[libhid-discuss] Opening multiple devices

[Warren Jasper]

Problem:  One of the shortcomings of the current implementation of 
libhid is that it does not handle multiple devices correctly.  For 
example, with
   two identical devices on the USB bus with the same vendor and product 
id's, libhid returns a handle to the first successful match.   I do not 
believe that
   this was the intended behavior of the package. 
Solution:
   I have attached a patch to hid_opening.c that should fix the 
problem.   It basically keeps a list of currently open device/interface 
pairs, and keeps searching
   for a new device/interface before looking for a match.  Before 
returning from hid_open for hid_force_open, it adds the device to the 
list of open
  device/interface pairs. 

This implementation does not work for different processes and is not 
currently thread safe.  However, libhid has these same issues.

Enjoy,

Warren
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