Merge branch 'tokio-1.6.x' into merge-1.6.1

tokio/CHANGELOG.md

@@ -1,3 +1,11 @@
+# 1.6.1 (May 28, 2021)
+
+This release reverts [#3518] because it doesn't work on some kernels due to
+a kernel bug. ([#3803])
+
+[#3518]: https://github.com/tokio-rs/tokio/issues/3518
+[#3803]: https://github.com/tokio-rs/tokio/issues/3803
+
 # 1.6.0 (May 14, 2021)
 
 ### Added

tokio/Cargo.toml

@@ -7,7 +7,7 @@ name = "tokio"
 #   - README.md
 # - Update CHANGELOG.md.
 # - Create "v1.0.x" git tag.
-version = "1.6.0"
+version = "1.6.1"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
@@ -42,7 +42,7 @@ full = [
   "time",
 ]
 
-fs = ["libc"]
+fs = []
 io-util = ["memchr", "bytes"]
 # stdin, stdout, stderr
 io-std = []
@@ -103,11 +103,11 @@ parking_lot = { version = "0.11.0", optional = true }
 tracing = { version = "0.1.21", default-features = false, features = ["std"], optional = true } # Not in full
 
 [target.'cfg(unix)'.dependencies]
-libc = { version = "0.2.87", optional = true }
+libc = { version = "0.2.42", optional = true }
 signal-hook-registry = { version = "1.1.1", optional = true }
 
 [target.'cfg(unix)'.dev-dependencies]
-libc = { version = "0.2.87" }
+libc = { version = "0.2.42" }
 nix = { version = "0.19.0" }
 
 [target.'cfg(windows)'.dependencies.winapi]

tokio/src/fs/file.rs

@@ -491,18 +491,14 @@ impl AsyncRead for File {
         loop {
             match inner.state {
                 Idle(ref mut buf_cell) => {
-                    let buf = buf_cell.as_mut().unwrap();
+                    let mut buf = buf_cell.take().unwrap();
 
                     if !buf.is_empty() {
                         buf.copy_to(dst);
+                        *buf_cell = Some(buf);
                         return Ready(Ok(()));
                     }
 
-                    if let Some(x) = try_nonblocking_read(me.std.as_ref(), dst) {
-                        return Ready(x);
-                    }
-
-                    let mut buf = buf_cell.take().unwrap();
                     buf.ensure_capacity_for(dst);
                     let std = me.std.clone();
 
