java.nio.file.attribute.PosixFilePermissions Maven / Gradle / Ivy
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/*
* Copyright (c) 2007, 2011, 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 java.nio.file.attribute;
import static java.nio.file.attribute.PosixFilePermission.*;
import java.util.*;
/**
* This class consists exclusively of static methods that operate on sets of
* {@link PosixFilePermission} objects.
*
* @since 1.7
*/
public final class PosixFilePermissions {
private PosixFilePermissions() { }
// Write string representation of permission bits to {@code sb}.
private static void writeBits(StringBuilder sb, boolean r, boolean w, boolean x) {
if (r) {
sb.append('r');
} else {
sb.append('-');
}
if (w) {
sb.append('w');
} else {
sb.append('-');
}
if (x) {
sb.append('x');
} else {
sb.append('-');
}
}
/**
* Returns the {@code String} representation of a set of permissions. It
* is guaranteed that the returned {@code String} can be parsed by the
* {@link #fromString} method.
*
* If the set contains {@code null} or elements that are not of type
* {@code PosixFilePermission} then these elements are ignored.
*
* @param perms
* the set of permissions
*
* @return the string representation of the permission set
*/
public static String toString(Set perms) {
StringBuilder sb = new StringBuilder(9);
writeBits(sb, perms.contains(OWNER_READ), perms.contains(OWNER_WRITE),
perms.contains(OWNER_EXECUTE));
writeBits(sb, perms.contains(GROUP_READ), perms.contains(GROUP_WRITE),
perms.contains(GROUP_EXECUTE));
writeBits(sb, perms.contains(OTHERS_READ), perms.contains(OTHERS_WRITE),
perms.contains(OTHERS_EXECUTE));
return sb.toString();
}
private static boolean isSet(char c, char setValue) {
if (c == setValue)
return true;
if (c == '-')
return false;
throw new IllegalArgumentException("Invalid mode");
}
private static boolean isR(char c) { return isSet(c, 'r'); }
private static boolean isW(char c) { return isSet(c, 'w'); }
private static boolean isX(char c) { return isSet(c, 'x'); }
/**
* Returns the set of permissions corresponding to a given {@code String}
* representation.
*
* The {@code perms} parameter is a {@code String} representing the
* permissions. It has 9 characters that are interpreted as three sets of
* three. The first set refers to the owner's permissions; the next to the
* group permissions and the last to others. Within each set, the first
* character is {@code 'r'} to indicate permission to read, the second
* character is {@code 'w'} to indicate permission to write, and the third
* character is {@code 'x'} for execute permission. Where a permission is
* not set then the corresponding character is set to {@code '-'}.
*
*
Usage Example:
* Suppose we require the set of permissions that indicate the owner has read,
* write, and execute permissions, the group has read and execute permissions
* and others have none.
*
* Set<PosixFilePermission> perms = PosixFilePermissions.fromString("rwxr-x---");
*
*
* @param perms
* string representing a set of permissions
*
* @return the resulting set of permissions
*
* @throws IllegalArgumentException
* if the string cannot be converted to a set of permissions
*
* @see #toString(Set)
*/
public static Set fromString(String perms) {
if (perms.length() != 9)
throw new IllegalArgumentException("Invalid mode");
Set result = EnumSet.noneOf(PosixFilePermission.class);
if (isR(perms.charAt(0))) result.add(OWNER_READ);
if (isW(perms.charAt(1))) result.add(OWNER_WRITE);
if (isX(perms.charAt(2))) result.add(OWNER_EXECUTE);
if (isR(perms.charAt(3))) result.add(GROUP_READ);
if (isW(perms.charAt(4))) result.add(GROUP_WRITE);
if (isX(perms.charAt(5))) result.add(GROUP_EXECUTE);
if (isR(perms.charAt(6))) result.add(OTHERS_READ);
if (isW(perms.charAt(7))) result.add(OTHERS_WRITE);
if (isX(perms.charAt(8))) result.add(OTHERS_EXECUTE);
return result;
}
/**
* Creates a {@link FileAttribute}, encapsulating a copy of the given file
* permissions, suitable for passing to the {@link java.nio.file.Files#createFile
* createFile} or {@link java.nio.file.Files#createDirectory createDirectory}
* methods.
*
* @param perms
* the set of permissions
*
* @return an attribute encapsulating the given file permissions with
* {@link FileAttribute#name name} {@code "posix:permissions"}
*
* @throws ClassCastException
* if the set contains elements that are not of type {@code
* PosixFilePermission}
*/
public static FileAttribute>
asFileAttribute(Set perms)
{
// copy set and check for nulls (CCE will be thrown if an element is not
// a PosixFilePermission)
perms = new HashSet<>(perms);
for (PosixFilePermission p: perms) {
if (p == null)
throw new NullPointerException();
}
final Set value = perms;
return new FileAttribute<>() {
@Override
public String name() {
return "posix:permissions";
}
@Override
public Set value() {
return Collections.unmodifiableSet(value);
}
};
}
}