michaelkuc6/blog_os
1
0
Fork 0
mirror of https://github.com/phil-opp/blog_os.git synced 2025-12-16 22:37:49 +00:00
Code Issues Projects Releases Wiki Activity

Unique::get/get_mut were renamed to as_ref/as_mut (#325)

Browse Source
This commit is contained in:
Philipp Oppermann
2017-05-12 21:32:38 +02:00
committed by GitHub
parent 160b986322
commit f3829346bc
4 changed files with 8 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
blog/content/post/04-printing-to-screen.md
View File

@@ -177,7 +177,7 @@ impl Writer {
}
fn buffer(&mut self) -> &mut Buffer {
unsafe{ self.buffer.get_mut() }
unsafe{ self.buffer.as_mut() }
}
fn new_line(&mut self) {/* TODO */}
@@ -189,8 +189,8 @@ If the byte is the [newline] byte `\n`, the writer does not print anything. Inst
When printing a byte, the writer checks if the current line is full. In that case, a `new_line` call is required before to wrap the line. Then it writes a new `ScreenChar` to the buffer at the current position. Finally, the current column position is advanced.
The `buffer()` auxiliary method converts the raw pointer in the `buffer` field into a safe mutable buffer reference. The unsafe block is needed because the [get_mut()] method of `Unique` is unsafe. But our `buffer()` method itself isn't marked as unsafe, so it must not introduce any unsafety (e.g. cause segfaults). To guarantee that, it's very important that the `buffer` field always points to a valid `Buffer`. It's like a contract that we must stand to every time we create a `Writer`. To ensure that it's not possible to create an invalid `Writer` from outside of the module, the struct must have at least one private field and public creation functions are not allowed either.
[get_mut()]: https://doc.rust-lang.org/nightly/core/ptr/struct.Unique.html#method.get_mut
The `buffer()` auxiliary method converts the raw pointer in the `buffer` field into a safe mutable buffer reference. The unsafe block is needed because the [as_mut()] method of `Unique` is unsafe. But our `buffer()` method itself isn't marked as unsafe, so it must not introduce any unsafety (e.g. cause segfaults). To guarantee that, it's very important that the `buffer` field always points to a valid `Buffer`. It's like a contract that we must stand to every time we create a `Writer`. To ensure that it's not possible to create an invalid `Writer` from outside of the module, the struct must have at least one private field and public creation functions are not allowed either.
[as_mut()]: https://doc.rust-lang.org/nightly/core/ptr/struct.Unique.html#method.as_mut
### Cannot Move out of Borrowed Content
When we try to compile it, we get the following error:

4
blog/content/post/06-page-tables.md
View File

@@ -670,11 +670,11 @@ We add some methods to get P4 references:
```rust
fn p4(&self) -> &Table<Level4> {
unsafe { self.p4.get() }
unsafe { self.p4.as_ref() }
}
fn p4_mut(&mut self) -> &mut Table<Level4> {
unsafe { self.p4.get_mut() }
unsafe { self.p4.as_mut() }
}
```