Fix tempfile to work for UNIX targets only

Author: Jefffrey

src/shims/unix/fs.rs

@@ -559,13 +559,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 );
             };
 
-            // currently we only support that the owner must always have
-            // read-write permissions and that none of the owner, group
-            // and other may have execute permissions.
-            let owner_has_read_write_permissions = mode & 0o600 == 0o600;
-            let has_any_execute_permissions = mode & 0o111 != 0;
-            if !owner_has_read_write_permissions || has_any_execute_permissions {
-                throw_unsup_format!("mode 0o{:o} is not supported", mode);
+            match this.tcx.sess.target.os.as_ref() {
+                // Support all modes on UNIX host
+                "linux" | "freebsd" | "android" | "macos" => {}
+                // Non-UNIX (aka Windows) only support default mode
+                _ =>
+                    if mode != 0o666 {
+                        throw_unsup_format!("non-default mode 0o{:o} is not supported", mode);
+                    },
             }
 
             mirror |= o_creat;

tests/pass-dep/tempfile.rs

@@ -6,7 +6,7 @@ use std::path::PathBuf;
 
 /// Test that the [`tempfile`] crate is compatible with miri.
 fn main() {
-    // test_tempfile(); // does not work when host!=target
+    test_tempfile();
     test_tempfile_in();
 }
 
@@ -28,10 +28,9 @@ fn tmp() -> PathBuf {
     }
 }
 
-// does not work when host!=target:
-// fn test_tempfile() {
-//     tempfile::tempfile().unwrap();
-// }
+fn test_tempfile() {
+    tempfile::tempfile().unwrap();
+}
 
 fn test_tempfile_in() {
     let dir_path = tmp();