linux-kernel - Re: Fwd: [PATCH net-next 1/2] lib: string: add strreplace

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Date:   Sun, 3 Mar 2019 19:32:53 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Fwd: [PATCH net-next 1/2] lib: string: add strreplace_nonalnum

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@...il.com>
>>>> To: Florian Fainelli <f.fainelli@...il.com>, Andrew Lunn <andrew@...n.ch>, David Miller <davem@...emloft.net>
>>>> CC: netdev@...r.kernel.org <netdev@...r.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:

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()


> thanks,
> 
> greg k-h
> 
Heiner