From 33ac2790b212ee30c88a43e1c783622b46035fd9 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 9 Dec 2024 09:46:49 -0800
Subject: [PATCH] ensure inputSize state value is reset during buftok.flush
 (#16760) (#16770)
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(cherry picked from commit e36cacedc83b8af9ca90453308cb9f46c10c1aff)

Co-authored-by: João Duarte <jsvd@users.noreply.github.com>
---
 .../spec/logstash/util/buftok_spec.rb         | 29 +++++++++++++++++++
 .../logstash/common/BufferedTokenizerExt.java |  3 +-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/logstash-core/spec/logstash/util/buftok_spec.rb b/logstash-core/spec/logstash/util/buftok_spec.rb
index cccb9c476e0..acdf2097709 100644
--- a/logstash-core/spec/logstash/util/buftok_spec.rb
+++ b/logstash-core/spec/logstash/util/buftok_spec.rb
@@ -43,6 +43,35 @@
     expect(subject.extract("\n\n\n")).to eq(["", "", ""])
   end
 
+  describe 'flush' do
+    let(:data) { "content without a delimiter" }
+    before(:each) do
+      subject.extract(data)
+    end
+
+    it "emits the contents of the buffer" do
+      expect(subject.flush).to eq(data)
+    end
+
+    it "resets the state of the buffer" do
+      subject.flush
+      expect(subject).to be_empty
+    end
+
+    context 'with decode_size_limit_bytes' do
+      subject { FileWatch::BufferedTokenizer.new("\n", 100) }
+
+      it "emits the contents of the buffer" do
+        expect(subject.flush).to eq(data)
+      end
+
+      it "resets the state of the buffer" do
+        subject.flush
+        expect(subject).to be_empty
+      end
+    end
+  end
+
   context 'with delimiter' do
     subject { FileWatch::BufferedTokenizer.new(delimiter) }
 
diff --git a/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java b/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
index 2d7b90bba7a..f704fcb0f7f 100644
--- a/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
+++ b/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
@@ -106,12 +106,13 @@ public RubyArray extract(final ThreadContext context, IRubyObject data) {
     public IRubyObject flush(final ThreadContext context) {
         final IRubyObject buffer = input.join(context);
         input.clear();
+        inputSize = 0;
         return buffer;
     }
 
     @JRubyMethod(name = "empty?")
     public IRubyObject isEmpty(final ThreadContext context) {
-        return input.empty_p();
+        return RubyUtil.RUBY.newBoolean(input.isEmpty() && (inputSize == 0));
     }
 
 }