Merge #15226: Allow creating blank (empty) wallets (alternative)

7687f7873 [wallet] Support creating a blank wallet (Andrew Chow)

Pull request description:

  Alternative (kind of) to #14938

  This PR adds a `blank` parameter to the `createwallet` RPC to create a wallet that has no private keys initially. `sethdseed` can then be used to make a clean wallet with a custom seed. `encryptwallet` can also be used to make a wallet that is born encrypted.

  Instead of changing the version number as done in #14938, a wallet flag is used to indicate that the wallet should be blank. This flag is set at creation, and then unset when the wallet is no longer blank. A wallet becomes non-blank when a HD seed is set or anything is imported. The main change to create a blank wallet is primarily taken from #14938.

  Also with this, the term "blank wallet" is used instead of "empty wallet" to avoid confusion with wallets that have balance which would also be referred to as "empty".

  This is built on top of #15225 in order to fix GUI issues.

Tree-SHA512: 824d685e11ac2259a26b5ece99c67a7bda94a570cd921472c464243ee356b7734595ad35cc439b34357135df041ed9cba951e6edac194935c3a55a1dc4fcbdea

1 files changed, 22 insertions, 1 deletions

diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 9dde7e1f94..c455b7cdad 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);