On 29/07/2017 19:02, Luis R. Rodriguez wrote:
On Fri, Jul 28, 2017 at 04:44:50PM +0200, Jan Tulak wrote:
And do we need better messages?
We could later when parsing the configuration file, yes. An abort is fine too but
seems rather grotesque. But also more importantly this is a matter of style and I
realize the old style is to just abort/assert, so I figured it would be a good time
now to ask ourselves if we want proper error messages dealt with / passed slowly
moving forward.
But yes, I do suspect we may want better error messages when parsing these. This
may mean for instance we want a string built into the struct that defines the sobopt
so we can use it to inform userspace using a pointer to the description rather than
doing a switch statement on each one and interpreting back to plain english.
The reason for better messages is reasonable. About the style... well,
it makes sense. But I would certainly not do this in this set. So, I
think about a way how to keep the current behavior, but slowly build up
the ground for something like what you suggest.
Using the same style of error-returning logic from the other email
([PATCH 1/7] mkfs: Save raw ...), the error argument pointer would be
optional. So, when you do parse_conf_val(OPT_D, D_AGCOUNT, str, NULL);
then you get the old behavior and any error causes a termination inside
of this function. But if you instead pass some pointer:
parse_conf_val(OPT_D, D_AGCOUNT, str, &err); then right now, we would
print the message but do not terminate. And later on, some other message
handling can be added.
If some value is out of range, or it is a
conflict, there is not much context needed, and better to not have to care
about these errors... Do you have an example when it would be helpful? If it
just spits out a return code, you have to add a check to every use and you
will have many times the same code like what is in getnum() at this moment
Not really, if we are parsing say D_AGCOUNT we could have a member as part of the
struct, say "description" then we can use say subopt[D_AGCOUNT].description on
the error message, perhaps the only thing that would change for instance would be
the context on which the error was run into, command line option passed or config
file read, say with the filename and line number.
How would we be able to detect an error happened and pass exactly where the
error happened otherwise on a config file for example?
Yes, I see the issue - getnum finds an error, but it doesn't know the
line in the config file to report it. But with what I write above about
the error handling, this could work.
if (c < sp->minval) {
if (config_file) illegal_config(str, line, opts, index, _("value is
too small"), err);
else illegal_option(str, opts, index, _("value is too small"), err);
}
... and later in the code, if you are in the config file, you could do
something like:
parse_conf_val(opt, subopt, str, &err);
if (err) report_invalid_line(current_line);
Thoughts?
Jan
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