Variable length arrays in ntdll definitions

[kubkon]

@daurnimator suggested leaving out the variable length arrays (VLAs) from some of our NT definitions; for example, we currently have something like this:

pub const FILE_NAME_INFORMATION = extern struct {
    FileNameLength: ULONG,
    FileName: [1]WCHAR,
};

where FileName is effectively a VLA which cannot be known a priori. The idea here is to weed that out leaving only the static elements, so in the above example, leaving in only FileNameLength. FileName VLA can then be accessed by taking a pointer just behind this static structure.

[kubkon]

For the record: PR where this discussion originated #5993.

[ikskuh]

I think it would be reasonable to include a getter function in structs that use VLAs:

pub const FILE_NAME_INFORMATION = extern struct {
    FileNameLength: ULONG,
    
    pub fn getFileName(self: *@This()) []WCHAR {
        return @intToPtr([*]WCHAR, @ptrToInt(self) + @sizeOf(ULONG))[0..self.FileNameLength];
    }
};

[kubkon]

I think it would be reasonable to include a getter function in structs that use VLAs:

pub const FILE_NAME_INFORMATION = extern struct {
    FileNameLength: ULONG,
    
    pub fn getFileName(self: *@This()) []WCHAR {
        return @intToPtr([*]WCHAR, @ptrToInt(self) + @sizeOf(ULONG))[0..self.FileNameLength];
    }
};

That's a cool idea, I like it!

[daurnimator]

I think it would be reasonable to include a getter function in structs that use VLAs:

Note that I've hit zig bugs doing this in the past.

• unreachable: /deps/zig/src/codegen.cpp:gen_const_val_ptr:6010 #2431 (comment)
• Offset/alignment for 0 bit types #4016
• other issues I can't find right now :(

might be fixed now though

[kubkon]

I think it would be reasonable to include a getter function in structs that use VLAs:

Note that I've hit zig bugs doing this in the past.

• #2431 (comment)
• Offset/alignment for 0 bit types #4016
• other issues I can't find right now :(

might be fixed now though

Thanks for the heads up @daurnimator!