Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 351 insertions, 0 deletions

diff --git a/third_party/rust/line-wrap/src/lib.rs b/third_party/rust/line-wrap/src/lib.rs
new file mode 100644
index 0000000000..3760d10175
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+++ b/third_party/rust/line-wrap/src/lib.rs
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+//! Efficiently insert line endings.
+//!
+//! If you have a buffer full of data and want to insert any sort of regularly-spaced separator,
+//! this will do it with a minimum of data copying. Commonly, this is to insert `\n` (see `lf()`) or `\r\n` (`crlf()`), but
+//! any byte sequence can be used.
+//!
+//! 1. Pick a line ending. For single byte separators, see `ByteLineEnding`, or for two bytes, `TwoByteLineEnding`. For
+//! arbitrary byte slices, use `SliceLineEnding`.
+//! 2. Call `line_wrap`.
+//! 3. Your data has been rearranged in place with the specified line ending inserted.
+//!
+//! # Examples
+//!
+//! ```
+//! use line_wrap::*;
+//! // suppose we have 80 bytes of data in a buffer and we want to wrap as per MIME.
+//! // Buffer is large enough to hold line endings.
+//! let mut data = vec![0; 82];
+//!
+//! assert_eq!(2, line_wrap(&mut data, 80, 76, &crlf()));
+//!
+//! // first line of zeroes
+//! let mut expected_data = vec![0; 76];
+//! // line ending
+//! expected_data.extend_from_slice(b"\r\n");
+//! // next line
+//! expected_data.extend_from_slice(&[0, 0, 0, 0]);
+//! assert_eq!(expected_data, data);
+//! ```
+//!
+//! # Performance
+//!
+//! On an i7 6850k:
+//!
+//! - 10 byte input, 1 byte line length takes ~60ns (~160MiB/s)
+//! - 100 byte input, 10 byte lines takes ~60ns (~1.6GiB/s)
+//!     - Startup costs dominate at these small lengths
+//! - 1,000 byte input, 100 byte lines takes ~65ns (~15GiB/s)
+//! - 10,000 byte input, 100 byte lines takes ~550ns (~17GiB/s)
+//! - In general, `SliceLineEncoding` is about 75% the speed of the fixed-length impls.
+//!
+//! Naturally, try `cargo +nightly bench` on your hardware to get more representative data.
+extern crate safemem;
+
+/// Unix-style line ending.
+pub fn lf() -> ByteLineEnding { ByteLineEnding::new(b'\n') }
+
+/// Windows-style line ending.
+pub fn crlf() -> TwoByteLineEnding { TwoByteLineEnding::new(b'\r', b'\n') }
+
+/// Writes line endings.
+///
+/// The trait allows specialization for the common single and double byte cases, netting nice
+/// throughput improvements over simply using a slice for everything.
+pub trait LineEnding {
+    /// Write the line ending into the slice, which starts at the point where the ending should be written and is len() in length
+    fn write_ending(&self, slice: &mut [u8]);
+    /// The length of this particular line ending (must be constant and > 0)
+    fn len(&self) -> usize;
+}
+
+/// A single byte line ending.
+///
+/// See `lf()`.
+///
+/// # Examples
+///
+/// ```
+/// use line_wrap::*;
+///
+/// let ending = ByteLineEnding::new(b'\n');
+///
+/// let mut data = vec![1, 2, 3, 4, 5, 6, 255, 255];
+///
+/// assert_eq!(2, line_wrap(&mut data[..], 6, 2, &ending));
+///
+/// assert_eq!(vec![1, 2, b'\n', 3, 4, b'\n', 5, 6], data);
+/// ```
+pub struct ByteLineEnding {
+    byte: u8
+}
+
+impl ByteLineEnding {
+    pub fn new(byte: u8) -> ByteLineEnding {
+        ByteLineEnding {
+            byte
+        }
+    }
+}
+
+impl LineEnding for ByteLineEnding {
+    #[inline]
+    fn write_ending(&self, slice: &mut [u8]) {
+        slice[0] = self.byte;
+    }
+
+    #[inline]
+    fn len(&self) -> usize {
+        1
+    }
+}
+
+/// A double byte line ending.
+///
+/// See `crlf()`.
