Merge #14291: wallet: Add ListWalletDir utility function

d56a0689354fb814510c6c393f3e07ac9362dc1f docs: Add release notes for listwalletdir RPC (João Barbosa)
0cb3cad166bbeb75e9cc1512286453f8e7d4f717 qa: Add tests for listwalletdir RPC (João Barbosa)
cc3377360c417780f5cbd7bd69b438817a9d60be rpc: Add listwalletdir RPC (João Barbosa)
d1b03b8e5f04a2cc9ebb985bd9a1aebd2068f757 interfaces: Add getWalletDir and listWalletDir to Node (João Barbosa)
fc4db35bfd78d85d6b52d5da3d89696160658450 wallet: Add ListWalletDir utility (João Barbosa)

Pull request description:

  `ListWalletDir` returns all available wallets in the current wallet directory.

  Based on MeshCollider work in pull #11485.

Tree-SHA512: 5843e3dbd1e0449f55bb8ea7c241a536078ff6ffcaad88ce5fcf8963971d48c78600fbc4f44919523b8a92329d5d8a5f567a3e0ccb0270fdd27366e19603a716

6 files changed, 119 insertions, 2 deletions

diff --git a/src/dummywallet.cpp b/src/dummywallet.cpp
index 3714187a96..3eb77354c1 100644
--- a/src/dummywallet.cpp
+++ b/src/dummywallet.cpp
@@ -34,6 +34,16 @@ void DummyWalletInit::AddWalletOptions() const
 
 const WalletInitInterface& g_wallet_init_interface = DummyWalletInit();
 
+fs::path GetWalletDir()
+{
+    throw std::logic_error("Wallet function called in non-wallet build.");
+}
+
+std::vector<fs::path> ListWalletDir()
+{
+    throw std::logic_error("Wallet function called in non-wallet build.");
+}
+
 std::vector<std::shared_ptr<CWallet>> GetWallets()
 {
     throw std::logic_error("Wallet function called in non-wallet build.");
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index d95b41657c..2b19e11f08 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -38,6 +38,8 @@
 #include <univalue.h>
 
 class CWallet;
+fs::path GetWalletDir();
+std::vector<fs::path> ListWalletDir();
 std::vector<std::shared_ptr<CWallet>> GetWallets();
 
 namespace interfaces {
@@ -218,6 +220,18 @@ class NodeImpl : public Node
         LOCK(::cs_main);
         return ::pcoinsTip->GetCoin(output, coin);
     }
+    std::string getWalletDir() override
+    {
+        return GetWalletDir().string();
+    }
+    std::vector<std::string> listWalletDir() override
+    {
+        std::vector<std::string> paths;
+        for (auto& path : ListWalletDir()) {
+            paths.push_back(path.string());
+        }
+        return paths;
+    }
     std::vector<std::unique_ptr<Wallet>> getWallets() override
     {
         std::vector<std::unique_ptr<Wallet>> wallets;
diff --git a/src/interfaces/node.h b/src/interfaces/node.h
index 8185c015a9..1f8bbbff7a 100644
--- a/src/interfaces/node.h
+++ b/src/interfaces/node.h
@@ -173,6 +173,12 @@ public:
     //! Get unspent outputs associated with a transaction.
     virtual bool getUnspentOutput(const COutPoint& output, Coin& coin) = 0;
 
+    //! Return default wallet directory.
+    virtual std::string getWalletDir() = 0;
+
+    //! Return available wallets in wallet directory.
+    virtual std::vector<std::string> listWalletDir() = 0;
+
     //! Return interfaces for accessing wallets (if any).
     virtual std::vector<std::unique_ptr<Wallet>> getWallets() = 0;
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index df10fb48cc..a3f5f8b211 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2443,6 +2443,38 @@ static UniValue getwalletinfo(const JSONRPCRequest& request)
     return obj;
 }
 
