Re: [PATCH v9 3/8] tools/misc: add xen-domctx to present domain context

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 24/09/2020 14:10, Paul Durrant wrote:
> This tool is analogous to 'xen-hvmctx' which presents HVM context.
> Subsequent patches will add 'dump' functions when new records are
> introduced.
>
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
> ---
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> Cc: Wei Liu <wl@xen.org>
>
> NOTE: Ian requested ack from Andrew

I mean - its a fairly throwaway piece of misc userspace, so ack.

However, it is largely superseded by the changes you need to make to
verify-stream-v2 so you might want to bear that in mind.

Also, I wonder if it is wise in general that we're throwing so many misc
debugging tools into sbin.

> +#include <inttypes.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +
> +#include <xenctrl.h>
> +#include <xen/xen.h>
> +#include <xen/domctl.h>
> +#include <xen/save.h>
> +
> +static void *buf = NULL;
> +static size_t len, off;
> +
> +#define GET_PTR(_x)                                                        \
> +    do {                                                                   \
> +        if ( len - off < sizeof(*(_x)) )                                   \
> +        {                                                                  \
> +            fprintf(stderr,                                                \
> +                    "error: need another %lu bytes, only %lu available\n", \

%zu is the correct formatter for size_t.

> +                    sizeof(*(_x)), len - off);                             \
> +            exit(1);                                                       \

Your error handling will be far more simple by using err() instead of
opencoding it.

~Andrew