Fixed bug where indeterminate values were being returned by RoundAbso…

…lute() with mode ROUND_SIGNAL; resulting in incorrect blocks being generated on some platforms including Ubuntu 12.04 amd64; also added various debugging outputs that were useful for tracking down this error.

contrib/debian/changelog

@@ -1,3 +1,11 @@
+freicoin (0.0.0+1beta5~precise3) precise; urgency=low
+
+  [ Mark Friedenbach ]
+    * Fix bug resulting in indeterminate rounding, resulting in incorrect
+      blocks on some platforms (observed on Ubuntu 12.04 amd64).
+
+ -- Mark Friedenbach <[email protected]>  Thu, 7 Dec 2012 18:00:00 -0800
+
 freicoin (0.0.0+1beta5~precise2) precise; urgency=low
 
   [ Mark Friedenbach ]

src/main.cpp

@@ -1955,7 +1955,7 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
         {
             bool fInvalid;
             if (!tx.FetchInputs(txdb, mapQueuedChanges, true, false, mapInputs, fInvalid))
-                return false;
+                return error("ConnectBlock() : unable to fetch inputs for transaction %s", tx.GetHash().ToString().c_str());
 
             if (fStrictPayToScriptHash)
             {
@@ -1974,15 +1974,16 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
             nFees += GetTimeAdjustedValue(qNet, pindex->nHeight - tx.nRefHeight);
 
             if (!tx.ConnectInputs(mapInputs, mapQueuedChanges, posThisTx, pindex, true, false, fStrictPayToScriptHash))
-                return false;
+                return error("ConnectBlock() : unable to connect inputs");
         }
 
         mapQueuedChanges[hashTx] = CTxIndex(posThisTx, tx.vout.size());
     }
 
-    mpq qCoinbaseValue = vtx[0].GetValueOut();
-    if ( GetTimeAdjustedValue(qCoinbaseValue, pindex->nHeight - vtx[0].nRefHeight) > GetBlockValue(pindex->nHeight, nFees) )
-        return false;
+    mpq qActualCoinbaseValue = GetTimeAdjustedValue(vtx[0].GetValueOut(), pindex->nHeight - vtx[0].nRefHeight);
+    mpq qAllowedCoinbaseValue = GetBlockValue(pindex->nHeight, nFees);
+    if ( qActualCoinbaseValue > qAllowedCoinbaseValue )
+        return error("ConnectBlock() : too many coins generated by coinbase: %s > %s", FormatMoney(qActualCoinbaseValue).c_str(), FormatMoney(qAllowedCoinbaseValue).c_str());
 
     std::map<CTxDestination, mpq> mapBudget;
 

src/util.cpp

@@ -511,7 +511,7 @@ mpq RoundAbsolute(const mpq &q, int mode, int magnitude)
     const mpq qOffset = q / qUnits;
     const mpz quotient = qOffset.get_num() / qOffset.get_den();
     const mpz remainder = qOffset.get_num() % qOffset.get_den();
-    const mpz remainder_times_two = abs(remainder *2);
+    const mpz remainder_times_two = abs(remainder) * 2;
 
     bool ret_next;
     switch (mode) {
@@ -546,11 +546,12 @@ mpq RoundAbsolute(const mpq &q, int mode, int magnitude)
     case ROUND_SIGNAL:
         if (remainder != 0)
             throw std::runtime_error("RoundAbsolute() : non-zero remainder in ROUND_SIGNAL mode");
+        ret_next = false;
         break;
     }
 
     if (ret_next) {
-        if (quotient > 0)
+        if (quotient >= 0)
             return (quotient + 1) * qUnits;
         else
             return (quotient - 1) * qUnits;