Libguestfs - Jan 2018 - [nbdkit PATCH] maint: Improve ./nbdkit handling of --opt=value

Although useful for in-tree debugging, the ./nbdkit script was not
very nice when it comes to using the '--longopt=value' single-string
form of options, compared to the two-string '--longopt value' form.
Since we used a glob for the multiple spellings of --exportname and
--pidfile, the script would try to treat the next argument literally
instead of recognizing that the argument was already consumed.
Likewise, the script was not recognizing '--filter=foo'.

Since the script already relies on bash, we can exploit bash's
case fallthrough (using ';&' instead of ';;'), to rewrite
inline
--filter=foo without having to duplicate logic.

This does NOT try to honor option abbreviations.  If you are testing
that aspect of getopt_long, don't use this script ;)

Signed-off-by: Eric Blake <eblake@redhat.com>
---

I'm pushing this one now, as it tripped me up during testing.

 nbdkit.in | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/nbdkit.in b/nbdkit.in
index d1caf57..996616d 100644
--- a/nbdkit.in
+++ b/nbdkit.in
@@ -65,6 +65,11 @@ verbose while [ $# -gt 0 ]; do
     case "$1" in
         # Flags that take an argument.  We must not rewrite the argument.
+	# But make sure globs don't mishandle longopts with =.
+	--export*=* | --pid*=*)
+	    args[$i]="$1"
+	    shift
+	    ;;
         -e | --export* | -g | --group | -i | --ip* | -P | --pid* | -p | --port
| --run | --selinux-label | -t | --threads | --tls | --tls-certificates | -U |
--unix | -u | --user)
             args[$i]="$1"
             ((++i))
@@ -80,6 +85,11 @@ while [ $# -gt 0 ]; do
             ;;

         # Filters can be rewritten if purely alphanumeric.
+	--filter=*)
+	    tmp=${1#*=}
+	    shift
+	    set - --filter "$tmp" "$@"
+	    ;& # fallthru
         --filter)
             args[$i]="--filter"
             ((++i))
-- 
2.14.3

On Tue, Jan 23, 2018 at 09:58:27PM -0600, Eric Blake
wrote:
> Although useful for in-tree debugging, the ./nbdkit script was not
> very nice when it comes to using the '--longopt=value'
single-string
> form of options, compared to the two-string '--longopt value' form.
> Since we used a glob for the multiple spellings of --exportname and
> --pidfile, the script would try to treat the next argument literally
> instead of recognizing that the argument was already consumed.
> Likewise, the script was not recognizing '--filter=foo'.
Right, this is the reason why all the tests use ‘--filter foo’, which
is annoying and awkward.
> Since the script already relies on bash, we can exploit bash's
> case fallthrough (using ';&' instead of ';;'), to
rewrite inline
> --filter=foo without having to duplicate logic.
Nice, I learn a new thing every day ...
> This does NOT try to honor option abbreviations.  If you are testing
> that aspect of getopt_long, don't use this script ;)
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
> 
> I'm pushing this one now, as it tripped me up during testing.
> 
>  nbdkit.in | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/nbdkit.in b/nbdkit.in
> index d1caf57..996616d 100644
> --- a/nbdkit.in
> +++ b/nbdkit.in
> @@ -65,6 +65,11 @@ verbose>  while [ $# -gt 0 ]; do
>      case "$1" in
>          # Flags that take an argument.  We must not rewrite the argument.
> +	# But make sure globs don't mishandle longopts with =.
> +	--export*=* | --pid*=*)
> +	    args[$i]="$1"
> +	    shift
> +	    ;;
>          -e | --export* | -g | --group | -i | --ip* | -P | --pid* | -p |
--port | --run | --selinux-label | -t | --threads | --tls | --tls-certificates |
-U | --unix | -u | --user)
>              args[$i]="$1"
>              ((++i))
> @@ -80,6 +85,11 @@ while [ $# -gt 0 ]; do
>              ;;
> 
>          # Filters can be rewritten if purely alphanumeric.
> +	--filter=*)
> +	    tmp=${1#*=}
> +	    shift
> +	    set - --filter "$tmp" "$@"
> +	    ;& # fallthru
>          --filter)
>              args[$i]="--filter"
>              ((++i))
Yup, this is great, ACK.

You might also want to adjust the tests to use ‘--filter=foo’ (no need
to review that change).

Rich.

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