fs: code improvement

Cargo.toml

@@ -7,8 +7,8 @@ edition = "2021"
 
 [dependencies]
 log = "0.4.20"
-uefi = { version = "0.26.0", features = ["alloc"], optional = true }
-uefi-services = { version = "0.23.0", optional = true }
+uefi = { version = "0.27.0", features = ["alloc"], optional = true }
+uefi-services = { version = "0.24.0", optional = true }
 ttf_renderer = { git = "https://github.com/codyd51/axle", branch="paging-demo" }
 agx_definitions = { git = "https://github.com/codyd51/axle", branch="paging-demo" }
 libgui = { git = "https://github.com/codyd51/axle", branch="paging-demo" }

rust-toolchain.toml

@@ -1,3 +1,4 @@
 [toolchain]
+channel = "nightly-2024-04-09" # rustc 1.79
 targets = ["x86_64-unknown-uefi"]
 

src/fs.rs

@@ -1,21 +1,12 @@
 use alloc::format;
 use alloc::vec::Vec;
-use uefi::{CStr16, cstr16};
-use uefi::fs::FileSystem;
+use uefi::{CString16};
+use uefi::fs::{FileSystem};
 use uefi::prelude::BootServices;
 
 pub fn read_file(boot_services: &BootServices, path: &str) -> Vec<u8> {
-    let mut input_as_u16s = path
-        .chars()
-        .map(|c| u16::try_from(c as u32))
-        .collect::<Result<Vec<u16>, _>>().expect("Failed to convert path characters to u16s");
-    // Add a null byte at the end, as CStr16 needs one
-    input_as_u16s.push(0);
-    let path_as_cstr16 = unsafe {
-        CStr16::from_u16_with_nul_unchecked(&input_as_u16s)
-    };
-
-    let mut sfs = boot_services.get_image_file_system(boot_services.image_handle()).unwrap();
+    let path_as_cstr16 = CString16::try_from(path).expect("Path should only contain UCS2-compatible characters.");
+    let sfs = boot_services.get_image_file_system(boot_services.image_handle()).unwrap();
     let mut fs = FileSystem::new(sfs);
-    fs.read(path_as_cstr16).expect(&format!("Failed to read file \"{path}\""))
+    fs.read(path_as_cstr16.as_ref()).expect(&format!("Should be able to read file \"{path}\""))
 }