[wallet] Support creating a blank wallet

A blank wallet is a wallet that has no keys, script or watch only things.
A new wallet flag indicating that it is blank will be set when the wallet
is blank. Once it is no longer blank (a seed has been generated, keys or
scripts imported, etc), the flag will be unset.

1 files changed, 22 insertions, 1 deletions

diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 4776b0eacc..0f7f3bab18 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -136,9 +136,21 @@ enum WalletFlags : uint64_t {
 
     // will enforce the rule that the wallet can't contain any private keys (only watch-only/pubkeys)
     WALLET_FLAG_DISABLE_PRIVATE_KEYS = (1ULL << 32),
+
+    //! Flag set when a wallet contains no HD seed and no private keys, scripts,
+    //! addresses, and other watch only things, and is therefore "blank."
+    //!
+    //! The only function this flag serves is to distinguish a blank wallet from
+    //! a newly created wallet when the wallet database is loaded, to avoid
+    //! initialization that should only happen on first run.
+    //!
+    //! This flag is also a mandatory flag to prevent previous versions of
+    //! bitcoin from opening the wallet, thinking it was newly created, and
+    //! then improperly reinitializing it.
+    WALLET_FLAG_BLANK_WALLET = (1ULL << 33),
 };
 
-static constexpr uint64_t g_known_wallet_flags = WALLET_FLAG_DISABLE_PRIVATE_KEYS;
+static constexpr uint64_t g_known_wallet_flags = WALLET_FLAG_DISABLE_PRIVATE_KEYS | WALLET_FLAG_BLANK_WALLET;
 
 /** A key pool entry */
 class CKeyPool
@@ -1132,6 +1144,12 @@ public:
     /* Returns true if HD is enabled */
     bool IsHDEnabled() const;
 
+    /* Returns true if the wallet can generate new keys */
+    bool CanGenerateKeys();
+
+    /* Returns true if the wallet can give out new addresses. This means it has keys in the keypool or can generate new keys */
+    bool CanGetAddresses(bool internal = false);
+
     /* Generates a new HD seed (will not be activated) */
     CPubKey GenerateNewSeed();
 
@@ -1169,6 +1187,9 @@ public:
     /** set a single wallet flag */
     void SetWalletFlag(uint64_t flags);
 
+    /** Unsets a single wallet flag */
+    void UnsetWalletFlag(uint64_t flag);
+
     /** check if a certain wallet flag is set */
     bool IsWalletFlagSet(uint64_t flag);