From: Seymour, Shane M Date: Thu, 25 Jun 2015 02:33:08 +0000 (+0000) Subject: sysfs.txt: update show method notes about sprintf/snprintf/scnprintf usage X-Git-Tag: firefly_0821_release~176^2~1222^2~7 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=223e8f01b072152cc4336e7dcb1cf8c21ab34432;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Shane Seymour Signed-off-by: Greg Kroah-Hartman --- diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index b35a64b82f9e..9494afb9476a 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -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.