Code/net/minecraft/world/level/validation/DirectoryValidator.java

package net.minecraft.world.level.validation;

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
import java.util.List;

public class DirectoryValidator {
    private final PathMatcher symlinkTargetAllowList;

    public DirectoryValidator(PathMatcher p_299405_) {
        this.symlinkTargetAllowList = p_299405_;
    }

    public void validateSymlink(Path p_289934_, List<ForbiddenSymlinkInfo> p_289972_) throws IOException {
        Path path = Files.readSymbolicLink(p_289934_);
        if (!this.symlinkTargetAllowList.matches(path)) {
            p_289972_.add(new ForbiddenSymlinkInfo(p_289934_, path));
        }
    }

    public List<ForbiddenSymlinkInfo> validateSymlink(Path p_299520_) throws IOException {
        List<ForbiddenSymlinkInfo> list = new ArrayList<>();
        this.validateSymlink(p_299520_, list);
        return list;
    }

    public List<ForbiddenSymlinkInfo> validateDirectory(Path p_301110_, boolean p_298035_) throws IOException {
        List<ForbiddenSymlinkInfo> list = new ArrayList<>();

        BasicFileAttributes basicfileattributes;
        try {
            basicfileattributes = Files.readAttributes(p_301110_, BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS);
        } catch (NoSuchFileException nosuchfileexception) {
            return list;
        }

        if (basicfileattributes.isRegularFile()) {
            throw new IOException("Path " + p_301110_ + " is not a directory");
        } else {
            if (basicfileattributes.isSymbolicLink()) {
                if (!p_298035_) {
                    this.validateSymlink(p_301110_, list);
                    return list;
                }

                p_301110_ = Files.readSymbolicLink(p_301110_);
            }

            this.validateKnownDirectory(p_301110_, list);
            return list;
        }
    }

    public void validateKnownDirectory(Path p_297387_, final List<ForbiddenSymlinkInfo> p_298980_) throws IOException {
        Files.walkFileTree(p_297387_, new SimpleFileVisitor<Path>() {
            private void validateSymlink(Path p_289935_, BasicFileAttributes p_289941_) throws IOException {
                if (p_289941_.isSymbolicLink()) {
                    DirectoryValidator.this.validateSymlink(p_289935_, p_298980_);
                }
            }

            public FileVisitResult preVisitDirectory(Path p_289946_, BasicFileAttributes p_289950_) throws IOException {
                this.validateSymlink(p_289946_, p_289950_);
                return super.preVisitDirectory(p_289946_, p_289950_);
            }

            public FileVisitResult visitFile(Path p_289986_, BasicFileAttributes p_289991_) throws IOException {
                this.validateSymlink(p_289986_, p_289991_);
                return super.visitFile(p_289986_, p_289991_);
            }
        });
    }
}