Segfault when requesting accessibility permission via macOS Accessibility API

I'm trying to create a Rust program that will ask for accessibility permission on macOS.

If the permission is granted (through Settings -> Privacy & Security -> Accessibility), then it works and returns true from AXIsProcessTrustedWithOptions.

But if the permission is not allowed, instead of prompting to ask for the permission, the program crashes with a segfault.

It seems the settings dictionary is created incorrectly, but I'm not sure why.

I created it by following AXIsProcessTrustedWithOptions Apple's docs and tested it on macOS 14.4.1 (Apple silicon).

use accessibility_sys::AXIsProcessTrustedWithOptions;
use core_foundation_sys::base::{CFRelease, TCFTypeRef};
use core_foundation_sys::dictionary::{CFDictionaryAddValue, CFDictionaryCreateMutable};
use core_foundation_sys::number::kCFBooleanTrue;
use std::ffi::CString;
use std::ptr;

fn main() {
    let mut is_allowed = false;
    unsafe {
        let options =
            CFDictionaryCreateMutable(ptr::null_mut(), 1, std::ptr::null(), std::ptr::null());
        let key = CString::new("AXTrustedCheckOptionPrompt").unwrap();
        let value = kCFBooleanTrue;
        CFDictionaryAddValue(options, key.as_ptr().as_void_ptr(), value.as_void_ptr());
        is_allowed = AXIsProcessTrustedWithOptions(options);
        CFRelease(options as *const _);
    }
    println!("Accessibility permission enabled: {}", is_allowed);
}

Solution

Thanks for the help in the comments, I used accessibility_sys::kAXTrustedCheckOptionPrompt instead of my own CString and now it doesn't crash! also added error handling

use std::{error::Error, ptr};
use accessibility_sys::{kAXTrustedCheckOptionPrompt, AXIsProcessTrustedWithOptions};
use core_foundation_sys::dictionary::{CFDictionaryAddValue, CFDictionaryCreateMutable};
use core_foundation_sys::base::{CFRelease, TCFTypeRef};
use core_foundation_sys::number::{kCFBooleanFalse, kCFBooleanTrue};


fn check_accessibility(ask_if_not_allowed: bool) -> Result<bool, Box<dyn Error>> {
    let is_allowed;
    unsafe {
        let options =
            CFDictionaryCreateMutable(ptr::null_mut(), 0, std::ptr::null(), std::ptr::null());
        let key = kAXTrustedCheckOptionPrompt;
        let value = if ask_if_not_allowed {kCFBooleanTrue} else {kCFBooleanFalse};
        if !options.is_null() {
            CFDictionaryAddValue(
                options,
                key.as_void_ptr(),
                value.as_void_ptr(),
            );
            is_allowed = AXIsProcessTrustedWithOptions(options);
            CFRelease(options as *const _);
        } else {
            return Err("options is null".into());
        }
    }
    Ok(is_allowed)
}

fn main() {
    let is_allowed = check_accessibility(true).unwrap();
    println!("Accessibility permission enabled: {}", is_allowed);
}