Skip to main content

​
Overview

The account_resize syscall changes the data storage size of an account. This can be used to expand or shrink the account’s data capacity.

​
Syscall Code

Code: 0x07 (TN_SYSCALL_CODE_ACCOUNT_RESIZE)

​
C SDK Function

ulong tsys_account_resize(ulong account_idx, ulong new_size);

​
Arguments

​
account_idx
ulong
required
Index of the account to resize. Must be writable by the current program.
​
new_size
ulong
required
New data size for the account in bytes. Must not exceed maximum account data size.

​
Return Value

Returns a syscall result code:
​
Success
ulong
  • TN_VM_SYSCALL_SUCCESS (0) - Account resized successfully
​
Error Codes
ulong
  • TN_VM_ERR_SYSCALL_INVALID_ACCOUNT_INDEX (-7) - Account index out of bounds
  • TN_VM_ERR_SYSCALL_ACCOUNT_DOES_NOT_EXIST (-8) - Account does not exist
  • TN_VM_ERR_SYSCALL_ACCOUNT_NOT_WRITABLE (-26) - Account not writable by current program
  • TN_VM_ERR_SYSCALL_ACCOUNT_TOO_BIG (-11) - New size exceeds maximum allowed
  • TN_VM_ERR_SYSCALL_INSUFFICIENT_PAGES (-25) - Not enough pages available for expansion

​
Resource Consumption

​
Compute Units

  • Base cost: TN_VM_SYSCALL_BASE_COST (512 units)
  • Additional cost: None (size changes don’t directly affect compute cost)
  • Total cost: Fixed at 512 units regardless of new size

​
Memory Pages

  • Page allocation: New pages allocated from transaction pool when expanding
  • Page deallocation: Excess pages returned to transaction pool when shrinking
  • Page granularity: Account data is managed in page-sized chunks
  • Minimum allocation: Account metadata always requires at least one page

​
Side Effects

  • Data size: Changes the account’s data size to the specified value
  • Memory allocation: Allocates or frees pages as needed
  • Metadata: Makes account metadata and data writable if not already
  • Data preservation: Existing data is preserved when expanding

​
Usage Notes

  • The new size must not exceed TN_ACCOUNT_DATA_SZ_MAX
  • When expanding: additional space is allocated and initialized
  • When shrinking: excess data is truncated and pages may be freed
  • If new size equals current size, the syscall succeeds immediately
  • Account must be writable by the current program
  • Sufficient pages must be available in the transaction’s page pool

​
Memory Management

  • Expansion: Allocates additional pages from the transaction page pool
  • Shrinking: May free pages back to the pool (implementation dependent)
  • Page alignment: Account data is managed in page-sized chunks
  • Data preservation: Existing data within the new size is preserved

​
Example

#include "tn_sdk_syscall.h"

// Resize account data to 2048 bytes
ulong account_idx = 1;
ulong new_size = 2048;

ulong result = tsys_account_resize(account_idx, new_size);

if (result == TN_VM_SYSCALL_SUCCESS) {
    // Account data size changed to 2048 bytes
    // Existing data preserved (up to new size)
    // Additional space initialized if expanded
}

// Check current size without changing it
result = tsys_account_resize(account_idx, current_size);
// This will succeed immediately if current_size matches actual size