refactor(tvix/nix-compat): reorganize wire and bytes r/7896

Move everything bytes-related into its own module, and re-export
both bytes and primitive in a flat space from wire/mod.rs.

Expose this if a `wire` feature flag is set. We only have `async` stuff
in here.

Change-Id: Ia4ce4791f13a5759901cc9d6ce6bd6bbcca587c7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11389
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
Reviewed-by: Brian Olsen <me@griff.name>

1 files changed, 0 insertions, 228 deletions

diff --git a/tvix/nix-compat/src/wire/bytes.rs b/tvix/nix-compat/src/wire/bytes.rs
deleted file mode 100644
index d299eea652..0000000000
--- a/tvix/nix-compat/src/wire/bytes.rs
+++ /dev/null
@@ -1,228 +0,0 @@
-use std::{
-    io::{Error, ErrorKind},
-    ops::RangeBounds,
-};
-
-use tokio::io::{AsyncReadExt, AsyncWriteExt};
-
-use super::primitive;
-
-/// 8 null bytes, used to write out padding.
-pub(crate) const EMPTY_BYTES: &[u8; 8] = &[0u8; 8];
-
-#[allow(dead_code)]
-/// Read a "bytes wire packet" from the AsyncRead.
-/// Rejects reading more than `allowed_size` bytes of payload.
-///
-/// The packet is made up of three parts:
-/// - a length header, u64, LE-encoded
-/// - the payload itself
-/// - null bytes to the next 8 byte boundary
-///
-/// Ensures the payload size fits into the `allowed_size` passed,
-/// and that the padding is actual null bytes.
-///
-/// On success, the returned `Vec<u8>` only contains the payload itself.
-/// On failure (for example if a too large byte packet was sent), the reader
-/// becomes unusable.
-///
-/// This buffers the entire payload into memory, a streaming version will be
-/// added later.
-pub async fn read_bytes<R, S>(r: &mut R, allowed_size: S) -> std::io::Result<Vec<u8>>
-where
-    R: AsyncReadExt + Unpin,
-    S: RangeBounds<u64>,
-{
-    // read the length field
-    let len = primitive::read_u64(r).await?;
-
-    if !allowed_size.contains(&len) {
-        return Err(std::io::Error::new(
-            std::io::ErrorKind::InvalidData,
-            "signalled package size not in allowed range",
-        ));
-    }
-
-    // calculate the total length, including padding.
-    // byte packets are padded to 8 byte blocks each.
-    let padded_len = padding_len(len) as u64 + (len as u64);
-    let mut limited_reader = r.take(padded_len);
-
-    let mut buf = Vec::new();
-
-    let s = limited_reader.read_to_end(&mut buf).await?;
-
-    // make sure we got exactly the number of bytes, and not less.
-    if s as u64 != padded_len {
-        return Err(std::io::Error::new(
-            std::io::ErrorKind::InvalidData,
-            "got less bytes than expected",
-        ));
-    }
-
-    let (_content, padding) = buf.split_at(len as usize);
-
-    // ensure the padding is all zeroes.
-    if !padding.iter().all(|e| *e == b'\0') {
-        return Err(std::io::Error::new(
-            std::io::ErrorKind::InvalidData,
-            "padding is not all zeroes",
-        ));
-    }
-
-    // return the data without the padding
-    buf.truncate(len as usize);
-    Ok(buf)
-}
-
-/// Read a "bytes wire packet" of from the AsyncRead and tries to parse as string.
-/// Internally uses [read_bytes].
-/// Rejects reading more than `allowed_size` bytes of payload.
-pub async fn read_string<R, S>(r: &mut R, allowed_size: S) -> std::io::Result<String>
-where
-    R: AsyncReadExt + Unpin,
-    S: RangeBounds<u64>,
-{
-    let bytes = read_bytes(r, allowed_size).await?;
-    String::from_utf8(bytes).map_err(|e| Error::new(ErrorKind::InvalidData, e))
-}
-
-/// Writes a "bytes wire packet" to a (hopefully buffered) [AsyncWriteExt].
-///
-/// Accepts anything implementing AsRef<[u8]> as payload.
-///
-/// See [read_bytes] for a description of the format.
-///
-/// Note: if performance matters to you, make sure your
-/// [AsyncWriteExt] handle is buffered. This function is quite
