[PATCH] lib: fwts_log_json: do more json object out of memory checking

[Alex Hung]

On 06/28/2012 09:22 PM, Colin King wrote:
> From: Colin Ian King <colin.king at canonical.com>
>
> The current json logging back-end is a bit sloppy because it
> neglects to check for any out of memory conditions when json
> objects are being created.  So add these checks and terminate
> with some form of understandable error message on a heap failure.
>
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>   src/lib/src/fwts_log_json.c |   77 +++++++++++++++++++++++++++++++++----------
>   1 file changed, 60 insertions(+), 17 deletions(-)
>
> diff --git a/src/lib/src/fwts_log_json.c b/src/lib/src/fwts_log_json.c
> index 75383a5..9afb74e 100644
> --- a/src/lib/src/fwts_log_json.c
> +++ b/src/lib/src/fwts_log_json.c
> @@ -40,7 +40,17 @@ static fwts_log_json_stack_t json_stack[MAX_JSON_STACK];
>   static int json_stack_index = 0;
>
>   /*
> - *  fwts_log_printf_son()
> + *  fwts_log_out_of_memory_json()
> + *	handle out of memory from json objects
> + */
> +static void fwts_log_out_of_memory_json(void)
> +{
> +	fprintf(stderr, "Out of memory allocating a json object.\n");
> +	exit(EXIT_FAILURE);
> +}
> +
> +/*
> + *  fwts_log_printf_json()
>    *	print to a log
>    */
>   static int fwts_log_print_json(
> @@ -57,6 +67,7 @@ static int fwts_log_print_json(
>   	time_t now;
>   	json_object *header;
>   	json_object *json_log = (json_object*)json_stack[json_stack_index-1].log;
> +	json_object *obj;
>   	char *str;
>
>   	if (!((field & LOG_FIELD_MASK) & fwts_log_filter))
> @@ -68,31 +79,53 @@ static int fwts_log_print_json(
>   	time(&now);
>   	localtime_r(&now, &tm);
>
> -	header = json_object_new_object();
> -	json_object_object_add(header, "line_num", json_object_new_int(log_file->line_number));
> +	if ((header = json_object_new_object()) == NULL)
> +		fwts_log_out_of_memory_json();
> +
> +	if ((obj = json_object_new_int(log_file->line_number)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "line_num", obj);
> +
>   	snprintf(tmpbuf, sizeof(tmpbuf), "%2.2d/%2.2d/%-2.2d",
>   		tm.tm_mday, tm.tm_mon + 1, (tm.tm_year+1900) % 100);
> -	json_object_object_add(header, "date", json_object_new_string(tmpbuf));
> +	if ((obj = json_object_new_string(tmpbuf)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "date", obj);
> +
>   	snprintf(tmpbuf, sizeof(tmpbuf), "%2.2d:%2.2d:%2.2d",
>   		tm.tm_hour, tm.tm_min, tm.tm_sec);
> -	json_object_object_add(header, "time", json_object_new_string(tmpbuf));
> -	json_object_object_add(header, "field_type",
> -		json_object_new_string(fwts_log_field_to_str_full(field)));
> +	if ((obj = json_object_new_string(tmpbuf)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "time", obj);
> +
> +	if ((obj = json_object_new_string(fwts_log_field_to_str_full(field))) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "field_type", obj);
>
>   	str = fwts_log_level_to_str(level);
>   	if (!strcmp(str, " "))
>   		str = "None";
> -	json_object_object_add(header, "level",
> -		json_object_new_string(str));
> +	if ((obj = json_object_new_string(str)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "level", obj);
> +
> +	if ((obj = json_object_new_string(*status ? status : "None")) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "status", obj);
>
> -	json_object_object_add(header, "status", json_object_new_string(*status ? status : "None"));
> -	json_object_object_add(header, "failure_label", json_object_new_string(label && *label ? label : "None"));
> +	if ((obj = json_object_new_string(label && *label ? label : "None")) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "failure_label", obj);
>
>   	/* Redundant really
> -	json_object_object_add(header, "owner",
> -		json_object_new_string(log->owner));
> +	if ((obj = json_object_new_string(log->owner)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "owner", obj);
>   	*/
> -	json_object_object_add(header, "log_text", json_object_new_string(buffer));
> +
> +	if ((obj = json_object_new_string(buffer)) == NULL)
> +		fwts_log_out_of_memory_json();
> +	json_object_object_add(header, "log_text", obj);
>
>   	json_object_array_add(json_log, header);
>   	log_file->line_number++;	/* This is academic really */
> @@ -123,15 +156,25 @@ static void fwts_log_section_begin_json(fwts_log_file *log_file, const char *nam
>   	json_object *json_obj;
>   	json_object *json_log;
>
> -	json_obj = json_object_new_object();
> -	json_log = json_object_new_array();
> +	if ((json_obj = json_object_new_object()) == NULL)
> +		fwts_log_out_of_memory_json();
> +
> +	if ((json_log = json_object_new_array()) == NULL)
> +		fwts_log_out_of_memory_json();
> +
> +	/*
> +	 * unfortunately json_object_object_add can fail on
> +	 * a strdup, but it doesn't check this and doesn't
> +	 * tell us about this either. Bit lame really.
> +	 */
>   	json_object_object_add(json_obj, name, json_log);
>
>   	json_stack[json_stack_index].obj = json_obj;
>   	json_stack[json_stack_index].log = json_log;
>
>   	if (json_stack_index > 0)
> -		json_object_array_add(json_stack[json_stack_index-1].log, json_obj);
> +		if (json_object_array_add(json_stack[json_stack_index-1].log, json_obj) != 0)
> +			fwts_log_out_of_memory_json();
>
>   	if (json_stack_index < MAX_JSON_STACK)
>   		json_stack_index++;
>
 >
Acked-by: Alex Hung <alex.hung at canonical.com>