Refactor winapi calls to surface errors

src/bin.rs

@@ -9,7 +9,8 @@ use std::ptr;
 
 use clap::{App, AppSettings, Arg};
 
-mod win_err;
+#[macro_use]
+mod win;
 
 fn main() -> Result<(), Box<dyn Error>> {
     let matches = App::new("notCUDA injector")
@@ -47,7 +48,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     cmd_line.push(0);
     let mut startup_info = unsafe { mem::zeroed::<detours_sys::_STARTUPINFOW>() };
     let mut proc_info = unsafe { mem::zeroed::<detours_sys::_PROCESS_INFORMATION>() };
-    let process_success = unsafe {
+    os_call!(
         detours_sys::DetourCreateProcessWithDllExW(
             ptr::null(),
             cmd_line.as_mut_ptr(),
@@ -60,13 +61,25 @@ fn main() -> Result<(), Box<dyn Error>> {
             &mut startup_info as *mut _,
             &mut proc_info as *mut _,
             "nvcuda_redirect.dll".as_ptr() as *const i8,
-            Option::None,
-        )
-    };
-    if process_success == 0 {
-        return Err(win_err::error_string(win_err::errno()))?;
-    }
+            Option::None
+        ),
+        0
+    );
     Ok(())
+    /*
+
+    cmd_line.as_mut_ptr(),
+    ptr::null_mut(),
+    ptr::null_mut(),
+    0,
+    0x10,
+    ptr::null_mut(),
+    ptr::null(),
+    &mut startup_info as *mut _,
+    &mut proc_info as *mut _,
+    "nvcuda_redirect.dll".as_ptr() as *const i8,
+    Option::None,
+    */
 }
 
 fn copy_to(from: &OsStr, to: &mut Vec<u16>) {

src/win.rs

@@ -1,10 +1,13 @@
 #![allow(non_snake_case)]
 
+use std::error;
+use std::error::Error;
+use std::fmt;
 use std::ptr;
 
 mod c {
     use std::ffi::c_void;
-    use std::os::raw::{c_ulong};
+    use std::os::raw::c_ulong;
 
     pub type DWORD = c_ulong;
     pub type HANDLE = LPVOID;
@@ -35,6 +38,49 @@ mod c {
     }
 }
 
+macro_rules! last_ident {
+    ($i:ident) => {
+        stringify!($i)
+    };
+    ($start:ident, $($cont:ident),+) => {
+        last_ident!($($cont),+)
+    };
+}
+
+macro_rules! os_call {
+    ($($path:ident)::+ ($($args:expr),*), $success:expr) => {
+        let result = unsafe{ $($path)::+ ($($args),+) };
+        if result != $success {
+            let name = last_ident!($($path),+);
+            let err_code = $crate::win::errno();
+            Err($crate::win::OsError{
+                function: name,
+                error_code: err_code as u32,
+                message: $crate::win::error_string(err_code)
+            })?;
+        }
+    };
+}
+
+#[derive(Debug)]
+pub struct OsError {
+    pub function: &'static str,
+    pub error_code: u32,
+    pub message: String,
+}
+
+impl fmt::Display for OsError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl error::Error for OsError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}
+
 pub fn errno() -> i32 {
     unsafe { c::GetLastError() as i32 }
 }