Setupapi SetupGetSourceFileLocationW return wrong result against Windows

for example, I have a setup inf contain the following lines:

[SourceDisksNames]
1 = %DiskDescription%,,,.\examplepath
[SourceDisksFiles]
example.sys = 1,

when I call SetupGetSourceFileLocationW, it returns source_id = 1, buffer = ".\examplepath"

on MS Win7, SetupGetSourceFileLocationW, returns source_id = 1, buffer = ""

the bug is in func get_source_id: loc 354~~365, these checks modify the inf context, makes the segment pointer move to another segment

Solution: comment loc 354~~365, modify loc 396

if (SetupGetStringFieldW( context, 4, buffer, buffer_size, required_size ))

to

if (SetupGetStringFieldW( context, 2, buffer, buffer_size, required_size ))