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dd: fix nocache flag handling at EOF #9818

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dd: fix nocache flag handling at EOF #9818

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44 changes: 10 additions & 34 deletions src/uu/dd/src/dd.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -219,17 +219,6 @@ impl Source {
Self::StdinFile(f)
}

/// The length of the data source in number of bytes.
///
/// If it cannot be determined, then this function returns 0.
fn len(&self) -> io::Result<i64> {
#[allow(clippy::match_wildcard_for_single_variants)]
match self {
Self::File(f) => Ok(f.metadata()?.len().try_into().unwrap_or(i64::MAX)),
_ => Ok(0),
}
}

fn skip(&mut self, n: u64) -> io::Result<u64> {
match self {
#[cfg(not(unix))]
Expand Down Expand Up @@ -668,17 +657,6 @@ impl Dest {
_ => Err(Errno::ESPIPE), // "Illegal seek"
}
}

/// The length of the data destination in number of bytes.
///
/// If it cannot be determined, then this function returns 0.
fn len(&self) -> io::Result<i64> {
#[allow(clippy::match_wildcard_for_single_variants)]
match self {
Self::File(f, _) => Ok(f.metadata()?.len().try_into().unwrap_or(i64::MAX)),
_ => Ok(0),
}
}
}

/// Decide whether the given buffer is all zeros.
Expand Down Expand Up @@ -1053,21 +1031,12 @@ impl BlockWriter<'_> {
/// depending on the command line arguments, this function
/// informs the OS to flush/discard the caches for input and/or output file.
fn flush_caches_full_length(i: &Input, o: &Output) -> io::Result<()> {
// TODO Better error handling for overflowing `len`.
// Using len=0 in posix_fadvise means "to end of file"
if i.settings.iflags.nocache {
let offset = 0;
#[allow(clippy::useless_conversion)]
let len = i.src.len()?.try_into().unwrap();
i.discard_cache(offset, len);
i.discard_cache(0, 0);
}
// Similarly, discard the system cache for the output file.
//
// TODO Better error handling for overflowing `len`.
if i.settings.oflags.nocache {
let offset = 0;
#[allow(clippy::useless_conversion)]
let len = o.dst.len()?.try_into().unwrap();
o.discard_cache(offset, len);
o.discard_cache(0, 0);
}

Ok(())
Expand Down Expand Up @@ -1175,6 +1144,7 @@ fn dd_copy(mut i: Input, o: Output) -> io::Result<()> {

let input_nocache = i.settings.iflags.nocache;
let output_nocache = o.settings.oflags.nocache;
let output_direct = o.settings.oflags.direct;

// Add partial block buffering, if needed.
let mut o = if o.settings.buffered {
Expand All @@ -1198,6 +1168,12 @@ fn dd_copy(mut i: Input, o: Output) -> io::Result<()> {
let loop_bsize = calc_loop_bsize(i.settings.count, &rstat, &wstat, i.settings.ibs, bsize);
let rstat_update = read_helper(&mut i, &mut buf, loop_bsize)?;
if rstat_update.is_empty() {
if input_nocache {
i.discard_cache(read_offset.try_into().unwrap(), 0);
}
if output_nocache || output_direct {
o.discard_cache(write_offset.try_into().unwrap(), 0);
}
break;
}
let wstat_update = o.write_blocks(&buf)?;
Expand Down
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