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Use this page when you need to inspect the current transaction, understand account indexing, or safely read account and block metadata.

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Transaction root

Most in-program reads start from: 
tsdk_txn_t const * txn = tsdk_get_txn( );
From there, the inline helpers in tn_sdk_txn.h expose the fields you usually care about.

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Transaction helper reference

HelperWhat it returns
tsdk_txn_get_instr_data(txn)Pointer to instruction bytes.
tsdk_txn_get_instr_data_sz(txn)Instruction byte length.
tsdk_txn_get_msg(txn)Message portion of the transaction.
tsdk_txn_get_msg_sz(txn_sz)Message size excluding trailing signature.
tsdk_txn_get_fee_payer_signature(txn, txn_sz)Pointer to the trailing fee-payer signature.
tsdk_txn_get_fee(txn)Requested fee.
tsdk_txn_get_nonce(txn)Transaction nonce.
tsdk_txn_get_start_slot(txn)First valid slot.
tsdk_txn_get_expiry_slot(txn)Last valid slot derived from start_slot + expiry_after.
tsdk_txn_get_chain_id(txn)Chain identifier.
tsdk_txn_get_requested_compute_units(txn)Requested compute units.
tsdk_txn_get_requested_memory_units(txn)Requested memory units.
tsdk_txn_has_fee_payer_state_proof(txn)Whether a fee-payer proof is present.
tsdk_txn_get_acct_addrs(txn)Pointer to fee payer, program, and remaining account pubkeys.
tsdk_txn_account_cnt(txn)Total account count exposed to the transaction.
tsdk_txn_readwrite_account_cnt(txn)Read-write account count from the header.
tsdk_txn_readonly_account_cnt(txn)Read-only account count from the header.
tsdk_txn_is_account_idx_writable(txn, idx)Whether the account index is writable in the transaction.
tsdk_txn_get_msg_sz(txn_sz) is the one helper in this group that only needs the total transaction size. It computes message size = txn_sz - TN_TXN_SIGNATURE_SZ, so it does not need the transaction pointer.

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Account indexing

The public helpers assume transaction account indexing like this:
Index rangeMeaning
0Fee payer
1Current program account
2+User-supplied read-write and read-only accounts
Use tsdk_is_account_idx_valid(idx) before indexing transaction-linked account data.

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Account metadata

tsdk_get_account_meta(account_idx) returns a tsdk_account_meta_t const * with:
FieldMeaning
versionWhether the metadata is present and versioned.
flagsBitfield of account properties (see flag constants below).
data_szAccount data size.
seqSequence number.
ownerOwner program pubkey.
balanceNative token balance.
nonceAccount nonce.
tsdk_account_exists(account_idx) is a convenient existence check built on top of metadata version.

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Account flag constants

The flags field on tsdk_account_meta_t is a bitfield. Test individual flags with bitwise AND:
ConstantValueMeaning
TSDK_ACCOUNT_FLAG_PROGRAM0x01Account contains executable program code.
TSDK_ACCOUNT_FLAG_PRIVILEGED0x02Account has privileged system-level access.
TSDK_ACCOUNT_FLAG_UNCOMPRESSABLE0x04Account cannot be compressed.
TSDK_ACCOUNT_FLAG_EPHEMERAL0x08Account exists only for the current transaction.
TSDK_ACCOUNT_FLAG_DELETED0x10Account has been deleted.
TSDK_ACCOUNT_FLAG_NEW0x20Account has never existed before this transaction.
TSDK_ACCOUNT_FLAG_COMPRESSED0x40Account state is compressed (removed from active ledger).
tsdk_account_meta_t const * meta = tsdk_get_account_meta( account_idx );
if( meta->flags & TSDK_ACCOUNT_FLAG_PROGRAM ) {
  /* account is a program */
}
Use tsys_account_set_flags(account_idx, flags) to modify flags on accounts owned by the current program.

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Account data pointers

tsdk_get_account_data_ptr(account_idx) returns a raw pointer into the VM account-data segment. Typical pattern: 
ushort account_idx = 2U;

if( !tsdk_is_account_idx_valid( account_idx ) ) tsdk_revert( 1UL );
if( !tsdk_account_exists( account_idx ) ) tsdk_revert( 2UL );

void * data = tsdk_get_account_data_ptr( account_idx );
tsdk_account_meta_t const * meta = tsdk_get_account_meta( account_idx );

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Block context

HelperUse it for
tsdk_get_current_block_ctx()Current slot, block time, block price, state root, current block hash, and block producer.
tsdk_get_past_block_ctx(blocks_in_past)Access a previous block context spaced by TSDK_BLOCK_CTX_VM_SPACING.
The block context struct is tsdk_block_ctx_t.

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Shadow stack and current program identity

HelperUse it for
tsdk_get_shadow_stack()Read call depth and CPI frame information.
tsdk_get_current_program_acc_idx()Resolve the current program’s transaction account index.
tsdk_get_current_program_acc_addr()Resolve the current program’s pubkey.
tsdk_is_program_reentrant()Detect whether the current program already appears lower in the call chain.
tsdk_is_account_authorized_by_idx(...)Check effective authorization by account index, including CPI auth/deauth state.
tsdk_is_account_authorized_by_pubkey(...)Check effective authorization by pubkey.
tsdk_is_account_owned_by_current_program(...)Check whether the current program owns an account.

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Notes

  • Do not assume every account index is valid just because the instruction payload contains it.
  • Metadata and data pointers come from VM-managed memory; treat them as borrowed pointers, not owned allocations.
  • Writable status comes from transaction context and syscalls, not from the presence of a data pointer alone.