Insufficient funds calculation is off

[madduck]

I am trying the following in geth (v1.3.3, Ubuntu):

d = 0xdeadbeef…
v = 1000
v = eth.getBalance(eth.coinbase) - eth.gasPrice * eth.estimateGas({from: eth.coinbase, to: d, value: v })
eth.sendTransaction({from: eth.coinbase, to: d, value: v})

but this yields:

Insufficient funds for gas * price + value
    at InvalidResponse (<anonymous>:-81662:-104)
    at send (<anonymous>:-156322:-104)
    at sendTransaction (<anonymous>:-133322:-104)
    at <anonymous>:1:1

which seems a bit weird. eth.estimateGas returns the going rate of 21,000. That should be all I need, no?

[madduck]

FTR, adding gas: 21000 to the eth.sendTransaction call makes it go through just fine.

[obscuren]

You need big integer arithmetic. JavaScript implements integers as 32 bit ints (2^32). It's very likely that your balance in wei exceeds that number:

> eth.getBalance(eth.coinbase)
1.2230537249418869769081e+22

Try something like

eth.getBalance(eth.coinbase).sub(eth.gasPrice).mul(....)

[madduck]

Thanks for the explanation! I hope the day doesn't come when an overflow or otherwise problem with the limited JavaScript scope yields to big losses.