From 2987f017b2e8395160cc7d20ea009622b9a6b3af Mon Sep 17 00:00:00 2001
From: Son Roy Almerol <sralmerol@sgl.com>
Date: Thu, 14 Nov 2024 15:25:12 -0500
Subject: [PATCH] check original file if open

---
 internal/agent/sftp/filter.go        | 16 ++++++++++++++
 internal/agent/sftp/windows.go       | 33 ++++++++++++++++++++++++++++
 internal/agent/snapshots/registry.go |  1 +
 internal/agent/snapshots/windows.go  |  4 ++++
 internal/backend/mount/mount.go      |  5 ++---
 5 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/internal/agent/sftp/filter.go b/internal/agent/sftp/filter.go
index 12ba5bc..196f1d5 100644
--- a/internal/agent/sftp/filter.go
+++ b/internal/agent/sftp/filter.go
@@ -3,8 +3,10 @@
 package sftp
 
 import (
+	"os"
 	"regexp"
 	"strings"
+	"time"
 	"unicode"
 )
 
@@ -121,6 +123,16 @@ func compileExcludedPaths() []*regexp.Regexp {
 var excludedPathRegexes = compileExcludedPaths()
 
 func (h *SftpHandler) skipFile(path string) bool {
+	stat, err := os.Lstat(path)
+	if err != nil {
+		return true
+	}
+
+	// skip probably opened files
+	if h.Snapshot.TimeStarted.Sub(stat.ModTime()) <= time.Minute {
+		return true
+	}
+
 	snapSplit := strings.Split(h.Snapshot.SnapshotPath, "\\")
 	snapRoot := strings.Join(snapSplit[:len(snapSplit)-1], "\\")
 
@@ -142,5 +154,9 @@ func (h *SftpHandler) skipFile(path string) bool {
 		return true
 	}
 
+	if isFileOpen(strings.Replace(pathWithoutSnap, "\\", ":\\", 1)) {
+		return true
+	}
+
 	return false
 }
diff --git a/internal/agent/sftp/windows.go b/internal/agent/sftp/windows.go
index 4a82512..2cebe2d 100644
--- a/internal/agent/sftp/windows.go
+++ b/internal/agent/sftp/windows.go
@@ -4,6 +4,7 @@ package sftp
 
 import (
 	"os"
+	"syscall"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
@@ -58,3 +59,35 @@ func invalidAttributes(path string) (bool, error) {
 
 	return false, nil
 }
+
+const ERROR_SHARING_VIOLATION syscall.Errno = 32
+
+func isFileOpen(path string) bool {
+	p, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return false
+	}
+
+	// Use CreateFileW system call to open the file with read-write and exclusive access
+	// FILE_SHARE_NONE ensures that the file cannot be opened by any other process
+	h, err := syscall.CreateFile(
+		p,
+		syscall.GENERIC_READ|syscall.GENERIC_WRITE,
+		0,
+		nil,
+		syscall.OPEN_EXISTING,
+		syscall.FILE_ATTRIBUTE_NORMAL,
+		0,
+	)
+
+	if err != nil {
+		// ERROR_SHARING_VIOLATION means the file is already open by another process
+		if errno, ok := err.(syscall.Errno); ok && errno == ERROR_SHARING_VIOLATION {
+			return true
+		}
+		return false
+	}
+
+	syscall.CloseHandle(h)
+	return false
+}
diff --git a/internal/agent/snapshots/registry.go b/internal/agent/snapshots/registry.go
index f6663a6..40506df 100644
--- a/internal/agent/snapshots/registry.go
+++ b/internal/agent/snapshots/registry.go
@@ -16,6 +16,7 @@ type WinVSSSnapshot struct {
 	SnapshotPath string    `json:"path"`
 	Id           string    `json:"vss_id"`
 	LastAccessed time.Time `json:"last_accessed"`
+	TimeStarted  time.Time `json:"time_started"`
 }
 
 type KnownSnapshots struct {
diff --git a/internal/agent/snapshots/windows.go b/internal/agent/snapshots/windows.go
index 3908b7b..f4f4cb5 100644
--- a/internal/agent/snapshots/windows.go
+++ b/internal/agent/snapshots/windows.go
@@ -46,6 +46,7 @@ func Snapshot(driveLetter string) (*WinVSSSnapshot, error) {
 		_ = os.Remove(snapshotPath)
 	}
 
+	timeStarted := time.Now()
 	// Attempt to create a new snapshot
 	err = vss.CreateLink(snapshotPath, volName)
 	if err != nil {
@@ -59,6 +60,8 @@ func Snapshot(driveLetter string) (*WinVSSSnapshot, error) {
 		} else if strings.Contains(err.Error(), "already exists") {
 			_ = vss.Remove(snapshotPath)
 			_ = os.Remove(snapshotPath)
+
+			timeStarted = time.Now()
 			err = vss.CreateLink(snapshotPath, volName)
 			if err != nil {
 				return nil, fmt.Errorf("Snapshot: error creating snapshot (%s to %s) -> %w", volName, snapshotPath, err)
@@ -80,6 +83,7 @@ func Snapshot(driveLetter string) (*WinVSSSnapshot, error) {
 		SnapshotPath: snapshotPath,
 		LastAccessed: time.Now(),
 		Id:           sc.ID,
+		TimeStarted:  timeStarted,
 	}
 	knownSnaps.Save(newSnapshot)
 
diff --git a/internal/backend/mount/mount.go b/internal/backend/mount/mount.go
index abf6900..69bde06 100644
--- a/internal/backend/mount/mount.go
+++ b/internal/backend/mount/mount.go
@@ -52,10 +52,9 @@ func Mount(target *store.Target) (*AgentMount, error) {
 		"--daemon",
 		"--no-seek",
 		"--read-only",
-		"--direct-io",
 		"--uid", "0",
 		"--gid", "0",
-		"--vfs-read-chunk-size", "0",
+		"--vfs-cache-mode", "minimal",
 		"--sftp-disable-hashcheck",
 		"--sftp-idle-timeout", "0",
 		"--sftp-key-file", privKeyFile,
@@ -75,7 +74,7 @@ func Mount(target *store.Target) (*AgentMount, error) {
 
 	agentMount.Cmd = mnt
 
-	err = mnt.Start()
+	err = mnt.Run()
 	if err != nil {
 		agentMount.Unmount()
 		return nil, fmt.Errorf("Mount: error starting rclone for sftp -> %w", err)