Re: [PATCH for-5.1 2/2] tpm: Improve help on TPM types when none are available

[Philippe Mathieu-Daudé]

On 7/23/20 1:58 PM, Markus Armbruster wrote:
> Help is a bit awkward when no TPM types are built into QEMU:
> 
>     $ upstream-qemu -tpmdev nonexistent,id=tpm0
>     upstream-qemu: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a 
> TPM backend type
>     Supported TPM types (choose only one):
> 
> Improve to
> 
>     upstream-qemu: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a 
> TPM backend type
>     No TPM backend types are available
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>  tpm.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/tpm.c b/tpm.c
> index f6045bb6da..cab206355a 100644
> --- a/tpm.c
> +++ b/tpm.c
> @@ -47,18 +47,23 @@ tpm_be_find_by_type(enum TpmType type)
>   */
>  static void tpm_display_backend_drivers(void)
>  {
> +    bool got_one = false;
>      int i;
>  
> -    fprintf(stderr, "Supported TPM types (choose only one):\n");
> -
>      for (i = 0; i < TPM_TYPE__MAX; i++) {
>          const TPMBackendClass *bc = tpm_be_find_by_type(i);
>          if (!bc) {
>              continue;
>          }
> -        fprintf(stderr, "%12s   %s\n", TpmType_str(i), bc->desc);
> +        if (!got_one) {
> +            error_printf("Supported TPM types (choose only one):\n");
> +            got_one = true;
> +        }
> +        error_printf("%12s   %s\n", TpmType_str(i), bc->desc);
> +    }
> +    if (!got_one) {
> +        error_printf("No TPM backend types are available\n");
>      }
> -    fprintf(stderr, "\n");
>  }
>  
>  /*
>