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

Update links to point to current version of the rust book (#536)

Browse Source
This commit is contained in:
Justin
2019-01-23 02:18:18 -07:00
committed by Philipp Oppermann
parent d83acc0fc8
commit 90ac6bf3b4
1 changed files with 5 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
blog/content/second-edition/posts/02-minimal-rust-kernel/index.md
View File

@@ -298,17 +298,17 @@ pub extern "C" fn _start() -> ! {
First, we cast the integer `0xb8000` into a [raw pointer]. Then we [iterate] over the bytes of the [static] `HELLO` [byte string]. We use the [`enumerate`] method to additionally get a running variable `i`. In the body of the for loop, we use the [`offset`] method to write the string byte and the corresponding color byte (`0xb` is a light cyan).
[iterate]: https://doc.rust-lang.org/book/second-edition/ch13-02-iterators.html
[static]: https://doc.rust-lang.org/book/first-edition/const-and-static.html#static
[iterate]: https://doc.rust-lang.org/stable/book/ch13-02-iterators.html
[static]: https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html#the-static-lifetime
[`enumerate`]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#method.enumerate
[byte string]: https://doc.rust-lang.org/reference/tokens.html#byte-string-literals
[raw pointer]: https://doc.rust-lang.org/stable/book/second-edition/ch19-01-unsafe-rust.html#dereferencing-a-raw-pointer
[raw pointer]: https://doc.rust-lang.org/stable/book/ch19-01-unsafe-rust.html#dereferencing-a-raw-pointer
[`offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.offset
Note that there's an [`unsafe`] block around all memory writes. The reason is that the Rust compiler can't prove that the raw pointers we create are valid. They could point anywhere and lead to data corruption. By putting them into an `unsafe` block we're basically telling the compiler that we are absolutely sure that the operations are valid. Note that an `unsafe` block does not turn off Rust's safety checks. It only allows you to do [four additional things].
[`unsafe`]: https://doc.rust-lang.org/stable/book/second-edition/ch19-01-unsafe-rust.html
[four additional things]: https://doc.rust-lang.org/stable/book/second-edition/ch19-01-unsafe-rust.html#unsafe-superpowers
[`unsafe`]: https://doc.rust-lang.org/stable/book/ch19-01-unsafe-rust.html
[four additional things]: https://doc.rust-lang.org/stable/book/ch19-01-unsafe-rust.html#unsafe-superpowers
I want to emphasize that **this is not the way we want to do things in Rust!** It's very easy to mess up when working with raw pointers inside unsafe blocks, for example, we could easily write behind the buffer's end if we're not careful.