From b89863461b64471650cd8ad49cc3bbdfc20c7d94 Mon Sep 17 00:00:00 2001
From: Michael Wilner <mwilner@connamara.tech>
Date: Fri, 24 Jan 2025 12:41:57 -0600
Subject: [PATCH] Protect concurrent usage of filestore

---
 store/file/file_store.go | 35 ++++++++++++++++++++++++-----------
 store/file/util.go       |  9 +++++++--
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/store/file/file_store.go b/store/file/file_store.go
index 085612d4e..c0a28531e 100644
--- a/store/file/file_store.go
+++ b/store/file/file_store.go
@@ -22,6 +22,7 @@ import (
 	"path"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/pkg/errors"
@@ -41,12 +42,14 @@ type fileStore struct {
 	sessionFname       string
 	senderSeqNumsFname string
 	targetSeqNumsFname string
-	bodyFile           *os.File
-	headerFile         *os.File
-	sessionFile        *os.File
-	senderSeqNumsFile  *os.File
-	targetSeqNumsFile  *os.File
-	fileSync           bool
+
+	fileMu            sync.Mutex
+	bodyFile          *os.File
+	headerFile        *os.File
+	sessionFile       *os.File
+	senderSeqNumsFile *os.File
+	targetSeqNumsFile *os.File
+	fileSync          bool
 }
 
 // NewStoreFactory returns a file-based implementation of MessageStoreFactory.
@@ -218,6 +221,9 @@ func (store *fileStore) populateCache() (creationTimePopulated bool, err error)
 }
 
 func (store *fileStore) setSession() error {
+	store.fileMu.Lock()
+	defer store.fileMu.Unlock()
+
 	if _, err := store.sessionFile.Seek(0, io.SeekStart); err != nil {
 		return fmt.Errorf("unable to rewind file: %s: %s", store.sessionFname, err.Error())
 	}
@@ -238,6 +244,8 @@ func (store *fileStore) setSession() error {
 }
 
 func (store *fileStore) setSeqNum(f *os.File, seqNum int) error {
+	store.fileMu.Lock()
+	defer store.fileMu.Unlock()
 	if _, err := f.Seek(0, io.SeekStart); err != nil {
 		return fmt.Errorf("unable to rewind file: %s: %s", f.Name(), err.Error())
 	}
@@ -304,6 +312,8 @@ func (store *fileStore) SetCreationTime(_ time.Time) {
 }
 
 func (store *fileStore) SaveMessage(seqNum int, msg []byte) error {
+	store.fileMu.Lock()
+	defer store.fileMu.Unlock()
 	offset, err := store.bodyFile.Seek(0, io.SeekEnd)
 	if err != nil {
 		return fmt.Errorf("unable to seek to end of file: %s: %s", store.bodyFname, err.Error())
@@ -339,6 +349,9 @@ func (store *fileStore) SaveMessageAndIncrNextSenderMsgSeqNum(seqNum int, msg []
 }
 
 func (store *fileStore) IterateMessages(beginSeqNum, endSeqNum int, cb func([]byte) error) error {
+	store.fileMu.Lock()
+	defer store.fileMu.Unlock()
+
 	// Sync files and seek to start of header file
 	if err := store.bodyFile.Sync(); err != nil {
 		return fmt.Errorf("unable to flush file: %s: %s", store.bodyFname, err.Error())
@@ -386,19 +399,19 @@ func (store *fileStore) GetMessages(beginSeqNum, endSeqNum int) ([][]byte, error
 
 // Close closes the store's files.
 func (store *fileStore) Close() error {
-	if err := closeFile(store.bodyFile); err != nil {
+	if err := closeSyncFile(store.bodyFile); err != nil {
 		return err
 	}
-	if err := closeFile(store.headerFile); err != nil {
+	if err := closeSyncFile(store.headerFile); err != nil {
 		return err
 	}
-	if err := closeFile(store.sessionFile); err != nil {
+	if err := closeSyncFile(store.sessionFile); err != nil {
 		return err
 	}
-	if err := closeFile(store.senderSeqNumsFile); err != nil {
+	if err := closeSyncFile(store.senderSeqNumsFile); err != nil {
 		return err
 	}
-	if err := closeFile(store.targetSeqNumsFile); err != nil {
+	if err := closeSyncFile(store.targetSeqNumsFile); err != nil {
 		return err
 	}
 
diff --git a/store/file/util.go b/store/file/util.go
index d181e8c27..9baf380f6 100644
--- a/store/file/util.go
+++ b/store/file/util.go
@@ -48,9 +48,14 @@ func createFilenamePrefix(s quickfix.SessionID) string {
 	return strings.Join(fname, "-")
 }
 
-// closeFile behaves like Close, except that no error is returned if the file does not exist.
-func closeFile(f *os.File) error {
+// closeSyncFile behaves like Sync and Close, except that no error is returned if the file does not exist.
+func closeSyncFile(f *os.File) error {
 	if f != nil {
+		if err := f.Sync(); err != nil {
+			if !os.IsNotExist(err) {
+				return err
+			}
+		}
 		if err := f.Close(); err != nil {
 			if !os.IsNotExist(err) {
 				return err