Auto merge of #117174 - Ayush1325:uefi-stdio-improve, r=workingjubilee

Improve UEFI stdio Fixed some things suggested in last PR: #116207 cc `@dvdhrm` cc `@nicholasbishop`

Author: bors

library/std/src/sys/pal/uefi/stdio.rs

@@ -4,51 +4,100 @@ use crate::mem::MaybeUninit;
 use crate::os::uefi;
 use crate::ptr::NonNull;
 
-const MAX_BUFFER_SIZE: usize = 8192;
+pub struct Stdin {
+ surrogate: Option<u16>,
+ incomplete_utf8: IncompleteUtf8,
+}
+
+struct IncompleteUtf8 {
+ bytes: [u8; 4],
+ len: u8,
+}
+
+impl IncompleteUtf8 {
+ pub const fn new() -> IncompleteUtf8 {
+ IncompleteUtf8 { bytes: [0; 4], len: 0 }
+ }
+
+ // Implemented for use in Stdin::read.
+ fn read(&mut self, buf: &mut [u8]) -> usize {
+ // Write to buffer until the buffer is full or we run out of bytes.
+ let to_write = crate::cmp::min(buf.len(), self.len as usize);
+ buf[..to_write].copy_from_slice(&self.bytes[..to_write]);
+
+ // Rotate the remaining bytes if not enough remaining space in buffer.
+ if usize::from(self.len) > buf.len() {
+ self.bytes.copy_within(to_write.., 0);
+ self.len -= to_write as u8;
+ } else {
+ self.len = 0;
+ }
+
+ to_write
+ }
+}
 
-pub struct Stdin;
 pub struct Stdout;
 pub struct Stderr;
 
 impl Stdin {
  pub const fn new() -> Stdin {
- Stdin
+ Stdin { surrogate: None, incomplete_utf8: IncompleteUtf8::new() }
  }
 }
 
 impl io::Read for Stdin {
  fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
- let st: NonNull<r_efi::efi::SystemTable> = uefi::env::system_table().cast();
- let stdin = unsafe { (*st.as_ptr()).con_in };
-
- // Try reading any pending data
- let inp = match read_key_stroke(stdin) {
- Ok(x) => x,
- Err(e) if e == r_efi::efi::Status::NOT_READY => {
- // Wait for keypress for new data
- wait_stdin(stdin)?;
- read_key_stroke(stdin).map_err(|x| io::Error::from_raw_os_error(x.as_usize()))?
- }
- Err(e) => {
- return Err(io::Error::from_raw_os_error(e.as_usize()));
- }
+ // If there are bytes in the incomplete utf-8, start with those.
+ // (No-op if there is nothing in the buffer.)
+ let mut bytes_copied = self.incomplete_utf8.read(buf);
+
+ let stdin: *mut r_efi::protocols::simple_text_input::Protocol = unsafe {
+ let st: NonNull<r_efi::efi::SystemTable> = uefi::env::system_table().cast();
+ (*st.as_ptr()).con_in
  };
 
- // Check if the key is printiable character
- if inp.scan_code != 0x00 {
- return Err(io::const_io_error!(io::ErrorKind::Interrupted, "Special Key Press"));
+ if bytes_copied == buf.len() {
+ return Ok(bytes_copied);
  }
 
- // SAFETY: Iterator will have only 1 character since we are reading only 1 Key
- // SAFETY: This character will always be UCS-2 and thus no surrogates.
- let ch: char = char::decode_utf16([inp.unicode_char]).next().unwrap().unwrap();
- if ch.len_utf8() > buf.len() {
- return Ok(0);
+ let ch = simple_text_input_read(stdin)?;
+ // Only 1 character should be returned.
+ let mut ch: Vec<Result<char, crate::char::DecodeUtf16Error>> =
+ if let Some(x) = self.surrogate.take() {
+ char::decode_utf16([x, ch]).collect()
+ } else {
+ char::decode_utf16([ch]).collect()
+ };
+
+ if ch.len() > 1 {
+ return Err(io::Error::new(io::ErrorKind::InvalidData, "invalid utf-16 sequence"));
  }
 
- ch.encode_utf8(buf);
+ match ch.pop().unwrap() {
+ Err(e) => {
+ self.surrogate = Some(e.unpaired_surrogate());
+ }
+ Ok(x) => {
+ // This will always be > 0
+ let buf_free_count = buf.len() - bytes_copied;
+ assert!(buf_free_count > 0);
+
+ if buf_free_count >= x.len_utf8() {
+ // There is enough space in the buffer for the character.
+ bytes_copied += x.encode_utf8(&mut buf[bytes_copied..]).len();
+ } else {
+ // There is not enough space in the buffer for the character.
+ // Store the character in the incomplete buffer.
+ self.incomplete_utf8.len =
+ x.encode_utf8(&mut self.incomplete_utf8.bytes).len() as u8;
+ // write partial character to buffer.
+ bytes_copied += self.incomplete_utf8.read(buf);
+ }
+ }
+ }
 
- Ok(ch.len_utf8())
+ Ok(bytes_copied)
  }
 }
 
@@ -90,11 +139,11 @@ impl io::Write for Stderr {
  }
 }
 
-// UCS-2 character should occupy 3 bytes at most in UTF-8
-pub const STDIN_BUF_SIZE: usize = 3;
+// UTF-16 character should occupy 4 bytes at most in UTF-8
+pub const STDIN_BUF_SIZE: usize = 4;
 
 pub fn is_ebadf(_err: &io::Error) -> bool {
- true
+ false
 }
 
 pub fn panic_output() -> Option<impl io::Write> {
@@ -105,19 +154,15 @@ fn write(
  protocol: *mut r_efi::protocols::simple_text_output::Protocol,
  buf: &[u8],
 ) -> io::Result<usize> {
- let mut utf16 = [0; MAX_BUFFER_SIZE / 2];
-
  // Get valid UTF-8 buffer
  let utf8 = match crate::str::from_utf8(buf) {
  Ok(x) => x,
  Err(e) => unsafe { crate::str::from_utf8_unchecked(&buf[..e.valid_up_to()]) },
  };
- // Clip UTF-8 buffer to max UTF-16 buffer we support
- let utf8 = &utf8[..utf8.floor_char_boundary(utf16.len() - 1)];
 
- for (i, ch) in utf8.encode_utf16().enumerate() {
-  utf16[i] = ch;
- }
+ let mut utf16: Vec<u16> = utf8.encode_utf16().collect();
+ // NULL terminate the string
+ utf16.push(0);
 
  unsafe { simple_text_output(protocol, &mut utf16) }?;
 
@@ -132,6 +177,18 @@ unsafe fn simple_text_output(
  if res.is_error() { Err(io::Error::from_raw_os_error(res.as_usize())) } else { Ok(()) }
 }
 
+fn simple_text_input_read(
+ stdin: *mut r_efi::protocols::simple_text_input::Protocol,
+) -> io::Result<u16> {
+ loop {
+ match read_key_stroke(stdin) {
+ Ok(x) => return Ok(x.unicode_char),
+ Err(e) if e == r_efi::efi::Status::NOT_READY => wait_stdin(stdin)?,
+ Err(e) => return Err(io::Error::from_raw_os_error(e.as_usize())),
+ }
+ }
+}
+
 fn wait_stdin(stdin: *mut r_efi::protocols::simple_text_input::Protocol) -> io::Result<()> {
  let boot_services: NonNull<r_efi::efi::BootServices> =
  uefi::env::boot_services().unwrap().cast();