Error when trying to send very precise amount #18

I generated block 100283 and collected a sub bitcent transaction fee. I get an "Insufficient funds" error when trying to send my exact balance to another address. It seems that there is either :

• wrong behaviour (should send the amount), or
• wrong error message, (the balance is ok but the client forbids me to send it)

Block : 000000000003d014210dcffd602715545bce976f0f257d99279c83c2778e7150

Here's the trace

<pre>david@box:~$ bitcoin getinfo { "version" : 31900, "balance" : 50.00638641, "blocks" : 100760, "connections" : 48, "proxy" : "", "generate" : true, "genproclimit" : -1, "difficulty" : 14484.16236123, "hashespersec" : 9273499, "testnet" : false, "keypoololdest" : 1291071649, "paytxfee" : 0.00000000, "errors" : "" } david@box:~$ bitcoin sendtoaddress 12DidCRRT9fqmSBReRNN8KjCktYGTVU1Jj 50.00638641 error: {"code":-4,"message":"Insufficient funds"}</pre>

Wow, I just sent 50 BTC, and now the client is reporting zero balance...

What happened:

Send 50.006... was rounded to 50.01 (amounts get rounded to two decimals). Causing insufficient funds message.

Send 50 ran into special-case code for micropayments; if making change would result in less than 0.01 coins (which would trigger the you-must-pay-a-0.01-fee transaction spam prevention code), then the sub-cent amount is sent along as a transaction fee.

At the very least, the RPC code should put the amount being sent in the insufficient funds message.

Doing something more with sub-cent transactions needs more careful thought...