From de4eea9d49b5d4d5e10e67e1ae2754bbb720564c Mon Sep 17 00:00:00 2001
From: Nym Seddon <unseddd@shh.xyz>
Date: Fri, 22 Jan 2021 02:45:39 +0000
Subject: [PATCH] Add ABI check for shims

---
 src/helpers.rs                     | 10 ++++++++
 src/machine.rs                     |  8 +++---
 src/shims/dlsym.rs                 |  6 +++--
 src/shims/foreign_items.rs         | 39 ++++++++++++++++++++++++++----
 src/shims/mod.rs                   |  4 ++-
 src/shims/posix/dlsym.rs           |  4 +++
 src/shims/posix/foreign_items.rs   |  6 ++++-
 src/shims/windows/dlsym.rs         |  6 ++++-
 src/shims/windows/foreign_items.rs |  6 ++++-
 9 files changed, 74 insertions(+), 15 deletions(-)

diff --git a/src/helpers.rs b/src/helpers.rs
index 4c989db0170..6a12a8f6ba3 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -9,6 +9,7 @@
 use rustc_middle::ty::{self, List, TyCtxt, layout::TyAndLayout};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
 use rustc_target::abi::{LayoutOf, Size, FieldsShape, Variants};
+use rustc_target::spec::abi::Abi;
 
 use rand::RngCore;
 
@@ -553,6 +554,15 @@ fn read_timespec(
     throw_ub_format!("incorrect number of arguments: got {}, expected {}", args.len(), N)
 }
 
+/// Check that the ABI is what we expect.
+pub fn check_abi<'a>(abi: Abi, exp_abi: Abi) -> InterpResult<'a, ()> {
+    if abi == exp_abi {
+        Ok(())
+    } else {
+        throw_ub_format!("calling a function with ABI {:?} using caller ABI {:?}", exp_abi, abi)
+    }
+}
+
 pub fn isolation_error(name: &str) -> InterpResult<'static> {
     throw_machine_stop!(TerminationInfo::UnsupportedInIsolation(format!(
         "{} not available when isolation is enabled",
diff --git a/src/machine.rs b/src/machine.rs
index d28aa34c75e..ab7abebaeab 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -353,24 +353,24 @@ fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         instance: ty::Instance<'tcx>,
-        _abi: Abi,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
-        ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
+        ecx.find_mir_or_eval_fn(instance, abi, args, ret, unwind)
     }
 
     #[inline(always)]
     fn call_extra_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         fn_val: Dlsym,
-        _abi: Abi,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         _unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx> {
-        ecx.call_dlsym(fn_val, args, ret)
+        ecx.call_dlsym(fn_val, abi, args, ret)
     }
 
     #[inline(always)]
diff --git a/src/shims/dlsym.rs b/src/shims/dlsym.rs
index 9b15cb9ac9a..a87d8a01757 100644
--- a/src/shims/dlsym.rs
+++ b/src/shims/dlsym.rs
@@ -1,4 +1,5 @@
 use rustc_middle::mir;
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
 use shims::posix::dlsym as posix;
@@ -29,13 +30,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn call_dlsym(
         &mut self,
         dlsym: Dlsym,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
         match dlsym {
-            Dlsym::Posix(dlsym) => posix::EvalContextExt::call_dlsym(this, dlsym, args, ret),
-            Dlsym::Windows(dlsym) => windows::EvalContextExt::call_dlsym(this, dlsym, args, ret),
+            Dlsym::Posix(dlsym) => posix::EvalContextExt::call_dlsym(this, dlsym, abi, args, ret),
+            Dlsym::Windows(dlsym) => windows::EvalContextExt::call_dlsym(this, dlsym, abi, args, ret),
         }
     }
 }
diff --git a/src/shims/foreign_items.rs b/src/shims/foreign_items.rs
index 237fb27d922..628e9b69e17 100644
--- a/src/shims/foreign_items.rs
+++ b/src/shims/foreign_items.rs
@@ -4,14 +4,14 @@
 
