fix: show a warning when SQLite DB is stored on NFS/SMB/FUSE (#1381)

backend/internal/utils/networked_filesystem_linux.go

@@ -0,0 +1,35 @@
+//go:build linux
+
+package utils
+
+import (
+	"fmt"
+	"syscall"
+)
+
+// Filesystem magic values from Linux's include/uapi/linux/magic.h, used by statfs(2).
+const (
+	nfsSuperMagic  = 0x6969
+	smbSuperMagic  = 0x517b
+	cifsSuperMagic = 0xff534d42
+	fuseSuperMagic = 0x65735546
+)
+
+// IsNetworkedFileSystem reports whether path is on a filesystem that is known to be unsafe for SQLite, specifically NFS, SMB/CIFS, or FUSE mounts.
+func IsNetworkedFileSystem(path string) (bool, error) {
+	var statfs syscall.Statfs_t
+	err := syscall.Statfs(path, &statfs)
+	if err != nil {
+		return false, fmt.Errorf("error executing statfs syscall: %w", err)
+	}
+
+	// Statfs_t.Type is arch-dependent (for example, int32 on some systems and int64 on others).
+	// Normalize through uint32 first so signed values still preserve the Linux bit pattern for magic numbers such as CIFS (0xff534d42), then compare in a wide unsigned form.
+	//nolint:gosec
+	switch uint64(uint32(statfs.Type)) {
+	case nfsSuperMagic, smbSuperMagic, cifsSuperMagic, fuseSuperMagic:
+		return true, nil
+	default:
+		return false, nil
+	}
+}