[PATCH 1/1] cut: Fix "-s" flag to omit blank lines

[Colin]

Hello,

Can this patch please be reviewed?

Thank you,
Colin McAllister

On Wed, Jul 17, 2024 at 4:33 PM Colin McAllister <colinmca242 at gmail.com>
wrote:

> Using cut with the delimiter flag ("-d") with the "-s" flag to only
> output lines containing the delimiter will print blank lines. This is
> deviant behavior from cut provided by GNU Coreutils. Blank lines should
> be omitted if "-s" is used with "-d".
>
> This change introduces a somewhat naiive, yet efficient solution, where
> line length is checked before looping though bytes. If line length is
> zero and the "-s" flag is used, the code will jump to parsing the next
> line to avoid printing a newline character.
>
> In addition, a test to cut.tests has been added to ensure that this
> regression is fixed and will not happen again in the future.
>
> Signed-off-by: Colin McAllister <colinmca242 at gmail.com>
> ---
>  coreutils/cut.c     | 6 ++++++
>  testsuite/cut.tests | 9 +++++++++
>  2 files changed, 15 insertions(+)
>
> diff --git a/coreutils/cut.c b/coreutils/cut.c
> index d129f9b9d..8de0c6766 100644
> --- a/coreutils/cut.c
> +++ b/coreutils/cut.c
> @@ -152,6 +152,12 @@ static void cut_file(FILE *file, const char *delim,
> const char *odelim,
>                         unsigned uu = 0, start = 0, end = 0, out = 0;
>                         int dcount = 0;
>
> +                       /* Blank line? */
> +                       if (!linelen) {
> +                               if (option_mask32 & CUT_OPT_SUPPRESS_FLGS)
> +                                       goto next_line;
> +                       }
> +
>                         /* Loop through bytes, finding next delimiter */
>                         for (;;) {
>                                 /* End of current range? */
> diff --git a/testsuite/cut.tests b/testsuite/cut.tests
> index 2458c019c..0b401bc00 100755
> --- a/testsuite/cut.tests
> +++ b/testsuite/cut.tests
> @@ -65,6 +65,15 @@ testing "cut with -d -f( ) -s" "cut -d' ' -f3 -s input
> && echo yes" "yes\n" "$in
>  testing "cut with -d -f(a) -s" "cut -da -f3 -s input"
> "n\nsium:Jim\n\ncion:Ed\n" "$input" ""
>  testing "cut with -d -f(a) -s -n" "cut -da -f3 -s -n input"
> "n\nsium:Jim\n\ncion:Ed\n" "$input" ""
>
> +input="\
> +
> +foo bar baz
> +
> +bing bong boop
> +
> +"
> +testing "cut with -d -s omits blank lines" "cut -d' ' -f2 -s input"
> "bar\nbong\n" "$input" ""
> +
>  # substitute for awk
>  optional FEATURE_CUT_REGEX
>  testing "cut -DF" "cut -DF 2,7,5" \
> --
> 2.34.1
>
>
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