-/// write-intesive.
-pub async fn write_bytes<W: AsyncWriteExt + Unpin, B: AsRef<[u8]>>(
-    w: &mut W,
-    b: B,
-) -> std::io::Result<()> {
-    // write the size packet.
-    primitive::write_u64(w, b.as_ref().len() as u64).await?;
-
-    // write the payload
-    w.write_all(b.as_ref()).await?;
-
-    // write padding if needed
-    let padding_len = padding_len(b.as_ref().len() as u64) as usize;
-    if padding_len != 0 {
-        w.write_all(&EMPTY_BYTES[..padding_len]).await?;
-    }
-    Ok(())
-}
-
-/// Computes the number of bytes we should add to len (a length in
-/// bytes) to be alined on 64 bits (8 bytes).
-pub(crate) fn padding_len(len: u64) -> u8 {
-    let modulo = len % 8;
-    if modulo == 0 {
-        0
-    } else {
-        8 - modulo as u8
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use tokio_test::{assert_ok, io::Builder};
-
-    use super::*;
-    use hex_literal::hex;
-
-    /// The maximum length of bytes packets we're willing to accept in the test
-    /// cases.
-    const MAX_LEN: u64 = 1024;
-
-    #[tokio::test]
-    async fn test_read_8_bytes() {
-        let mut mock = Builder::new()
-            .read(&8u64.to_le_bytes())
-            .read(&12345678u64.to_le_bytes())
-            .build();
-
-        assert_eq!(
-            &12345678u64.to_le_bytes(),
-            read_bytes(&mut mock, 0u64..MAX_LEN)
-                .await
-                .unwrap()
-                .as_slice()
-        );
-    }
-
-    #[tokio::test]
-    async fn test_read_9_bytes() {
-        let mut mock = Builder::new()
-            .read(&9u64.to_le_bytes())
-            .read(&hex!("01020304050607080900000000000000"))
-            .build();
-
-        assert_eq!(
-            hex!("010203040506070809"),
-            read_bytes(&mut mock, 0u64..MAX_LEN)
-                .await
-                .unwrap()
-                .as_slice()
-        );
-    }
-
-    #[tokio::test]
-    async fn test_read_0_bytes() {
-        // A empty byte packet is essentially just the 0 length field.
-        // No data is read, and there's zero padding.
-        let mut mock = Builder::new().read(&0u64.to_le_bytes()).build();
-
-        assert_eq!(
-            hex!(""),
-            read_bytes(&mut mock, 0u64..MAX_LEN)
-                .await
-                .unwrap()
-                .as_slice()
-        );
-    }
-
-    #[tokio::test]
-    /// Ensure we don't read any further than the size field if the length
-    /// doesn't match the range we want to accept.
-    async fn test_read_reject_too_large() {
-        let mut mock = Builder::new().read(&100u64.to_le_bytes()).build();
-
-        read_bytes(&mut mock, 10..10)
-            .await
-            .expect_err("expect this to fail");
-    }
-
-    #[tokio::test]
-    async fn test_write_bytes_no_padding() {
-        let input = hex!("6478696f34657661");
-        let len = input.len() as u64;
-        let mut mock = Builder::new()
-            .write(&len.to_le_bytes())
-            .write(&input)
-            .build();
-        assert_ok!(write_bytes(&mut mock, &input).await)
-    }
-    #[tokio::test]
-    async fn test_write_bytes_with_padding() {
-        let input = hex!("322e332e3137");
-        let len = input.len() as u64;
-        let mut mock = Builder::new()
-            .write(&len.to_le_bytes())
-            .write(&hex!("322e332e31370000"))
-            .build();
-        assert_ok!(write_bytes(&mut mock, &input).await)
-    }
-
-    #[tokio::test]
-    async fn test_write_string() {
-        let input = "Hello, World!";
-        let len = input.len() as u64;
-        let mut mock = Builder::new()
-            .write(&len.to_le_bytes())
-            .write(&hex!("48656c6c6f2c20576f726c6421000000"))
-            .build();
-        assert_ok!(write_bytes(&mut mock, &input).await)
-    }
-}