Ignore FileNotFoundExceptions on Files#walk usages. Fixes: #666

Author: TBlueF

core/src/main/java/de/bluecolored/bluemap/core/resources/pack/Pack.java

@@ -30,6 +30,7 @@
 import de.bluecolored.bluemap.core.resources.ResourcePath;
 import de.bluecolored.bluemap.core.resources.adapter.ResourcesGson;
 import de.bluecolored.bluemap.core.resources.pack.resourcepack.ResourcePack;
+import de.bluecolored.bluemap.core.util.FileHelper;
 import de.bluecolored.bluemap.core.util.Key;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
@@ -182,7 +183,7 @@ protected static Stream<Path> walk(Path root) {
         if (!Files.exists(root)) return Stream.empty();
         if (Files.isRegularFile(root)) return Stream.of(root);
         try {
-            return Files.walk(root);
+            return FileHelper.walk(root);
         } catch (IOException ex) {
             throw new CompletionException(ex);
         }

core/src/main/java/de/bluecolored/bluemap/core/storage/file/FileGridStorage.java

@@ -28,6 +28,7 @@
 import de.bluecolored.bluemap.core.storage.ItemStorage;
 import de.bluecolored.bluemap.core.storage.compression.CompressedInputStream;
 import de.bluecolored.bluemap.core.storage.compression.Compression;
+import de.bluecolored.bluemap.core.util.FileHelper;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import org.jetbrains.annotations.Nullable;
@@ -77,11 +78,10 @@ public ItemStorage cell(int x, int z) {
         return new FileItemStorage(getItemPath(x, z), compression, atomic);
     }
 
-    @SuppressWarnings("resource")
     @Override
     public Stream<Cell> stream() throws IOException {
         if (!Files.exists(root)) return Stream.empty();
-        return Files.walk(root)
+        return FileHelper.walk(root)
                 .filter(Files::isRegularFile)
                 .<Cell>map(itemPath -> {
                     Path path = itemPath;

core/src/main/java/de/bluecolored/bluemap/core/storage/file/FileMapStorage.java

@@ -31,6 +31,7 @@
 import de.bluecolored.bluemap.core.storage.MapStorage;
 import de.bluecolored.bluemap.core.storage.compression.Compression;
 import de.bluecolored.bluemap.core.util.DeletingPathVisitor;
+import de.bluecolored.bluemap.core.util.FileHelper;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -154,7 +155,7 @@ public void delete(DoublePredicate onProgress) throws IOException {
         final LinkedList<Path> subFiles;
 
         // collect sub-files to be able to provide progress-updates
-        try (Stream<Path> pathStream = Files.walk(root, 3)) {
+        try (Stream<Path> pathStream = FileHelper.walk(root, 3)) {
             subFiles = pathStream.collect(Collectors.toCollection(LinkedList::new));
         }
         subFilesCount = subFiles.size();

core/src/main/java/de/bluecolored/bluemap/core/util/FileHelper.java

@@ -34,7 +34,11 @@
 import java.nio.file.WatchService;
 import java.nio.file.*;
 import java.nio.file.attribute.FileAttribute;
+import java.util.Spliterator;
+import java.util.Spliterators;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
 
 public class FileHelper {
 
@@ -140,4 +144,30 @@ public static boolean awaitExistence(Path path, long timeout, TimeUnit unit) thr
         }
     }
 
+    /**
+     * Adapted version of {@link Files#walk(Path, int, FileVisitOption...)}.
+     * This version ignores NoSuchFileException if they occur while iterating the file-tree.
+     */
+    public static Stream<Path> walk(Path start, int maxDepth, FileVisitOption... options) throws IOException {
+        FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options);
+        try {
+            Spliterator<FileTreeWalker.Event> spliterator =
+                    Spliterators.spliteratorUnknownSize(iterator, Spliterator.DISTINCT);
+            return StreamSupport.stream(spliterator, false)
+                    .onClose(iterator::close)
+                    .map(FileTreeWalker.Event::file);
+        } catch (Error|RuntimeException e) {
+            iterator.close();
+            throw e;
+        }
+    }
+
+    /**
+     * Adapted version of {@link Files#walk(Path, FileVisitOption...)} .
+     * This version ignores NoSuchFileException if they occur while iterating the file-tree.
+     */
+    public static Stream<Path> walk(Path start, FileVisitOption... options) throws IOException {
+        return walk(start, Integer.MAX_VALUE, options);
+    }
+
 }

core/src/main/java/de/bluecolored/bluemap/core/util/FileTreeIterator.java

@@ -0,0 +1,144 @@
+/*
+ * This file is part of BlueMap, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+/*
+ * Copyright (c) 2013, 2023, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package de.bluecolored.bluemap.core.util;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.FileVisitOption;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ * Adapted version of java.nio.file.FileTreeIterator.
+ * This version ignores NoSuchFileException if they occur while iterating the file-tree.
+ * Required to implement FileHelper#walk
+ */
+class FileTreeIterator implements Iterator<FileTreeWalker.Event>, Closeable {
+    private final FileTreeWalker walker;
+    private FileTreeWalker.Event next;
+
+    /**
+     * Creates a new iterator to walk the file tree starting at the given file.
+     *
+     * @throws  IllegalArgumentException
+     *          if {@code maxDepth} is negative
+     * @throws  IOException
+     *          if an I/O errors occurs opening the starting file
+     * @throws  SecurityException
+     *          if the security manager denies access to the starting file
+     * @throws  NullPointerException
+     *          if {@code start} or {@code options} is {@code null} or
+     *          the options array contains a {@code null} element
+     */
+    FileTreeIterator(Path start, int maxDepth, FileVisitOption... options)
+            throws IOException
+    {
+        this.walker = new FileTreeWalker(List.of(options), maxDepth);
+        this.next = walker.walk(start);
+        assert next.type() == FileTreeWalker.EventType.ENTRY ||
+                next.type() == FileTreeWalker.EventType.START_DIRECTORY;
+
+        // IOException if there is a problem accessing the starting file
+        IOException ioe = next.ioeException();
+        if (ioe != null)
+            throw ioe;
+    }
+
+    private void fetchNextIfNeeded() {
+        if (next == null) {
+            FileTreeWalker.Event ev = walker.next();
+            while (ev != null) {
+                IOException ioe = ev.ioeException();
+                if (ioe != null) {
+                    if (ioe instanceof NoSuchFileException)
+                        continue; // ignore NoSuchFileExceptions, and just continue iterating
+                    throw new UncheckedIOException(ioe);
+                }
+
+                // END_DIRECTORY events are ignored
+                if (ev.type() != FileTreeWalker.EventType.END_DIRECTORY) {
+                    next = ev;
+                    return;
+                }
+                ev = walker.next();
+            }
+        }
+    }
+
+    @Override
+    public boolean hasNext() {
+        if (!walker.isOpen())
+            throw new IllegalStateException();
+        fetchNextIfNeeded();
+        return next != null;
+    }
+
+    @Override
+    public FileTreeWalker.Event next() {
+        if (!walker.isOpen())
+            throw new IllegalStateException();
+        fetchNextIfNeeded();
+        if (next == null)
+            throw new NoSuchElementException();
+        FileTreeWalker.Event result = next;
+        next = null;
+        return result;
+    }
+
+    @Override
+    public void close() {
+        walker.close();
+    }
+
+}