From 89fd441e9a6372fabe81cb937f5762112f71369d Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Thu, 24 Dec 2020 16:42:45 -0700
Subject: [PATCH] Remove tmp files on start up

---
 db.go         |  5 +++++
 litestream.go | 15 +++++++++++++++
 replicator.go |  5 +++++
 3 files changed, 25 insertions(+)

diff --git a/db.go b/db.go
index 4deca94..cfc848c 100644
--- a/db.go
+++ b/db.go
@@ -163,6 +163,11 @@ func (db *DB) Open() (err error) {
 		m[r.Name()] = struct{}{}
 	}
 
+	// Clear old temporary files that my have been left from a crash.
+	if err := removeTmpFiles(db.MetaPath()); err != nil {
+		return fmt.Errorf("cannot remove tmp files: %w", err)
+	}
+
 	// Start monitoring SQLite database in a separate goroutine.
 	db.wg.Add(1)
 	go func() { defer db.wg.Done(); db.monitor() }()
diff --git a/litestream.go b/litestream.go
index 3e53d29..44e8b3d 100644
--- a/litestream.go
+++ b/litestream.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 
@@ -123,6 +124,20 @@ func FormatWALFilename(index int) string {
 	return fmt.Sprintf("%016x%s", index, WALExt)
 }
 
+// removeTmpFiles recursively finds and removes .tmp files.
+func removeTmpFiles(root string) error {
+	return filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return nil // skip errored files
+		} else if info.IsDir() {
+			return nil // skip directories
+		} else if !strings.HasSuffix(path, ".tmp") {
+			return nil // skip non-temp files
+		}
+		return os.Remove(path)
+	})
+}
+
 // HexDump returns hexdump output but with duplicate lines removed.
 func HexDump(b []byte) string {
 	const prefixN = len("00000000")
diff --git a/replicator.go b/replicator.go
index 4c5ba2c..2f4dabc 100644
--- a/replicator.go
+++ b/replicator.go
@@ -92,6 +92,11 @@ func (r *FileReplicator) Stop() {
 
 // monitor runs in a separate goroutine and continuously replicates the DB.
 func (r *FileReplicator) monitor(ctx context.Context) {
+	// Clear old temporary files that my have been left from a crash.
+	if err := removeTmpFiles(r.dst); err != nil {
+		log.Printf("%s(%s): cannot remove tmp files: %w", r.db.Path(), r.Name(), err)
+	}
+
 	// Continuously check for new data to replicate.
 	ch := make(chan struct{})
 	close(ch)