dd: use seek for stdin skip when possible #9821
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GNU testsuite comparison: |
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| Ok(pos) | ||
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| Some(Err(e)) if e.raw_os_error() == Some(libc::ESPIPE) => { |
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I usually prefer using e.kind() over e.raw_os_error(). Is there a reason to use libc::ESPIPE over ?std::io::NotSeekable
Edit: Realized that std::io::NotSeekable might not be the equivalent code for this on documentation
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Wait, is lib::ESPIPE not equivalently supported through Rust's ErrorKind?
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I'm unsure what the difference is between the two, I can try it out now to see if it still passes all of the tests
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There isn't a difference between using libc's errors or Rust's ErrorKind; I just thought it looks a bit more idiomatic relying on Rust's ErrorKind over libc's errno values.
But I think this is one of those cases where libc::ESPIPE might fall under Rust's std::io::Other error, which isn't that descriptive.
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Yea this one is not the equivalent, the stable ErrorKind does not have a matching variant for this use case.
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The dd/skip-seek-past-file test is checking that the default implementation uses skip as the reader by putting a set of inputs that would cause an out of bounds read if skip was not used, but for things like pipe inputs using copy is the right approach to use and we have other GNU tests that rely on that behaviour. This PR uses skip as the default then falls back to copy.