Improve handling of database read errors.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

src/chain.cpp

@@ -95,7 +95,10 @@ CBlockHeader CBlockIndex::GetBlockHeader() const
         header.nSolution        = nSolution;
     } else {
         CDiskBlockIndex dbindex;
-        assert(pblocktree->ReadDiskBlockIndex(GetBlockHash(), dbindex));
+        if (!pblocktree->ReadDiskBlockIndex(GetBlockHash(), dbindex)) {
+            LogPrintf("%s: Failed to read index entry", __func__);
+            throw std::runtime_error("Failed to read index entry");
+        }
         header.nSolution        = dbindex.GetSolution();
     }
     return header;

src/main.cpp

@@ -6134,7 +6134,11 @@ void static CheckBlockIndex(const Consensus::Params& consensusParams)
                 }
             }
         }
-        // assert(pindex->GetBlockHash() == pindex->GetBlockHeader().GetHash()); // Perhaps too slow
+        // try {
+        //     assert(pindex->GetBlockHash() == pindex->GetBlockHeader().GetHash()); // Perhaps too slow
+        // } catch (const runtime_error&) {
+        //     assert(!"Failed to read index entry");
+        // }
         // End: actual consistency checks.
 
         // Try descending into the first subnode.

src/rest.cpp

@@ -154,8 +154,12 @@ static bool rest_headers(HTTPRequest* req,
         }
 
         if (rf == RF_BINARY || rf == RF_HEX) {
-            for (const CBlockIndex *pindex : headers) {
-                ssHeader << pindex->GetBlockHeader();
+            try {
+                for (const CBlockIndex *pindex : headers) {
+                    ssHeader << pindex->GetBlockHeader();
+                }
+            } catch (const std::runtime_error&) {
+                return RESTERR(req, HTTP_INTERNAL_SERVER_ERROR, "Failed to read index entry");
             }
         }
     }

src/rpc/blockchain.cpp

@@ -684,15 +684,18 @@ UniValue getblockheader(const UniValue& params, bool fHelp)
 
     CBlockIndex* pblockindex = mapBlockIndex[hash];
 
-    if (!fVerbose)
-    {
-        CDataStream ssBlock(SER_NETWORK, PROTOCOL_VERSION);
-        ssBlock << pblockindex->GetBlockHeader();
-        std::string strHex = HexStr(ssBlock.begin(), ssBlock.end());
-        return strHex;
+    try {
+        if (!fVerbose) {
+            CDataStream ssBlock(SER_NETWORK, PROTOCOL_VERSION);
+            ssBlock << pblockindex->GetBlockHeader();
+            std::string strHex = HexStr(ssBlock.begin(), ssBlock.end());
+            return strHex;
+        } else {
+            return blockheaderToJSON(pblockindex);
+        }
+    } catch (const runtime_error&) {
+        throw JSONRPCError(RPC_DATABASE_ERROR, "Failed to read index entry");
     }
-
-    return blockheaderToJSON(pblockindex);
 }
 
 UniValue getblock(const UniValue& params, bool fHelp)

src/txdb.cpp

@@ -634,7 +634,12 @@ bool CBlockTreeDB::LoadBlockIndexGuts(
                 CBlockHeader header;
                 {
                     LOCK(cs_main);
-                    header = pindexNew->GetBlockHeader();
+                    try {
+                        header = pindexNew->GetBlockHeader();
+                    } catch (const runtime_error&) {
+                        return error("LoadBlockIndex(): failed to read index entry: diskindex hash = %s",
+                            diskindex.GetBlockHash().ToString());
+                    }
                 }
                 if (header.GetHash() != diskindex.GetBlockHash())
                     return error("LoadBlockIndex(): inconsistent header vs diskindex hash: header hash = %s, diskindex hash = %s",