On Wed, Apr 19, 2023 at 05:31:27PM +0200, Laszlo Ersek wrote:
> Embedding a shell script in a multi-line C string literal is an exercise
> in pain. I can see why the original author (whom I shall not look up with
> git-blame :) ) went for the easy route. Still, we want the source code to
> fit in 80 columns.
> 
> At Eric's suggestion, also:
> 
> - replace the non-portable control operator "|&" with the portable
>   redirection operator "2>&1" and the portable control operator "|";
> 
> - replace the "if ...; then exit 1; else exit 0; fi" constructs with "!
>   ...".

Reviewed-by: Eric Blake <ebl...@redhat.com>

> Notes:
>     v2:
>     
>     - v1: 
> https://listman.redhat.com/archives/libguestfs/2023-April/031298.html
>     
>     - incorporate Eric's recommendations (commit message, code)
> 
>  tests/requires.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/requires.c b/tests/requires.c
> index 199e30605473..2b7031532fe2 100644
> --- a/tests/requires.c
> +++ b/tests/requires.c
> @@ -57,7 +57,8 @@ requires_qemu_nbd_tls_support (const char *qemu_nbd)
>     * interested in the error message that it prints.
>     */
>    snprintf (cmd, sizeof cmd,
> -            "if %s --object tls-creds-x509,id=tls0 |& grep -sq 'TLS 
> credentials support requires GNUTLS'; then exit 1; else exit 0; fi",
> +            "! %s --object tls-creds-x509,id=tls0 2>&1 \\\n"
> +            "  | grep -sq 'TLS credentials support requires GNUTLS'\n",

The four bytes " \\\n " portion between the two lines are not
essential (the shell grammar doesn't care if there is a newline at
this point); in fact, if you put the | before \n instead of after, you
can use a newline without needing the \.  But I don't see any point
changing this code yet again just to golf out a few more bytes.  Let's
leave it as written in your v2.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org
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