Re: Fwd: [PATCH net-next 1/2] lib: string: add strreplace_nonalnum

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Mar 03, 2019 at 07:32:53PM +0100, Heiner Kallweit wrote:
> On 03.03.2019 19:15, Greg Kroah-Hartman wrote:
> > On Sun, Mar 03, 2019 at 07:04:21PM +0100, Heiner Kallweit wrote:
> >> On 03.03.2019 18:55, Greg Kroah-Hartman wrote:
> >>> On Sun, Mar 03, 2019 at 06:47:32PM +0100, Heiner Kallweit wrote:
> >>>> I submitted this through the netdev tree, maybe relevant for you as well.
> >>>> See also here: https://marc.info/?t=155103900100003&r=1&w=2
> >>>>
> >>>> -------- Forwarded Message --------
> >>>> Subject: [PATCH net-next 1/2] lib: string: add strreplace_nonalnum
> >>>> Date: Sun, 3 Mar 2019 18:20:50 +0100
> >>>> From: Heiner Kallweit <hkallweit1@gmail.com>
> >>>> To: Florian Fainelli <f.fainelli@gmail.com>, Andrew Lunn <andrew@lunn.ch>, David Miller <davem@davemloft.net>
> >>>> CC: netdev@vger.kernel.org <netdev@vger.kernel.org>
> >>>>
> >>>> Add a new function strreplace_nonalnum that replaces all
> >>>> non-alphanumeric characters. Such functionality is needed e.g. when a
> >>>> string is supposed to be used in a sysfs file name. If '\0' is given
> >>>> as new character then non-alphanumeric characters are cut. 
> >>>
> >>> sysfs doesn't have any such requirements, it can use whatever you want
> >>> to give it for a filename.
> >>>
> >> Even a slash?
> > 
> > Is a slash an illegal character for a file to have?  It's up to the vfs
> > to care about this, don't force random parts of the kernel to care :)
> > 
> >> HWMON drivers is an example where such functionality occurs open-coded.
> > 
> > Is that data coming from userspace or from a kernel driver?
> > 
> Usually from a kernel driver. That's what
> Documentation/hwmon/hwmon-kernel-api.txt says:

Usually?  So userspace can set the name?

> All supported hwmon device registration functions only accept valid device
> names. Device names including invalid characters (whitespace, '*', or '-')
> will be rejected. The 'name' parameter is mandatory.
> 
> The hwmon subsystem has an own function to check for such characters:
> hwmon_is_bad_char()

It looks like hwmon is the only thing that cares about this then, why
do you want to make this a common function?

thanks,

greg k-h