From 35f546d4cbe53c94e2c688751aa51191c618c4ce Mon Sep 17 00:00:00 2001
From: Sam Mulube <sam.mulube@appital.io>
Date: Mon, 7 Sep 2026 00:24:28 +0100
Subject: [PATCH] Fix potential deadlock in FieldMap.GetTime

In FieldMap.GetTime the code took an RLock(), then called GetBytes()
which attempted to RLock the mutex again. This could lead to potential
deadlock so here we swap out that call for the existing getBytesNoLock
method which appears to be exactly for this purpose.
---
 field_map.go      |  2 +-
 field_map_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/field_map.go b/field_map.go
index 4aac64b1d..d982cdb3b 100644
--- a/field_map.go
+++ b/field_map.go
@@ -196,7 +196,7 @@ func (m FieldMap) GetTime(tag Tag) (t time.Time, err MessageRejectError) {
 	m.rwLock.RLock()
 	defer m.rwLock.RUnlock()
 
-	bytes, err := m.GetBytes(tag)
+	bytes, err := m.getBytesNoLock(tag)
 	if err != nil {
 		return
 	}
diff --git a/field_map_test.go b/field_map_test.go
index 0e9078734..ac58342a4 100644
--- a/field_map_test.go
+++ b/field_map_test.go
@@ -17,7 +17,9 @@ package quickfix
 
 import (
 	"bytes"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -202,3 +204,46 @@ func TestFieldMap_Remove(t *testing.T) {
 	assert.False(t, fMap.Has(1))
 	assert.True(t, fMap.Has(2))
 }
+
+// TestFieldMap_GetTimeConcurrentWithSet verifies the fix guarding against
+// recursive read-locking in GetTime.
+func TestFieldMap_GetTimeConcurrentWithSet(t *testing.T) {
+	var fMap FieldMap
+	fMap.init()
+	fMap.SetField(Tag(1), FIXUTCTimestamp{Time: time.Now()})
+	fMap.SetField(Tag(2), FIXString("blah"))
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 50000; i++ {
+			fMap.SetField(Tag(2), FIXString("blah"))
+		}
+	}()
+
+	for r := 0; r < 8; r++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := 0; i < 50000; i++ {
+				if _, err := fMap.GetTime(Tag(1)); err != nil {
+					t.Error(err)
+					return
+				}
+			}
+		}()
+	}
+
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(60 * time.Second):
+		t.Fatal("deadlock: GetTime did not complete concurrently with writers")
+	}
+}