1 files changed, 172 insertions, 0 deletions
diff --git a/crates/windows-kernel-rs/src/user_ptr.rs b/crates/windows-kernel-rs/src/user_ptr.rs
new file mode 100644
index 0000000..54dcb58
--- /dev/null
+++ b/crates/windows-kernel-rs/src/user_ptr.rs
@@ -0,0 +1,172 @@
+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 {
+  pub unsafe fn new_buffered(ptr: *mut cty::c_void, read_size: usize, write_size: usize) -> Self {
+    Self::Buffered {
+      ptr,
+      read_size,
+      write_size,
+    }
+  }
+
+  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,
+    }
+  }
+
+  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(())
+  }
+}