[AWSs3 Input] Handle unexpectedEOF errors (#42420)

* return EOF error again as errS3DownloadFailed

Signed-off-by: Andreas Gkizas <andreas.gkizas@elastic.co>

---------

Signed-off-by: Andreas Gkizas <andreas.gkizas@elastic.co>
Co-authored-by: Kavindu Dodanduwa <Kavindu-Dodan@users.noreply.github.com>
(cherry picked from commit e6781f3)

CHANGELOG.next.asciidoc

@@ -198,6 +198,7 @@ otherwise no tag is added. {issue}42208[42208] {pull}42403[42403]
 - Fix entityanalytics activedirectory provider full sync use before initialization bug. {pull}42682[42682]
 - In the `http_endpoint` input, fix the check for a missing HMAC HTTP header. {pull}42756[42756]
 - Prevent computer details being returned for user queries by Activedirectory Entity Analytics provider. {issue}11818[11818] {pull}42796[42796]
+- Handle unexpectedEOF error in aws-s3 input and enforce retrying using download failed error {pull}42420[42756]
 
 *Heartbeat*
 

x-pack/filebeat/input/awss3/s3_objects.go

@@ -266,7 +266,12 @@ func (p *s3ObjectProcessor) addGzipDecoderIfNeeded(body io.Reader) (io.Reader, e
 }
 
 func (p *s3ObjectProcessor) readJSON(r io.Reader) error {
-	dec := json.NewDecoder(r)
+	var buf bytes.Buffer
+	if _, err := io.Copy(&buf, r); err != nil {
+		// If an error occurs during the download, handle it here
+		return fmt.Errorf("%w: %w", errS3DownloadFailed, err)
+	}
+	dec := json.NewDecoder(&buf)
 	dec.UseNumber()
 
 	for dec.More() && p.ctx.Err() == nil {