This changes the uevent buffer functions to use a struct instead of a
long list of parameters. It does no longer require the caller to do the
proper buffer termination and size accounting, which is currently wrong
in some places. It fixes a known bug where parts of the uevent
environment are overwritten because of wrong index calculations.

Many thanks to Mathieu Desnoyers for finding bugs and improving the
error handling.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

This class is result of "external power" and "battery" classes merge,
as suggested by David Woodhouse. He also implemented uevent support.

Here how userspace seeing it now:

    	# ls /sys/class/power\ supply/
    	ac  main-battery  usb

    	# cat /sys/class/power\ supply/ac/type
    	AC

    	# cat /sys/class/power\ supply/usb/type
    	USB

    	# cat /sys/class/power\ supply/main-battery/type
    	Battery

    	# cat /sys/class/power\ supply/ac/online
    	1

    	# cat /sys/class/power\ supply/usb/online
    	0

    	# cat /sys/class/power\ supply/main-battery/status
    	Charging

    	# cat /sys/class/leds/h5400\:red-left/trigger
    	none h5400-radio timer hwtimer ac-online usb-online
    	main-battery-charging-or-full [main-battery-charging]
    	main-battery-full

Signed-off-by: Anton Vorontsov <cbou@mail.ru>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>