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fix: fix nulldata too big chunk size handling #465

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Merged
rkalis merged 1 commit into from
Sep 29, 2026
+10 −8
Merged

fix: fix nulldata too big chunk size handling #465

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6 changes: 4 additions & 2 deletions packages/cashc/src/generation/GenerateTargetTraversal.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -950,7 +950,8 @@ export default class GenerateTargetTraversal extends AstTraversal {
this.visit(element);

// OP_SIZE is a signed VM number, so it is empty for empty elements, and has an extra 0x00 byte for 128-255 bytes.
// In those cases (and for 76-127 bytes) we convert it to a single byte, and prepend OP_PUSHDATA1.
// In those cases (and for 76-127 bytes) we convert it to a single byte, and prepend OP_PUSHDATA1. Chunks over 255
// bytes are not supported, so the size's high byte has to be 0x00 (an OP_0 would be empty and never match it).
this.emit(Op.OP_SIZE, endLocationData);
this.emit(Op.OP_DUP, endLocationData);
this.emit(encodeInt(1n), endLocationData);
Expand All @@ -961,7 +962,8 @@ export default class GenerateTargetTraversal extends AstTraversal {
this.emit(Op.OP_NUM2BIN, endLocationData);
this.emit(encodeInt(1n), endLocationData);
this.emit(Op.OP_SPLIT, endLocationData);
this.emit(Op.OP_DROP, endLocationData);
this.emit(hexToBin('00'), endLocationData);
this.emit(Op.OP_EQUALVERIFY, endLocationData);
this.emit(hexToBin('4c'), endLocationData);
this.emit(Op.OP_SWAP, endLocationData);
this.emit(Op.OP_CAT, endLocationData);
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10 changes: 5 additions & 5 deletions ...s/cashc/test/generation/fixtures/valid-contract-files/locking_bytecode_nulldata_chunks.ts
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Expand Up @@ -20,20 +20,20 @@ export const fixtures: Fixture[] = [
// pkh (known length)
+ '14 OP_3 OP_ROLL OP_CAT OP_CAT '
// data (unknown length)
+ 'OP_ROT OP_SIZE OP_DUP OP_1 4c OP_WITHIN OP_NOTIF OP_2 OP_NUM2BIN OP_1 OP_SPLIT OP_DROP 4c OP_SWAP OP_CAT OP_ENDIF '
+ 'OP_ROT OP_SIZE OP_DUP OP_1 4c OP_WITHIN OP_NOTIF OP_2 OP_NUM2BIN OP_1 OP_SPLIT 00 OP_EQUALVERIFY 4c OP_SWAP OP_CAT OP_ENDIF '
+ 'OP_SWAP OP_CAT OP_CAT '
// ]));
+ 'OP_EQUAL',
debug: {
bytecode: '8201148800cd016a03026d027e05046d656d6f7e0114537a7e7e7b827651014ca5645280517f75014c7c7e687c7e7e87',
sourceMap: '2:19:2:30;;;4:27:4:28;:16::45:1;:49::112:0;:78::84;::::1;:86::99:0;::::1;:101::104:0;;;::::1;;:106::110:0;::::1;;;;;;;;;;;;;;;;;;:8::114',
bytecode: '8201148800cd016a03026d027e05046d656d6f7e0114537a7e7e7b827651014ca5645280517f010088014c7c7e687c7e7e87',
sourceMap: '2:19:2:30;;;4:27:4:28;:16::45:1;:49::112:0;:78::84;::::1;:86::99:0;::::1;:101::104:0;;;::::1;;:106::110:0;::::1;;;;;;;;;;;;;;;;;;;:8::114',
logs: [],
requires: [
{ ip: 35, line: 4 },
{ ip: 36, line: 4 },
],
sourceTags: '0:2:pv',
},
fingerprint: '334d3b680b5a80af6ff0a2158f339b6edfd530828669f34b06e7c9aa41556126',
fingerprint: 'd5b78e3ef9d4e50fad5d0c10a5e3cb2a12390b8f18b4795098985801bf0c3e8f',
},
},
];
2 changes: 1 addition & 1 deletion website/docs/language/globals.md
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Expand Up @@ -247,7 +247,7 @@ Creates new P2SH32 locking bytecode for the script hash, where `scriptHash` is t
new LockingBytecodeNullData(bytes[] chunks): bytes
```

Creates new OP_RETURN locking bytecode with `chunks` as its OP_RETURN data. Each chunk is pushed the same way as in the SDK's `addOpReturnOutput()`: with `OP_PUSHDATA1` for empty chunks and chunks of 76-255 bytes, and with a direct push for chunks of 1-75 bytes. Chunks larger than 255 bytes are not supported, and cause a compile error when their size is known at compile time.
Creates new OP_RETURN locking bytecode with `chunks` as its OP_RETURN data. Each chunk is pushed the same way as in the SDK's `addOpReturnOutput()`: with `OP_PUSHDATA1` for empty chunks and chunks of 76-255 bytes, and with a direct push for chunks of 1-75 bytes. Chunks larger than 255 bytes are not supported: they cause a compile error when their size is known at compile time, and fail the contract's execution otherwise.

:::note
`LockingBytecodeNullData` outputs are provably unspendable, so any BCH sent there would be burned. For these outputs no dust-minimum is enforced so often `LockingBytecodeNullData` outputs have 0 BCH on them.
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