From 17d40c6057c88f4c432b0d7bac88e1b84cb7e67f Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:03:36 +0200
Subject: Adding upstream version 1.65.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 library/std/src/net/display_buffer.rs | 40 +++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 library/std/src/net/display_buffer.rs

(limited to 'library/std/src/net/display_buffer.rs')

diff --git a/library/std/src/net/display_buffer.rs b/library/std/src/net/display_buffer.rs
new file mode 100644
index 000000000..7aadf06e9
--- /dev/null
+++ b/library/std/src/net/display_buffer.rs
@@ -0,0 +1,40 @@
+use crate::fmt;
+use crate::mem::MaybeUninit;
+use crate::str;
+
+/// Used for slow path in `Display` implementations when alignment is required.
+pub struct DisplayBuffer<const SIZE: usize> {
+    buf: [MaybeUninit<u8>; SIZE],
+    len: usize,
+}
+
+impl<const SIZE: usize> DisplayBuffer<SIZE> {
+    #[inline]
+    pub const fn new() -> Self {
+        Self { buf: MaybeUninit::uninit_array(), len: 0 }
+    }
+
+    #[inline]
+    pub fn as_str(&self) -> &str {
+        // SAFETY: `buf` is only written to by the `fmt::Write::write_str` implementation
+        // which writes a valid UTF-8 string to `buf` and correctly sets `len`.
+        unsafe {
+            let s = MaybeUninit::slice_assume_init_ref(&self.buf[..self.len]);
+            str::from_utf8_unchecked(s)
+        }
+    }
+}
+
+impl<const SIZE: usize> fmt::Write for DisplayBuffer<SIZE> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        let bytes = s.as_bytes();
+
+        if let Some(buf) = self.buf.get_mut(self.len..(self.len + bytes.len())) {
+            MaybeUninit::write_slice(buf, bytes);
+            self.len += bytes.len();
+            Ok(())
+        } else {
+            Err(fmt::Error)
+        }
+    }
+}
-- 
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