Re: [PATCH] storage-daemon: include current command line option in the errors

[Kevin Wolf <kwolf@redhat.com>]

Am 26.02.2021 um 12:03 hat Paolo Bonzini geschrieben:
> Use the location management facilities that the emulator uses, so that
> the current command line option appears in the error message.
> 
> Before:
> 
>   $ storage-daemon/qemu-storage-daemon --nbd key..=
>   qemu-storage-daemon: Invalid parameter 'key..'
> 
> After:
> 
>   $ storage-daemon/qemu-storage-daemon --nbd key..=
>   qemu-storage-daemon: --nbd key..=: Invalid parameter 'key..'
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  storage-daemon/qemu-storage-daemon.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c
> index 9021a46b3a..a8f8d83f6f 100644
> --- a/storage-daemon/qemu-storage-daemon.c
> +++ b/storage-daemon/qemu-storage-daemon.c
> @@ -152,6 +152,20 @@ static void init_qmp_commands(void)
>                           qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
>  }
>  
> +static int getopt_set_loc(int argc, char **argv, const char *optstring,
> +                          const struct option *longopts)
> +{
> +    int c, save_index;
> +
> +    optarg = NULL;
> +    save_index = optind;
> +    c = getopt_long(argc, argv, optstring, longopts, NULL);
> +    if (optarg) {
> +        loc_set_cmdline(argv, save_index, MAX(1, optind - save_index));

This save_index approach isn't perfect because getopt may skip
non-option arguments and they will be included in the help text:

    $ build/storage-daemon/qemu-storage-daemon foo --object iothread
    qemu-storage-daemon: foo --object iothread: Parameter 'id' is missing

    $ build/storage-daemon/qemu-storage-daemon foo --object iothread,id=t
    qemu-storage-daemon: --object iothread,id=t foo: Unexpected argument: foo

However, without changing the interface of loc_set_cmdline(), getting
the right index seems hard. Not sure what is the best way for fixing
this or if it's worth the effort.

Kevin

> +    }
> +    return c;
> +}
> +
>  static void process_options(int argc, char *argv[])
>  {
>      int c;
> @@ -174,7 +188,7 @@ static void process_options(int argc, char *argv[])
>       * they are given on the command lines. This means that things must be
>       * defined first before they can be referenced in another option.
>       */
> -    while ((c = getopt_long(argc, argv, "hT:V", long_options, NULL)) != -1) {
> +    while ((c = getopt_set_loc(argc, argv, "hT:V", long_options)) != -1) {
>          switch (c) {
>          case '?':
>              exit(EXIT_FAILURE);
> @@ -283,6 +297,7 @@ static void process_options(int argc, char *argv[])
>          error_report("Unexpected argument: %s", argv[optind]);
>          exit(EXIT_FAILURE);
>      }
> +    loc_set_none();
>  }
>  
>  int main(int argc, char *argv[])
> -- 
> 2.26.2
>