From 904c7bf488b23ca5496b55260f8cfa997fcc3e90 Mon Sep 17 00:00:00 2001
From: Piotr Sarna <sarna@chiselstrike.com>
Date: Tue, 13 Dec 2022 10:57:47 +0100
Subject: [PATCH] vwal: introduce iVersion for being future-proof

Similarly to how other interfaces work, the version number in WAL methods
lets the user know which functions are supported, and which aren't yet.
---
 ext/vwal/vwal.c | 1 +
 src/wal.c       | 1 +
 src/wal.h       | 1 +
 3 files changed, 3 insertions(+)

diff --git a/ext/vwal/vwal.c b/ext/vwal/vwal.c
index 619770d602..4a1537363b 100644
--- a/ext/vwal/vwal.c
+++ b/ext/vwal/vwal.c
@@ -116,6 +116,7 @@ static void v_get_wal_pathname(char *buf, const char *orig, int orig_len) {
 __attribute__((__visibility__("default")))
 void libsql_register_vwal() {
   static libsql_wal_methods methods = {
+    .iVersion = 1,
     .xOpen = v_open,
     .xClose = v_close,
     .xLimit = v_limit,
diff --git a/src/wal.c b/src/wal.c
index bc751ae823..43d0d65189 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -4111,6 +4111,7 @@ libsql_wal_methods *libsql_wal_methods_find(const char *zName) {
     zName = "default";
   }
   if (methods_head == NULL && strncmp(zName, "default", 7) == 0) {
+    methods.iVersion = 1;
     methods.xOpen = sqlite3WalOpen;
     methods.xClose = sqlite3WalClose;
     methods.xLimit = sqlite3WalLimit;
diff --git a/src/wal.h b/src/wal.h
index 6383fb5e6a..82fda26609 100644
--- a/src/wal.h
+++ b/src/wal.h
@@ -33,6 +33,7 @@
 typedef struct Wal Wal;
 
 typedef struct libsql_wal_methods {
+  int iVersion; /* Current version is 1, versioning is here for backward compatibility *.
   /* Open and close a connection to a write-ahead log. */
   int (*xOpen)(sqlite3_vfs*, sqlite3_file* , const char*, int no_shm_mode, i64 max_size, struct libsql_wal_methods*, Wal**);
   int (*xClose)(Wal*, sqlite3* db, int sync_flags, int nBuf, u8 *zBuf);