[Toybox] [PATCH] ls: Ensure file names are separated by 2 spaces

[enh]

new tests? (including the difficult combining-character case?)

On Thu, Oct 17, 2019 at 8:35 AM Andrew Ilijic <ilijic.andrew at gmail.com> wrote:
>
> From d4c03b672d8b18f7ce021e4fcb02e8bb86f38f5f Mon Sep 17 00:00:00 2001
> From: Andrew Ilijic <ilijic.andrew at gmail.com>
> Date: Thu, 17 Oct 2019 11:03:19 -0400
> Subject: [PATCH] ls: Ensure file names are separated by 2 spaces
>
> We need two spaces between filenames because that is the convention
> followed by other implementations. More importantly, if we do not have
> two spaces, certain Unicode file names cause filenames to run together.
> In Unicode, combining characters come before the character they modify.
> If a filename ends in a combining character, the combining character
> attaches to the space that follows it, causing the space not to be
> visible. Having a two-space gap stops the above issue from happening.
>
> For context and a bit more information, see mailing list link below.
> https://www.mail-archive.com/toybox@lists.landley.net/msg05986.html
> ---
>  toys/posix/ls.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/toys/posix/ls.c b/toys/posix/ls.c
> index 0956902f..d4c0211a 100644
> --- a/toys/posix/ls.c
> +++ b/toys/posix/ls.c
> @@ -384,7 +384,8 @@ static void listfiles(int dirfd, struct dirtree *indir)
>        memset(colsizes, 0, columns*sizeof(unsigned));
>        for (ul=0; ul<dtlen; ul++) {
>          entrylen(sort[next_column(ul, dtlen, columns, &c)], len);
> -        *len += totpad+1;
> +        // Add `2` to `totpad` to ensure two spaces between filenames
> +        *len += totpad+2;
>          if (c == columns) break;
>          // Expand this column if necessary, break if that puts us over budget
>          if (*len > colsizes[c]) {
> --
> 2.11.0
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