Add safe errno (#256)

Safe errno is a global Value in libcc2rs. Refcount rules will write the
correct errno number into this global Value

Author: lucic71

libcc2rs/src/compat.rs

@@ -1,7 +1,12 @@
 // Copyright (c) 2022-present INESC-ID.
 // Distributed under the MIT license that can be found in the LICENSE file.
 
+use std::cell::RefCell;
 use std::ffi::c_void;
+use std::rc::Rc;
+
+use crate::rc::Ptr;
+use crate::{AsPointer, Value};
 
 unsafe extern "C" {
     #[cfg(target_os = "linux")]
@@ -40,6 +45,14 @@ pub unsafe fn malloc_usable_size(ptr: *mut c_void) -> usize {
 /// # Safety
 ///
 /// Invokes the platform specific errno.
-pub unsafe fn cpp2rust_errno() -> *mut i32 {
+pub unsafe fn cpp2rust_errno_unsafe() -> *mut i32 {
     unsafe { platform_errno_location() }
 }
+
+thread_local! {
+    static ERRNO: Value<i32> = Rc::new(RefCell::new(0));
+}
+
+pub fn cpp2rust_errno() -> Ptr<i32> {
+    ERRNO.with(AsPointer::as_pointer)
+}

rules/errno/tgt_refcount.rs

@@ -0,0 +1,8 @@
+// Copyright (c) 2022-present INESC-ID.
+// Distributed under the MIT license that can be found in the LICENSE file.
+
+use libcc2rs::*;
+
+fn f1() -> Ptr<i32> {
+    libcc2rs::cpp2rust_errno()
+}

rules/errno/tgt_unsafe.rs

@@ -2,5 +2,5 @@
 // Distributed under the MIT license that can be found in the LICENSE file.
 
 unsafe fn f1() -> *mut i32 {
-    libcc2rs::cpp2rust_errno()
+    libcc2rs::cpp2rust_errno_unsafe()
 }

rules/src/modules.rs

@@ -40,6 +40,8 @@ pub mod deque_tgt_refcount;
 pub mod deque_tgt_unsafe;
 #[path = r#"../dirent/tgt_unsafe.rs"#]
 pub mod dirent_tgt_unsafe;
+#[path = r#"../errno/tgt_refcount.rs"#]
+pub mod errno_tgt_refcount;
 #[path = r#"../errno/tgt_unsafe.rs"#]
 pub mod errno_tgt_unsafe;
 #[path = r#"../eventfd/tgt_unsafe.rs"#]

tests/unit/errno.c

@@ -1,4 +1,4 @@
-// no-compile: refcount
+// panic: refcount
 #include <assert.h>
 #include <errno.h>
 #include <stdio.h>

