Delete file on multipart cancel

This commit makes sure that the temporary file used for multipart
storage is deleted when the source stream is malformed or cancelled.

Closes gh-28740

spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.io.IOException;
 import java.nio.channels.Channel;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.http.HttpHeaders;
@@ -91,4 +93,12 @@ abstract class MultipartUtils {
 		}
 	}
 
+	public static void deleteFile(Path file) {
+		try {
+			Files.delete(file);
+		}
+		catch (IOException ignore) {
+		}
+	}
+
 }

spring-web/src/main/java/org/springframework/http/codec/multipart/PartGenerator.java

@@ -609,6 +609,7 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 			}
 			else {
 				MultipartUtils.closeChannel(newState.channel);
+				MultipartUtils.deleteFile(newState.file);
 				this.content.forEach(DataBufferUtils::release);
 			}
 		}
@@ -640,6 +641,8 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 
 		private volatile boolean closeOnDispose = true;
 
+		private volatile boolean deleteOnDispose = true;
+
 
 		public IdleFileState(WritingFileState state) {
 			this.headers = state.headers;
@@ -654,16 +657,20 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 			if (PartGenerator.this.maxDiskUsagePerPart == -1 || count <= PartGenerator.this.maxDiskUsagePerPart) {
 
 				this.closeOnDispose = false;
+				this.deleteOnDispose = false;
 				WritingFileState newState = new WritingFileState(this);
 				if (changeState(this, newState)) {
 					newState.writeBuffer(dataBuffer);
 				}
 				else {
 					MultipartUtils.closeChannel(this.channel);
+					MultipartUtils.deleteFile(this.file);
 					DataBufferUtils.release(dataBuffer);
 				}
 			}
 			else {
+				MultipartUtils.closeChannel(this.channel);
+				MultipartUtils.deleteFile(this.file);
 				DataBufferUtils.release(dataBuffer);
 				emitError(new DataBufferLimitException(
 						"Part exceeded the disk usage limit of " + PartGenerator.this.maxDiskUsagePerPart +
@@ -674,6 +681,7 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 		@Override
 		public void partComplete(boolean finalPart) {
 			MultipartUtils.closeChannel(this.channel);
+			this.deleteOnDispose = false;
 			emitPart(DefaultParts.part(this.headers, this.file, PartGenerator.this.blockingOperationScheduler));
 			if (finalPart) {
 				emitComplete();
@@ -685,6 +693,9 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 			if (this.closeOnDispose) {
 				MultipartUtils.closeChannel(this.channel);
 			}
+			if (this.deleteOnDispose) {
+				MultipartUtils.deleteFile(this.file);
+			}
 		}
 
 
@@ -710,6 +721,8 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 
 		private volatile boolean finalPart;
 
+		private volatile boolean disposed;
+
 
 		public WritingFileState(CreateFileState state, Path file, WritableByteChannel channel) {
 			this.headers = state.headers;
@@ -761,11 +774,15 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 			if (this.completed) {
 				newState.partComplete(this.finalPart);
 			}
+			else if (this.disposed) {
+				newState.dispose();
+			}
 			else if (changeState(this, newState)) {
 				requestToken();
 			}
 			else {
 				MultipartUtils.closeChannel(this.channel);
+				MultipartUtils.deleteFile(this.file);
 			}
 		}
 
@@ -779,6 +796,8 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 				return Mono.empty();
 			}
 			catch (IOException ex) {
+				MultipartUtils.closeChannel(this.channel);
+				MultipartUtils.deleteFile(this.file);
 				return Mono.error(ex);
 			}
 			finally {
@@ -786,6 +805,12 @@ final class PartGenerator extends BaseSubscriber<MultipartParser.Token> {
 			}
 		}
 
+		@Override
+		public void dispose() {
+			this.disposed = true;
+		}
+
+
 		@Override
 		public String toString() {
 			return "WRITE-FILE";