Warn about dummy error produced in isolation mode

Author: atsmtat

src/helpers.rs

@@ -397,6 +397,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         Ok(())
     }
 
+    /// Helper function used inside the shims of foreign functions
+    /// which produce a dummy error when isolation is enabled. It is
+    /// used to print a warning informing this decision to the user.
+    fn warn_foreign_in_isolation(&self, name: &str) {
+        let this = self.eval_context_ref();
+        this.tcx.sess.warn(&format!("`{}` in isolation mode produced a dummy error", name));
+    }
+
     /// Helper function used inside the shims of foreign functions to assert that the target OS
     /// is `target_os`. It panics showing a message with the `name` of the foreign function
     /// if this is not the case.

src/shims/env.rs

@@ -337,8 +337,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 Err(e) => this.set_last_error_from_io_error(e)?,
             }
         } else {
-            // Emulate an error in isolation mode
-            let err = Error::new(ErrorKind::NotFound, "`getcwd` not available in isolation mode");
+            // Return a dummy error in isolation mode, after printing a warning about it.
+            this.warn_foreign_in_isolation("getcwd");
+            let err = Error::new(ErrorKind::NotFound, "dummy error in isolation mode");
             this.set_last_error_from_io_error(err)?;
         }
         Ok(Scalar::null_ptr(&*this.tcx))
@@ -364,8 +365,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 Err(e) => this.set_last_error_from_io_error(e)?,
             }
         } else {
-            // Emulate an error in isolation mode
-            let err = Error::new(ErrorKind::NotFound, "`GetCurrentDirectoryW` not available in isolation mode");
+            // Return a dummy error in isolation mode, after printing a warning about it.
+            this.warn_foreign_in_isolation("GetCurrentDirectoryW");
+            let err = Error::new(ErrorKind::NotFound, "dummy error in isolation mode");
             this.set_last_error_from_io_error(err)?;
         }
         Ok(0)
@@ -390,9 +392,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 }
             }
         } else {
-            // Emulate an error in isolation mode
-            let err = Error::new(ErrorKind::NotFound, "`chdir` not available in isolation mode");
+            // Return a dummy error in isolation mode, after printing a warning about it.
+            this.warn_foreign_in_isolation("chdir");
+            let err = Error::new(ErrorKind::NotFound, "dummy error in isolation mode");
             this.set_last_error_from_io_error(err)?;
+
             Ok(-1)
         }
     }
@@ -418,8 +422,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 }
             }
         } else {
-            // Emulate an error in isolation mode
-            let err = Error::new(ErrorKind::NotFound, "`SetCurrentDirectoryW` not available in isolation mode");
+            // Return a dummy error in isolation mode, after printing a warning about it.
+            this.warn_foreign_in_isolation("SetCurrentDirectoryW");
+            let err = Error::new(ErrorKind::NotFound, "dummy error in isolation mode");
             this.set_last_error_from_io_error(err)?;
             Ok(0)
         }