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Overview

The account_set_flags syscall modifies specific flags on an account, such as marking it as a program account. Only certain flags can be modified.

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Syscall Code

Code: 0x0E (TN_SYSCALL_CODE_ACCOUNT_SET_FLAGS)

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C SDK Function

ulong tsys_account_set_flags(ushort account_idx, uchar flags);

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Arguments

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account_idx
ushort
required
Index of the account to modify. Must be writable by the current program.
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flags
uchar
required
New flags value. Only modifiable flags will be changed.

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Return Value

Returns a syscall result code:
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Success
ulong
  • TN_VM_SYSCALL_SUCCESS (0) - Flags updated successfully
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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_INVALID_FLAGS (-40) - Attempted to modify non-modifiable flags
  • TN_VM_ERR_SYSCALL_ACCOUNT_IS_NOT_PROGRAM (-16) - Account data is not valid program bytecode (when setting PROGRAM flag)
  • TN_VM_ERR_SYSCALL_PROGRAM_IN_CALL_STACK (-49) - Cannot unset PROGRAM flag while program is in the call stack

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Resource Consumption

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Compute Units

  • Base cost: TN_VM_SYSCALL_BASE_COST (512 units)
  • Additional cost: None
  • Total cost: Fixed at 512 units regardless of flag changes

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Memory Pages

  • Page usage: No direct page allocation
  • Metadata impact: May trigger metadata page allocation if not already writable
  • Program validation: Temporary memory usage when validating program bytecode

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Side Effects

  • Account flags: Updates the account’s flag bits
  • Account metadata: Makes account metadata writable if not already
  • Program validation: Validates bytecode when setting PROGRAM flag
  • Write permissions: May remove account writability when marking as program

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Modifiable Flags

Only certain flags can be modified:
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TN_ACCOUNT_FLAG_PROGRAM
flag
Marks the account as containing executable program bytecode. When setting this flag, the account data is validated as valid program bytecode.

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Flag Setting Behavior

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PROGRAM Flag

Setting the flag:
  • Account data is validated as valid program bytecode
  • Account is automatically made non-writable (security measure)
  • Validation failure causes the syscall to fail
Clearing the flag:
  • Cannot be cleared while the program is in the call stack (current program or any caller)
  • Returns TN_VM_ERR_SYSCALL_PROGRAM_IN_CALL_STACK if program is executing
  • Once cleared, account becomes a regular data account

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Usage Notes

  • Only the account owner (program) can modify flags
  • Attempts to modify non-modifiable flags result in an error
  • If no flags actually change, the syscall succeeds immediately
  • Program validation is performed when setting the PROGRAM flag
  • Account must exist and be writable by the current program

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Security Considerations

  • Setting the PROGRAM flag automatically removes account writability
  • This prevents modification of executable code after deployment
  • The PROGRAM flag cannot be cleared while the program is in the call stack
  • This prevents a program from invalidating itself or its callers during execution

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Example

#include "tn_sdk_syscall.h"

// Mark account as a program (requires valid bytecode)
ushort account_idx = 3;
uchar current_flags = get_account_flags(account_idx);
uchar new_flags = current_flags | TN_ACCOUNT_FLAG_PROGRAM;

ulong result = tsys_account_set_flags(account_idx, new_flags);

if (result == TN_VM_SYSCALL_SUCCESS) {
    // Account is now marked as a program
    // Account has been made non-writable
    // Bytecode has been validated
}

// Remove program flag (make it a data account again)
new_flags = current_flags & ~TN_ACCOUNT_FLAG_PROGRAM;
result = tsys_account_set_flags(account_idx, new_flags);

// Attempt to modify non-modifiable flag (will fail)
uchar invalid_flags = current_flags | TN_ACCOUNT_FLAG_DELETED;  // Not modifiable
result = tsys_account_set_flags(account_idx, invalid_flags);
// Returns TN_VM_ERR_SYSCALL_INVALID_FLAGS