Merge branch '7.0.x'

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

@@ -546,6 +546,7 @@ final class MultipartParser extends BaseSubscriber<DataBuffer> {
 					// iterate over buffers in reverse order
 					DataBufferUtils.release(boundaryBuffer);
 					DataBuffer prev;
+					boolean found = false;
 					while ((prev = this.queue.pollLast()) != null) {
 						int prevByteCount = prev.readableByteCount();
 						int prevLen = prevByteCount + len;
@@ -555,6 +556,7 @@ final class MultipartParser extends BaseSubscriber<DataBuffer> {
 							DataBufferUtils.release(prev);
 							enqueue(body);
 							flush();
+							found = true;
 							break;
 						}
 						else {
@@ -563,11 +565,21 @@ final class MultipartParser extends BaseSubscriber<DataBuffer> {
 							len += prevByteCount;
 						}
 					}
+					if (!found) {
+						// all buffered bytes were boundary bytes: the part had an empty body
+						emitBody(buffer.factory().allocateBuffer(0), true);
+					}
 				}
 				else /* if (len == 0) */ {
 					// buffer starts with complete delimiter, flush out the previous buffers
 					DataBufferUtils.release(boundaryBuffer);
-					flush();
+					if (this.queue.isEmpty()) {
+						// nothing was ever buffered for this part: the part had an empty body
+						emitBody(buffer.factory().allocateBuffer(0), true);
+					}
+					else {
+						flush();
+					}
 				}
 
 				changeState(this, new HeadersState(), buffer);

spring-web/src/test/java/org/springframework/http/codec/multipart/DefaultPartHttpMessageReaderTests.java

@@ -316,7 +316,7 @@ class DefaultPartHttpMessageReaderTests extends AbstractLeakCheckingTests {
 	@ParameterizedDefaultPartHttpMessageReaderTest
 	void emptyLastPart(DefaultPartHttpMessageReader reader) throws InterruptedException {
 		MockServerHttpRequest request = createRequest(
-				"empty-part.multipart", "LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD");
+				"empty-part-last.multipart", "LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD");
 
 		Flux<Part> result = reader.read(forClass(Part.class), request, emptyMap());
 
@@ -329,6 +329,22 @@ class DefaultPartHttpMessageReaderTests extends AbstractLeakCheckingTests {
 		latch.await();
 	}
 
+	@ParameterizedDefaultPartHttpMessageReaderTest  // gh-37264
+	void emptyPartNotLast(DefaultPartHttpMessageReader reader) throws InterruptedException {
+		MockServerHttpRequest request = createRequest(
+				"empty-part.multipart", "simple-boundary");
+
+		Flux<Part> result = reader.read(forClass(Part.class), request, emptyMap());
+
+		CountDownLatch latch = new CountDownLatch(2);
+		StepVerifier.create(result)
+				.consumeNextWith(part -> testPart(part, "file", "", latch)).as("file")
+				.consumeNextWith(part -> testPart(part, "action", "asd", latch)).as("action")
+				.verifyComplete();
+
+		latch.await();
+	}
+
 
 	private void testBrowser(DefaultPartHttpMessageReader reader, String fileName, String boundary)
 			throws InterruptedException {

spring-web/src/test/resources/org/springframework/http/multipart/empty-part-last.multipart

@@ -0,0 +1,13 @@
+--LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD
+Content-Disposition: form-data; name="files"; filename="file17312898095703516893.tmp"
+Content-Type: application/octet-stream
+Content-Length: 0
+
+
+--LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD
+Content-Disposition: form-data; name="files"; filename="file14790463448453253614.tmp"
+Content-Type: application/octet-stream
+Content-Length: 0
+
+
+--LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD--

spring-web/src/test/resources/org/springframework/http/multipart/empty-part.multipart

@@ -1,13 +1,9 @@
---LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD
-Content-Disposition: form-data; name="files"; filename="file17312898095703516893.tmp"
-Content-Type: application/octet-stream
-Content-Length: 0
+--simple-boundary
+Content-Disposition: form-data; name="file"; filename="test.txt"
 
 
---LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD
-Content-Disposition: form-data; name="files"; filename="file14790463448453253614.tmp"
-Content-Type: application/octet-stream
-Content-Length: 0
+--simple-boundary
+Content-Disposition: form-data; name="action"
 
-
---LiG0chJ0k7YtLt-FzTklYFgz50i88xJCW5jD--
+asd
+--simple-boundary--