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir;
-use rustc_target::{abi::{Align, Size}, spec::PanicStrategy};
+use rustc_target::{abi::{Align, Size}, spec::{PanicStrategy, abi::Abi}};
 use rustc_middle::ty;
 use rustc_apfloat::Float;
 use rustc_span::symbol::sym;
 
 use crate::*;
 use super::backtrace::EvalContextExt as _;
-use helpers::check_arg_count;
+use helpers::{check_abi, check_arg_count};
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
@@ -112,6 +112,7 @@ fn realloc(
     fn emulate_foreign_item(
         &mut self,
         def_id: DefId,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
@@ -130,12 +131,14 @@ fn emulate_foreign_item(
         let (dest, ret) = match ret {
             None => match link_name {
                 "miri_start_panic" => {
+                    check_abi(abi, Abi::Rust)?;
                     this.handle_miri_start_panic(args, unwind)?;
                     return Ok(None);
                 }
                 // This matches calls to the foreign item `panic_impl`.
                 // The implementation is provided by the function with the `#[panic_handler]` attribute.
                 "panic_impl" => {
+                    check_abi(abi, Abi::Rust)?;
                     let panic_impl_id = tcx.lang_items().panic_impl().unwrap();
                     let panic_impl_instance = ty::Instance::mono(tcx, panic_impl_id);
                     return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
@@ -143,12 +146,14 @@ fn emulate_foreign_item(
                 | "exit"
                 | "ExitProcess"
                 => {
+                    check_abi(abi, if link_name == "exit" { Abi::C } else { Abi::System })?;
                     let &[code] = check_arg_count(args)?;
                     // it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
                     let code = this.read_scalar(code)?.to_i32()?;
                     throw_machine_stop!(TerminationInfo::Exit(code.into()));
                 }
                 "abort" => {
+                    check_abi(abi, Abi::C)?;
                     throw_machine_stop!(TerminationInfo::Abort("the program aborted execution".to_owned()))
                 }
                 _ => throw_unsup_format!("can't call (diverging) foreign function: {}", link_name),
@@ -165,6 +170,7 @@ fn emulate_foreign_item(
             // Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
             // also be a custom user-provided implementation via `#![feature(panic_runtime)]`
             "__rust_start_panic" | "__rust_panic_cleanup" => {
+                check_abi(abi, Abi::C)?;
                 // This replicates some of the logic in `inject_panic_runtime`.
                 // FIXME: is there a way to reuse that logic?
                 let panic_runtime = match this.tcx.sess.panic_strategy() {
@@ -179,7 +185,7 @@ fn emulate_foreign_item(
         }
 
         // Third: functions that return.
-        if this.emulate_foreign_item_by_name(link_name, args, dest, ret)? {
+        if this.emulate_foreign_item_by_name(link_name, abi, args, dest, ret)? {
             trace!("{:?}", this.dump_place(*dest));
             this.go_to_block(ret);
         }
@@ -193,6 +199,7 @@ fn emulate_foreign_item(
     fn emulate_foreign_item_by_name(
         &mut self,
         link_name: &str,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         dest: PlaceTy<'tcx, Tag>,
         ret: mir::BasicBlock,
@@ -204,6 +211,7 @@ fn emulate_foreign_item_by_name(
         match link_name {
             // Miri-specific extern functions
             "miri_static_root" => {
+                check_abi(abi, Abi::Rust)?;
                 let &[ptr] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 let ptr = this.force_ptr(ptr)?;
@@ -215,23 +223,27 @@ fn emulate_foreign_item_by_name(
 
             // Obtains a Miri backtrace. See the README for details.
             "miri_get_backtrace" => {
+                check_abi(abi, Abi::Rust)?;
                 this.handle_miri_get_backtrace(args, dest)?;
             }
 
             // Resolves a Miri backtrace frame. See the README for details.
             "miri_resolve_frame" => {
+                check_abi(abi, Abi::Rust)?;
                 this.handle_miri_resolve_frame(args, dest)?;
             }
 
