File picker returns an incorrect path for USB devices on Windows

[gen2brain]

File picker returns an incorrect path for USB devices on Windows

[ncruces]

My guess is that the shGetPathFromIDList is not writing the null terminator to buf.

So, because you're reusing the buffer for "display name" and the result ("full path"), you were getting F:\ (the "full path") partially overwriting ScanDisk (F:\) (the "display name"). Or something like that.

The reason it only failed for root folders, is that the those are probably the only ones where "full path" is shorter than "display name". The fix works, because buf is zero initialized and big enough to hold the result (MAX_PATH) so shGetPathFromIDList not writing a null terminator should not be a problem. And I don't see a point in trying to get the "display name" any way?

If it does work (I didn't test it) please do a PR with the fix for @gen2brain to consider?

[ncruces]

Try removing/commenting this line:

dlgs/file_windows.go

Line 90 in f2c7498

bi.displayName = &buf[0]

And replacing:

dlgs/file_windows.go

Line 96 in f2c7498

return stringFromUtf16Ptr(bi.displayName), true

With:

return stringFromUtf16Ptr(&buf[0]), true 

[philenius]

Thank you for your response, @ncruces. If I understood you correctly, then you suggested to change the function dirDialog() to look like this (?):

// dirDialog displays directory dialog.
func dirDialog(title string) (string, bool) {
	var bi browseinfoW
	buf := make([]uint16, maxPath)

	t, _ := syscall.UTF16PtrFromString(title)

	bi.title = t
        // Commented this line
	// bi.displayName = &buf[0]
	bi.flags = bifEditBox | bifNewDialogStyle

	lpItem := shBrowseForFolder(&bi)
	ok := shGetPathFromIDList(lpItem, &buf[0])
	if ok {
                // Replaced this line
		//return stringFromUtf16Ptr(bi.displayName), true
		return stringFromUtf16Ptr(&buf[0]), true
	}

	return "", false
}

I don't understand why changing these two lines should make a difference? Nethertheless, I tried it with your changes and I still get an incorrect path when I select a USB device (same error as described in the first message of this issue).

Edit: my mistake, Go did not recompile the changes in my local copy of dlgs. It actually works! Now, I can select the root of USB devices as well as child directories of USB devices and dlgs returns the correct file / directory path. Would you mind explaining to me why passing the pointer directly to stringFromUtf16Ptr works? Can this pointer / buffer only be read once?

[philenius]

Thank you. I agree with you, the "display name" is not being used nor returned from this function, so it's useless.

[gen2brain]

@philenius Can I merge PR? I cannot test on Windows.

[ncruces]

I think so, yes. This is how I do it in my lib:
https://github.com/ncruces/zenity/blob/master/file_windows.go#L306

Also thanks, your code helped me a lot with the text entry dialog (and will help me a lot with the list dialog)!

[philenius]

@gen2brain sorry for my delayed response, yes you can merge the PR (I see that you already did so, thank you). I can only prove that my changes work at least on my Windows 10 machine. Here's a GIF where I select the root of a USB device subsequently a child directory. Both use cases work as expected: