Support fileno as name in FileIO

tests/snippets/stdlib_io.py

@@ -1,4 +1,5 @@
 from io import BufferedReader, FileIO
+import os
 
 fi = FileIO('README.md')
 bb = BufferedReader(fi)
@@ -14,3 +15,9 @@ with FileIO('README.md') as fio:
 	assert len(result) <= 8*1024
 	assert len(result) >= 0
 	assert isinstance(result, bytes)
+
+fd = os.open('README.md', os.O_RDONLY)
+
+with FileIO(fd) as fio:
+	res2 = fio.read()
+	assert res == res2

vm/src/stdlib/io.rs

@@ -2,9 +2,7 @@
  * I/O core tools.
  */
 use std::cell::RefCell;
-use std::fs::File;
 use std::io::prelude::*;
-use std::io::BufReader;
 use std::io::Cursor;
 use std::io::SeekFrom;
 
@@ -20,6 +18,7 @@ use crate::obj::objbytearray::PyByteArray;
 use crate::obj::objbytes;
 use crate::obj::objint;
 use crate::obj::objstr;
+use crate::obj::objtype;
 use crate::obj::objtype::PyClassRef;
 use crate::pyobject::{BufferProtocol, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
@@ -305,47 +304,43 @@ fn file_io_init(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
         vm,
         args,
-        required = [(file_io, None), (name, Some(vm.ctx.str_type()))],
+        required = [(file_io, None), (name, None)],
         optional = [(mode, Some(vm.ctx.str_type()))]
     );
 
-    let rust_mode = mode.map_or("r".to_string(), objstr::get_value);
+    let file_no = if objtype::isinstance(&name, &vm.ctx.str_type()) {
+        let rust_mode = mode.map_or("r".to_string(), objstr::get_value);
+        let args = vec![
+            name.clone(),
+            vm.ctx
+                .new_int(compute_c_flag(&rust_mode).to_bigint().unwrap()),
+        ];
+        os::os_open(vm, PyFuncArgs::new(args, vec![]))?
+    } else if objtype::isinstance(&name, &vm.ctx.int_type()) {
+        name.clone()
+    } else {
+        return Err(vm.new_type_error("name parameter must be string or int".to_string()));
+    };
 
-    match compute_c_flag(&rust_mode).to_bigint() {
-        Some(os_mode) => {
-            let args = vec![name.clone(), vm.ctx.new_int(os_mode)];
-            let file_no = os::os_open(vm, PyFuncArgs::new(args, vec![]))?;
-
-            vm.set_attr(file_io, "name", name.clone())?;
-            vm.set_attr(file_io, "fileno", file_no)?;
-            vm.set_attr(file_io, "closefd", vm.new_bool(false))?;
-            vm.set_attr(file_io, "closed", vm.new_bool(false))?;
-
-            Ok(vm.get_none())
-        }
-        None => Err(vm.new_type_error(format!("invalid mode {}", rust_mode))),
-    }
+    vm.set_attr(file_io, "name", name.clone())?;
+    vm.set_attr(file_io, "fileno", file_no)?;
+    vm.set_attr(file_io, "closefd", vm.new_bool(false))?;
+    vm.set_attr(file_io, "closed", vm.new_bool(false))?;
+    Ok(vm.get_none())
 }
 
 fn file_io_read(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(file_io, None)]);
-    let py_name = vm.get_attribute(file_io.clone(), "name")?;
-    let f = match File::open(objstr::get_value(&py_name)) {
-        Ok(v) => Ok(v),
-        Err(_) => Err(vm.new_type_error("Error opening file".to_string())),
-    };
 
-    let buffer = match f {
-        Ok(v) => Ok(BufReader::new(v)),
-        Err(_) => Err(vm.new_type_error("Error reading from file".to_string())),
-    };
+    let file_no = vm.get_attribute(file_io.clone(), "fileno")?;
+    let raw_fd = objint::get_value(&file_no).to_i64().unwrap();
+
+    let mut handle = os::rust_file(raw_fd);
 
     let mut bytes = vec![];
-    if let Ok(mut buff) = buffer {
-        match buff.read_to_end(&mut bytes) {
-            Ok(_) => {}
-            Err(_) => return Err(vm.new_value_error("Error reading from Buffer".to_string())),
-        }
+    match handle.read_to_end(&mut bytes) {
+        Ok(_) => {}
+        Err(_) => return Err(vm.new_value_error("Error reading from Buffer".to_string())),
     }
 
     Ok(vm.ctx.new_bytes(bytes))