 
             // Standard C allocation
             "malloc" => {
+                check_abi(abi, Abi::C)?;
                 let &[size] = check_arg_count(args)?;
                 let size = this.read_scalar(size)?.to_machine_usize(this)?;
                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
                 this.write_scalar(res, dest)?;
             }
             "calloc" => {
+                check_abi(abi, Abi::C)?;
                 let &[items, len] = check_arg_count(args)?;
                 let items = this.read_scalar(items)?.to_machine_usize(this)?;
                 let len = this.read_scalar(len)?.to_machine_usize(this)?;
@@ -241,11 +253,13 @@ fn emulate_foreign_item_by_name(
                 this.write_scalar(res, dest)?;
             }
             "free" => {
+                check_abi(abi, Abi::C)?;
                 let &[ptr] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 this.free(ptr, MiriMemoryKind::C)?;
             }
             "realloc" => {
+                check_abi(abi, Abi::C)?;
                 let &[old_ptr, new_size] = check_arg_count(args)?;
                 let old_ptr = this.read_scalar(old_ptr)?.check_init()?;
                 let new_size = this.read_scalar(new_size)?.to_machine_usize(this)?;
@@ -257,6 +271,7 @@ fn emulate_foreign_item_by_name(
             // (Usually these would be forwarded to to `#[global_allocator]`; we instead implement a generic
             // allocation that also checks that all conditions are met, such as not permitting zero-sized allocations.)
             "__rust_alloc" => {
+                check_abi(abi, Abi::Rust)?;
                 let &[size, align] = check_arg_count(args)?;
                 let size = this.read_scalar(size)?.to_machine_usize(this)?;
                 let align = this.read_scalar(align)?.to_machine_usize(this)?;
@@ -269,6 +284,7 @@ fn emulate_foreign_item_by_name(
                 this.write_scalar(ptr, dest)?;
             }
             "__rust_alloc_zeroed" => {
+                check_abi(abi, Abi::Rust)?;
                 let &[size, align] = check_arg_count(args)?;
                 let size = this.read_scalar(size)?.to_machine_usize(this)?;
                 let align = this.read_scalar(align)?.to_machine_usize(this)?;
@@ -283,6 +299,7 @@ fn emulate_foreign_item_by_name(
                 this.write_scalar(ptr, dest)?;
             }
             "__rust_dealloc" => {
+                check_abi(abi, Abi::Rust)?;
                 let &[ptr, old_size, align] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 let old_size = this.read_scalar(old_size)?.to_machine_usize(this)?;
@@ -296,6 +313,7 @@ fn emulate_foreign_item_by_name(
                 )?;
             }
             "__rust_realloc" => {
+                check_abi(abi, Abi::Rust)?;
                 let &[ptr, old_size, align, new_size] = check_arg_count(args)?;
                 let ptr = this.force_ptr(this.read_scalar(ptr)?.check_init()?)?;
                 let old_size = this.read_scalar(old_size)?.to_machine_usize(this)?;
@@ -316,6 +334,7 @@ fn emulate_foreign_item_by_name(
 
             // C memory handling functions
             "memcmp" => {
+                check_abi(abi, Abi::C)?;
                 let &[left, right, n] = check_arg_count(args)?;
                 let left = this.read_scalar(left)?.check_init()?;
                 let right = this.read_scalar(right)?.check_init()?;
@@ -336,6 +355,7 @@ fn emulate_foreign_item_by_name(
                 this.write_scalar(Scalar::from_i32(result), dest)?;
             }
             "memrchr" => {
+                check_abi(abi, Abi::C)?;
                 let &[ptr, val, num] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 let val = this.read_scalar(val)?.to_i32()? as u8;
@@ -354,6 +374,7 @@ fn emulate_foreign_item_by_name(
                 }
             }
             "memchr" => {
+                check_abi(abi, Abi::C)?;
                 let &[ptr, val, num] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 let val = this.read_scalar(val)?.to_i32()? as u8;
@@ -371,6 +392,7 @@ fn emulate_foreign_item_by_name(
                 }
             }
             "strlen" => {
+                check_abi(abi, Abi::C)?;
                 let &[ptr] = check_arg_count(args)?;
                 let ptr = this.read_scalar(ptr)?.check_init()?;
                 let n = this.memory.read_c_str(ptr)?.len();
@@ -386,6 +408,7 @@ fn emulate_foreign_item_by_name(
             | "asinf"
             | "atanf"
             => {
+                check_abi(abi, Abi::C)?;
                 let &[f] = check_arg_count(args)?;
                 // FIXME: Using host floats.
                 let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
@@ -405,6 +428,7 @@ fn emulate_foreign_item_by_name(
             | "hypotf"
             | "atan2f"
             => {
+                check_abi(abi, Abi::C)?;
                 let &[f1, f2] = check_arg_count(args)?;
                 // underscore case for windows, here and below
                 // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
@@ -426,6 +450,7 @@ fn emulate_foreign_item_by_name(
             | "asin"
             | "atan"
             => {
+                check_abi(abi, Abi::C)?;
                 let &[f] = check_arg_count(args)?;
                 // FIXME: Using host floats.
                 let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
@@ -445,6 +470,7 @@ fn emulate_foreign_item_by_name(
             | "hypot"
             | "atan2"
             => {
+                check_abi(abi, Abi::C)?;
                 let &[f1, f2] = check_arg_count(args)?;
                 // FIXME: Using host floats.
                 let f1 = f64::from_bits(this.read_scalar(f1)?.to_u64()?);
@@ -460,6 +486,7 @@ fn emulate_foreign_item_by_name(
             | "ldexp"
             | "scalbn"
             => {
+                check_abi(abi, Abi::C)?;
                 let &[x, exp] = check_arg_count(args)?;
                 // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
                 let x = this.read_scalar(x)?.to_f64()?;
@@ -481,10 +508,12 @@ fn emulate_foreign_item_by_name(
 
             // Architecture-specific shims
             "llvm.x86.sse2.pause" if this.tcx.sess.target.arch == "x86" || this.tcx.sess.target.arch == "x86_64" => {
+                check_abi(abi, Abi::C)?;
                 let &[] = check_arg_count(args)?;
                 this.yield_active_thread();
             }
             "llvm.aarch64.hint" if this.tcx.sess.target.arch == "aarch64" => {
+                check_abi(abi, Abi::C)?;
                 let &[hint] = check_arg_count(args)?;
                 let hint = this.read_scalar(hint)?.to_i32()?;
                 match hint {
@@ -499,8 +528,8 @@ fn emulate_foreign_item_by_name(
 
             // Platform-specific shims
             _ => match this.tcx.sess.target.os.as_str() {
-                "linux" | "macos" => return shims::posix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
-                "windows" => return shims::windows::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
+                "linux" | "macos" => return shims::posix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
+                "windows" => return shims::windows::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
                 target => throw_unsup_format!("the target `{}` is not supported", target),
             }
         };
diff --git a/src/shims/mod.rs b/src/shims/mod.rs
index 90dcc4d8ff1..c2b8809efbb 100644
--- a/src/shims/mod.rs
+++ b/src/shims/mod.rs
@@ -16,6 +16,7 @@
 use log::trace;
 
 use rustc_middle::{mir, ty};
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
 use helpers::check_arg_count;
@@ -25,6 +26,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn find_mir_or_eval_fn(
         &mut self,
         instance: ty::Instance<'tcx>,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
@@ -48,7 +50,7 @@ fn find_mir_or_eval_fn(
             // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
             // foreign function
             // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
-            return this.emulate_foreign_item(instance.def_id(), args, ret, unwind);
+            return this.emulate_foreign_item(instance.def_id(), abi, args, ret, unwind);
         }
 
