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https://github.com/uutils/coreutils
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Merge pull request #4191 from jfinkels/dd-sparse
dd: correctly set file size when conv=sparse
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commit
5efdc51609
2 changed files with 47 additions and 1 deletions
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@ -324,6 +324,17 @@ impl Dest {
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Self::File(f, _) => f.seek(io::SeekFrom::Start(n)),
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}
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}
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/// Truncate the underlying file to the current stream position, if possible.
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fn truncate(&mut self) -> io::Result<()> {
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match self {
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Self::Stdout(_) => Ok(()),
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Self::File(f, _) => {
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let pos = f.stream_position()?;
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f.set_len(pos)
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}
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}
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}
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}
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/// Decide whether the given buffer is all zeros.
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@ -406,7 +417,6 @@ impl<'a> Output<'a> {
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// suppress the error by calling `Result::ok()`. This matches
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// the behavior of GNU `dd` when given the command-line
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// argument `of=/dev/null`.
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if !settings.oconv.notrunc {
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dst.set_len(settings.seek).ok();
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}
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@ -570,6 +580,18 @@ impl<'a> Output<'a> {
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// Flush the output, if configured to do so.
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self.sync()?;
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// Truncate the file to the final cursor location.
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//
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// Calling `set_len()` may result in an error (for example,
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// when calling it on `/dev/null`), but we don't want to
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// terminate the process when that happens. Instead, we
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// suppress the error by calling `Result::ok()`. This matches
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// the behavior of GNU `dd` when given the command-line
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// argument `of=/dev/null`.
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if !self.settings.oconv.notrunc {
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self.dst.truncate().ok();
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}
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// Print the final read/write statistics.
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let prog_update = ProgUpdate::new(rstat, wstat, start.elapsed(), true);
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prog_tx.send(prog_update).unwrap_or(());
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@ -1394,3 +1394,27 @@ fn test_sync_delayed_reader() {
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assert_eq!(&output.stdout, &expected);
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assert_eq!(&output.stderr, b"0+8 records in\n4+0 records out\n");
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}
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/// Test for making a sparse copy of the input file.
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#[test]
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fn test_sparse() {
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let (at, mut ucmd) = at_and_ucmd!();
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// Create a file and make it a large sparse file.
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//
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// On common Linux filesystems, setting the length to one megabyte
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// should cause the file to become a sparse file, but it depends
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// on the system.
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std::fs::File::create(at.plus("infile"))
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.unwrap()
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.set_len(1024 * 1024)
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.unwrap();
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// Perform a sparse copy.
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ucmd.args(&["bs=32K", "if=infile", "of=outfile", "conv=sparse"])
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.succeeds();
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// The number of bytes in the file should be accurate though the
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// number of blocks stored on disk may be zero.
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assert_eq!(at.metadata("infile").len(), at.metadata("outfile").len());
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}
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