Subject: Re: [bitcoindev] Update on the Great Consensus Cleanup Revival

From: Antoine Riard <[email-masked]>
Date: Sat, 15 Feb 2025 13:13:24 -0800 (PST)

Hi Peter,

I'm talking about this check in VerifyScript as of commit 43e71f74 in 
bitcoin core.

```
    if ((flags & SCRIPT_VERIFY_SIGPUSHONLY) != 0 && 
!scriptSig.IsPushOnly()) {
        return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY);
    }
```

In my understanding, we never set SCRIPT_VERIFY_SIGPUSHONLY, neither in 
MANDATORY_SCRIPT_VERIFY_FLAGS,
nor in STANDARD_SCRIPT_VERIFY_FLAGS, and this sounds okay as it's a script 
check pertaining to BIP62
rule 2, and BIP62 was never activated. As far as I can tell, that's more a 
stale check just right 
there in the interpreter code paths.

We still return SCRIPT_ERR_SIG_PUSHONLY for P2SH spends, verifying the 
scriptSig is push-only.

All the unit tests (i.e `script_tests.cpp`) are manually setting the 
SCRIPT_VERIFY_SIGPUSHONLY flag
to verify the logic correctness, even it appears as never being set for 
block validation.

The original PR is there: https://github.com/bitcoin/bitcoin/pull/5065

Feel free to point me out if I'm missing something obvious here.

Best,
Antoine
OTS hash: 42e2e614fea49ec876539e28b323718df3ef734b3a4b247fcc649f0704ea1b61
Le vendredi 14 février 2025 à 17:45:54 UTC, Peter Todd a écrit :

> On Fri, Feb 07, 2025 at 05:02:46AM -0800, Antoine Riard wrote:
> > This might be a stylistic note, though I could point in bitcoin core 
> code 
> > today implemented
> > check in the script interpreter right in the crux of consensus code 
> paths 
> > that is just stale
> > due to a never-activated BIP (-- yes I'm starring at you SIGPUSHONLY).
>
> What specifically do you mean by this? You mean the
> SCRIPT_ERR_SIG_PUSHONLY error condition?
>
> -- 
> https://petertodd.org 'peter'[:-1]@petertodd.org
>

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