@@ -760,186 +756,3 @@ impl Inner {
         }
     }
 }
-
-#[cfg(all(target_os = "linux", not(test)))]
-pub(crate) fn try_nonblocking_read(
-    file: &crate::fs::sys::File,
-    dst: &mut ReadBuf<'_>,
-) -> Option<std::io::Result<()>> {
-    use std::sync::atomic::{AtomicBool, Ordering};
-
-    static NONBLOCKING_READ_SUPPORTED: AtomicBool = AtomicBool::new(true);
-    if !NONBLOCKING_READ_SUPPORTED.load(Ordering::Relaxed) {
-        return None;
-    }
-    let out = preadv2::preadv2_safe(file, dst, -1, preadv2::RWF_NOWAIT);
-    if let Err(err) = &out {
-        match err.raw_os_error() {
-            Some(libc::ENOSYS) => {
-                NONBLOCKING_READ_SUPPORTED.store(false, Ordering::Relaxed);
-                return None;
-            }
-            Some(libc::ENOTSUP) | Some(libc::EAGAIN) => return None,
-            _ => {}
-        }
-    }
-    Some(out)
-}
-
-#[cfg(any(not(target_os = "linux"), test))]
-pub(crate) fn try_nonblocking_read(
-    _file: &crate::fs::sys::File,
-    _dst: &mut ReadBuf<'_>,
-) -> Option<std::io::Result<()>> {
-    None
-}
-
-#[cfg(target_os = "linux")]
-mod preadv2 {
-    use libc::{c_int, c_long, c_void, iovec, off_t, ssize_t};
-    use std::os::unix::prelude::AsRawFd;
-
-    use crate::io::ReadBuf;
-
-    pub(crate) fn preadv2_safe(
-        file: &std::fs::File,
-        dst: &mut ReadBuf<'_>,
-        offset: off_t,
-        flags: c_int,
-    ) -> std::io::Result<()> {
-        unsafe {
-            /* We have to defend against buffer overflows manually here.  The slice API makes
-             * this fairly straightforward. */
-            let unfilled = dst.unfilled_mut();
-            let mut iov = iovec {
-                iov_base: unfilled.as_mut_ptr() as *mut c_void,
-                iov_len: unfilled.len(),
-            };
-            /* We take a File object rather than an fd as reading from a sensitive fd may confuse
-             * other unsafe code that assumes that only they have access to that fd. */
-            let bytes_read = preadv2(
-                file.as_raw_fd(),
-                &mut iov as *mut iovec as *const iovec,
-                1,
-                offset,
-                flags,
-            );
-            if bytes_read < 0 {
-                Err(std::io::Error::last_os_error())
-            } else {
-                /* preadv2 returns the number of bytes read, e.g. the number of bytes that have
-                 * written into `unfilled`. So it's safe to assume that the data is now
-                 * initialised */
-                dst.assume_init(bytes_read as usize);
-                dst.advance(bytes_read as usize);
-                Ok(())
-            }
-        }
-    }
-
-    #[cfg(test)]
-    mod test {
-        use super::*;
-
-        #[test]
-        fn test_preadv2_safe() {
-            use std::io::{Seek, Write};
-            use std::mem::MaybeUninit;
-            use tempfile::tempdir;
-
-            let tmp = tempdir().unwrap();
-            let filename = tmp.path().join("file");
-            const MESSAGE: &[u8] = b"Hello this is a test";
-            {
-                let mut f = std::fs::File::create(&filename).unwrap();
-                f.write_all(MESSAGE).unwrap();
-            }
-            let f = std::fs::File::open(&filename).unwrap();
-
-            let mut buf = [MaybeUninit::<u8>::new(0); 50];
-            let mut br = ReadBuf::uninit(&mut buf);
-
-            // Basic use:
-            preadv2_safe(&f, &mut br, 0, 0).unwrap();
-            assert_eq!(br.initialized().len(), MESSAGE.len());
-            assert_eq!(br.filled(), MESSAGE);
-
-            // Here we check that offset works, but also that appending to a non-empty buffer
-            // behaves correctly WRT initialisation.
-            preadv2_safe(&f, &mut br, 5, 0).unwrap();
-            assert_eq!(br.initialized().len(), MESSAGE.len() * 2 - 5);
-            assert_eq!(br.filled(), b"Hello this is a test this is a test".as_ref());
-
-            // offset of -1 means use the current cursor.  This has not been advanced by the
-            // previous reads because we specified an offset there.
-            preadv2_safe(&f, &mut br, -1, 0).unwrap();
-            assert_eq!(br.remaining(), 0);
-            assert_eq!(
-                br.filled(),
-                b"Hello this is a test this is a testHello this is a".as_ref()
-            );
-
-            // but the offset should have been advanced by that read
-            br.clear();
-            preadv2_safe(&f, &mut br, -1, 0).unwrap();
-            assert_eq!(br.filled(), b" test");
-
-            // This should be in cache, so RWF_NOWAIT should work, but it not being in cache
-            // (EAGAIN) or not supported by the underlying filesystem (ENOTSUP) is fine too.
-            br.clear();
-            match preadv2_safe(&f, &mut br, 0, RWF_NOWAIT) {
-                Ok(()) => assert_eq!(br.filled(), MESSAGE),
-                Err(e) => assert!(matches!(
-                    e.raw_os_error(),
-                    Some(libc::ENOTSUP) | Some(libc::EAGAIN)
-                )),
-            }
-
-            // Test handling large offsets
-            {
-                // I hope the underlying filesystem supports sparse files
-                let mut w = std::fs::OpenOptions::new()
-                    .write(true)
-                    .open(&filename)
-                    .unwrap();
-                w.set_len(0x1_0000_0000).unwrap();
-                w.seek(std::io::SeekFrom::Start(0x1_0000_0000)).unwrap();
-                w.write_all(b"This is a Large File").unwrap();
-            }
-
-            br.clear();
-            preadv2_safe(&f, &mut br, 0x1_0000_0008, 0).unwrap();
-            assert_eq!(br.filled(), b"a Large File");
-        }
-    }
-
-    fn pos_to_lohi(offset: off_t) -> (c_long, c_long) {
-        // 64-bit offset is split over high and low 32-bits on 32-bit architectures.
-        // 64-bit architectures still have high and low arguments, but only the low
-        // one is inspected.  See pos_from_hilo in linux/fs/read_write.c.
-        const HALF_LONG_BITS: usize = core::mem::size_of::<c_long>() * 8 / 2;
-        (
-            offset as c_long,
-            // We want to shift this off_t value by size_of::<c_long>(). We can't do
-            // it in one shift because if they're both 64-bits we'd be doing u64 >> 64
-            // which is implementation defined.  Instead do it in two halves:
-            ((offset >> HALF_LONG_BITS) >> HALF_LONG_BITS) as c_long,
-        )
-    }
-
-    pub(crate) const RWF_NOWAIT: c_int = 0x00000008;
-    unsafe fn preadv2(
-        fd: c_int,
-        iov: *const iovec,
-        iovcnt: c_int,
-        offset: off_t,
-        flags: c_int,
-    ) -> ssize_t {
-        // Call via libc::syscall rather than libc::preadv2.  preadv2 is only supported by glibc
-        // and only since v2.26.  By using syscall we don't need to worry about compatiblity with
-        // old glibc versions and it will work on Android and musl too.  The downside is that you
-        // can't use `LD_PRELOAD` tricks any more to intercept these calls.
-        let (lo, hi) = pos_to_lohi(offset);
-        libc::syscall(libc::SYS_preadv2, fd, iov, iovcnt, lo, hi, flags) as ssize_t
-    }
-}

tokio/tests/fs_file.rs

@@ -22,27 +22,6 @@ async fn basic_read() {
 
     assert_eq!(n, HELLO.len());
     assert_eq!(&buf[..n], HELLO);
-
-    // Drop the data from the cache to stimulate uncached codepath on Linux (see preadv2 in
-    // file.rs)
-    #[cfg(target_os = "linux")]
-    {
-        use std::os::unix::io::AsRawFd;
-        nix::unistd::fsync(tempfile.as_raw_fd()).unwrap();
-        nix::fcntl::posix_fadvise(
-            tempfile.as_raw_fd(),
-            0,
-            0,
-            nix::fcntl::PosixFadviseAdvice::POSIX_FADV_DONTNEED,
-        )
-        .unwrap();
-    }
-
-    let mut file = File::open(tempfile.path()).await.unwrap();
-    let n = file.read(&mut buf).await.unwrap();
-
-    assert_eq!(n, HELLO.len());
-    assert_eq!(&buf[..n], HELLO);
 }
 
 #[tokio::test]