C#•3y ago•

66 replies

✅ ✅ Vararg P/Invoke (x86) throws BadImageFormatException (0x80131124 "Index not found")

I am attempting to perform vararg P/Invokes following signatures I see on pinvoke.net and, e.g., https://stackoverflow.com/questions/2124490/what-is-the-proper-pinvoke-signature-for-a-function-that-takes-var-args

This led me to the following P/Invokes:

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int sprintf(IntPtr buffer, string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int _scprintf(string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int sprintf(IntPtr buffer, string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int _scprintf(string format, __arglist);

invoked as such:

public static void CLRPrintfHook(string fmt, nint va0, nint va1, // ...
// {...}
_scprintf(fmt, __arglist(va0, va1));

public static void CLRPrintfHook(string fmt, nint va0, nint va1, // ...
// {...}
_scprintf(fmt, __arglist(va0, va1));

specifically for

<PlatformTarget>x86</PlatformTarget>

<PlatformTarget>x86</PlatformTarget>

using .NET 7.

But they result in a

BadImageFormatException

BadImageFormatException

with result 0x80131124, "Index not found." See image. I do not have problems issuing P/Invokes to, e.g.

_vscprintf

_vscprintf

and

vsprintf

vsprintf

which take

va_list

va_list

instead of varargs as the final argument.

For posterity, the working P/Invokes are declared as:

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int _vscprintf(string format, IntPtr ptr);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int vsprintf(IntPtr buffer, string format, IntPtr args);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int _vscprintf(string format, IntPtr ptr);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int vsprintf(IntPtr buffer, string format, IntPtr args);

Any idea as to what I could be doing wrong? Or is this plain unsupported?

✅ ✅ Vararg P/Invoke (x86) throws BadImageFormatException (0x80131124 "Index not found")

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int sprintf(IntPtr buffer, string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int _scprintf(string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int sprintf(IntPtr buffer, string format, __arglist);

[DllImport("msvcrt.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static unsafe extern int _scprintf(string format, __arglist);

invoked as such:

public static void CLRPrintfHook(string fmt, nint va0, nint va1, // ...
// {...}
_scprintf(fmt, __arglist(va0, va1));

public static void CLRPrintfHook(string fmt, nint va0, nint va1, // ...
// {...}
_scprintf(fmt, __arglist(va0, va1));

specifically for

<PlatformTarget>x86</PlatformTarget>

<PlatformTarget>x86</PlatformTarget>

using .NET 7.

But they result in a

BadImageFormatException

BadImageFormatException

with result 0x80131124, "Index not found." See image. I do not have problems issuing P/Invokes to, e.g.

_vscprintf

_vscprintf

and

vsprintf

vsprintf

which take

va_list

va_list

instead of varargs as the final argument.

For posterity, the working P/Invokes are declared as:

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int _vscprintf(string format, IntPtr ptr);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int vsprintf(IntPtr buffer, string format, IntPtr args);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int _vscprintf(string format, IntPtr ptr);

    [LibraryImport("msvcrt.dll", StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(System.Runtime.InteropServices.Marshalling.AnsiStringMarshaller))]
    [UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static partial int vsprintf(IntPtr buffer, string format, IntPtr args);

Any idea as to what I could be doing wrong? Or is this plain unsupported?

✅ ✅ Vararg P/Invoke (x86) throws BadImageFormatException (0x80131124 "Index not found")

✅ ✅ Vararg P/Invoke (x86) throws BadImageFormatException (0x80131124 "Index not found")

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