+///
+/// # Examples
+///
+/// ```
+/// use line_wrap::*;
+///
+/// let ending = TwoByteLineEnding::new(b'\r', b'\n');
+///
+/// let mut data = vec![1, 2, 3, 4, 5, 6, 255, 255, 255, 255];
+///
+/// assert_eq!(4, line_wrap(&mut data[..], 6, 2, &ending));
+///
+/// assert_eq!(vec![1, 2, b'\r', b'\n', 3, 4, b'\r', b'\n', 5, 6], data);
+/// ```
+pub struct TwoByteLineEnding {
+    byte0: u8,
+    byte1: u8,
+}
+
+impl TwoByteLineEnding {
+    pub fn new(byte0: u8, byte1: u8) -> TwoByteLineEnding {
+        TwoByteLineEnding {
+            byte0,
+            byte1,
+        }
+    }
+}
+
+impl LineEnding for TwoByteLineEnding {
+    #[inline]
+    fn write_ending(&self, slice: &mut [u8]) {
+        slice[0] = self.byte0;
+        slice[1] = self.byte1;
+    }
+
+    #[inline]
+    fn len(&self) -> usize {
+        2
+    }
+}
+
+/// A byte slice line ending.
+///
+/// Gives up some throughput compared to the specialized single/double byte impls, but works with
+/// any length.
+///
+/// # Examples
+///
+/// ```
+/// use line_wrap::*;
+///
+/// let ending = SliceLineEnding::new(b"xyz");
+///
+/// let mut data = vec![1, 2, 3, 4, 5, 6, 255, 255, 255, 255, 255, 255];
+///
+/// assert_eq!(6, line_wrap(&mut data[..], 6, 2, &ending));
+///
+/// assert_eq!(vec![1, 2, b'x', b'y', b'z', 3, 4, b'x', b'y', b'z', 5, 6], data);
+/// ```
+pub struct SliceLineEnding<'a> {
+    slice: &'a [u8]
+}
+
+impl<'a> SliceLineEnding<'a> {
+    pub fn new(slice: &[u8]) -> SliceLineEnding {
+        SliceLineEnding {
+            slice
+        }
+    }
+}
+
+impl<'a> LineEnding for SliceLineEnding<'a> {
+    #[inline]
+    fn write_ending(&self, slice: &mut [u8]) {
+        slice.copy_from_slice(self.slice);
+    }
+
+    #[inline]
+    fn len(&self) -> usize {
+        self.slice.len()
+    }
+}
+
+/// Insert line endings into the input.
+///
+/// Endings are inserted after each complete line, except the last line, even if the last line takes
+/// up the full line width.
+///
+/// - `buf` must be large enough to handle the increased size after endings are inserted. In other
+/// words, `buf.len() >= input_len / line_len * line_ending.len()`.
+/// - `input_len` is the length of the unwrapped  in `buf`.
+/// - `line_len` is the desired line width without line ending characters.
+///
+/// Returns the number of line ending bytes added.
+///
+/// # Panics
+///
+/// - When `line_ending.len() == 0`
+/// - When `buf` is too small to contain the original input and its new line endings
+pub fn line_wrap<L: LineEnding>(
+    buf: &mut [u8],
+    input_len: usize,
+    line_len: usize,
+    line_ending: &L,
+) -> usize {
+    assert!(line_ending.len() > 0);
+
+    if input_len <= line_len {
+        return 0;
+    }
+
+    let line_ending_len = line_ending.len();
+    let line_wrap_params = line_wrap_parameters(input_len, line_len, line_ending_len);
+
+    // ptr.offset() is undefined if it wraps, and there is no checked_offset(). However, because
+    // we perform this check up front to make sure we have enough capacity, we know that none of
+    // the subsequent pointer operations (assuming they implement the desired behavior of course!)
+    // will overflow.
