Function sys_listmounts

kernel/src/syscalls.rs:839–878

Get a list of mounted paths in a memory handle

(context_ptr: *mut Context)

/// Get a list of mounted paths in a memory handle
fn sys_listmounts(context_ptr: *mut Context) {
    if let Some(mut thread) = process::take_current_thread() {
        thread.set_context(context_ptr);
        let context = unsafe {&mut (*context_ptr)};

        // Get a JSON string containing VFS mounts
        let json = thread.vfs().to_json();

        // No longer need thread, needed
        // by process::new_memory_chunk
        process::set_current_thread(thread);

        // Allocate memory chunk to hold the data
        let num_bytes = json.len() as u64;
        let num_pages = (num_bytes >> 12) +
            if (num_bytes & 4095) != 0 {1} else {0};

        match process::new_memory_chunk(
            num_pages,
            0xFFFF_FFFF_FFFF_FFFF) {
            Ok((virtaddr, _physaddr)) => {
                // Copy string into memory chunk
                unsafe {
                    ptr::copy_nonoverlapping(json.as_ptr(),
                                             virtaddr.as_u64() as *mut u8,
                                             json.len());
                }

                context.rax = 0; // No error
                context.rdi = virtaddr.as_u64() as usize;
                context.rsi = json.len();
            }
            Err(code) => {
                context.rax = code;
                context.rdi = 0;
                context.rsi = 0;
            }
        }
    }
}

/// Remove a mount point.
/// Most of this code is the same as `sys_mount`