coccinelle: api: add device_attr_show script

// SPDX-License-Identifier: GPL-2.0-only

///

/// From Documentation/filesystems/sysfs.txt:

///  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().

///

// Confidence: High

// Copyright: (C) 2020 Denis Efremov ISPRAS

// Options: --no-includes --include-headers

//

virtual report

virtual org

virtual context

virtual patch

@r depends on !patch@

identifier show, dev, attr, buf;

position p;

@@

ssize_t show(struct device *dev, struct device_attribute *attr, char *buf)

{

	<...

*	return snprintf@p(...);

	...>

}

@rp depends on patch@

identifier show, dev, attr, buf;

@@

ssize_t show(struct device *dev, struct device_attribute *attr, char *buf)

{

	<...

	return

-		snprintf

+		scnprintf

			(...);

	...>

}

@script: python depends on report@

p << r.p;

@@

coccilib.report.print_report(p[0], "WARNING: use scnprintf or sprintf")

@script: python depends on org@

p << r.p;

@@

coccilib.org.print_todo(p[0], "WARNING: use scnprintf or sprintf")