         // Otherwise, load the MIR.
diff --git a/src/shims/posix/dlsym.rs b/src/shims/posix/dlsym.rs
index 52d9844bed5..e05419f47e9 100644
--- a/src/shims/posix/dlsym.rs
+++ b/src/shims/posix/dlsym.rs
@@ -1,6 +1,8 @@
 use rustc_middle::mir;
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
+use helpers::check_abi;
 use shims::posix::linux::dlsym as linux;
 use shims::posix::macos::dlsym as macos;
 
@@ -27,10 +29,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn call_dlsym(
         &mut self,
         dlsym: Dlsym,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
+        check_abi(abi, Abi::C)?;
         match dlsym {
             Dlsym::Linux(dlsym) => linux::EvalContextExt::call_dlsym(this, dlsym, args, ret),
             Dlsym::MacOs(dlsym) => macos::EvalContextExt::call_dlsym(this, dlsym, args, ret),
diff --git a/src/shims/posix/foreign_items.rs b/src/shims/posix/foreign_items.rs
index f92242f56d9..e576c6f32e9 100644
--- a/src/shims/posix/foreign_items.rs
+++ b/src/shims/posix/foreign_items.rs
@@ -2,9 +2,10 @@
 
 use rustc_middle::mir;
 use rustc_target::abi::{Align, LayoutOf, Size};
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
-use helpers::check_arg_count;
+use helpers::{check_abi, check_arg_count};
 use shims::posix::fs::EvalContextExt as _;
 use shims::posix::sync::EvalContextExt as _;
 use shims::posix::thread::EvalContextExt as _;
@@ -14,12 +15,15 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn emulate_foreign_item_by_name(
         &mut self,
         link_name: &str,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         dest: PlaceTy<'tcx, Tag>,
         ret: mir::BasicBlock,
     ) -> InterpResult<'tcx, bool> {
         let this = self.eval_context_mut();
 
+        check_abi(abi, Abi::C)?;
+
         match link_name {
             // Environment related shims
             "getenv" => {
diff --git a/src/shims/windows/dlsym.rs b/src/shims/windows/dlsym.rs
index c88a1646115..ce119d1090b 100644
--- a/src/shims/windows/dlsym.rs
+++ b/src/shims/windows/dlsym.rs
@@ -1,9 +1,10 @@
 use rustc_middle::mir;
+use rustc_target::spec::abi::Abi;
 
 use log::trace;
 
 use crate::*;
-use helpers::check_arg_count;
+use helpers::{check_abi, check_arg_count};
 use shims::windows::sync::EvalContextExt as _;
 
 #[derive(Debug, Copy, Clone)]
@@ -38,6 +39,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn call_dlsym(
         &mut self,
         dlsym: Dlsym,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
     ) -> InterpResult<'tcx> {
@@ -45,6 +47,8 @@ fn call_dlsym(
         let (dest, ret) = ret.expect("we don't support any diverging dlsym");
         assert!(this.tcx.sess.target.os == "windows");
 
+        check_abi(abi, Abi::System)?;
+
         match dlsym {
             Dlsym::AcquireSRWLockExclusive => {
                 let &[ptr] = check_arg_count(args)?;
diff --git a/src/shims/windows/foreign_items.rs b/src/shims/windows/foreign_items.rs
index 17d566d18ee..52b68b9f1bc 100644
--- a/src/shims/windows/foreign_items.rs
+++ b/src/shims/windows/foreign_items.rs
@@ -2,9 +2,10 @@
 
 use rustc_middle::mir;
 use rustc_target::abi::Size;
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
-use helpers::check_arg_count;
+use helpers::{check_abi, check_arg_count};
 use shims::windows::sync::EvalContextExt as _;
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
@@ -12,12 +13,15 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn emulate_foreign_item_by_name(
         &mut self,
         link_name: &str,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         dest: PlaceTy<'tcx, Tag>,
         _ret: mir::BasicBlock,
     ) -> InterpResult<'tcx, bool> {
         let this = self.eval_context_mut();
 
+        check_abi(abi, Abi::System)?;
+
         // Windows API stubs.
         // HANDLE = isize
         // DWORD = ULONG = u32