On Fri, Feb 12, 2021 at 04:01:48PM -0600, Eric W. Biederman wrote:
> Joe Perches <j...@perches.com> writes:
>
> > Convert S_<FOO> permissions to the more readable octal.
> >
> > Done using:
> > $ ./scripts/checkpatch.pl -f --fix-inplace --types=SYMBOLIC_PERMS
> > fs/proc/*.[ch]
> >
> > No difference in generated .o files allyesconfig x86-64
> >
> > Link:
> > https://lore.kernel.org/lkml/ca+55afw5v23t-zvdzp-mmd_eyxf8wbafwwb59934fv7g21u...@mail.gmail.com/
>
>
> I will be frank. I don't know what 0644 means. I can never remember
> which bit is read, write or execute. So I like symbolic constants.
Heh, I'm the other way, I can't remember what S_IRUGO means.
but I think there's another way which improves the information
density:
#define DIR_RO_ALL(NAME, iops, fops) DIR(NAME, 0555, iops, fops)
...
(or S_IRUGO or whatever expands to 0555)
There's really only a few combinations --
root read-only,
everybody read-only
root-write, others-read
everybody-write
and execute is only used by proc for directories, not files, so I think
there's only 8 combinations we'd need (and everybody-write is almost
unused ...)
> Perhaps we can do something like:
>
> #define S_IRWX 7
> #define S_IRW_ 6
> #define S_IR_X 5
> #define S_IR__ 4
> #define S_I_WX 3
> #define S_I_W_ 2
> #define S_I__X 1
> #define S_I___ 0
>
> #define MODE(TYPE, USER, GROUP, OTHER) \
> (((S_IF##TYPE) << 9) | \
> ((S_I##USER) << 6) | \
> ((S_I##GROUP) << 3) | \
> (S_I##OTHER))
>
> Which would be used something like:
> MODE(DIR, RWX, R_X, R_X)
> MODE(REG, RWX, R__, R__)
>
> Something like that should be able to address the readability while
> still using symbolic constants.
I think that's been proposed before.
