dd: don't fail echo 1 | dd *flag=nocache

Author: oech3

src/uu/dd/src/dd.rs

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore fname, ftype, tname, fpath, specfile, testfile, unspec, ifile, ofile, outfile, fullblock, urand, fileio, atoe, atoibm, behaviour, bmax, bremain, cflags, creat, ctable, ctty, datastructures, doesnt, etoa, fileout, fname, gnudd, iconvflags, iseek, nocache, noctty, noerror, nofollow, nolinks, nonblock, oconvflags, oseek, outfile, parseargs, rlen, rmax, rremain, rsofar, rstat, sigusr, wlen, wstat oconv canonicalized FADV DONTNEED ESPIPE SPIPE bufferedoutput, SETFL
+// spell-checker:ignore fname, ftype, tname, fpath, specfile, testfile, unspec, ifile, ofile, outfile, fullblock, urand, fileio, atoe, atoibm, behaviour, bmax, bremain, cflags, creat, ctable, ctty, datastructures, doesnt, etoa, fileout, fname, gnudd, iconvflags, iseek, nocache, noctty, noerror, nofollow, nolinks, nonblock, oconvflags, oseek, outfile, parseargs, rlen, rmax, rremain, rsofar, rstat, sigusr, wlen, wstat oconv canonicalized FADV DONTNEED ESPIPE bufferedoutput, SETFL
 
 mod blocks;
 mod bufferedoutput;
@@ -314,8 +314,7 @@ impl Source {
                 fadvise(f, offset, std::num::NonZeroU64::new(len), DontNeed)?;
                 Ok(())
             }
-            // fadvise for nonseekable returns this error. We manually do that...
-            _ => Err(rustix::io::Errno::SPIPE.into()),
+            _ => Ok(()), // ESPIPE, but GNU silently ignore it
         }
     }
 }
@@ -700,8 +699,7 @@ impl Dest {
                 fadvise(f, offset, std::num::NonZeroU64::new(len), DontNeed)?;
                 Ok(())
             }
-            // fadvise for nonseekable returns this error. We manually do that...
-            _ => Err(rustix::io::Errno::SPIPE.into()),
+            _ => Ok(()), // ESPIPE, but GNU silently ignore it
         }
     }
 }