[patch 3/5] Driver core: Documentation: use snprintf and strnlen

[patch 3/5] Driver core: Documentation: use snprintf and strnlen

[domen]

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From: Jan Veldeman <jan@mind.be>



Documentation should give the good example of using snprintf and
strnlen in stead of sprintf and strlen.

PAGE_SIZE is used as the maximal length to reflect the behaviour of
show/store.


Signed-off-by: Jan Veldeman <Jan.Veldeman@advalvas.be>
Signed-off-by: Domen Puncer <domen@coderock.org>


---
 sysfs.txt |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Index: quilt/Documentation/filesystems/sysfs.txt
===================================================================
--- quilt.orig/Documentation/filesystems/sysfs.txt
+++ quilt/Documentation/filesystems/sysfs.txt
@@ -216,13 +216,13 @@ A very simple (and naive) implementation
 
 static ssize_t show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
-        return sprintf(buf,"%s\n",dev->name);
+        return snprintf(buf,PAGE_SIZE,"%s\n",dev->name);
 }
 
 static ssize_t store_name(struct device * dev, const char * buf)
 {
 	sscanf(buf,"%20s",dev->name);
-	return strlen(buf);
+	return strnlen(buf,PAGE_SIZE);
 }
 
 static DEVICE_ATTR(name,S_IRUGO,show_name,store_name);

--

Re: [patch 3/5] Driver core: Documentation: use snprintf and strnlen

[Ingo Oeser]

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Hi Domen,

On Sunday 31 July 2005 13:12, domen@coderock.org wrote:
> From: Jan Veldeman <jan@mind.be>
> Documentation should give the good example of using snprintf and
> strnlen in stead of sprintf and strlen.
> 
> PAGE_SIZE is used as the maximal length to reflect the behaviour of
> show/store.

The whole part of the Documentation is obsoleted by the fact,
that struct device has no structure member called "name".

People hacking sysfs should also try to hack the docu to match or
at least remove the obsolete parts of it.

So you can drop this patch altogether, I think.


Regards

Ingo Oeser



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Re: [patch 3/5] Driver core: Documentation: use snprintf and strnlen

[Jan Veldeman]

Hi Ingo,

Ingo Oeser wrote:

> On Sunday 31 July 2005 13:12, domen@coderock.org wrote:
> > From: Jan Veldeman <jan@mind.be>
> > Documentation should give the good example of using snprintf and
> > strnlen in stead of sprintf and strlen.
> > 
> > PAGE_SIZE is used as the maximal length to reflect the behaviour of
> > show/store.
> 
> The whole part of the Documentation is obsoleted by the fact,
> that struct device has no structure member called "name".
> 
> People hacking sysfs should also try to hack the docu to match or
> at least remove the obsolete parts of it.
> 
> So you can drop this patch altogether, I think.
> 
> 

Even though the example doesn't work (the comment below the example even
indicates it shouldn't be done), I would suggest to still apply this
patch, as it shows the good usage of snprintf in stead of sprintf:

Somebody who looks at the documentation will certainly change the
contents of the attribute (this is by all means the reason for such an
example), but will not likely change the way sprintf is used.

Best regards,
Jan