Resolve not null/non-null inconsistency, a couple comment improvements

Author: CraftSpider

src/shims/windows/fs.rs

@@ -403,17 +403,16 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         n: &OpTy<'tcx>,               // ULONG
         byte_offset: &OpTy<'tcx>,     // PLARGE_INTEGER
         key: &OpTy<'tcx>,             // PULONG
-        dest: &MPlaceTy<'tcx>,        // NTSTATUS
+        dest: &MPlaceTy<'tcx>,        // return type: NTSTATUS
     ) -> InterpResult<'tcx, ()> {
-        // ^ Returns NTSTATUS (u32 on Windows)
         let this = self.eval_context_mut();
         let handle = this.read_handle(handle, "NtWriteFile")?;
         let event = this.read_handle(event, "NtWriteFile")?;
         let apc_routine = this.read_pointer(apc_routine)?;
         let apc_ctx = this.read_pointer(apc_ctx)?;
         let buf = this.read_pointer(buf)?;
         let count = this.read_scalar(n)?.to_u32()?;
-        let byte_offset = this.read_target_usize(byte_offset)?; // is actually a pointer
+        let byte_offset = this.read_target_usize(byte_offset)?; // is actually a pointer, but we only support null
         let key = this.read_pointer(key)?;
         let io_status_block =
             this.deref_pointer_as(io_status_block, this.windows_ty_layout("IO_STATUS_BLOCK"))?;
@@ -426,13 +425,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         if !this.ptr_is_null(apc_routine)? {
             throw_unsup_format!(
-                "`NtWriteFile` `ApcRoutine` parameter is not null, which is unsupported"
+                "`NtWriteFile` `ApcRoutine` parameter is non-null, which is unsupported"
             );
         }
 
         if !this.ptr_is_null(apc_ctx)? {
             throw_unsup_format!(
-                "`NtWriteFile` `ApcContext` parameter is not null, which is unsupported"
+                "`NtWriteFile` `ApcContext` parameter is non-null, which is unsupported"
             );
         }
 
@@ -443,7 +442,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         }
 
         if !this.ptr_is_null(key)? {
-            throw_unsup_format!("`NtWriteFile` `Key` parameter is not null, which is unsupported");
+            throw_unsup_format!("`NtWriteFile` `Key` parameter is non-null, which is unsupported");
         }
 
         let fd = match handle {
@@ -510,17 +509,16 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         n: &OpTy<'tcx>,               // ULONG
         byte_offset: &OpTy<'tcx>,     // PLARGE_INTEGER
         key: &OpTy<'tcx>,             // PULONG
-        dest: &MPlaceTy<'tcx>,        // NTSTATUS
+        dest: &MPlaceTy<'tcx>,        // return type: NTSTATUS
     ) -> InterpResult<'tcx, ()> {
-        // ^ Returns NTSTATUS (u32 on Windows)
         let this = self.eval_context_mut();
         let handle = this.read_handle(handle, "NtReadFile")?;
         let event = this.read_handle(event, "NtReadFile")?;
         let apc_routine = this.read_pointer(apc_routine)?;
         let apc_ctx = this.read_pointer(apc_ctx)?;
         let buf = this.read_pointer(buf)?;
         let count = this.read_scalar(n)?.to_u32()?;
-        let byte_offset = this.read_target_usize(byte_offset)?; // is actually a pointer
+        let byte_offset = this.read_target_usize(byte_offset)?; // is actually a pointer, but we only support null
         let key = this.read_pointer(key)?;
         let io_status_block =
             this.deref_pointer_as(io_status_block, this.windows_ty_layout("IO_STATUS_BLOCK"))?;
@@ -531,13 +529,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         if !this.ptr_is_null(apc_routine)? {
             throw_unsup_format!(
-                "`NtReadFile` `ApcRoutine` parameter is not null, which is unsupported"
+                "`NtReadFile` `ApcRoutine` parameter is non-null, which is unsupported"
             );
         }
 
         if !this.ptr_is_null(apc_ctx)? {
             throw_unsup_format!(
-                "`NtReadFile` `ApcContext` parameter is not null, which is unsupported"
+                "`NtReadFile` `ApcContext` parameter is non-null, which is unsupported"
             );
         }
 
@@ -548,7 +546,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         }
 
         if !this.ptr_is_null(key)? {
-            throw_unsup_format!("`NtReadFile` `Key` parameter is not null, which is unsupported");
+            throw_unsup_format!("`NtReadFile` `Key` parameter is non-null, which is unsupported");
         }
 
         // See NtWriteFile above for commentary on this