qos-sdk Reference

qos_sdk::input::read

Reads the JSON payload provided by the host environment (typically passed from the guest's Micro-UI upon scanning the QR code).

#Signature

pub fn read() -> Option<Vec<u8>>

#Usage

Because Q-OS WASM modules execute in a #[no_std] environment, this function returns a raw byte vector. You will typically use a lightweight JSON parser like serde-json-core or microserde to deserialize the bytes into a Rust struct.

src/lib.rs

use qos_sdk::input;

#[no_mangle]
pub extern "C" fn run() -> i32 {
    // 1. Read input bytes from host
    if let Some(bytes) = input::read() {
        // 2. Convert to string (if expecting UTF-8)
        if let Ok(json_str) = core::str::from_utf8(&bytes) {
            qos_sdk::log_msg(qos_sdk::LogLevel::Info, "Received payload");
            // 3. Parse JSON...
        }
    }
    0
}

#Under the Hood

This wrapper calls the raw ABI function __qos_input_len() to determine the buffer size, allocates a Vec<u8>, and then calls __qos_input_read(*mut u8) to instruct the host to write the payload directly into the WASM sandbox's linear memory.

←SDK Overview write_output→