It's possible for the HARDWARE\DEVICEMAP\SERIALCOMM key to not exist in
the registry if there are no serial ports at all and never have been, as
discovered on my rather minimalist gaming machine.
Handle that case gracefully and return an empty list.
RegOpenKeyEx() and RegQueryInfoKey() return system error codes directly,
not by setting the thread-local errno equivalent that is returned by
GetLastError().
When returning SP_ERR_FAIL, our API specifies that sp_last_error_code()
may be called immediately afterwards to get the system error code. In
this case that would not work, as it would call GetLastError() and miss
the directly-returned result.
We therefore need to call SetLastError() with the error code before
returning with SP_ERR_FAIL.
In wc_to_utf8() in windows.c, the zero terminator is written to an invalid
array index, which results in 2 bytes being zeroed in a random place in the
stack. This sometimes causes a crash when running sp_list_ports() (depending
on string length and compiler optimisation settings).
sizeof(wc_str) returns the size in bytes, so cannot be used directly as an
index into that array, it should be divided by sizeof(WCHAR). Otherwise the
zero terminator index is approximately twice what it should be.
This fixes bug #1031.
USB composite devices can contain an ACM serial interface.
On Windows, the correct iSerial descriptor field is assigned to the parent
(composite) device instead of to the actual serial interface. A bogus
value is returned if the serial interface is asked to provide the S/N.
This patch provides a fallback for this kind of device (tested on Android
with adb + cdc gadgets and on Arduino Zero Programming Port)
