minor corrections

Author: pvdrz

src/eval.rs

@@ -78,7 +78,7 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
     );
     // Complete initialization.
     MemoryExtra::init_extern_statics(&mut ecx)?;
-    EnvVars::init(&mut ecx, config.excluded_env_vars);
+    EnvVars::init(&mut ecx, config.excluded_env_vars)?;
 
     // Setup first stack-frame
     let main_instance = ty::Instance::mono(tcx, main_id);

src/machine.rs

@@ -85,7 +85,7 @@ pub struct MemoryExtra<'tcx> {
     /// (helps for debugging memory leaks).
     tracked_alloc_id: Option<AllocId>,
 
-    /// Place where the `environ` static is stored. Its value should not change after initialization.
+    /// Place where the `environ` static is stored. Lazily initialized, but then never changes.
     pub(crate) environ: Option<MPlaceTy<'tcx, Tag>>,
 }
 

src/shims/env.rs

@@ -20,7 +20,7 @@ impl EnvVars {
     pub(crate) fn init<'mir, 'tcx>(
         ecx: &mut InterpCx<'mir, 'tcx, Evaluator<'tcx>>,
         excluded_env_vars: Vec<String>,
-    ) {
+    ) -> InterpResult<'tcx> {
         if ecx.machine.communicate {
             for (name, value) in env::vars() {
                 if !excluded_env_vars.contains(&name) {
@@ -30,7 +30,7 @@ impl EnvVars {
                 }
             }
         }
-        ecx.update_environ().unwrap();
+        ecx.update_environ()
     }
 }
 

tests/compile-fail/environ-gets-deallocated.rs

@@ -1,9 +1,23 @@
-extern "C" {
+//ignore-windows: TODO env var emulation stubbed out on Windows
+
+#[cfg(target_os="linux")]
+fn get_environ() -> *const *const u8 {
+  extern "C" {
     static environ: *const *const u8;
+  }
+  environ
+}
+
+#[cfg(target_os="macos")]
+fn get_environ() -> *const *const u8 {
+    extern "C" {
+        fn _NSGetEnviron() -> *mut *const *const u8;
+    }
+    unsafe { *_NSGetEnviron() }
 }
 
 fn main() {
-    let pointer = unsafe { environ };
+    let pointer = get_environ();
     let _x = unsafe { *pointer };
     std::env::set_var("FOO", "BAR");
     let _y = unsafe { *pointer }; //~ ERROR dangling pointer was dereferenced