SHQueryRecycleBin 不适用于 .net Core

Question

I have Methods Out of which : 1 Use "SHQueryRecycleBin" to Query Recycle Bin & Other Use "SHEmptyRecycleBin" To Delete Recycle Bin, Both of em Works Fine without any issue on my .Net 4.8 Projects.

But While i am trying to use the same code on .Net Core 3.1 "SHQueryRecycleBin" Simply Refuse To Work & Throw "HRESULT -2147024809" .

To Check I Tried it on {.Net 4.8} vs {.Net Core 3.1} Console, WinForm & Wpf App & it worked Everytime on .net Framework.

Code Sample :

[DllImport("shell32.dll")]
static extern int SHQueryRecycleBin(string pszRootPath, ref 
SHQUERYRBINFO  pSHQueryRBInfo);

[StructLayout(LayoutKind.Sequential, Pack=1)] // also tried pack=4 
public struct SHQUERYRBINFO
{
    public int  cbSize;
    public ulong i64Size;
    public ulong i64NumItems;
}

public static int GetCount()
{
    SHQUERYRBINFO sqrbi = new SHQUERYRBINFO();
    sqrbi.cbSize = Marshal.SizeOf(typeof(SHQUERYRBINFO));
    int hresult = SHQueryRecycleBin(string.Empty, ref sqrbi);
    return (int)sqrbi.i64NumItems;
}

Answer 1

I had an inkling as to what the problem might be before I tried your code.

If you run your code as is, you receive a HRESULT of -2147024809 from SHQueryRecycleBin .

This is actually a HRESULT of 0x80070057 , which is the error ERROR_INVALID_PARAMETER (or ' The parameter is incorrect ' if you prefer plain English). This indicates that there is an issue with one or more of the parameters being sent to the Win32 call.

In the case of your code, the culprit is your StructLayout declaration of SHQUERYRBINFO . You have defined a Pack alignment size of 1 (and tried 4), but are using ulong s in the struct . A Win32 ulong is 8 bytes, so you should use 8 as the Pack size in .Net Core:

...

[StructLayout(LayoutKind.Sequential, Pack = 8)]
public struct SHQUERYRBINFO
{
    ...

Incidentally, if you omit the Pack parameter completely, the default value of 8 will be used.