test that modifications to the source don't become visible after io::copy
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@ -83,6 +83,48 @@ fn copies_append_mode_sink() -> Result<()> {
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Ok(())
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}
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#[test]
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fn dont_splice_pipes_from_files() -> Result<()> {
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// splicing to a pipe and then modifying the source could lead to changes
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// becoming visible in an unexpected order.
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use crate::io::SeekFrom;
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use crate::os::unix::fs::FileExt;
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use crate::process::{ChildStdin, ChildStdout};
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use crate::sys_common::FromInner;
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let (read_end, write_end) = crate::sys::pipe::anon_pipe()?;
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let mut read_end = ChildStdout::from_inner(read_end);
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let mut write_end = ChildStdin::from_inner(write_end);
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let tmp_path = tmpdir();
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let file = tmp_path.join("to_be_modified");
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let mut file =
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crate::fs::OpenOptions::new().create_new(true).read(true).write(true).open(file)?;
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const SZ: usize = libc::PIPE_BUF as usize;
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// put data in page cache
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let mut buf: [u8; SZ] = [0x01; SZ];
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file.write_all(&buf).unwrap();
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// copy page into pipe
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file.seek(SeekFrom::Start(0)).unwrap();
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assert!(io::copy(&mut file, &mut write_end).unwrap() == SZ as u64);
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// modify file
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buf[0] = 0x02;
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file.write_at(&buf, 0).unwrap();
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// read from pipe
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read_end.read_exact(buf.as_mut_slice()).unwrap();
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assert_eq!(buf[0], 0x01, "data in pipe should reflect the original, not later modifications");
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Ok(())
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}
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#[bench]
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fn bench_file_to_file_copy(b: &mut test::Bencher) {
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const BYTES: usize = 128 * 1024;
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