os.rs

#[cfg(windows)]
mod os_defs {
    pub use winapi::shared::{
        ntdef::{HRESULT, LPCSTR, LPCWSTR, LPSTR, LPWSTR, WCHAR},
        wtypes::BSTR,
    };

    pub use winapi::um::combaseapi::CoTaskMemFree;
    pub use winapi::um::oleauto::{SysFreeString, SysStringLen};
}

#[cfg(not(windows))]
mod os_defs {
    pub type CHAR = i8;
    pub type UINT = u32;
    pub type WCHAR = widestring::WideChar;
    pub type OLECHAR = WCHAR;
    pub type LPSTR = *mut CHAR;
    pub type LPWSTR = *mut WCHAR;
    pub type LPCSTR = *const CHAR;
    pub type LPCWSTR = *const WCHAR;
    pub type BSTR = *mut OLECHAR;
    pub type LPBSTR = *mut BSTR;
    pub type HRESULT = i32;

    #[allow(non_snake_case)]
    pub unsafe fn CoTaskMemFree(p: *mut libc::c_void) {
        // https://github.com/microsoft/DirectXShaderCompiler/blob/a8d9780046cb64a1cea842fa6fc28a250e3e2c09/include/dxc/Support/WinAdapter.h#L46
        libc::free(p)
    }

    #[allow(non_snake_case)]
    pub unsafe fn SysFreeString(p: BSTR) {
        // TODO: Update link
        libc::free((p as *mut libc::c_char).offset(-4) as *mut _)
    }

    /// Returns the size of `p` in bytes, without terminating NULL character
    #[allow(non_snake_case)]
    pub unsafe fn SysStringByteLen(p: BSTR) -> UINT {
        // The first four bytes before the pointer contain the length prefix:
        // https://docs.microsoft.com/en-us/previous-versions/windows/desktop/automat/bstr
        if p.is_null() {
            0
        } else {
            *(p as *const UINT).offset(-1)
        }
    }

    /// Returns the size of `p` in characters, without terminating NULL character
    #[allow(non_snake_case)]
    pub unsafe fn SysStringLen(p: BSTR) -> UINT {
        SysStringByteLen(p) / std::mem::size_of::<OLECHAR>() as UINT
    }
}

pub use os_defs::*;