super(file, followLinks);
        }

        @Override
        public String name() {
            return "unix";
        }

        @Override
        public void setAttribute(String attribute, Object value)
            throws IOException
        {
            if (attribute.equals(MODE_NAME)) {
                setMode((Integer)value);
                return;
            }
            if (attribute.equals(UID_NAME)) {
                setOwners((Integer)value, -1);
                return;
            }
            if (attribute.equals(GID_NAME)) {
                setOwners(-1, (Integer)value);
                return;
            }
            super.setAttribute(attribute, value);
        }

        @Override
        public Map<String,Object> readAttributes(String[] requested)
            throws IOException
        {
            AttributesBuilder builder =
                AttributesBuilder.create(unixAttributeNames, requested);
            UnixFileAttributes attrs = readAttributes();
            addRequestedPosixAttributes(attrs, builder);
            if (builder.match(MODE_NAME))
                builder.add(MODE_NAME, attrs.mode());
            if (builder.match(INO_NAME))
                builder.add(INO_NAME, attrs.ino());
            if (builder.match(DEV_NAME))
                builder.add(DEV_NAME, attrs.dev());
            if (builder.match(RDEV_NAME))
                builder.add(RDEV_NAME, attrs.rdev());
            if (builder.match(NLINK_NAME))
                builder.add(NLINK_NAME, attrs.nlink());
            if (builder.match(UID_NAME))
                builder.add(UID_NAME, attrs.uid());
            if (builder.match(GID_NAME))
                builder.add(GID_NAME, attrs.gid());
            if (builder.match(CTIME_NAME))
                builder.add(CTIME_NAME, attrs.ctime());
            return builder.unmodifiableMap();
        }
    }

    static Basic createBasicView(UnixPath file, boolean followLinks) {
        return new Basic(file, followLinks);
    }

    static Posix createPosixView(UnixPath file, boolean followLinks) {
        return new Posix(file, followLinks);
    }

    static Unix createUnixView(UnixPath file, boolean followLinks) {
        return new Unix(file, followLinks);
    }

    static FileOwnerAttributeViewImpl createOwnerView(UnixPath file, boolean followLinks) {
        return new FileOwnerAttributeViewImpl(createPosixView(file, followLinks));
    }
}