Re: [PATCH 3/3] tools lib traceevent: Introduce pevent_strerror

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 2012-06-12 at 16:42 +0900, Namhyung Kim wrote:

> +/*
> + * This must have a same ordering as the enum pevent_errno.
> + */
> +static const char * const pevent_error_str[] = {
> +	"failed to allocate memory",
> +	"failed to parse event",
> +	"failed to read event id",
> +	"failed to read event format",
> +	"failed to read event print fmt",
> +	"failed to allocate field name for ftrace",
> +};
> +

Here's a little macro trick to keep the strings and enums always in
sync:

#define __PEVENT_ERRNO_CODES \
 _C(PEVENT_ERRNO__MEM_ALLOC_FAILED,	"failed to allocate memory"),	\
 _C(PEVENT_ERRNO__PARSE_EVENT_FAILED,	"failed to parse event"),	\
 _C(PEVENT_ERRNO__READ_ID_FAILED,	"failed to read event id"),	\
 _C(PEVENT_ERRNO__READ_FORMAT_FAILED,	"failed to read event format"),	\
 _C(PEVENT_ERRNO__READ_PRINT_FAILED,	"failed to read event print fmt"),\
 _C(PEVENT_ERRNO__OLD_FTRACE_ARG_FAILED,"failed to allocate field name for ftrace"),

#undef _C
#define _C(a,b) b
static const char * const pevent_error_str[] = { __PEVENT_ERROR_CODES };

#undef _C
#define _C(a, b) a

enum pevent_errno {
	__PEVENT_ERRNO__BEFORE_START		= -100000 - 1,
	__PEVENT_ERRNO_CODES
	__PEVENT_ERRNO__END,
};

#define __PEVENT_ERRNO__START (__PEVENT_ERRNO__BEFORE_START + 1)

Just saying ;-)

-- Steve