[Toybox] df.c patch and POSIXLY_CORRECT

[Rob Landley]

Digging through the backlog of patches Ashwini Sharma sent, I'd prefer
not to apply one particular gnusim in the df.c patch: I'm not a fan of
the "POSIXLY_ME_HARDER" environment variable check.

http://en.wikipedia.org/wiki/POSIX#Controversies

If we want our behavior to match posix even when nobody else does, we
can change the behavior. If we want to have a different behavior and
document the deviation, we can do that (and that's what we currently
do). If we want a compile time "be stupid when posix says something
stupid/obsolete" kconfig option, we can do that too. But at runtime, I
prefer consistent behavior. (You an also alias "df" to "df -P", the way
people alias --color into ls.)

Doing what posix says to do when people don't _expect_ that has been
filed as a bug before:

https://bugs.tizen.org/jira/browse/TC-1787

I can do TOYBOX_STRICT_POSIX compile time option if people think that's
a good idea. As one big global switch disabling sed -i and putting cpio
in 6 byte mode incompatible with all modern uses, breaking tar into
near-uselessness, disabling half the commands... (If this seems silly,
how is testing it at runtime instead of at compile time any less of a
can of worms? I've already _got_ CONFIG_DF_PEDANTIC...)

Anybody feel like standing up and defending POSIXLY_CORRECT? (While
_not_ doing an LSB_CORRECT?)

Rob

P.S. Part of the df patch does:

   if (CFG_DF_PEDANTIC && (toys.optflags & FLAG_P)) {
-    xprintf("%s %lld %lld %lld %lld%% %s\n", device, size, used, avail,
-      percent, mt->dir);
+    xprintf("%s% *lld % 10lld % 10lld % 7lld%% %s\n", device, len,
+        size, used, avail, percent, mt->dir);

Except the posix standard itself currently says:

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/df.html

  The remaining output with -P shall consist of one line of information
  for each specified file system. These lines shall be formatted as
  follows:

  "%s %d %d %d %d%% %s\n", <file system name>, <total space>,
      <space used>, <space free>, <percentage used>,
      <file system root>

I varied that to use 64 bit values instead of 32 bit ones (because in
2013 POSIX still thinks partitions max out at 2 gigs), but the reason I
didn't insert spacing is the standard said _not_ to, and -P mode is
posix. Adding POSIXLY_CORRECT and then adding non-posix spaces to the
output is just confusing...

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