tests/unit/out/refcount/errno.rs

@@ -0,0 +1,60 @@
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::cell::RefCell;
+use std::collections::BTreeMap;
+use std::io::prelude::*;
+use std::io::{Read, Seek, Write};
+use std::os::fd::AsFd;
+use std::rc::{Rc, Weak};
+pub fn test_errno_0() {
+    libcc2rs::cpp2rust_errno().write(0);
+    assert!(((((libcc2rs::cpp2rust_errno().read()) == 0) as i32) != 0));
+    libcc2rs::cpp2rust_errno().write(42);
+    assert!(((((libcc2rs::cpp2rust_errno().read()) == 42) as i32) != 0));
+    let saved: Value<i32> = Rc::new(RefCell::new((libcc2rs::cpp2rust_errno().read())));
+    assert!(((((*saved.borrow()) == 42) as i32) != 0));
+    libcc2rs::cpp2rust_errno().write(0);
+}
+pub fn test_errno_preserved_across_strdup_1() {
+    libcc2rs::cpp2rust_errno().write(99);
+    let d: Value<Ptr<u8>> = Rc::new(RefCell::new(libcc2rs::strdup_refcount(
+        Ptr::from_string_literal(b"hello"),
+    )));
+    assert!((((!((*d.borrow()).is_null())) as i32) != 0));
+    assert!(((((libcc2rs::cpp2rust_errno().read()) == 99) as i32) != 0));
+    libcc2rs::free_refcount(((*d.borrow()).clone() as Ptr<u8>).to_any());
+    libcc2rs::cpp2rust_errno().write(0);
+}
+pub fn test_errno_from_fseek_2() {
+    libcc2rs::cpp2rust_errno().write(0);
+    let r: Value<i32> = Rc::new(RefCell::new(
+        if (match 0 {
+            0 => libcc2rs::cin().with_mut(|__v: &mut ::std::fs::File| {
+                __v.seek(std::io::SeekFrom::Start(0_i64 as u64))
+            }),
+            1 => libcc2rs::cin()
+                .with_mut(|__v: &mut ::std::fs::File| __v.seek(std::io::SeekFrom::Current(0_i64))),
+            2 => libcc2rs::cin()
+                .with_mut(|__v: &mut ::std::fs::File| __v.seek(std::io::SeekFrom::End(0_i64))),
+            _ => Err(std::io::Error::other("unsupported whence for fseek.")),
+        })
+        .is_ok()
+        {
+            0
+        } else {
+            -1
+        },
+    ));
+    assert!(((((*r.borrow()) == -1_i32) as i32) != 0));
+    assert!(((((libcc2rs::cpp2rust_errno().read()) == 29) as i32) != 0));
+    libcc2rs::cpp2rust_errno().write(0);
+}
+pub fn main() {
+    std::process::exit(main_0());
+}
+fn main_0() -> i32 {
+    ({ test_errno_0() });
+    ({ test_errno_preserved_across_strdup_1() });
+    ({ test_errno_from_fseek_2() });
+    return 0;
+}

tests/unit/out/unsafe/errno.rs

@@ -7,29 +7,29 @@ use std::io::{Read, Seek, Write};
 use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
 use std::rc::Rc;
 pub unsafe fn test_errno_0() {
-    (*libcc2rs::cpp2rust_errno()) = 0;
-    assert!(((((*libcc2rs::cpp2rust_errno()) == (0)) as i32) != 0));
-    (*libcc2rs::cpp2rust_errno()) = 42;
-    assert!(((((*libcc2rs::cpp2rust_errno()) == (42)) as i32) != 0));
-    let mut saved: i32 = (*libcc2rs::cpp2rust_errno());
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 0;
+    assert!(((((*libcc2rs::cpp2rust_errno_unsafe()) == (0)) as i32) != 0));
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 42;
+    assert!(((((*libcc2rs::cpp2rust_errno_unsafe()) == (42)) as i32) != 0));
+    let mut saved: i32 = (*libcc2rs::cpp2rust_errno_unsafe());
     assert!(((((saved) == (42)) as i32) != 0));
-    (*libcc2rs::cpp2rust_errno()) = 0;
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 0;
 }
 pub unsafe fn test_errno_preserved_across_strdup_1() {
-    (*libcc2rs::cpp2rust_errno()) = 99;
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 99;
     let mut d: *mut libc::c_char =
         libcc2rs::strdup_unsafe((c"hello".as_ptr().cast_mut()).cast_const());
     assert!((((!((d).is_null())) as i32) != 0));
-    assert!(((((*libcc2rs::cpp2rust_errno()) == (99)) as i32) != 0));
+    assert!(((((*libcc2rs::cpp2rust_errno_unsafe()) == (99)) as i32) != 0));
     libcc2rs::free_unsafe((d as *mut libc::c_char as *mut ::libc::c_void));
-    (*libcc2rs::cpp2rust_errno()) = 0;
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 0;
 }
 pub unsafe fn test_errno_from_fseek_2() {
-    (*libcc2rs::cpp2rust_errno()) = 0;
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 0;
     let mut r: i32 = libc::fseek(libcc2rs::stdin_unsafe(), 0_i64 as ::libc::c_long, 0);
     assert!(((((r) == (-1_i32)) as i32) != 0));
-    assert!(((((*libcc2rs::cpp2rust_errno()) == (29)) as i32) != 0));
-    (*libcc2rs::cpp2rust_errno()) = 0;
+    assert!(((((*libcc2rs::cpp2rust_errno_unsafe()) == (29)) as i32) != 0));
+    (*libcc2rs::cpp2rust_errno_unsafe()) = 0;
 }
 pub fn main() {
     unsafe {