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hidraw: Return string lengths for certain ioctls
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Authored by grembo on May 17 2022, 9:43 AM.
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Summary

The hidraw(4) driver provides a set of Linux compatible ioctls. Three
of these return the length of the copied string on Linux, but they
always return 0 on FreeBSD:

  • HIDIOCGRAWPHYS
  • HIDIOCGRAWNAME
  • HIDIOCGRAWUNIQ

I noticed this while implementing hidraw(4) support for FreeBSD in
python-fido2[0], so there is some real-world software relying on
this return value (I would assume that this isn't the only one).

This patch aims to fix this by returning the length of the copied
string (including the trailing NUL character) in the affected ioctls.

[0]
https://github.com/Yubico/python-fido2/pull/139
https://github.com/Yubico/python-fido2/blob/master/fido2/hid/linux.py#L63-L74

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grembo edited the summary of this revision. (Show Details)
  • Make strlen calculation behave like on Linux (count trailing NUL)
This revision is now accepted and ready to land.May 17 2022, 9:29 PM