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use crate::error::Error;
pub enum UserPtr {
Buffered {
ptr: *mut cty::c_void,
read_size: usize,
write_size: usize,
},
Direct {
read_ptr: *const cty::c_void,
write_ptr: *mut cty::c_void,
read_size: usize,
write_size: usize,
},
Neither,
}
impl UserPtr {
/// # Safety
/// `unsafe`
pub unsafe fn new_buffered(ptr: *mut cty::c_void, read_size: usize, write_size: usize) -> Self {
Self::Buffered {
ptr,
read_size,
write_size,
}
}
/// # Safety
/// `unsafe`
pub unsafe fn new_direct(
read_ptr: *const cty::c_void,
write_ptr: *mut cty::c_void,
read_size: usize,
write_size: usize,
) -> Self {
Self::Direct {
read_ptr,
write_ptr,
read_size,
write_size,
}
}
/// # Safety
/// `unsafe`
pub unsafe fn new_neither() -> Self { Self::Neither }
pub fn read_size(&self) -> usize {
match self {
Self::Buffered {
read_size, ..
} => *read_size,
Self::Direct {
read_size, ..
} => *read_size,
Self::Neither => 0,
}
}
pub fn write_size(&self) -> usize {
match self {
Self::Buffered {
write_size, ..
} => *write_size,
Self::Direct {
write_size, ..
} => *write_size,
Self::Neither => 0,
}
}
pub fn as_slice(&self) -> &[u8] {
let (ptr, size) = match self {
Self::Buffered {
ptr,
read_size,
..
} => (*ptr as _, *read_size),
Self::Direct {
read_ptr,
read_size,
..
} => (*read_ptr, *read_size),
Self::Neither => (core::ptr::null(), 0),
};
if ptr.is_null() || size == 0 {
&[]
} else {
unsafe { core::slice::from_raw_parts(ptr as *const u8, size) }
}
}
pub fn as_mut_slice(&mut self) -> &mut [u8] {
let (ptr, size) = match self {
Self::Buffered {
ptr,
write_size,
..
} => (*ptr, *write_size),
Self::Direct {
write_ptr,
write_size,
..
} => (*write_ptr, *write_size),
Self::Neither => (core::ptr::null_mut(), 0),
};
if ptr.is_null() || size == 0 {
&mut []
} else {
unsafe { core::slice::from_raw_parts_mut(ptr as *mut u8, size) }
}
}
pub fn read<T: Copy + Default>(&self) -> Result<T, Error> {
let (ptr, size) = match self {
Self::Buffered {
ptr,
read_size,
..
} => (*ptr as _, *read_size),
Self::Direct {
read_ptr,
read_size,
..
} => (*read_ptr, *read_size),
Self::Neither => (core::ptr::null(), 0),
};
if ptr.is_null() || size == 0 {
return Err(Error::INVALID_PARAMETER);
}
if core::mem::size_of::<T>() > size {
return Err(Error::INVALID_USER_BUFFER);
}
let mut obj = T::default();
unsafe {
core::ptr::copy_nonoverlapping(ptr as _, &mut obj, 1);
}
Ok(obj)
}
pub fn write<T: Copy>(&mut self, obj: &T) -> Result<(), Error> {
let (ptr, size) = match self {
Self::Buffered {
ptr,
write_size,
..
} => (*ptr, *write_size),
Self::Direct {
write_ptr,
write_size,
..
} => (*write_ptr, *write_size),
Self::Neither => (core::ptr::null_mut(), 0),
};
if ptr.is_null() || size == 0 {
return Err(Error::INVALID_PARAMETER);
}
if core::mem::size_of::<T>() > size {
return Err(Error::INVALID_USER_BUFFER);
}
unsafe {
core::ptr::copy_nonoverlapping(obj, ptr as _, 1);
}
Ok(())
}
}
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