+    assert!(
+        buf.len() >= line_wrap_params.total_len,
+        "Buffer must be able to hold encoded data after line wrapping"
+    );
+
+    // Move the last line, either partial or full, by itself as it does not have a line ending
+    // afterwards
+    let last_line_start = input_len.checked_sub(line_wrap_params.last_line_len)
+        .expect("Last line start index underflow");
+    // last line starts immediately after all the wrapped full lines
+    let new_line_start = line_wrap_params.total_full_wrapped_lines_len;
+
+    safemem::copy_over(
+        buf,
+        last_line_start,
+        new_line_start,
+        line_wrap_params.last_line_len,
+    );
+
+    let mut total_line_ending_bytes = 0;
+
+    // initialize so that the initial decrement will set them correctly
+    let mut old_line_start = last_line_start;
+    let mut new_line_start = line_wrap_params.total_full_wrapped_lines_len;
+
+    // handle the full lines
+    for _ in 0..line_wrap_params.lines_with_endings {
+        // the index after the end of the line ending we're about to write is the start of the next
+        // line
+        let end_of_line_ending = new_line_start;
+        let start_of_line_ending = end_of_line_ending
+            .checked_sub(line_ending_len)
+            .expect("Line ending start index underflow");
+
+        // doesn't underflow because it's decremented `line_wrap_params.lines_with_endings` times
+        old_line_start = old_line_start.checked_sub(line_len)
+            .expect("Old line start index underflow");
+        new_line_start = new_line_start.checked_sub(line_wrap_params.line_with_ending_len)
+            .expect("New line start index underflow");
+
+        safemem::copy_over(buf, old_line_start, new_line_start, line_len);
+
+        line_ending.write_ending(&mut buf[start_of_line_ending..(end_of_line_ending)]);
+        total_line_ending_bytes += line_ending_len;
+    }
+
+    assert_eq!(line_wrap_params.total_line_endings_len, total_line_ending_bytes);
+
+    total_line_ending_bytes
+}
+
+#[derive(Debug, PartialEq)]
+struct LineWrapParameters {
+    line_with_ending_len: usize,
+    // number of lines that need an ending
+    lines_with_endings: usize,
+    // length of last line (which never needs an ending)
+    last_line_len: usize,
+    // length of lines that need an ending (which are always full lines), with their endings
+    total_full_wrapped_lines_len: usize,
+    // length of all lines, including endings for the ones that need them
+    total_len: usize,
+    // length of the line endings only
+    total_line_endings_len: usize,
+}
+
+/// Calculations about how many lines we'll get for a given line length, line ending, etc.
+/// This assumes that the last line will not get an ending, even if it is the full line length.
+// Inlining improves short input single-byte by 25%.
+#[inline]
+fn line_wrap_parameters(
+    input_len: usize,
+    line_len: usize,
+    line_ending_len: usize,
+) -> LineWrapParameters {
+    let line_with_ending_len = line_len
+        .checked_add(line_ending_len)
+        .expect("Line length with ending exceeds usize");
+
+    if input_len <= line_len {
+        // no wrapping needed
+        return LineWrapParameters {
+            line_with_ending_len,
+            lines_with_endings: 0,
+            last_line_len: input_len,
+            total_full_wrapped_lines_len: 0,
+            total_len: input_len,
+            total_line_endings_len: 0,
+        };
+    };
+
+    // lines_with_endings > 0, last_line_len > 0
+    let (lines_with_endings, last_line_len) = if input_len % line_len > 0 {
+        // Every full line has an ending since there is a partial line at the end
+        (input_len / line_len, input_len % line_len)
+    } else {
+        // Every line is a full line, but no trailing ending.
+        // Subtraction will not underflow since we know input_len > line_len.
+        (input_len / line_len - 1, line_len)
+    };
+
+    // Should we expose exceeding usize via Result to be kind to 16-bit users? Or is that
+    // always going to be a panic anyway in practice?
+
+    // length of just the full lines with line endings
+    let total_full_wrapped_lines_len = lines_with_endings
+        .checked_mul(line_with_ending_len)
+        .expect("Full lines with endings length exceeds usize");
+    // all lines with appropriate endings, including the last line
+    let total_len = total_full_wrapped_lines_len
+        .checked_add(last_line_len)
+        .expect("All lines with endings length exceeds usize");
+    let total_line_endings_len = lines_with_endings
+        .checked_mul(line_ending_len)
+        .expect("Total line endings length exceeds usize");
+
+    LineWrapParameters {
+        line_with_ending_len,
+        lines_with_endings,
+        last_line_len,
+        total_full_wrapped_lines_len,
+        total_len,
+        total_line_endings_len,
+    }
+}
+
+#[cfg(test)]
+mod tests;
\ No newline at end of file