+static UniValue listwalletdir(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 0) {
+        throw std::runtime_error(
+            "listwalletdir\n"
+            "Returns a list of wallets in the wallet directory.\n"
+            "{\n"
+            "  \"wallets\" : [                (json array of objects)\n"
+            "    {\n"
+            "      \"name\" : \"name\"          (string) The wallet name\n"
+            "    }\n"
+            "    ,...\n"
+            "  ]\n"
+            "}\n"
+            "\nExamples:\n"
+            + HelpExampleCli("listwalletdir", "")
+            + HelpExampleRpc("listwalletdir", "")
+        );
+    }
+
+    UniValue wallets(UniValue::VARR);
+    for (const auto& path : ListWalletDir()) {
+        UniValue wallet(UniValue::VOBJ);
+        wallet.pushKV("name", path.string());
+        wallets.push_back(wallet);
+    }
+
+    UniValue result(UniValue::VOBJ);
+    result.pushKV("wallets", wallets);
+    return result;
+}
+
 static UniValue listwallets(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.size() != 0)
@@ -4096,6 +4128,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "listsinceblock",                   &listsinceblock,                {"blockhash","target_confirmations","include_watchonly","include_removed"} },
     { "wallet",             "listtransactions",                 &listtransactions,              {"dummy","count","skip","include_watchonly"} },
     { "wallet",             "listunspent",                      &listunspent,                   {"minconf","maxconf","addresses","include_unsafe","query_options"} },
+    { "wallet",             "listwalletdir",                    &listwalletdir,                 {} },
     { "wallet",             "listwallets",                      &listwallets,                   {} },
     { "wallet",             "loadwallet",                       &loadwallet,                    {"filename"} },
     { "wallet",             "lockunspent",                      &lockunspent,                   {"unlock","transactions"} },
diff --git a/src/wallet/walletutil.cpp b/src/wallet/walletutil.cpp
index 34c76ec4c4..c0c9afe13e 100644
--- a/src/wallet/walletutil.cpp
+++ b/src/wallet/walletutil.cpp
@@ -4,6 +4,8 @@
 
 #include <wallet/walletutil.h>
 
+#include <util.h>
+
 fs::path GetWalletDir()
 {
     fs::path path;
@@ -25,3 +27,51 @@ fs::path GetWalletDir()
 
     return path;
 }
+
+static bool IsBerkeleyBtree(const fs::path& path)
+{
+    // A Berkeley DB Btree file has at least 4K.
+    // This check also prevents opening lock files.
+    boost::system::error_code ec;
+    if (fs::file_size(path, ec) < 4096) return false;
+
+    fs::ifstream file(path.string(), std::ios::binary);
+    if (!file.is_open()) return false;
+
+    file.seekg(12, std::ios::beg); // Magic bytes start at offset 12
+    uint32_t data = 0;
+    file.read((char*) &data, sizeof(data)); // Read 4 bytes of file to compare against magic
+
+    // Berkeley DB Btree magic bytes, from:
+    //  https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
+    //  - big endian systems - 00 05 31 62
+    //  - little endian systems - 62 31 05 00
+    return data == 0x00053162 || data == 0x62310500;
+}
+
+std::vector<fs::path> ListWalletDir()
+{
+    const fs::path wallet_dir = GetWalletDir();
+    std::vector<fs::path> paths;
+
+    for (auto it = fs::recursive_directory_iterator(wallet_dir); it != end(it); ++it) {
+        if (it->status().type() == fs::directory_file && IsBerkeleyBtree(it->path() / "wallet.dat")) {
+            // Found a directory which contains wallet.dat btree file, add it as a wallet.
+            paths.emplace_back(fs::relative(it->path(), wallet_dir));
+        } else if (it.level() == 0 && it->symlink_status().type() == fs::regular_file && IsBerkeleyBtree(it->path())) {
+            if (it->path().filename() == "wallet.dat") {
+                // Found top-level wallet.dat btree file, add top level directory ""
+                // as a wallet.
+                paths.emplace_back();
+            } else {
+                // Found top-level btree file not called wallet.dat. Current bitcoin
+                // software will never create these files but will allow them to be
+                // opened in a shared database environment for backwards compatibility.
+                // Add it to the list of available wallets.
+                paths.emplace_back(fs::relative(it->path(), wallet_dir));
+            }
+        }
+    }
+
+    return paths;
+}
diff --git a/src/wallet/walletutil.h b/src/wallet/walletutil.h
index 7c42954616..77f5ca428d 100644
--- a/src/wallet/walletutil.h
+++ b/src/wallet/walletutil.h
@@ -5,10 +5,14 @@
 #ifndef BITCOIN_WALLET_WALLETUTIL_H
 #define BITCOIN_WALLET_WALLETUTIL_H
 
-#include <chainparamsbase.h>
-#include <util.h>
+#include <fs.h>
+
+#include <vector>
 
 //! Get the path of the wallet directory.
 fs::path GetWalletDir();
 
+//! Get wallets in wallet directory.
+std::vector<fs::path> ListWalletDir();
+
 #endif // BITCOIN_WALLET_WALLETUTIL_H