hook_account

Summary. Write the 20-byte AccountID of the account the running hook is installed on into hook memory.

Signature.

int64_t hook_account(uint32_t write_ptr, uint32_t write_len);

Parameters.

Name	Type	Description
write_ptr	uint32_t	Destination buffer in WASM memory.
write_len	uint32_t	Buffer length; must be at least 20.

Return value. Returns 20 (the number of bytes written) on success. Errors: OUT_OF_BOUNDS (-1) if the buffer is outside memory; TOO_SMALL (-4) if write_len < 20.

Common failure patterns.

• Passing a buffer smaller than 20 bytes → TOO_SMALL.
• An out-of-range pointer or length → OUT_OF_BOUNDS.

Caveats / notes.

• Writes exactly 20 raw bytes (an AccountID), not an r-address. Use util_raddr to convert to the human-readable form.
• The "hook account" is the account whose hook is executing — not necessarily the sender of the originating transaction. Compare with otxn_field(sfAccount).

Minimal example.

uint8_t acc[20];
hook_account((uint32_t)acc, 20);

Practical example.

int64_t hook(uint32_t reserved)
{
    _g(1, 1);
    uint8_t acc[20];

    // bounds and size checks return the documented error codes
    ASSERT(hook_account(1000000, 20) == OUT_OF_BOUNDS);
    ASSERT(hook_account((uint32_t)acc, 19) == TOO_SMALL);
    ASSERT(hook_account((uint32_t)acc, 20) == 20);

    accept((uint32_t)acc, 20, 0);   // return the accid
}

Related APIs. otxn_field, util_raddr.