cstr16 to str improvements after review

Author: phip1611

src/data_types/strs.rs

@@ -165,28 +165,23 @@ impl CStr16 {
         }
     }
 
-    /// Write a string slice into the provided buffer. If it fails, then most probably, because
-    /// the buffer is not big enough. In that case, the buffer will contain the correct string
-    /// until the point, where the size was not enough.
+    /// Writes each [`Char16`] as a [´char´] (4 bytes long in Rust language) into the buffer.
+    /// It is up the the implementer of [`core::fmt::Write`] to convert the char to a string
+    /// with proper encoding/charset. For example, in the case of [`core::alloc::string::String`]
+    /// all Rust chars (UTF-32) get converted to UTF-8.
     ///
     /// ## Example
     ///
-    /// ```rust
-    /// use uefi::data_types::ArrayString;
-    /// use uefi::{CStr16, Char16};
+    /// ```ignore
     /// let firmware_vendor_c16_str: CStr16 = ...;
-    /// // crate "arrayvec" uses stack-allocated arrays for Strings => no heap
+    /// // crate "arrayvec" uses stack-allocated arrays for Strings => no heap allocations
     /// let mut buf = arrayvec::ArrayString::<128>::new();
     /// firmware_vendor_c16_str.as_str_in_buf(&mut buf);
     /// log::info!("as rust str: {}", buf.as_str());
     /// ```
-    pub fn as_str_in_buf(&self, buf: &mut dyn core::fmt::Write) -> Result<(), ()> {
+    pub fn as_str_in_buf(&self, buf: &mut dyn core::fmt::Write) -> core::fmt::Result {
         for c16 in self.iter() {
-            let res = buf.write_char(char::from(*c16));
-            if let Err(err) = res {
-                log::error!("Failed to write CStr16 as &str into buffer. Buffer too small? ({})", err);
-                return Err(())
-            }
+            buf.write_char(char::from(*c16))?;
         }
         Ok(())
     }

uefi-test-runner/src/main.rs

@@ -25,6 +25,12 @@ fn efi_main(image: Handle, mut st: SystemTable<Boot>) -> Status {
     // Initialize utilities (logging, memory allocation...)
     uefi_services::init(&mut st).expect_success("Failed to initialize utilities");
 
+    /* unit tests here */
+    /*let mut buf = String::new();
+    st.firmware_vendor().as_str_in_buf(&mut buf).unwrap();
+    st.stdout().write_str(buf.as_str()).unwrap();
+    assert_eq!("EDK II", buf.as_str());*/
+
     // Reset the console before running all the other tests.
     st.stdout()
         .reset(false)