Subject: Re: [PATCH v3 1/4] log: fix memory leak if --graph is passed multiple times

From: Junio C Hamano <[email-masked]>
Date: Fri, 11 Feb 2022 10:51:12 -0800

Alex Henrie <[email-masked]> writes:

> +void graph_clear(struct git_graph *graph)
> +{
> +	if (!graph)
> +		return;
> +
> +	free(graph->columns);
> +	free(graph->new_columns);
> +	free(graph->mapping);
> +	free(graph->old_mapping);

These four are pointer members that graph_init() allocates storage
for, so releasing resources held by these four members in clear()
makes it symmetrical.

The .columns and .new_columns members are arrays of "struct column",
but each element in the array does not own any external memory, so
freeing the arrays is sufficient.  The .mapping and .old_mapping
members are arrays of int and freeing them is also sufficient.

Looking good.

> +	free(graph);
> +}
> +
>  static void graph_update_state(struct git_graph *graph, enum graph_state s)
>  {
>  	graph->prev_state = graph->state;
> diff --git a/graph.h b/graph.h
> index 8313e293c7..e88632a014 100644
> --- a/graph.h
> +++ b/graph.h
> @@ -139,6 +139,11 @@ void graph_set_column_colors(const char **colors, unsigned short colors_max);
>   */
>  struct git_graph *graph_init(struct rev_info *opt);
>  
> +/*
> + * Free a struct git_graph.
> + */
> +void graph_clear(struct git_graph *graph);
> +
>  /*
>   * Update a git_graph with a new commit.
>   * This will cause the graph to begin outputting lines for the new commit
> diff --git a/revision.c b/revision.c
> index ad4286fbdd..816061f3d9 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -2426,6 +2426,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
>  	} else if (!strcmp(arg, "--graph")) {
>  		revs->topo_order = 1;
>  		revs->rewrite_parents = 1;
> +		graph_clear(revs->graph);
>  		revs->graph = graph_init(revs);

Makes sense.  Will queue.

>  	} else if (!strcmp(arg, "--encode-email-headers")) {
>  		revs->encode_email_headers = 1;