Delete redundant communicate flag from miri config and machine

Added a new function `communicate()` on machine and replaced the uses
of flag with the new function.

Author: atsmtat

src/bin/miri.rs

@@ -291,7 +291,6 @@ fn main() {
                     miri_config.check_abi = false;
                 }
                 "-Zmiri-disable-isolation" => {
-                    miri_config.communicate = true;
                     miri_config.isolated_op = miri::IsolatedOp::Allow;
                 }
                 "-Zmiri-ignore-leaks" => {

src/eval.rs

@@ -22,7 +22,7 @@ pub enum AlignmentCheck {
     Int,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum RejectOpWith {
     /// Do not print warning about rejected isolated op
     NoWarning,
@@ -34,7 +34,7 @@ pub enum RejectOpWith {
     WarningWithoutBacktrace,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum IsolatedOp {
     /// Reject op requiring communication with the host. Usually, miri
     /// returns an error code for such op, and prints a warning
@@ -93,7 +93,6 @@ impl Default for MiriConfig {
             stacked_borrows: true,
             check_alignment: AlignmentCheck::Int,
             check_abi: true,
-            communicate: false,
             isolated_op: IsolatedOp::Reject(RejectOpWith::WarningWithoutBacktrace),
             ignore_leaks: false,
             excluded_env_vars: vec![],
@@ -259,7 +258,7 @@ pub fn eval_main<'tcx>(tcx: TyCtxt<'tcx>, main_id: DefId, config: MiriConfig) ->
                 }
                 SchedulingAction::ExecuteTimeoutCallback => {
                     assert!(
-                        ecx.machine.communicate,
+                        ecx.machine.communicate(),
                         "scheduler callbacks require disabled isolation, but the code \
                         that created the callback did not check it"
                     );

src/helpers.rs

@@ -140,7 +140,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
         let mut data = vec![0; usize::try_from(len).unwrap()];
 
-        if this.machine.communicate {
+        if this.machine.communicate() {
             // Fill the buffer using the host's rng.
             getrandom::getrandom(&mut data)
                 .map_err(|err| err_unsup_format!("host getrandom failed: {}", err))?;
@@ -391,7 +391,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     /// disabled. It returns an error using the `name` of the foreign function if this is not the
     /// case.
     fn check_no_isolation(&self, name: &str) -> InterpResult<'tcx> {
-        if !self.eval_context_ref().machine.communicate {
+        if !self.eval_context_ref().machine.communicate() {
             isolation_error(name)?;
         }
         Ok(())

src/machine.rs

@@ -263,10 +263,6 @@ pub struct Evaluator<'mir, 'tcx> {
     /// TLS state.
     pub(crate) tls: TlsData<'tcx>,
 
-    /// If enabled, the `env_vars` field is populated with the host env vars during initialization
-    /// and random number generation is delegated to the host.
-    pub(crate) communicate: bool,
-
     /// What should Miri do when an op requires communicating with the host,
     /// such as accessing host env vars, random number generation, and
     /// file system access.
@@ -319,7 +315,6 @@ impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
             argv: None,
             cmd_line: None,
             tls: TlsData::default(),
-            communicate: config.communicate,
             isolated_op: config.isolated_op,
             validate: config.validate,
             enforce_abi: config.check_abi,
@@ -334,6 +329,10 @@ impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
             exported_symbols_cache: FxHashMap::default(),
         }
     }
+
+    pub(crate) fn communicate(&self) -> bool {
+        self.isolated_op == IsolatedOp::Allow
+    }
 }
 
 /// A rustc InterpCx for Miri.

src/shims/env.rs

@@ -46,7 +46,7 @@ impl<'tcx> EnvVars<'tcx> {
             excluded_env_vars.push("TERM".to_owned());
         }
 
-        if ecx.machine.communicate {
+        if ecx.machine.communicate() {
             for (name, value) in env::vars() {
                 if !excluded_env_vars.contains(&name) {
                     let var_ptr = match target_os {

src/shims/posix/fs.rs

@@ -662,7 +662,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let fd = this.read_scalar(fd_op)?.to_i32()?;
 
         if let Some(file_descriptor) = this.machine.file_handler.handles.remove(&fd) {
-            let result = file_descriptor.close(this.machine.communicate)?;
+            let result = file_descriptor.close(this.machine.communicate())?;
             this.try_unwrap_io_result(result)
         } else {
             this.handle_not_found()
@@ -687,6 +687,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         // We cap the number of read bytes to the largest value that we are able to fit in both the
         // host's and target's `isize`. This saves us from having to handle overflows later.
         let count = count.min(this.machine_isize_max() as u64).min(isize::MAX as u64);
+        let communicate = this.machine.communicate();
 
         if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
             trace!("read: FD mapped to {:?}", file_descriptor);
@@ -696,9 +697,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             let mut bytes = vec![0; count as usize];
             // `File::read` never returns a value larger than `count`,
             // so this cannot fail.
-            let result = file_descriptor
-                .read(this.machine.communicate, &mut bytes)?
-                .map(|c| i64::try_from(c).unwrap());
+            let result =
+                file_descriptor.read(communicate, &mut bytes)?.map(|c| i64::try_from(c).unwrap());
 
             match result {
                 Ok(read_bytes) => {
@@ -733,12 +733,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         // We cap the number of written bytes to the largest value that we are able to fit in both the
         // host's and target's `isize`. This saves us from having to handle overflows later.
         let count = count.min(this.machine_isize_max() as u64).min(isize::MAX as u64);
+        let communicate = this.machine.communicate();
 
         if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
             let bytes = this.memory.read_bytes(buf, Size::from_bytes(count))?;
-            let result = file_descriptor
-                .write(this.machine.communicate, &bytes)?
-                .map(|c| i64::try_from(c).unwrap());
+            let result =
+                file_descriptor.write(communicate, &bytes)?.map(|c| i64::try_from(c).unwrap());
             this.try_unwrap_io_result(result)
         } else {
             this.handle_not_found()
@@ -771,9 +771,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             return Ok(-1);
         };
 
+        let communicate = this.machine.communicate();
         if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
             let result = file_descriptor
-                .seek(this.machine.communicate, seek_from)?
+                .seek(communicate, seek_from)?
                 .map(|offset| i64::try_from(offset).unwrap());
             this.try_unwrap_io_result(result)
         } else {