bitcoin-util: Add evalscript subcommand #35788

ajtowns commented at 1:56 AM on July 24, 2026: contributor

Adds an evalscript subcommand for using bitcoin's consensus logic to evaluate script fragments. Intended for debugging and development.

Examples:

# check a script fragment's behaviour
$ bitcoin-util evalscript '1 2 ADD'
{
  "script": {
    "asm": "1 2 OP_ADD",
    "hex": "515293",
    "type": "nonstandard"
  },
  "sigversion": "witness_v0",
  "script_flags": [
    "CHECKLOCKTIMEVERIFY",
    "CHECKSEQUENCEVERIFY",
    "DERSIG",
    "NULLDUMMY",
    "P2SH",
    "TAPROOT",
    "WITNESS"
  ],
  "dummy_sig_checker": true,
  "stack_after": [
    "03"
  ],
  "sigop_cost": 0,
  "success": true
}

# validate a real signature
$ bitcoin-util -sigversion=base \
    -spentoutput=00f2052a0100000043410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3ac \
    -tx=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 \
    evalscript '0x410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3 CHECKSIG' \
    '304402204e45e16932b8af514961a1d3a1a25fdf3f4f7732e9d624c6c61548ab5fb8cd410220181522ec8eca07de4860a4acdd12909d831cc56cbbac4622082221a8768d1d0901'
{
  "script": {
    "asm": "0411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3 OP_CHECKSIG",
    "hex": "410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3ac",
    "type": "pubkey"
  },
  "sigversion": "base",
  "script_flags": [
    "CHECKLOCKTIMEVERIFY",
    "CHECKSEQUENCEVERIFY",
    "DERSIG",
    "NULLDUMMY",
    "P2SH",
    "TAPROOT",
    "WITNESS"
  ],
  "dummy_sig_checker": false,
  "stack_after": [
    "01"
  ],
  "sigop_cost": 4,
  "success": true
}

script: expose CastToBool function f3ad9ba72c

[consensus] script/interpreter: Expose OP_SUCCESS logic

Review with `git diff --color-moved=zebra --color-moved-ws=allow-indentation-change`

9d1482911d

DrahtBot commented at 1:56 AM on July 24, 2026: contributor

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35788.

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ACK	jeanpablojp

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Conflicts

Reviewers, this pull request conflicts with the following ones:

#30342 (kernel, logging: Pass Logger instances to kernel objects by ryanofsky)
#29247 (CAT in Tapscript (BIP-347) by arminsabouri)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

ajtowns commented at 2:02 AM on July 24, 2026: contributor

Previously included in bitcoin-inquisition (https://github.com/bitcoin-inquisition/bitcoin/pull/58, also https://github.com/bitcoin-inquisition/bitcoin/pull/64 and https://github.com/bitcoin-inquisition/bitcoin/pull/79).

Makes minimal changes to consensus logic, but still has to duplicate a bunch of code to get equivalent behaviour, might be worthwhile simplifying that API in followups, and potentially exposing as a kernel API of some sort?

bitcoin-util: Introduce evalscript subcommand f0556b061d

tests: Add functional test for bitcoin-util evalscript a64f2ac5b1

ajtowns force-pushed on Jul 24, 2026

DrahtBot added the label CI failed on Jul 24, 2026

DrahtBot removed the label CI failed on Jul 24, 2026

jeanpablojp commented at 6:16 PM on August 19, 2026: contributor

tACK a64f2ac5b11ac95a43d11c2846e461de0b6eb48a

Ran tool_utils, the script unit tests and feature_taproot on the head, and both examples from the description reproduce here.

The PR description mentions -tx, but I noticed no case in bitcoin-util-test.json uses -tx, so that path goes uncovered. To confirm, I disabled the -input range check and the suite still passes. Would it be worth adding a case like that?