From: Philip Guenther <guenther@gmail.com>
Subject: Re: pax: line-buffer file list output
To: "Todd C. Miller" <millert@openbsd.org>
Cc: tech@openbsd.org
Date: Fri, 10 May 2024 13:21:49 -0700

ok guenther@

On Fri, May 10, 2024 at 11:44 AM Todd C. Miller <millert@openbsd.org> wrote:

> One thing that has bugged me for years is that pax/tar fully buffers
> the file list output when used in a pipeline.  For example, given:
>
>     $ tar cf - * | ssh otherhost "tar vxf -"
>
> the file list output will all be displayed at the end instead of
> as the files are written.  If the list file handle is not stderr,
> making it line buffered fixes this.
>
>  - todd
>
> Index: bin/pax/cpio.c
> ===================================================================
> RCS file: /cvs/src/bin/pax/cpio.c,v
> diff -u -p -u -r1.114 options.c
> --- bin/pax/options.c   17 Apr 2024 18:12:12 -0000      1.114
> +++ bin/pax/options.c   10 May 2024 18:38:02 -0000
> @@ -277,21 +277,20 @@ options(int argc, char **argv)
>         if (strcmp(NM_TAR, argv0) == 0) {
>                 op_mode = OP_TAR;
>                 tar_options(argc, argv);
> -               return;
> -       }
>  #ifndef NOCPIO
> -       else if (strcmp(NM_CPIO, argv0) == 0) {
> +       } else if (strcmp(NM_CPIO, argv0) == 0) {
>                 op_mode = OP_CPIO;
>                 cpio_options(argc, argv);
> -               return;
> -       }
>  #endif /* !NOCPIO */
> -       /*
> -        * assume pax as the default
> -        */
> -       argv0 = NM_PAX;
> -       op_mode = OP_PAX;
> -       pax_options(argc, argv);
> +       } else {
> +               argv0 = NM_PAX;
> +               op_mode = OP_PAX;
> +               pax_options(argc, argv);
> +       }
> +
> +       /* Line-buffer the file list output as needed. */
> +       if (listf != stderr)
> +               setvbuf(listf, NULL, _IOLBF, 0);
>  }
>
>  /*
>
>