Re: [PATCH v2 02/12] commit-graph: verify file header information

> During a run of 'git commit-graph verify', list the issues with the
> header information in the commit-graph file. Some of this information
> is inferred from the loaded 'struct commit_graph'. Some header
> information is checked as part of load_commit_graph_one().
>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  commit-graph.c | 32 +++++++++++++++++++++++++++++++-
>  1 file changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/commit-graph.c b/commit-graph.c
> index b25aaed128..d2db20e49a 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -818,7 +818,37 @@ void write_commit_graph(const char *obj_dir,
>         oids.nr = 0;
>  }
>
> +static int verify_commit_graph_error;
> +
> +static void graph_report(const char *fmt, ...)
> +{
> +       va_list ap;
> +       struct strbuf sb = STRBUF_INIT;
> +       verify_commit_graph_error = 1;
> +
> +       va_start(ap, fmt);
> +       strbuf_vaddf(&sb, fmt, ap);
> +
> +       fprintf(stderr, "%s\n", sb.buf);
> +       strbuf_release(&sb);
> +       va_end(ap);
> +}

>  int verify_commit_graph(struct commit_graph *g)
>  {
> -       return !g;
> +       if (!g) {
> +               graph_report("no commit-graph file loaded");
> +               return 1;
> +       }