Rollup merge of #95294 - sourcefrog:doc-copy, r=dtolnay

Document Linux kernel handoff in std::io::copy and std::fs::copy
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Dylan DPC 2022-03-30 09:10:04 +02:00 committed by GitHub
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2 changed files with 19 additions and 3 deletions

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@ -1729,11 +1729,17 @@ pub fn rename<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()>
/// This function currently corresponds to the `open` function in Unix
/// with `O_RDONLY` for `from` and `O_WRONLY`, `O_CREAT`, and `O_TRUNC` for `to`.
/// `O_CLOEXEC` is set for returned file descriptors.
///
/// On Linux (including Android), this function attempts to use `copy_file_range(2)`,
/// and falls back to reading and writing if that is not possible.
///
/// On Windows, this function currently corresponds to `CopyFileEx`. Alternate
/// NTFS streams are copied but only the size of the main stream is returned by
/// this function. On MacOS, this function corresponds to `fclonefileat` and
/// `fcopyfile`.
/// Note that, this [may change in the future][changes].
/// this function.
///
/// On MacOS, this function corresponds to `fclonefileat` and `fcopyfile`.
///
/// Note that platform-specific behavior [may change in the future][changes].
///
/// [changes]: io#platform-specific-behavior
///

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@ -39,6 +39,16 @@ use crate::mem::MaybeUninit;
/// Ok(())
/// }
/// ```
///
/// # Platform-specific behavior
///
/// On Linux (including Android), this function uses `copy_file_range(2)`,
/// `sendfile(2)` or `splice(2)` syscalls to move data directly between file
/// descriptors if possible.
///
/// Note that platform-specific behavior [may change in the future][changes].
///
/// [changes]: crate::io#platform-specific-behavior
#[stable(feature = "rust1", since = "1.0.0")]
pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> Result<u64>
where