bug#64540: [PATCH] od: exit out on failure to write to stdout

[Pádraig Brady]

On 09/07/2023 23:54, Pádraig Brady wrote:
> On 09/07/2023 20:11, Paul Eggert wrote:
> > On 2023-07-09 07:11, Pádraig Brady wrote:
> >
> > > Note the patch looks wrong as it would close the input always.
> > > We can fix that up easily enough anyway.
> >
> > If it's easy and doesn't hurt performance in the usual case, that's of
> > course fine.
> >
> >
> > > For my reference a short list of utils to check (that might inf loop) are:
> > >      cat comm cp cut dd dirname expand factor fmt fold head join ls nl numfmt
> > >      od paste pr printf ptx readlink realpath seq shuf sort stat tac tail
> > >      tee tr tsort unexpand uniq wc yes
> >
> > There's no point to complicating programs that have bounded input for
> > other reasons, as they'll report errors soon enough for those other
> > reasons. The main problem comes from programs like 'cat' and 'od' that
> > can read from "infinite" input like /dev/urandom and can write indefinitely.
> >
> > So I think we needn't worry about dirname, ptx, readlink, realpath,
> > sort, stat, tac, tsort, wc. For example, we needn't worry about 'sort'
> > because it needs to read all its input before outputting anything, and
> > it cannot read all of /dev/urandom. As long as these programs eventually
> > check for write errors, which I expect they all do, that should be good
> > enough.
> >
> > Even for programs like 'od' there is no need to check every output
> > function; just check occasionally, when it's convenient.
>
> Yes completely agreed.
> The shortlist above is for my reference for commands to review,
> not for commands to adjust.

The attached patch-set addresses two classes of issue:
1. Doubled error messages upon write errors
2. Continued processing upon write errors  (the orig problem reported).

For class 1, we include fixes for:
  expand, factor, paste, shuf, tr, unexpand

For class 2, we include fixes for:
  od, uniq, cut, comm, join
For class 2, we do _not_ include fixes for these utils
which are more awkward / less important in this context:
  fmt, fold, nl, numfmt, pr

I'll update NEWS with this info before pushing.

cheers,
Pádraig

0001-tests-ensure-utilties-exit-promptly-upon-write-error.patch
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0002-all-avoid-repeated-diagnostic-upon-write-error.patch
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0003-od-promptly-diagnose-write-errors.patch
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0004-uniq-promptly-diagnose-write-errors.patch
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0005-cut-promptly-diagnose-write-errors.patch
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0006-comm-promptly-diagnose-write-errors.patch
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0007-join-promptly-diagnose-write-errors.patch
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