Re: [PATCH 3/3] mkfs: hook up suboption parsing to ini files

Dave Chinner
2020-08-27T00:00:05Z

On Wed, Aug 26, 2020 at 05:21:13PM -0500, Eric Sandeen wrote:
> On 8/25/20 8:56 PM, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> >
> > Now we have the config file parsing hooked up and feeding in
> > parameters to mkfs, wire the parameters up to the existing CLI
> > option parsing functions. THis gives the config file exactly the
> > same capabilities and constraints as the command line option
> > specification.
>
> And as such, as you already mentioned, respecifications on the command
> line will fail. That can be documented in the man page :)
>
> The section names will need to be documented too.
>
> (In a very much not-bikeshedding way, we could consider [b] rather than
> [block] so you can cover it with "the section names match the option
> characters, i.e. for -b one would use section name [b]" but I really don't
> care and will not mention this again because as long as it's documented
> it's fine.)

No, I want the ini file to be human readable. The other thing to
consider here is that this is the equivalent of the long option
CLI parameter definition (i.e. -b size=foo vs --block="size=foo").
They'll get documented in the man page....

> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> > include/linux.h | 2 +-
> > mkfs/xfs_mkfs.c | 121 +++++++++++++++++++++++++++++++++++++-----------
> > 2 files changed, 95 insertions(+), 28 deletions(-)
> >
> > diff --git a/include/linux.h b/include/linux.h
> > index 57726bb12b74..03b3278bb895 100644
> > --- a/include/linux.h
> > +++ b/include/linux.h
> > @@ -92,7 +92,7 @@ static __inline__ void platform_uuid_unparse(uuid_t *uu, char *buffer)
> > uuid_unparse(*uu, buffer);
> > }
> >
> > -static __inline__ int platform_uuid_parse(char *buffer, uuid_t *uu)
> > +static __inline__ int platform_uuid_parse(const char *buffer, uuid_t *uu)
> > {
> > return uuid_parse(buffer, *uu);
> > }
> > diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> > index 6a373d614a56..deaed551b6d1 100644
> > --- a/mkfs/xfs_mkfs.c
> > +++ b/mkfs/xfs_mkfs.c
> > @@ -142,6 +142,13 @@ enum {
> > * name MANDATORY
> > * Name is a single char, e.g., for '-d file', name is 'd'.
> > *
> > + * ini_name MANDATORY
> > + * Name is a string, not longer than MAX_INI_NAME_LEN, that is used as the
> > + * section name for this option set in INI format config files. The only
> > + * option set this is not required for is the command line config file
> > + * specification options, everything else must be configurable via config
> > + * files.
>
> Nothing actually enforces this MANDATORY, right, this is just documentation.
> So the fact that struct opt_params copts doesn't have it, is fine.
>
> > @@ -967,13 +984,24 @@ respec(
> >
> > static void
> > unknown(
> > - char opt,
> > - char *s)
> > + const char opt,
> > + const char *s)
>
> (can all of the constification could maybe go in its own patch just to cut
> down on the patch doomscrolling or does it have to go with the other changes?)

It is a result of the ini parser callback using "const char *" for
it's variables. I just whack-a-moled it to get it compile.

> > {
> > fprintf(stderr, _("unknown option -%c %s\n"), opt, s);
> > usage();
> > }
> >
> > +static void
> > +unknown_cfgfile_opt(
> > + const char *section,
> > + const char *name,
> > + const char *value)
> > +{
> > + fprintf(stderr, _("unknown config file option: [%s]:%s=%s\n"),
> > + section, name, value);
>
> If we allow more than one -c subopt in the future we might want to print
> the filename. Wouldn't /hurt/ to do so now, or just remember to do it if
> we ever add a 2nd -c subopt.

OK.

>
> > + usage();
> > +}
> > +
> > static void
> > check_device_type(
> > const char *name,
> > @@ -1379,7 +1407,7 @@ getnum(
> > */
> > static char *
> > getstr(
> > - char *str,
> > + const char *str,
> > struct opt_params *opts,
> > int index)
> > {
> > @@ -1388,14 +1416,14 @@ getstr(
> > /* empty strings for string options are not valid */
> > if (!str || *str == '\0')
> > reqval(opts->name, opts->subopts, index);
> > - return str;
> > + return (char *)str;
>
> (what's the cast for?)

Because I got tired of whack-a-mole and these returned strings are
stored in the cli parameter structure and I didn't feel like chasing
the const rabbit down that hole.

i.e. the const on the input parameter goes as far as the input
parsing to verify it runs, and the verified input string that is
returned and stored is no longer const. Perhaps it would be better
to just strdup the string here and return that instead?

> > @@ -1682,23 +1710,22 @@ sector_opts_parser(
> > }
> >
> > static struct subopts {
> > - char opt;
> > struct opt_params *opts;
> > int (*parser)(struct opt_params *opts,
> > int subopt,
> > - char *value,
> > + const char *value,
> > struct cli_params *cli);
> > } subopt_tab[] = {
> > - { 'b', &bopts, block_opts_parser },
> > - { 'c', &copts, cfgfile_opts_parser },
> > - { 'd', &dopts, data_opts_parser },
> > - { 'i', &iopts, inode_opts_parser },
> > - { 'l', &lopts, log_opts_parser },
> > - { 'm', &mopts, meta_opts_parser },
> > - { 'n', &nopts, naming_opts_parser },
> > - { 'r', &ropts, rtdev_opts_parser },
> > - { 's', &sopts, sector_opts_parser },
> > - { '\0', NULL, NULL },
> > + { &bopts, block_opts_parser },
> > + { &copts, cfgfile_opts_parser },
> > + { &dopts, data_opts_parser },
> > + { &iopts, inode_opts_parser },
> > + { &lopts, log_opts_parser },
> > + { &mopts, meta_opts_parser },
> > + { &nopts, naming_opts_parser },
> > + { &ropts, rtdev_opts_parser },
> > + { &sopts, sector_opts_parser },
> > + { NULL, NULL },
> > };
> >
> > static void
> > @@ -1712,12 +1739,12 @@ parse_subopts(
> > int ret = 0;
> >
> > while (sop->opts) {
> > - if (sop->opt == opt)
> > + if (opt && sop->opts->name == opt)
> > break;
> > sop++;
> > }
> >
> > - /* should never happen */
> > + /* Should not happen */
>
> ok? :)

Ah, I modified this function first, then realised that it would be
better to keep the subopt table iteration separate because we didn't
need to use getsubopt() to separate "name=value" strings. I'll clean
that up.

> Overall this seems remarkably tidy, thanks.

I've been saying config file parsing is simple and easy to fit into
the existing option parsing infrastructure for a long time. :)

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com