Auto merge of #976 - christianpoveda:unlink-shim, r=oli-obk

Add unlink shim to delete files

r? @oli-obk
This closes the whole create, write, read, delete circle for file handling.

src/shims/foreign_items.rs

@@ -418,7 +418,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 }
             }
 
-            "__errno_location" => {
+            "__errno_location" | "__error" => {
                 let errno_scalar: Scalar<Tag> = this.machine.last_error.unwrap().into();
                 this.write_scalar(errno_scalar, dest)?;
             }
@@ -502,6 +502,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
             }
 
+            "unlink" => {
+                let result = this.unlink(args[0])?;
+                this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
+            }
+
             "strlen" => {
                 let ptr = this.read_scalar(args[0])?.not_undef()?;
                 let n = this.memory().read_c_str(ptr)?.len();

src/shims/io.rs

@@ -1,5 +1,5 @@
 use std::collections::HashMap;
-use std::fs::{File, OpenOptions};
+use std::fs::{File, OpenOptions, remove_file};
 use std::io::{Read, Write};
 
 use rustc::ty::layout::Size;
@@ -205,6 +205,24 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         })
     }
 
+    fn unlink( &mut self, path_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
+        let this = self.eval_context_mut();
+
+        if !this.machine.communicate {
+            throw_unsup_format!("`write` not available when isolation is enabled")
+        }
+
+        let path_bytes = this
+            .memory()
+            .read_c_str(this.read_scalar(path_op)?.not_undef()?)?;
+        let path = std::str::from_utf8(path_bytes)
+            .map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", path_bytes))?;
+
+        let result = remove_file(path).map(|_| 0);
+
+        this.consume_result(result)
+    }
+
     /// Helper function that gets a `FileHandle` immutable reference and allows to manipulate it
     /// using the `f` closure.
     ///

tests/run-pass/file_manipulation.rs

@@ -1,11 +1,10 @@
 // ignore-windows: File handling is not implemented yet
 // compile-flags: -Zmiri-disable-isolation
 
-use std::fs::File;
+use std::fs::{File, remove_file};
 use std::io::{Read, Write};
 
 fn main() {
-    // FIXME: remove the file and delete it when `rm` is implemented.
     let path = "./tests/hello.txt";
     let bytes = b"Hello, World!\n";
     // Test creating, writing and closing a file (closing is tested when `file` is dropped).
@@ -22,4 +21,10 @@ fn main() {
     // Reading until EOF should get the whole text.
     file.read_to_end(&mut contents).unwrap();
     assert_eq!(bytes, contents.as_slice());
+    // Removing file should succeed
+    remove_file(path).unwrap();
+    // Opening non-existing file should fail
+    assert!(File::open(path).is_err());
+    // Removing non-existing file should fail
+    assert!(remove_file(path).is_err());
 }