using SetupDiGetDeviceInterfaceDetail

[Joe B.]

Hello,
This is my first attempt at posting to the newsgroup. My apologies if I
have directed this question to the wrong bunch.

I am trying to use SetupDiGetDeviceInterfaceDetail function in order to get
a handle to a USB HID device so that I can open it using CreateFile.
After struggling with this function for a couple of days, I feel that I
finally understand what it does and what I have to provide it. However,
when I run my program, I get an arcane error message which says "the user
supplied buffer is not valid for the requested operation". I called the
function once to get the required size and that worked telling me I needed
170 bytes. I allocated that much TCHAR for the DevicePath buffer. Then I
cast the buffer as the structure called for in the function parameter list.
Can anyone help me figure out what I'm doing wronb? Shall I post my source
code? Can you point me to a reference that might help me out.
Thanks,
Joe

[Ben Voigt]

"Joe B." <jo*********@comcast.netwrote in message
news:uC**************@TK2MSFTNGP06.phx.gbl...

Hello,
This is my first attempt at posting to the newsgroup. My apologies if I
have directed this question to the wrong bunch.

I am trying to use SetupDiGetDeviceInterfaceDetail function in order to
get
a handle to a USB HID device so that I can open it using CreateFile.
After struggling with this function for a couple of days, I feel that I
finally understand what it does and what I have to provide it. However,
when I run my program, I get an arcane error message which says "the user
supplied buffer is not valid for the requested operation". I called the
function once to get the required size and that worked telling me I needed
170 bytes. I allocated that much TCHAR for the DevicePath buffer. Then I
cast the buffer as the structure called for in the function parameter
list.
Can anyone help me figure out what I'm doing wronb? Shall I post my
source
code? Can you point me to a reference that might help me out.

Make sure that you properly initialize the buffer, setting
cbSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA)
and not the allocated size, because the cbSize field is used by Win32 API as
a kind of version number. The fourth parameter should be the allocated size
(170).

Thanks,
Joe

[Joe B.]

Ben,
Many thanks. That seems to have gotten me past the invalid buffer thing.
Joe

"Ben Voigt" <rb*@nospam.nospamwrote in message
news:uD**************@TK2MSFTNGP06.phx.gbl...

>
"Joe B." <jo*********@comcast.netwrote in message
news:uC**************@TK2MSFTNGP06.phx.gbl...

>Hello,
This is my first attempt at posting to the newsgroup. My apologies if I
have directed this question to the wrong bunch.

I am trying to use SetupDiGetDeviceInterfaceDetail function in order to
get
a handle to a USB HID device so that I can open it using CreateFile.
After struggling with this function for a couple of days, I feel that I
finally understand what it does and what I have to provide it. However,
when I run my program, I get an arcane error message which says "the user
supplied buffer is not valid for the requested operation". I called the
function once to get the required size and that worked telling me I
needed
170 bytes. I allocated that much TCHAR for the DevicePath buffer. Then
I
cast the buffer as the structure called for in the function parameter
list.
Can anyone help me figure out what I'm doing wronb? Shall I post my
source
code? Can you point me to a reference that might help me out.

Make sure that you properly initialize the buffer, setting
cbSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA)
and not the allocated size, because the cbSize field is used by Win32 API
as a kind of version number. The fourth parameter should be the allocated
size (170).

>Thanks,
Joe