Libguestfs - Apr 2023 - [libnbd PATCH v2] tests/requires: wrap source code at 80 characters

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
"!
  ...".

Note: in my "interop/test-suite.log", I see
> SKIP: interop-qemu-nbd-tls-certs
> ===============================>
> requires test -d /home/lacos/src/v2v/libnbd/tests/pki
> Test skipped because prerequisite is missing or not working.
> SKIP interop-qemu-nbd-tls-certs (exit status: 77)
>
> SKIP: interop-qemu-nbd-tls-psk
> =============================>
> requires test -f /home/lacos/src/v2v/libnbd/tests/keys.psk
> Test skipped because prerequisite is missing or not working.
> SKIP interop-qemu-nbd-tls-psk (exit status: 77)
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2172516
Signed-off-by: Laszlo Ersek <lersek at 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",
             qemu_nbd);
   requires (cmd);
 }
@@ -72,7 +73,8 @@ requires_qemu_nbd_tls_psk_support (const char *qemu_nbd)
    * interested in the error message that it prints.
    */
   snprintf (cmd, sizeof cmd,
-            "if %s --object tls-creds-psk,id=tls0 / |& grep -sq
'invalid object type'; then exit 1; else exit 0; fi",
+            "! %s --object tls-creds-psk,id=tls0 / 2>&1 \\\n"
+            "  | grep -sq 'invalid object type'\n",
             qemu_nbd);
   requires (cmd);
 }

base-commit: a458f0644de0fa541b055299fe6a58e1f42d0073

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 <eblake at 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