add support for the tempfile crate

Author: Pointerbender

src/shims/unix/fs.rs

@@ -585,8 +585,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 );
             };
 
-            if mode != 0o666 {
-                throw_unsup_format!("non-default mode 0o{:o} is not supported", mode);
+            // 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);
             }
 
             mirror |= o_creat;

test_dependencies/Cargo.lock

@@ -13,6 +13,7 @@ tokio = { version = "1.0", features = ["full"] }
 libc = "0.2"
 page_size = "0.5"
 num_cpus = "1.10.1"
+tempfile = "3"
 
 getrandom_1 = { package = "getrandom", version = "0.1" }
 getrandom = { version = "0.2" }

test_dependencies/Cargo.toml

@@ -20,6 +20,7 @@ fn main() {
     test_file_open_unix_extra_third_arg();
     #[cfg(target_os = "linux")]
     test_o_tmpfile_flag();
+    test_tempfile();
 }
 
 fn tmp() -> PathBuf {
@@ -165,3 +166,9 @@ fn test_o_tmpfile_flag() {
             .raw_os_error(),
     );
 }
+
+/// Test that the [`tempfile`] crate is compatible with miri.
+fn test_tempfile() {
+    let dir_path = tmp();
+    tempfile::tempfile_in(dir_path).unwrap();
+}