Function from_err_ptr 

pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T>

Transform a kernel “error pointer” to a normal pointer.

Some kernel C API functions return an “error pointer” which optionally embeds an errno. Callers are supposed to check the returned pointer for errors. This function performs the check and converts the “error pointer” to a normal pointer in an idiomatic fashion.

Note that a NULL pointer is not considered an error pointer, and is returned as-is, wrapped in Ok.

Examples

fn devm_platform_ioremap_resource(
    pdev: &mut PlatformDevice,
    index: u32,
) -> Result<*mut kernel::ffi::c_void> {
    // SAFETY: `pdev` points to a valid platform device. There are no safety requirements
    // on `index`.
    from_err_ptr(unsafe { bindings::devm_platform_ioremap_resource(pdev.to_ptr(), index) })
}

// SAFETY: ...
let einval_err = from_err_ptr(unsafe { bindings::einval_err_ptr() });
assert_eq!(einval_err, Err(EINVAL));

// SAFETY: ...
let null_ok = from_err_ptr(unsafe { bindings::null_ptr() });
assert_eq!(null_ok, Ok(core::ptr::null_mut()));

// SAFETY: ...
let non_null = from_err_ptr(unsafe { bindings::non_null_ptr() }).unwrap();
assert_ne!(non_null, core::ptr::null_mut());