Add helper function to write structs

Author: pvdrz

src/helpers.rs

@@ -4,7 +4,7 @@ use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX};
 use rustc::mir;
 use rustc::ty::{
     self,
-    layout::{self, Align, Size},
+    layout::{self, Align, Size, LayoutOf},
 };
 
 use rand::RngCore;
@@ -295,4 +295,37 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
         }
     }
+
+    fn write_c_ints(
+        &mut self,
+        ptr: &Pointer<Tag>,
+        bits: &[i128],
+        ty_names: &[&str],
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+
+        let tcx = &{ this.tcx.tcx };
+
+        let mut sizes = Vec::new();
+
+        for name in ty_names {
+            let ty = this.resolve_path(&["libc", name])?.ty(*tcx);
+            sizes.push(this.layout_of(ty)?.size);
+        }
+
+        let allocation = this.memory_mut().get_mut(ptr.alloc_id)?;
+        let mut offset = Size::from_bytes(0);
+
+        for (value, size) in bits.iter().zip(sizes) {
+            allocation.write_scalar(
+                tcx,
+                ptr.offset(offset, tcx)?,
+                Scalar::from_int(*value, size).into(),
+                size,
+            )?;
+            offset += size;
+        }
+
+        Ok(())
+    }
 }

src/shims/foreign_items.rs

@@ -511,8 +511,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 if !this.machine.communicate {
                     throw_unsup_format!("`clock_gettime` not available when isolation is enabled")
                 } else {
-                    let tcx = &{ this.tcx.tcx };
-
                     let clk_id = this.read_scalar(args[0])?.to_i32()?;
 
                     if clk_id != this.eval_libc_i32("CLOCK_REALTIME")? {
@@ -522,14 +520,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     } else {
                         let tp = this.force_ptr(this.read_scalar(args[1])?.not_undef()?)?;
 
-                        let long = this.resolve_path(&["libc", "c_long"])?.ty(*tcx);
-                        let time_t = this.resolve_path(&["libc", "time_t"])?.ty(*tcx);
-
-                        let tv_sec_size = this.layout_of(time_t)?.size;
-                        let tv_nsec_size = this.layout_of(long)?.size;
-
-                        let allocation = this.memory_mut().get_mut(tp.alloc_id)?;
-
                         let mut sign = 1;
 
                         let duration = std::time::SystemTime::now()
@@ -539,20 +529,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                                 e.duration()
                             });
 
-                        allocation.write_scalar(
-                            tcx,
-                            tp,
-                            Scalar::from_int(sign * (duration.as_secs() as i64), tv_sec_size)
-                                .into(),
-                            tv_sec_size,
-                        )?;
-
-                        allocation.write_scalar(
-                            tcx,
-                            tp.offset(tv_sec_size, tcx)?,
-                            Scalar::from_int(duration.subsec_nanos() as i64, tv_nsec_size).into(),
-                            tv_nsec_size,
-                        )?;
+                        let tv_sec = sign * (duration.as_secs() as i128);
+                        let tv_nsec = duration.subsec_nanos() as i128;
+
+                        this.write_c_ints(&tp, &[tv_sec, tv_nsec], &["time_t", "c_long"])?;
 
                         this.write_scalar(Scalar::from_int(0i32, dest.layout.size), dest)?;
                     }
@@ -563,8 +543,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 if !this.machine.communicate {
                     throw_unsup_format!("`gettimeofday` not available when isolation is enabled")
                 } else {
-                    let tcx = &{ this.tcx.tcx };
-
                     let tz = this.read_scalar(args[1])?.not_undef()?;
                     // Using tz is obsolete and should always be null
                     if !this.is_null(tz)? {
@@ -574,14 +552,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     } else {
                         let tv = this.force_ptr(this.read_scalar(args[0])?.not_undef()?)?;
 
-                        let time_t = this.resolve_path(&["libc", "time_t"])?.ty(*tcx);
-                        let suseconds_t = this.resolve_path(&["libc", "suseconds_t"])?.ty(*tcx);
-
-                        let tv_sec_size = this.layout_of(time_t)?.size;
-                        let tv_usec_size = this.layout_of(suseconds_t)?.size;
-
-                        let allocation = this.memory_mut().get_mut(tv.alloc_id)?;
-
                         let mut sign = 1;
 
                         let duration = std::time::SystemTime::now()
@@ -591,20 +561,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                                 e.duration()
                             });
 
-                        allocation.write_scalar(
-                            tcx,
-                            tv,
-                            Scalar::from_int(sign * (duration.as_secs() as i64), tv_sec_size)
-                                .into(),
-                            tv_sec_size,
-                        )?;
-
-                        allocation.write_scalar(
-                            tcx,
-                            tv.offset(tv_sec_size, tcx)?,
-                            Scalar::from_int(duration.subsec_micros() as i64, tv_usec_size).into(),
-                            tv_usec_size,
-                        )?;
+                        let tv_sec = sign * (duration.as_secs() as i128);
+                        let tv_usec = duration.subsec_micros() as i128;
+
+                        this.write_c_ints(&tv, &[tv_sec, tv_usec], &["time_t", "suseconds_t"])?;
 
                         this.write_scalar(Scalar::from_int(0i32, dest.layout.size), dest)?;
                     }