Auto merge of #3240 - Jefffrey:tempfile, r=RalfJung

Support for tempfile crate on UNIX hosts

Reviving old PR: #2720

Attempted to apply the changes as suggested by #2720 (comment)

To fix tempfile to work for UNIX targets only and fall back to previous behaviour of only supporting default mode for Windows targets

src/shims/unix/fs.rs

@@ -559,8 +559,21 @@ 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);
+            #[cfg(unix)]
+            {
+                // Support all modes on UNIX host
+                use std::os::unix::fs::OpenOptionsExt;
+                options.mode(mode);
+            }
+            #[cfg(not(unix))]
+            {
+                // Only support default mode for non-UNIX (i.e. Windows) host
+                if mode != 0o666 {
+                    throw_unsup_format!(
+                        "non-default mode 0o{:o} is not supported on non-Unix hosts",
+                        mode
+                    );
+                }
             }
 
             mirror |= o_creat;

test_dependencies/Cargo.toml

@@ -11,6 +11,7 @@ edition = "2021"
 # all dependencies (and their transitive ones) listed here can be used in `tests/`.
 libc = "0.2"
 num_cpus = "1.10.1"
+tempfile = "3"
 
 getrandom_01 = { package = "getrandom", version = "0.1" }
 getrandom_02 = { package = "getrandom", version = "0.2", features = ["js"] }

tests/pass-dep/tempfile.rs

@@ -0,0 +1,21 @@
+//@ignore-target-windows: File handling is not implemented yet
+//@ignore-host-windows: Only supported for UNIX hosts
+//@compile-flags: -Zmiri-disable-isolation
+
+#[path = "../utils/mod.rs"]
+mod utils;
+
+/// Test that the [`tempfile`] crate is compatible with miri for UNIX hosts and targets
+fn main() {
+    test_tempfile();
+    test_tempfile_in();
+}
+
+fn test_tempfile() {
+    tempfile::tempfile().unwrap();
+}
+
+fn test_tempfile_in() {
+    let dir_path = utils::tmp();
+    tempfile::tempfile_in(dir_path).unwrap();
+}