Commit 223e8f01 authored Jun 25, 2015 by Seymour, Shane M Committed by Greg Kroah-Hartman Aug 05, 2015

sysfs.txt: update show method notes about sprintf/snprintf/scnprintf usage



Changed the documentation to allow sprintf() when the buffer
provided by sysfs cannot be overflowed. Explicitly say
snprintf() must never be used in a show function to format
data to be returned to user space.

Change based on a discussion about the patch
st: convert DRIVER_ATTR macros to DRIVER_ATTR_RO

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shane Seymour <shane.seymour@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 64526370

Documentation/filesystems/sysfs.txt

+4 −1

Original line number	Diff line number	Diff line
		@@ -212,7 +212,10 @@ Other notes:
		- show() methods should return the number of bytes printed into the
		buffer. This is the return value of scnprintf().

		- show() should always use scnprintf().
		- show() must not use snprintf() when formatting the value to be
		returned to user space. If you can guarantee that an overflow
		will never happen you can use sprintf() otherwise you must use
		scnprintf().

		- store() should return the number of bytes used from the buffer. If the
		entire buffer has been used, just return the count argument.