From 71f9a84d22a85884c29f1b4823aba8a55a026a65 Mon Sep 17 00:00:00 2001
From: Arjen Poutsma <poutsmaa@vmware.com>
Date: Tue, 13 Sep 2022 11:24:32 +0200
Subject: [PATCH] Fix releasing bug in StringDecoder

This commit fixes an issue in StringDecoder, where, if the buffer did
not contain any delimiters, it was released before it was relayed to
any subscribers.

Closes gh-29119
---
 .../core/codec/StringDecoder.java             |  7 +++++--
 .../client/WebClientIntegrationTests.java     | 20 +++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
index 15e6325f72..031fe10a7d 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
@@ -143,13 +143,14 @@ public final class StringDecoder extends AbstractDataBufferDecoder<String> {
 	private Collection<DataBuffer> processDataBuffer(
 			DataBuffer buffer, DataBufferUtils.Matcher matcher, LimitedDataBufferList chunks) {
 
+		boolean release = true;
 		try {
 			List<DataBuffer> result = null;
 			do {
 				int endIndex = matcher.match(buffer);
 				if (endIndex == -1) {
 					chunks.add(buffer);
-					DataBufferUtils.retain(buffer); // retain after add (may raise DataBufferLimitException)
+					release = false;
 					break;
 				}
 				DataBuffer split = buffer.split(endIndex + 1);
@@ -177,7 +178,9 @@ public final class StringDecoder extends AbstractDataBufferDecoder<String> {
 			return (result != null ? result : Collections.emptyList());
 		}
 		finally {
-			DataBufferUtils.release(buffer);
+			if (release) {
+				DataBufferUtils.release(buffer);
+			}
 		}
 	}
 
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
index 8be90ef25b..07c5adaa05 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
@@ -1258,6 +1258,26 @@ class WebClientIntegrationTests {
 				.verify();
 	}
 
+	@ParameterizedWebClientTest
+	void retrieveTextDecodedToFlux(ClientHttpConnector connector) {
+		startServer(connector);
+
+		prepareResponse(response -> response
+				.setHeader("Content-Type", "text/plain")
+				.setBody("Hey now"));
+
+		Flux<String> result = this.webClient.get()
+				.uri("/")
+				.accept(MediaType.TEXT_PLAIN)
+				.retrieve()
+				.bodyToFlux(String.class);
+
+		StepVerifier.create(result)
+				.expectNext("Hey now")
+				.expectComplete()
+				.verify(Duration.ofSeconds(3));
+	}
+
 	private <T> Mono<T> doMalformedChunkedResponseTest(
 			ClientHttpConnector connector, Function<ResponseSpec, Mono<T>> handler) {