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rust-bitcoin-unsafe-fast
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Debug assert that target != zero in difficulty calc 

The `difficulty` calculation requires dividing a target value by `self`.
Add an assertion that `self` is not zero to help devs debug this.

Note that this should never really be hit, but its possible there is a
bug somewhere causing the target to be set to zero - so this may help
debugging.

Also, add panics section to rustdocs.
This commit is contained in:
Tobin C. Harding 2024-01-29 07:28:04 +11:00
parent c1ba496a07
commit 104dee9376
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7
bitcoin/src/pow.rs
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@ -227,10 +227,17 @@ impl Target {
/// integer but `difficulty()` returns only 128 bits this means for targets below approximately /// integer but `difficulty()` returns only 128 bits this means for targets below approximately
/// `0xffff_ffff_ffff_ffff_ffff_ffff` `difficulty()` will saturate at `u128::MAX`. /// `0xffff_ffff_ffff_ffff_ffff_ffff` `difficulty()` will saturate at `u128::MAX`.
/// ///
/// # Panics
///
/// Panics if `self` is zero (divide by zero).
///
/// [max]: Target::max /// [max]: Target::max
/// [target]: crate::blockdata::block::Header::target /// [target]: crate::blockdata::block::Header::target
#[cfg_attr(all(test, mutate), mutate)] #[cfg_attr(all(test, mutate), mutate)]
pub fn difficulty(&self, network: Network) -> u128 { pub fn difficulty(&self, network: Network) -> u128 {
// Panic here may be eaiser to debug than during the actual division.
assert_ne!(self.0, U256::ZERO, "divide by zero");
let max = match network { let max = match network {
Network::Bitcoin => Target::MAX_ATTAINABLE_MAINNET, Network::Bitcoin => Target::MAX_ATTAINABLE_MAINNET,
Network::Testnet => Target::MAX_ATTAINABLE_TESTNET, Network::Testnet => Target::MAX_ATTAINABLE_TESTNET,