Merge pull request 'wallet: add read-only record scan boundary' (#40) from wallet-store-read-abstraction into main

4 files changed, 78 insertions, 38 deletions

diff --git a/docs/storage.md b/docs/storage.md
index 4dd35bd..e533589 100644
--- a/docs/storage.md
+++ b/docs/storage.md
@@ -41,6 +41,9 @@ level schema migration is intentionally introduced.
 ## `wallet.dat`
 
 `wallet.dat` is accessed through `CWalletDB`.
+Read-only tooling should go through `ScanWalletRecords()` instead of opening a
+Berkeley DB cursor directly. That keeps migration checks, audits, and future
+backends behind one record-stream boundary.
 
 | Key shape | Value | Secret? | Meaning |
 |---|---|---:|---|
diff --git a/src/db.cpp b/src/db.cpp
index 9f62964..4fa72af 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -932,6 +932,45 @@ bool CWalletDB::LoadWallet(vector<unsigned char>& vchDefaultKeyRet)
     return true;
 }
 
+bool ScanWalletRecords(CWalletRecordVisitor& visitor, string& strErrorRet)
+{
+    class CWalletScanDB : public CWalletDB
+    {
+    public:
+        CWalletScanDB() : CWalletDB("r") { }
+        using CDB::GetCursor;
+        using CDB::ReadAtCursor;
+    };
+
+    strErrorRet.clear();
+    CWalletScanDB dbWallet;
+    Dbc* pcursor = dbWallet.GetCursor();
+    if (!pcursor)
+    {
+        strErrorRet = "could not open a wallet cursor";
+        return false;
+    }
+    CAutoCursor cursorGuard(pcursor);
+
+    loop
+    {
+        CDataStream ssKey(SER_DISK);
+        CDataStream ssValue(SER_DISK);
+        int ret = dbWallet.ReadAtCursor(pcursor, ssKey, ssValue);
+        if (ret == DB_NOTFOUND)
+            break;
+        if (ret != 0)
+        {
+            strErrorRet = strprintf("could not read wallet record: Berkeley DB error %d", ret);
+            return false;
+        }
+        if (!visitor.VisitWalletRecord(ssKey, ssValue, strErrorRet))
+            return false;
+    }
+
+    return true;
+}
+
 bool LoadWallet()
 {
     vector<unsigned char> vchDefaultKey;
diff --git a/src/db.h b/src/db.h
index 4fb5cfd..2816957 100644
--- a/src/db.h
+++ b/src/db.h
@@ -524,6 +524,17 @@ public:
     bool LoadWallet(vector<unsigned char>& vchDefaultKeyRet);
 };
 
+class CWalletRecordVisitor
+{
+public:
+    virtual ~CWalletRecordVisitor() { }
+    virtual bool VisitWalletRecord(const CDataStream& ssKey,
+                                   const CDataStream& ssValue,
+                                   string& strErrorRet) = 0;
+};
+
+bool ScanWalletRecords(CWalletRecordVisitor& visitor, string& strErrorRet);
+
 bool LoadWallet();
 
 // Writes a wallet.dat that opens on its own, anywhere -- see the definition in
diff --git a/src/walletcmd.cpp b/src/walletcmd.cpp
index ce0da02..71f1ec3 100644
--- a/src/walletcmd.cpp
+++ b/src/walletcmd.cpp
@@ -553,51 +553,38 @@ static void CountWalletStorageType(const std::string& strType,
 static bool ReadWalletStorageCounts(WalletStorageAuditCounts& counts,
                                     std::string& strError)
 {
-    class CWalletAuditDB : public CWalletDB
+    class CWalletStorageCountVisitor : public CWalletRecordVisitor
     {
     public:
-        CWalletAuditDB() : CWalletDB("r") { }
-        using CDB::GetCursor;
-        using CDB::ReadAtCursor;
-    };
-
-    CWalletAuditDB walletdb;
-    Dbc* pcursor = walletdb.GetCursor();
-    if (!pcursor)
-    {
-        strError = "cannot open wallet.dat cursor";
-        return false;
-    }
+        WalletStorageAuditCounts& counts;
 
-    for (;;)
-    {
-        CDataStream ssKey(SER_DISK);
-        CDataStream ssValue(SER_DISK);
-        int ret = walletdb.ReadAtCursor(pcursor, ssKey, ssValue);
-        if (ret == DB_NOTFOUND)
-            break;
-        if (ret != 0)
-        {
-            pcursor->close();
-            strError = strprintf("Berkeley DB cursor read failed (%d)", ret);
-            return false;
-        }
+        explicit CWalletStorageCountVisitor(WalletStorageAuditCounts& countsIn)
+            : counts(countsIn) { }
 
-        counts.nTotal++;
-        try
+        bool VisitWalletRecord(const CDataStream& ssKeyIn,
+                               const CDataStream& ssValue,
+                               std::string& strErrorRet)
         {
-            std::string strType;
-            ssKey >> strType;
-            CountWalletStorageType(strType, counts);
-        }
-        catch (...)
-        {
-            counts.nMalformed++;
+            (void)ssValue;
+            (void)strErrorRet;
+            counts.nTotal++;
+            try
+            {
+                CDataStream ssKey = ssKeyIn;
+                std::string strType;
+                ssKey >> strType;
+                CountWalletStorageType(strType, counts);
+            }
+            catch (...)
+            {
+                counts.nMalformed++;
+            }
+            return true;
         }
-    }
+    };
 
-    pcursor->close();
-    return true;
+    CWalletStorageCountVisitor visitor(counts);
+    return ScanWalletRecords(visitor, strError);
 }
 
 static std::string WalletStorageAuditJson(const WalletStorageAuditCounts& counts)