Function str_from_header

native/shared/src/string_header.rs:25–35

Extract a &str from a *const StringHeader pointer (Perry string format).

(ptr: *const u8)

/// Extract a &str from a *const StringHeader pointer (Perry string format).
pub fn str_from_header(ptr: *const u8) -> &'static str {
    if ptr.is_null() || (ptr as usize) < 0x1000 {
        return "";
    }
    unsafe {
        let header = ptr as *const StringHeader;
        let len = (*header).byte_len as usize;
        let data = ptr.add(std::mem::size_of::<StringHeader>());
        std::str::from_utf8_unchecked(std::slice::from_raw_parts(data, len))
    }
}

/// Allocate a Perry 0.5.x heap string suitable for returning across the
/// FFI boundary (declared as `returns: "string"` in package.json). Layout