Keep the Monero wallet out of iCloud backups

apps/ios/Koins/Bridge/KoinsMoneroWallet.mm

@@ -14,7 +14,22 @@ static std::string walletPath(NSString *name) {
   return std::string([dir stringByAppendingPathComponent:name].UTF8String);
 }
 
+// Keep wallet files out of iCloud/iTunes backups: the seed in the Keychain is
+// device-only and the file is rebuildable from it, so backing it up would only
+// consume the user's quota (it peaks near 120 MB while a wallet restored from
+// genesis scans). Must run after every write, since wallet2 rewrites these
+// files on each save.
+static void excludeWalletFilesFromBackup(const std::string &walletPathString) {
+  NSString *base = [NSString stringWithUTF8String:walletPathString.c_str()];
+  if (base.length == 0) return;
+  for (NSString *suffix in @[ @"", @".keys", @".address.txt", @".mms" ]) {
+    NSURL *url = [NSURL fileURLWithPath:[base stringByAppendingString:suffix]];
+    [url setResourceValue:@YES forKey:NSURLIsExcludedFromBackupKey error:nil];
+  }
+}
+
 static monero_wallet_full *g_wallet = nullptr;
+static std::string g_walletPath;
 static NSString *g_daemonURL = @"xmr-node.cakewallet.com:18081";
 static NSArray<NSString *> *g_fallbackDaemons = nil;
 static std::atomic<bool> s_cachedConnected(false);
@@ -82,6 +97,8 @@ static void connectDaemon(monero_wallet_full *w) {
           connectDaemon(g_wallet);
           resp[@"address"] = [NSString stringWithUTF8String:g_wallet->get_address(0, 0).c_str()];
           try { resp[@"mnemonic"] = [NSString stringWithUTF8String:g_wallet->get_seed().c_str()]; } catch (...) {}
+          g_walletPath = path;
+          excludeWalletFilesFromBackup(g_walletPath);
         } else {
           monero_wallet_config config;
           config.m_path = path;
@@ -94,6 +111,8 @@ static void connectDaemon(monero_wallet_full *w) {
           connectDaemon(w);
           resp[@"address"] = [NSString stringWithUTF8String:w->get_address(0, 0).c_str()];
           resp[@"mnemonic"] = [NSString stringWithUTF8String:w->get_seed().c_str()];
+          g_walletPath = path;
+          excludeWalletFilesFromBackup(g_walletPath);
         }
       } else if ([op isEqualToString:@"openWallet"] || [op isEqualToString:@"restoreWallet"]) {
         if (g_wallet) {
@@ -118,6 +137,8 @@ static void connectDaemon(monero_wallet_full *w) {
           g_wallet = monero_wallet_full::create_wallet(config, nullptr);
         }
         connectDaemon(g_wallet);
+        g_walletPath = walletPath(req[@"name"]);
+        excludeWalletFilesFromBackup(g_walletPath);
         resp[@"address"] = [NSString stringWithUTF8String:g_wallet->get_address(0, 0).c_str()];
       } else if ([op isEqualToString:@"getSeed"]) {
         if (g_wallet) {
@@ -145,12 +166,14 @@ static void connectDaemon(monero_wallet_full *w) {
           delete g_wallet;
           g_wallet = nullptr;
         }
+        g_walletPath.clear();
       } else if ([op isEqualToString:@"saveWallet"]) {
         // monero-cpp never persists while syncing, so scan progress survives a
         // restart only if this is called explicitly. save() pauses the sync
         // thread while it writes.
         if (g_wallet) {
           g_wallet->save();
+          excludeWalletFilesFromBackup(g_walletPath);
           resp[@"saved"] = @YES;
         } else {
           resp[@"error"] = @"No wallet open";