r314189:

Fix up NULL/'\0' uses and fix 2 derefs after NULL

CID:		1018898, 1018899

r314190:

Fix some minor style nits: put parentheses around return values

r314191:

Fix up r314189

The conditional in do_buff_decode(..) after the while loop was accidentally
inverted. Only increment the pointer for fmt if it's not NUL.

Abort format processing as soon as we have no enough data.

- Add missing va_end's after corresponding va_start's to cleanup state
- Eliminate questionable bzero'ing of va_list passed in to
  do_buff_decode(..) and do_encode(..) from buff_{de,en}code_visit(..)
  and csio_{de,en}code_visit(..). Make va_list a pointer instead and
  pass NULL into the underlying functions to handler this in a portable
  way.
- Do some minor style(9) clean up in affected functions.

Differential Revision: https://reviews.freebsd.org/D6072
MFC after: 3 days
Reported by: cppcheck, Coverity
CID: 1018500-1018503
Reviewed by: cem
Sponsored by: EMC / Isilon Storage Division

(csio_decode_visit() and family).

Reviewed by:	ken

related patches. These include:
	* Mode page editting can be scripted. This involves two
	  things: first, if stdin is not a tty, changes are read from
	  stdin rather than invoking $EDITOR. Second, and more
	  importantly, not all modepage entries must be included in the
	  change set. This means that camcontrol can now gracefully handle
	  more intrusive editting from the $EDITOR, including removal or
	  rearrangement of lines. It also means that you can do stuff
	  like:
		# echo "WCE: 1" | camcontrol modepage da3 -m 8 -e
		# newfs /dev/da3
		# echo "WCE: 0" | camcontrol modepage da3 -m 8 -e
	* Range-checking on user-supplied input values. modeedit.c now
	  uses the field width specifiers to determine the maximum
	  allowable value for a field. If the user enters a value larger
	  than the maximum, it clips the value to the max and warns the
	  user. This also involved patching cam_cmdparse.c to be more
	  consistent with regards to the "count" parameter to arg_put
	  (previously is was the length of strings and 1 for all integral
	  types). The cam_cdbparse(3) man page was also updated to reflect
	  the revised semantics.
	* In the process, I removed the 64 entry limit on mode pages (not
	  that we were even close to hitting that limit). This was a nice
	  side-effect of the other changes.
	* Technically, the new mode editting functionality allows editting
	  of character array entries in mode pages (type 'c' or 'z'),
	  however since buff_encode doesn't grok them it is currently
	  useless.
	* Camcontrol gained two new options related to mode pages: -l and
	  -b. The former lists all available mode pages for a given
	  device. The latter forces mode page display in binary format
	  (the default when no mode page definition was found in
	  scsi_modes).
	* Added support for mode page names to scsi_modes. Allows names to
	  be displayed alongside mode numbers in the mode page
	  listing. Updated scsi_modes to use the new functionality. This
	  also adds the semicolon into the scsi_modes syntax as an
	  optional mode page definition terminator. This is needed to name
	  pages without providing a page format definition.
	* Updated scsi_all.h to include a structure describing mode page
	  headers.
	* Added $FreeBSD$ line to scsi_modes.

Inspired by:	dwhite
Reviewed by:	ken

checking in some functions.

Submitted by:	dfr
Modified by:	ken

Submitted by: "Kenneth D. Merry" <ken@FreeBSD.org>