com.github.fge.filesystem.posix.PosixModes Maven / Gradle / Ivy

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package com.github.fge.filesystem.posix;

import com.github.fge.filesystem.exceptions.InvalidIntModeException;

import javax.annotation.Nonnull;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.PosixFilePermission;
import java.util.EnumSet;
import java.util.Set;

public final class PosixModes
{
    // TODO: hardcoded; but POSIX permissions will not change anytime soon
    static final PosixFilePermission[] PERMISSIONS
        = PosixFilePermission.values();

    private static final int PERMISSIONS_LENGTH = PERMISSIONS.length;
    private static final int INT_MODE_MAX = (1 << PERMISSIONS_LENGTH) - 1;

    private PosixModes()
    {
        throw new Error("nice try!");
    }

    /**
     * Convert an integer into a set of {@link PosixFilePermission}s
     *
     * Note that this method will not try and read {@code 755} "in octal";
     * you must prefix your integer with {@code 0} so that the
     * constant be octal, as in {@code 0755}.
     *
     * @param intMode the mode
     * @return a set of POSIX permissions
     * @throws InvalidIntModeException invalid integer mode
     *
     * @see Files#setPosixFilePermissions(Path, Set)
     */
    @Nonnull
    public static Set intModeToPosix(int intMode)
    {
        if ((intMode & INT_MODE_MAX) != intMode)
            throw new InvalidIntModeException();

        final Set set
            = EnumSet.noneOf(PosixFilePermission.class);

        for (int i = 0; i < PERMISSIONS_LENGTH; i++) {
            if ((intMode & 1) == 1)
                set.add(PERMISSIONS[PERMISSIONS_LENGTH - i - 1]);
            /*
             * We're OK with >> instead of >>>, the sign bit will never be set
             */
            intMode >>= 1;
        }

        return set;
    }
}