state_foreign

Retrieve the data pointed to, on another account, by a Hook State key and write it to an output buffer

Behaviour

• Read a 20 byte Account ID from the aread_ptr

• Read a 32 byte Hook State key from the kread_ptr

• Write the data (value) at that key at that Account ID to the buffer pointed to by write_ptr

Definition

C

int64_t state_foreign (
    uint32_t write_ptr,
    uint32_t write_len,
    uint32_t kread_ptr,
    uint32_t kread_len,
    uint32_t nread_ptr,
    uint32_t nread_len,
    uint32_t aread_ptr,
    uint32_t aread_len  
);

Example

C

#define SBUF(str) (uint32_t)(str), sizeof(str)
uint8_t ns[32] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
int64_t lookup =
    state_foreign(SBUF(blacklist_status), SBUF(otxn_accid), SBUF(ns), SBUF(blacklist_accid));
if (lookup < 0)
     rollback(SBUF("Error: could not find key on foreign state."), 1);

Parameters

Name	Type	Description
write_ptr	uint32_t	A pointer to the buffer to write the data in the Hook State into.
write_len	uint32_t	The length of the write buffer.
kread_ptr	uint32_t	Pointer to a buffer containing the Hook State key.
kread_len	uint32_t	The length of the Hook State key. (Should be 32.)
nread_ptr	uint32_t	A pointer to the buffer containing the 32 byte Namespace to lookup the state on
nread_len	uint32_t	The length of the namespace buffer (Should be 32).
aread_ptr	uint32_t	A pointer to a buffer containing the 20 byte Account ID to look up state on.
aread_len	uint32_t	The length of the Account buffer. (Should always be 20).

📘Hint

Ensure you check the return value. A state lookup can fail of a range of reasons and the buffer will then contain whatever it did before the call (typically all zeros).

Return Code

Type

Description

int64_t

The number of bytes written to the write buffer. If negative, an error: OUT_OF_BOUNDS - pointers/lengths specified outside of hook memory. DOESNT_EXIST - the specified Hook State key doesn't have an associated value on the ledger at the time of the call. TOO_BIG - the key specified by read_ptr and read_len was larger than 32 bytes. TOO_SMALL - the output buffer was too small to store the Hook State data. INVALID_ACCOUNT - the account specified at aread_ptr is invalid or does not exist.