Function parseNullData

src/simplicity/elements/env.c:189–234

Determine if 'scriptPubKey' is a TX_NULL_DATA script, and fill 'result' with (digests of) the push data opcodes. * If 'scriptPubKey' isn't a TX_NULL_DATA, then 'result->op' is set to NULL. * Otherwise '*result' is set to '(parsedNullData){ .op = *allocation, .len = countNullDataCodes(scriptPubKey) }. * and then the 'opcode result->op[result->len]' array is filled in with (digests of) the pus da

 *               countNullDataCodes(scriptPubKey) <= *allocationLen
 */
static void parseNullData(parsedNullData* result, opcode** allocation, size_t* allocationLen, const rawElementsBuffer* scriptPubKey) {
  *result = (parsedNullData){ .op = *allocation };

  if (0 == scriptPubKey->len || 0x6a != scriptPubKey->buf[0] ) { result->op = NULL; return; }

  for (uint_fast32_t i = 1; i < scriptPubKey->len; ++result->len) {
    unsigned char code = scriptPubKey->buf[i++];
    if (*allocationLen <= result->len || 0x60 < code) { result->op = NULL; return; }
    if (0x4f <= code) {
      (*allocation)[result->len].code = OP_1NEGATE + (code - 0x4f);
    } else {
      uint_fast32_t skip = 0;
      if (code < 0x4c) {
        skip = code;
        (*allocation)[result->len].code = OP_IMMEDIATE;
      } else {
        if (scriptPubKey->len == i) { result->op = NULL; return; }
        skip = scriptPubKey->buf[i++];
        if (code < 0x4d) {
          (*allocation)[result->len].code = OP_PUSHDATA;
        } else {
          if (scriptPubKey->len == i) { result->op = NULL; return; }
          skip += (uint_fast32_t)(scriptPubKey->buf[i++]) << 8;
          if (code < 0x4e) {
            (*allocation)[result->len].code = OP_PUSHDATA2;
          } else {
            if (scriptPubKey->len == i) { result->op = NULL; return; }
            skip += (uint_fast32_t)(scriptPubKey->buf[i++]) << 16;
            if (scriptPubKey->len == i) { result->op = NULL; return; }
            skip += (uint_fast32_t)(scriptPubKey->buf[i++]) << 24;
            (*allocation)[result->len].code = OP_PUSHDATA4;
          }
        }
      }
      if (scriptPubKey->len - i < skip) { result->op = NULL; return; }
      {
        sha256_context ctx = sha256_init((*allocation)[result->len].dataHash.s);
        sha256_uchars(&ctx, &scriptPubKey->buf[i], skip);
        sha256_finalize(&ctx);
      }
      i += skip;
    }
  }
  *allocation += result->len; /* C requires '*allocation != NULL', even when 'result->len == 0'. */
  *allocationLen -= result->len;
}

/* Initialize a 'sigOutput' from a 'rawElementsOutput', copying or hashing the data as needed.
 *